Next Article in Journal
Artificial Intelligence and Wastewater Treatment: A Global Scientific Perspective through Text Mining
Previous Article in Journal
Direct Probability Integral Method for Seismic Performance Assessment of Earth Dam Subjected to Stochastic Mainshock–Aftershock Sequences
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Water
Volume 15
Issue 19
10.3390/w15193486
water-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Review

Response of Forest Plant Diversity to Drought: A Review

by
Tian-Ye Zhang
,
Dong-Rui Di
*,
Xing-Liang Liao
and
Wei-Yu Shi
College of Geographical Sciences, Southwest University, Chongqing 400715, China
*
Author to whom correspondence should be addressed.
Water 2023, 15(19), 3486; https://doi.org/10.3390/w15193486
Submission received: 6 September 2023 / Revised: 28 September 2023 / Accepted: 2 October 2023 / Published: 5 October 2023
(This article belongs to the Section Water and Climate Change)
Browse Figure
Review Reports Versions Notes

Abstract

:
Forests, being the primary repository of terrestrial biodiversity, possess a significant capacity to regulate the phenomenon of climate change. It is additionally crucial to consider how natural disasters affect the state and development of forest biodiversity. The alteration of climate patterns over recent decades has had a discernible impact on forest ecosystems, specifically the damage caused by drought to ecosystems, has become increasingly evident. Nevertheless, there is limited research to elucidate the relationship between forest biodiversity and drought, as well as to explore the mechanisms of biodiversity response to drought. This review synthesizes the existing literature on the effects of climate change on forests across various scales and examines the adaptive responses of forest communities to drought-induced stress. Forest biodiversity can be influenced by various factors, including the severity of drought, initial climatic conditions, and the composition of species in drylands. During periods of drought, the biodiversity of forests is influenced by a range of intricate physiological and ecological factors, encompassing the capacity of plants to withstand drought conditions and their subsequent ability to recuperate following such periods. Moreover, the choice of different drought indices and biodiversity estimation methods has implications for subsequent response studies.

1. Introduction

In the preceding century, the climate has exhibited a notable pattern of ongoing climate fluctuations, accompanied by a rise in the occurrence and severity of extreme climates. These include, but are not limited to, extreme drought, heavy rainfall, and intense heat, all of which possess the potential to significantly impact the biogeochemical feedback mechanisms within the climate system [1]. Forests play a crucial role as the primary treasure trove of biodiversity in terrestrial ecosystems [2]. The presence of a diverse range of plant species within forest ecosystem enhances its ability to withstand disturbances and promotes the production of biomass for carbon storage and utilization in forest-based products. Nevertheless, the occurrence of extensive forest mortality events is frequently attributed to drought, which is often compounded by various abiotic and biotic factors [3,4]. In recent years, scholarly research has indicated that the escalating rise in global temperatures has exacerbated the adverse consequences of drought on forest ecosystems and exerted an impact on terrestrial net primary productivity [5,6]. If the projected climate patterns persist, the rising temperatures and prolonged regional warming will have implications for the growth of trait variables and the plant composition structure of forest trees. This could result in atypical alterations in forest tree mortality within certain climatic zones, potentially leading to forest dieback, diminished biomass, and reduced biodiversity [7]. In the realm of ecological studies, the significance of biodiversity in the regulation of ecosystem functions, such as the mitigation of climate extremes’ impact on ecosystems, has been widely acknowledged for a considerable period of time [8]. Hence, the relationship between drought and the diversity of tree species is progressively manifesting and assuming greater significance in light of the escalating duration of droughts.
Previous studies have extensively documented the impacts of climate change on the survival of forest trees and the significance of forest species diversity for forest function [9,10]. This review provides a comprehensive overview of the existing research on the impact of drought on forest biodiversity. It aims to summarize the current state of knowledge and highlight potential gaps in previous studies regarding the mechanisms by which forest plants respond to drought conditions. In Section 2, we provide a comprehensive explanation of the drought concept as well as the techniques employed to assess and quantify forest biodiversity. Section 3 of the paper explains the mechanisms by which drought impacts forest diversity. In Section 4, the authors delve into the processes and interactions that influence the response of diversity to drought conditions. Finally, Section 5 provides a summary of the key findings and conclusions. This review aims to investigate the impact and mechanisms of forest biodiversity response to drought, enhancing our comprehension of the significance of forest plant diversity within the framework of climate change. In this overview, we cover all forest ecosystems, including forests in different climatic zones, managed forests, and natural forests.

2. Drought and Forest Biodiversity

In the existing studies, there are many concepts and indicators that deal with drought, but so far there is no universally accepted standard to define drought [11,12]. Various methods for estimating or measuring biodiversity have been employed in previous studies. Understanding drought indicators and diversity measures from multiple perspectives is a key step in studying the effects of drought on forest plant diversity.

2.1. Selection of the Drought Definition and Index

The survey shows that the wide divergence of definitions of drought is one of the major obstacles to drought research [13]. According to the World Meteorological Organization (WMO), the term “drought” is defined as a prolonged and recurring deficiency in precipitation (World Meteorological Organization, 1975). The definition provided here is of a general and elementary nature, and it is important to note that the conceptualization of drought may differ based on the specific variables employed to characterize it. For example, meteorological drought is commonly employed as an indicator of insufficient precipitation, denoting a condition of water scarcity resulting from an imbalance between evaporation and precipitation over a specific time period wherein water loss exceeds water gain. And agricultural drought pertains to a state of water insufficiency arising from an imbalance between soil moisture and the water requirements of crops, forests, pastures, and livestock, wherein the available soil moisture fails to meet the demands of these entities [14]. For different research objectives, it is necessary to choose the corresponding definition of drought.
The drought index serves as the primary factor in assessing the impact of drought and determining various drought parameters, such as intensity, duration, severity, and spatial extent. It is widely employed on temporal scales of one year or one month [15]. To date, a multitude of drought indices, exceeding 100 in number, have been put forth [16]. These indices are designed to capture various manifestations of drought, such as meteorological drought, agricultural drought, and hydrological drought. Drought events have been quantitatively defined using a range of drought indices, including the standardized precipitation index (SPI) [17], the standardized precipitation-evapotranspiration index (SPEI) [18], the Palmer Drought Severity Index (PDSI) [19], the and crop moisture index (CMI) [20]. These indices have gained significant popularity in the field. Among these drought indices, SPI is simple and can respond well to soil moisture and soil humidity changes and can accurately predict crop yield; however, it does not consider the effect of evapotranspiration, and the development of SPEI has compensated for this lack [21,22]. PDSI varies from site to site and it is more suitable for wide plains, such as in the United States [23].
To summarize, the presence of various interpretations of drought can introduce ambiguity when evaluating the ecological consequences of drought and can result in variations in the effectiveness of drought indices across different regions. Hence, special attention needs to be paid to the definition of drought and the use of drought indices when studying ecosystem responses to drought.

2.2. Methods to Estimate and Measure Forest Biodiversity

Forest biodiversity can be defined as the comprehensive range of life forms existing at various levels within a forested region, encompassing trees, plants, animals, and microorganisms [15]. We are mainly concerned here with the diversity of forest plants. Various studies have examined the impact of drought on forest plant diversity across different spatial and temporal scales [24,25]. These studies have employed diverse indicators of biodiversity and monitoring techniques, yielding notably disparate outcomes.

2.2.1. Field Monitoring of Forest Plant Diversity

Forest inventory data serve as a valuable instrument for assessing the characteristics, abundance, and state of forest resources across extensive geographical regions. Utilizing forest inventory data for the estimation of biodiversity indicators presents a pragmatic approach to redefining biodiversity based on quantifiable attributes. The utilization of forest inventory data for the purpose of estimating forest biodiversity enables the facilitation of spatial comparisons across local, national, and international regions, as well as temporal comparisons. Plots are the primary sampling unit for forest inventories, and sample units are selected objectively through strict probability in order to ensure the confidence of the estimates [26]. The estimation of forest biodiversity attributes involves the utilization of spatial sampling techniques to randomly select additional points within the study area. These selected points serve as the center for creating plots with appropriate radii or angle counts, which take into account the underlying area factor. The forest attributes of the trees encompassed within the plot or angle counts are then recorded for analysis [27]. Ultimately, the quantification of plant species in a specific geographical region, known as plant species richness, is derived through the analysis of forest inventory data, or consolidating the information pertaining to plant species into numerical values or indicator values through mathematical methodologies.
In addition to forest inventory data, there are many other monitoring activities used to assess forest plant diversity. The establishment of biodiversity monitoring networks is one of the most effective ways of obtaining field monitoring data on forests. It measures population and community indicators in natural systems in a methodologically screened set of sample plots to monitor changes in trends [28]. Effective biodiversity monitoring is not only about collecting data, but also about analyzing and mining the data and presenting the results in an appropriate form to decision makers and the public. For example, the Forest Global Earth Observatory (FGEO) is currently the largest forest biodiversity monitoring network in the world. Forest GEO adopts a unified monitoring standard, i.e., each woody plant individual >1 cm diameter at breast height (DBH) is tagged, spatially localized, identified to species, measured at DBH, and rechecked every 5 years. In addition, a program has been developed to monitor all phases of plant life history, such as seedling, seed production, phenology, dead wood, and decaying wood [29].

2.2.2. Remote Sensing Monitoring of Forest Plant Diversity

Historically, the monitoring of forest plant diversity has heavily relied on comprehensive field surveys. However, these surveys require a lot of time and labor. Furthermore, the results of such surveys can be more susceptible to limitations, including the selection of sample sites, survey methodologies, sampling intensity, and the expertise of the individuals conducting the surveys [30]. Simultaneously, field surveys primarily concentrate on species and sample site levels, posing challenges in attaining uninterrupted monitoring of forest plant diversity across various spatial and temporal scales, including landscape, regional, and even global extents [31]. The integration of remote sensing information with field surveys enables the study of vegetation diversity dynamics across various scales, leveraging the advantageous features of remote sensing, including its wide observation area, rapid imaging speed, and cost effectiveness. In addition, this method facilitates the expeditious determination of the extent of biodiversity decline across extensive regions, a critical aspect in assessing biodiversity on a broad scale and over extended periods of time [32]. The monitoring methods for biodiversity through remote sensing can be classified into two main categories, namely direct and indirect methods [33]. The direct method refers to the utilization of satellite sensors with high spatial and spectral resolutions to directly identify species, populations, or communities. The study utilizes QuickBird high-resolution multispectral data and LiDAR data to identify forest species through image segmentation and target-based classification techniques [34]. Their findings showed good results for both data sources individually. However, the integration of these two data sources resulted in even higher accuracy, as evidenced by a Kappa coefficient reaching up to 91.6%. In past studies, WorldView-3 satellite images have been used to classify six different forest species in tropical forest environments [35]. The classification accuracy of their methodology was determined to be 85.37%. Furthermore, the indirect approach refers to utilizing remote sensing data to retrieve indicators or parameters that are closely associated with biodiversity. Subsequently, statistical models are developed using field-measured data to infer biodiversity. Vegetation indices, plant biochemical components, and vegetation structure are also associated with estimating diversity [36]. The utilization of the normalized vegetation index (NDVI) is frequently employed as an indicator of species diversity at a regional scale [37]. Conversely, in densely vegetated regions, the enhanced vegetation index (EVI) has been found to be a better alternative to NDVI [38]. It is worth noting that alterations in leaf chlorophyll, nitrogen content, pigments, water, and other biochemical constituents linked to spectral variability are also a means to assess forest species diversity [39].
Although various remote sensing means are widely used in biodiversity research and can obtain information on the composition, structure, and function of ecosystems, they still have certain limitations. From the point of view of remote sensing technology itself, the limitations of the existing technology used for biodiversity monitoring mainly focus on data acquisition and processing [40]. Currently, remote sensing platforms are mainly based on optical sensors, and there is a lack of data sources reflecting the vertical structure of forests. The difficulty of processing remotely sensed data also imposes certain limitations on its application in biodiversity research. Remote sensing monitoring of biodiversity also lacks a harmonized system of indicators for routine and cyclical monitoring of the state of biodiversity and an assessment of its changes [41]. In addition, the direct detection method of remote sensing mostly detects tree species without considering other plants, making it limited in monitoring forest biodiversity.

3. Mechanisms of Drought Effects on Forest Plant Diversity

The impacts of drought events on forest plant diversity may not manifest immediately, but rather tend to materialize during the protracted period of recuperation. One of the adverse impacts of drought on biodiversity is the reduction in ecosystem productivity and the corresponding rise in mortality rates. The response of individual species to drought is contingent upon their drought resistance mechanisms, which encompass their capacity to endure drought conditions and recuperate following the initiation of drought, as well as the interplay between these mechanisms.

3.1. Eco Physiological Responses to Drought

The responses of plants to drought events are multifaceted and the presence of water deficits caused by drought have diverse impacts on plants. Drought induces a deficiency in soil water content, leading to a reduction in its water retaining efficacy, thereby impacting the movement of water across the soil–tree–atmosphere continuum [42]. In the context of drought, drought stress arises when the level of soil moisture falls below a certain threshold. At the whole plant level, the consequences of drought stress are commonly characterized by a decline in both photosynthesis and growth. After a prolonged period of drought, even with “normal” precipitation, drought conditions can still occur in deeper soil layers, which can affect deep-rooted or flat-rooted trees differently. This is the vertical difference in trees. These effects are linked to modifications in carbon and nitrogen metabolism [43]. Furthermore, transpiration serves as a catalyst for water movement and facilitates the extraction of water from the soil and its subsequent transportation to the leaves [44]. During periods of drought, there is a notable escalation in transpiration rates. This heightened evapotranspiration, coupled with diminished soil water content, results in a reduction of water potential along the pathway. Consequently, the majority of tree species respond by closing their stomata. In the event of an extended period of drought, there is a possibility that the continuity of water transportation systems may be permanently disturbed, resulting in significant loss of roots or branches [45]. Consequently, this disruption has a cascading effect on the overall structure and composition of the forest.
Water stress is a condition that results in the closure of stomata, leading to a reduction in the rate of transpiration. This, in turn, causes a decrease in water potential within the tissues of plants, resulting in a decline in photosynthesis and the inhibition of growth. Besides the hydraulic failure caused by drought, factors such as carbon starvation and biological attack also contribute to plant mortality. The closure of plant stomata serves as a mechanism to prevent the uptake of carbon dioxide thereby reducing water loss. At elevated temperatures, alterations in insect and pathogen populations can exacerbate the detrimental effects on plants, potentially leading to increased damage and mortality [46]. The mortality of plants exerts a profound and enduring influence on the biodiversity of forest ecosystems.

3.2. Species Resistance to Drought

Plants typically manifest four distinct response mechanisms in the face of drought-induced stress, namely drought avoidance, drought escape, drought resistance, and drought recovery. Drought resistance and drought avoidance represent the primary mechanisms employed by plants to mitigate the effects of water deficit stress. Forest vegetation has the capacity to react to drought and high temperatures by either evading unfavorable conditions or alleviating the detrimental impacts of physiological stressors. Plants have evolved various mechanisms to safeguard the photosynthetic apparatus (PSA) against diverse forms of stress. At the cellular level, plants employ metabolic alterations to mitigate the detrimental impacts of drought-induced stress [47]. Numerous plant systems exhibit the ability to endure desiccation, albeit with varying levels of success. The variation in drought resistance among plants is contingent upon the distinct response mechanisms of each species. One of the most basic mechanisms for drought resistance involves the closure of stomata in plants, which subsequently leads to a reduction in transpiration rates. The root system is potentially the initial organ to perceive drought-induced stress, and longer and more compact root systems could potentially augment the ability to withstand drought conditions. Alterations in the patterns of gene expression typically manifest during the initial phases of plant adaptation to drought conditions and certain modifications have the potential to confer enduring safeguarding effects. It has been observed that plants tend to accumulate a specific type of metabolite, known as a ”compatible solute”, under stressful conditions [48]. These solutes exhibit high concentrations within the cellular environment, thereby facilitating osmoregulation and providing protection to enzymes and membrane structures. The Mitogen-Activated Protein Kinase (MAPK) pathway plays a crucial role in mediating signal transduction in response to a range of stressors, such as cold, injury, and drought [49]. The involvement of cotton MAPK in the regulation of osmotic pressure and water loss in response to water stress has already been explained [50]. At the level of leaf physiology, the dissipation of excitation energy serves as a significant defense mechanism against drought conditions, alongside photosynthetic carbon metabolism. This process is accompanied by the downregulation of photochemistry in long-term carbon metabolism [51]. In addition to drought-resistant mechanisms for individual plants, plant communities also have corresponding drought-resistant mechanisms, including interactions between plants and interactions between plants and other organisms. For example, drought-induced complementary and competitive effects among plants can effectively resist drought, and animal and microbial interactions with plants also have drought-resistant effects (refer to Table 1).

3.3. Post-Drought Resilience of Species

The potential for ecological restoration through vegetation recovery lies in the ability of plants to overcome persistent mechanisms of drought resistance. Currently, seed banks have assumed a crucial role in facilitating population recovery, particularly for angiosperm shrub, grass, and forb species. These seed banks consist of seeds that have been developed and stored in the soil or other protected structures prior to any disturbance, thereby representing in situ seed banks. After experiencing stress, seeds that are stored in the soil have the potential to facilitate the rapid succession of various functional plant types, thereby replacing the dominance of plants that perished in previous forest droughts [67]. Seeds re-establish populations after drought-induced mortality, landing in specific drought-prone locations through dispersal, thereby potentially introducing more drought-resistant species at a specific drought-prone site (refer to Table 1). Regeneration of forest understory vegetation is observed to occur prior to the onset of stress, and it is typically characterized by a high abundance of shade-tolerant species. Consequently, the subsequent recovery of communities may exhibit equal levels of abundance in these particular species [64,68]. Seed dispersal plays a crucial role in the restoration of vegetation, particularly for seeds that have specific requirements. The recovery of vegetation on sites experiencing drought stress is typically reliant on the dispersal of seeds from nearby propagating trees through wind or animal-mediated processes [69]. Upon arrival at a specific location, the seeds are required to undergo the germination process and subsequent growth in order to successfully facilitate the restoration of a forest ecosystem. The survival and growth of seedlings are highly susceptible to environmental factors and the subsequent yearly weather patterns can significantly impact the regeneration of forests [70]. Weather conditions in low-elevation forests located in the western region of the United States have exhibited a growing inability to meet the minimum thresholds required for the successful regeneration of forests [71]. In the context of climate change, the recovery of tree species is constrained by factors such as climate stress and precipitation conditions. When vegetation that once experienced drought is re-exposed to climatic conditions that are unfavorable for seed growth, such as drought and high temperatures, the system is susceptible to species reorganization and significant changes in forest plant diversity. The eventual achievement of a successful recovery is contingent, to some extent, on the recruiting capacity in resource competition within the disrupted community. Over the course of time, it is more probable for competing vegetation, typically in the form of shrubs, to establish itself [72]. In instances where aspen and conifer species coexist within a given region, it has been observed that the aspen initially exhibits dominance within the restored tree community. However, the composition of this community typically transitions towards conifer dominance over time, probably because the high germination capacity of aspen seedlings dominates in the early stages, and in later stages a short-lived species reorganization results from the shade-resistance of young conifers and higher adult tree height and longevity [73]. Nevertheless, according to recent scholarly work, irrespective of the species’ ability to adapt to drought disturbance patterns, the process of recovery is rendered more challenging under prevailing climate change conditions in numerous ecosystems [74]. Subsequently, with the population gradually recovering from the drought disturbance, the following recovery phase manifests itself as a community reorganization.

4. Feedback of Forest Plant Diversity to Drought

In the past two decades, certain areas have encountered, or are currently facing, extreme weather conditions, such as elevated temperatures and prolonged periods of drought, as a consequence of worldwide climate change [75]. The profound drought experienced during the summer of 2003 had a significant effect on the arboreal population within the forests of Western Europe. This climatic event resulted in a sudden surge in tree mortality, tree dieback, and premature defoliation. The impact of forest biomes was observed across various levels, encompassing above-ground and below-ground species [76]. It is anticipated that certain regions will encounter significant and extensive drought within the forthcoming 30 to 90 years [77]. The significance of forest biodiversity in the regulation of ecosystem functions, particularly in mitigating the susceptibility of ecosystems to climate-related pressures, has been widely acknowledged. While ecosystems are susceptible to droughts, the impact of drought on forest plant diversity remains uncertain as various studies have produced conflicting findings. The impact on biodiversity can be influenced by the intensity, duration, and frequency of droughts. Research indicates that the duration of a drought event may have greater significance than its intensity, and the effects of specific extreme droughts may be contingent upon the overall temporal pattern of drought intensity [78]. Hence, in this section, we first review the moderating role of forest biodiversity on the effects of drought. It then proceeds to discuss the immediate and intermediate-term reactions of forest biodiversity to drought, as well as the enduring consequences of drought on biodiversity.

4.1. The Role of Forest Biodiversity in Regulating Drought

The widely accepted consensus in the scientific community is that forest biodiversity plays a crucial role in regulating ecological functions. Therefore, it can be anticipated that the diversity of tree species in a particular forest community affected by drought will contribute to the regulation of the impacts of drought on trees [79]. The promotion of plant diversity through the implementation of methods such as mixed-species forests have been suggested as significant strategies for mitigating risks and adapting to the challenges posed by climate change. Several studies have provided evidence indicating that species’ interactions within diverse forest ecosystems can mitigate the effects of drought and water stress [80,81]. The presence of complementary resource acquisition strategies among tree species has the potential to mitigate interspecific competition and enhance the occurrence of facilitative interactions, thereby promoting tree growth and enhancing resilience to extreme drought events [82]. This, in turn, can help mitigate the adverse effects of drought on forest growth. Nevertheless, the efficacy of forest biodiversity in regulating drought is not consistently reliable, and the relationship between diversity and drought tends to be more complex, thereby introducing potential inconsistencies in experimental outcomes across various studies. For example, in the experiments of Grossiord, C et al. it was found that higher plant diversity increased resistance to drought events only in drought-prone environments, thus, plant diversity does not always improve resistance of forest ecosystems to drought [83].

4.2. Short- and Mid-Term Effects of Drought

In one study, the impact of a severe drought on forest species composition, diversity, and productivity in western Iran was examined [84]. By comparing the diversity of plant species during the drought year to the diversity before and after the drought, it was observed that both the diversity index and richness index experienced a significant decrease during the drought period, followed by a significant increase after the drought. The vegetative cover of certain species exhibited a notable reduction during the drought event, leading to the disappearance of certain species. However, subsequent precipitation events facilitated the reappearance of these species. Furthermore, the drought event also facilitated the emergence of previously unobserved species [84]. The impacts of short- to medium-term droughts on plant diversity primarily manifest as reduced productivity and increased mortality rates. In the region of the Amazon Forest, which has undergone significant environmental changes in the past, there is a notable deviation from the typical pattern of increased plant species diversity [85]. This deviation occurs specifically during periods when ecological responses to warming, drought, and extended dry seasons are constrained by water limitations. The study also indicates that drought conditions can lead to a decrease in the abundance of plant species due to reduced productivity [86]. Additionally, there is a risk of plant imbalances and potential extinction events, as several plant, dispersal, and pollinator species may be unable to adapt to climate change.
In the context of soil, it is commonly observed that severe drought conditions tend to have a negative impact on microbial activity and carbohydrate composition. This can be attributed to the distinct responses exhibited by fungi and bacteria when facing drought stress. Consequently, the occurrence of drought leads to a decrease in important soil ecosystem processes, such as the carbon and nutrients cycling. This has an impact on the growth and performance of plants, as well as the composition of vegetation, due to the changes of effectiveness for nutrient availability [87]. The vulnerability of biodiversity exhibits variation across species’ size, age, growth rate, and location [88]. The risk of environmental challenges is most pronounced in transitional zones, such as the interface between the Mediterranean and Euro-Siberian regions [89]. This heightened risk can be attributed to the occurrence of severe droughts and the subsequent increase in evapotranspiration. Furthermore, the impact of drought-induced changes is particularly significant in the transition zone located between two distinct biomes [90]. For instance, in the Amazon basin, it is observed that drought conditions lead to the reduction of forest area at the forest edge and in the transition zone to savanna [91]. This phenomenon consequently triggers significant alterations in the composition of steppe and forest species. Studies have shown that species with a rapid growth rate exhibit greater susceptibility to drought interruptions compared to those with slower growth rates [92]. Similarly, ecosystems characterized by higher fertility and early evolutionary development are more prone to drought vulnerability [93]. The most vulnerable trees are typically large in size and have a long lifespan and are found in the majority of locations. These trees contribute significantly to the biomass and productivity of forests. Consequently, the demise of these trees has a substantial influence on both biodiversity and carbon stocks within the ecosystem [94]. Establishing deep roots is a strategic approach employed by plants to bolster their chances of survival amidst seasonal droughts through the absorption of groundwater. However, the most detrimental factor affecting plant diversity is the confluence of deep-water tables and heightened mortality rates resulting from droughts. This is due to the fact that plants with deep roots cannot survive in deep aquifers, and plants without deep roots cannot survive droughts with high mortality rates [95].
The resilience mechanisms of forest biodiversity, specifically in relation to vegetation, enable vegetation to exhibit a notable resistance to drought events of short- and medium-term durations. These mechanisms have been elaborated upon in the preceding section. For instance, subsequent to the severe drought experienced in Europe in 2003, a yearly examination of 124 × 100 m2 plots conducted under the RENECO-FOR long-term monitoring indicated minimal alterations in community composition [96]. However, certain changes occurred which were more likely attributed to the canopy opening following the drought rather than the drought itself [97]. Significant alterations in plant community composition occur only after the closure of the vegetation canopy, which typically takes several years. Additionally, the occurrence of drought had a favorable impact on the biodiversity of forests, as evidenced by an augmentation in the quantity of upright (branches) and horizontal (twigs, logs) deceased organic matter [98]

4.3. Long-Term Effects of Drought and Global Climate Change

Typically, the heightened severity of drought conditions, characterized by prolonged duration and heightened intensity, expedites the depletion of soil water and the mortality of plants. Consequently, this results in an escalated pace of species alteration. The primary factor influencing vegetation dynamics in Mediterranean, boreal, and temperate forests is the frequency of drought events [99]. The decrease in European oak populations is subsequently linked to the adverse impacts of intermittent droughts [100]. The present alterations in the geographical distribution and demographic composition of numerous species are frequently linked to the phenomenon of global climate change [101]. Some scientists believe that drought resistance may be reduced by cyclicity [102]. However, an alternative perspective posits that extreme weather events, such as drought, can actually result in intensified natural selection processes. Consequently, long-term drought conditions create the potential for the gradual evolution of genes associated with drought resistance [103]. Prolonged droughts have multifaceted impacts on forest ecosystems. In addition to causing tree dieback and altering the composition of species, drought can also have significant implications for ecosystem functions. Specifically, it has the potential to transform forests from carbon dioxide sinks into sources.
It has also been demonstrated that prolonged drought in tropical forests may affect the diversity of forests with different humidity levels differently. Drought contributes to an increase in the taxonomic and functional diversity of humid forests, whereas it contributes to the development of dry tropical forests in the direction of enhanced functional, taxonomic and phylogenetic homogeneity [104]. It has also been shown that subsequent droughts usually have more detrimental effects than the initial drought; however, these effects vary by ecosystem, with gymnosperm- and conifer-dominated ecosystems being more susceptible to the effects of multiple droughts [105]. Thus, different types of forest ecosystems in different climatic zones are likely to have different response processes.
Moreover, the enduring consequences of drought are not solely contingent upon the frequency and severity of drought events, but are also intricately connected to the ramifications of other atmospheric, climatic, and habitat alterations that predominantly engage in intricate interactions, thereby heightening the uncertainty surrounding the impacts of drought on biodiversity. Finally, because past and present climate conditions do not provide a suitable analogy, combinations of conditions that exist today may change in the future, and these climate changes may lead to species assemblages that have never co-occurred before [106]. In addition, the drought may also have some positive effects in the long run. Some species can even grow more after drought than before, presumably to compensate for reduced growth during the drought [107]. The gradual disappearance of single-species (managed) forests after a prolonged drought may result in a more diverse community.

5. Conclusions and Outlook

In recent decades, it has been increasingly recognized that drought events exert a substantial influence on the biodiversity of forest ecosystems. This review focused on examining the response to drought conditions in various ecological contexts, ranging from individual vegetation to species and ultimately to ecosystem scale. Additionally, the mechanisms underlying plant community alterations in the presence of drought-induced stress were discussed.
The physiological mechanisms governing vegetation adaptation and mortality in response to drought conditions exhibit considerable instability and unpredictability. These mechanisms are typically influenced by factors such as the timing and severity (duration and intensity) of the drought, the regional-specific climatic conditions, and the original species composition of the plant community. When a plant community is faced with a severe drought disturbance, the individuals within the community employ strategies to enhance their resistance to drought conditions. Following the disturbance event, certain plant species exhibiting a greater drought resistance can persist, while others experience detrimental effects. Certain plants have resilience to recover, while others succumb to unfavorable conditions and perish. The impacts of drought on various species are contingent upon the severity and duration of the event. In response to drought, certain species may have an increase in their coverage. In some cases, certain species may completely disappear, whereas others may reemerge following the ecosystem recovery after the drought disturbance. In addition to this, there will be a number of species that appear for the first time (refer to Figure 1). Therefore, the frequency of extreme drought events can have significant impacts on entire ecosystems. The many complex and interacting feedback mechanisms that do not consistently reflect the climate make it difficult, and currently impossible, to model biodiversity feedback to an arid climate. Moreover, differences in the methods used to estimate aridity indices and biodiversity may also lead to bias in the conclusions of the study. Therefore, we can adopt different estimation methods to verify each other when studying the corresponding study of biodiversity to drought. In order to obtain precise estimations regarding the impact of drought events on forest biodiversity, it is imperative to employ reliable forest datasets and models to simulate the dynamics of diversity. More notably, the diversity of forests under different systems varies considerably (e.g., natural systems and management systems); although, the diversity of boreal forests and tropical rainforests can vary considerably under the same natural system, so their response to drought may be different.
In response to the uncertainties raised above, some issues that should be prioritized in our future research include: (i) the intensity, duration, and frequency of droughts, as well as the initial climatic conditions and species composition of the dryland, which are factors that need to be considered for control prior to the experiment; (ii) the scale of the study needs to be considered before a specific study is conducted, as different scale ranges require different factors to be considered and will have different response mechanisms to drought; (iii) in order to accurately estimate the response of forest plant diversity to drought events, we need to consider the limitations of different estimation methods and more accurately estimate data at different scales through multiple comparisons and validation of diversity estimation methods; and (iv) in subsequent studies, we need to focus on different forest systems, such as natural systems and management systems. In addition, there is a need to clearly define different ecosystems prior to research and to try to find a consistent response of biodiversity to drought in different types of forests, such as tropical rainforests, savanna systems, and boreal forests.
In conclusion, the effects of drought on forest biodiversity are complex and process oriented. However, understanding the mechanisms involved in the response process can help us improve the planning and management of forest ecosystems in the face of climate change in the future.

Author Contributions

Writing—original draft preparation, T.-Y.Z. and W.-Y.S., writing—review and editing, X.-L.L., D.-R.D. and W.-Y.S. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the National Natural Science Foundation of China (No. 41975114), the Chongqing Outstanding Youth Science Foundation (No. cstc2021jcyj-jqX0025), Doctoral Initial Project of Southwest University (SWU-KR23002), and the Chongqing elite-innovation and entrepreneurship demonstration team (to Weiyu Shi).

Data Availability Statement

No new data were created or analyzed in this study. Data sharing is not applicable to this article.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Yi, C.X.; Pendall, E.; Ciais, P. Focus on extreme events and the carbon cycle. Environ. Res. Lett. 2015, 10, 70201. [Google Scholar] [CrossRef]
  2. Diaz, S.; Fargione, J.; Chapin, F.S.; Tilman, D. Biodiversity loss threatens human well-being. PLoS Biol. 2006, 4, 1300–1305. [Google Scholar] [CrossRef]
  3. Allen, C.D.; Macalady, A.K. A global overview of drought and heat-induced tree mortality reveals emerging climate change risks for forests. For. Ecol. Manag. 2010, 259, 660–684. [Google Scholar] [CrossRef]
  4. McDowell, N.G.; Beerling, D.J.; Breshears, D.D. The interdependence of mechanisms underlying climate-driven vegetation mortality. Trends Ecol. Evol. 2011, 26, 523–532. [Google Scholar] [CrossRef]
  5. Breshears, D.D.; Cobb, N.S.; Rich, P.M. Regional vegetation die-off in response to global-change-type drought. Proc. Natl. Acad. Sci. USA 2005, 102, 15144–15148. [Google Scholar] [CrossRef] [PubMed]
  6. Anderegg, W.R.L.; Berry, J.A. The roles of hydraulic and carbon stress in a widespread climate-induced forest die-off. Proc. Natl. Acad. Sci. USA 2012, 109, 233–237. [Google Scholar] [CrossRef]
  7. Van Mantgem, P.J.; Stephenson, N.L. Apparent climatically induced increase of tree mortality rates in a temperate forest. Ecol. Soc. Am. Annu. Meet. Abstr. 2007, 10, 909–916. [Google Scholar] [CrossRef]
  8. Poorter, L.; van der Sande, M.T. Diversity enhances carbon storage in tropical forests. Glob. Ecol. Biogeogr. 2015, 24, 1314–1328. [Google Scholar] [CrossRef]
  9. Morin, X.; Fahse, L. Tree species richness promotes productivity in temperate forests through strong complementarity between species. Ecol. Lett. 2011, 14, 1211–1219. [Google Scholar] [CrossRef]
  10. Jactel, H.; Brockerhoff, E.G. Tree diversity reduces herbivory by forest insects. Ecol. Lett. 2007, 10, 835–848. [Google Scholar] [CrossRef]
  11. Redmond, K.T. The depiction of drought—A commentary. Bull. Am. Meteorol. Soc. 2002, 83, 1143–1147. [Google Scholar] [CrossRef]
  12. Mishra, A.K.; Singh, V.P. A review of drought concepts. J. Hydrol. 2010, 391, 204–216. [Google Scholar] [CrossRef]
  13. Endt, P.M.; Patter, D.M.; Buechner, W.W. An objective approach to definitions and investigations of continental hydrologic droughts. VUJICA YEVJEVICH: Fort Collins, Colorado State University, 1967, 19 p. (Hydrology paper no. 23). J. Hydrol. 1951, 7, 491–494. [Google Scholar]
  14. Zelenhasic, E.; Salvai, A. A method of streamflow drought analysis. Water Resour. Res. 1987, 23, 156–168. [Google Scholar] [CrossRef]
  15. Zhang, H.; Sun, X.P.; Dai, M.Q. Improving crop drought resistance with plant growth regulators and rhizobacteria: Mechanisms, applications, and perspectives. Plant Commun. 2022, 3, 100228. [Google Scholar] [CrossRef]
  16. Heim, R.R., Jr. A review of twentieth-century drought indices used in the United States. Bull. Am. Meteorol. Soc. 2002, 83, 1149–1165. [Google Scholar] [CrossRef]
  17. Mckee, T.B.; Doesken, N.J.; Kleist, J. The Relationship of Drought Frequency and Duration to Time Scales. In Proceedings of the 8th Conference on Applied Climatology, Anaheim, CA, USA, 17–22 January 1993. [Google Scholar]
  18. Vicente-Serrano, S.M.; Beguería, S.; López-Moreno, J.I. A Multiscalar Drought Index Sensitive to Global Warming: The Standardized Precipitation Evapotranspiration Index. J. Clim. 2010, 23, 1696–1718. [Google Scholar] [CrossRef]
  19. Palmer, W.C. Meteorological Drought: US Department of Commerce; US Department of Commerce: Washington, DC, USA, 1965.
  20. Palmer, W.C. Keeping Track of Crop Moisture Conditions, Nationwide: The New Crop Moisture Index. Weatherwise 1968, 21, 156–161. [Google Scholar] [CrossRef]
  21. Sims, A.P.; Niyogi, D.D.S.; Raman, S. Adopting drought indices for estimating soil moisture: A North Carolina case study. Geophys. Res. Lett. 2002, 29, 24-1–24-4. [Google Scholar] [CrossRef]
  22. Oh, T.S.; Moon, Y.I.; Kim, S.S.; Gu, S.P. Frequency analysis of meteorologic drought indices using boundary kernel density function. J. Korean Soc. Civ. Eng. B 2011, 31, 87–98. [Google Scholar]
  23. Eslamian, S.; Ostad-Ali-Askari, K.; Singh, V.P.; Dalezios, N.R.; Matouq, M. A Review of Drought Indices. Int. J. Civ. Eng. 2017, 3, 48–66. [Google Scholar]
  24. Liu, D.; Wang, T.; Peñuelas, J.; Piao, S. Drought resistance enhanced by tree species diversity in global forests. Nat. Geosci. 2022, 15, 800–804. [Google Scholar] [CrossRef]
  25. Liang, J.; Crowther, T.W.; Picard, N.; Wiser, S. Positive biodiversity-productivity relationship predominant in global forests. Science 2016, 354, aaf8957. [Google Scholar] [CrossRef]
  26. Motz, K.; Sterba, H.; Pommerening, A. Sampling measures of tree diversity. For. Ecol. Manag. 2010, 260, 1985–1996. [Google Scholar] [CrossRef]
  27. Han, F. Sampling theory for forest inventory. For. Ecol. Manag. 1989, 26, 151. [Google Scholar] [CrossRef]
  28. Vos, P.; Meelis, E.; Keurs, W.J.T. A Framework for the Design of Ecological Monitoring Programs as a Tool for Environmental and Nature Management. Environ. Monit. Assess. 2000, 61, 317–344. [Google Scholar] [CrossRef]
  29. Anderson-Teixeira, K.J.; Davies, S.J.; Bennett, A.C.; Gonzalez-Akre, E.B. CTFS-ForestGEO: A worldwide network monitoring forests in an era of global change. Glob. Change Biol. 2015, 21, 528–549. [Google Scholar] [CrossRef] [PubMed]
  30. Gotelli, N.J.; Colwell, R.K. Quantifying biodiversity: Procedures and pitfalls in the measurement and comparison of species richness. Ecol. Lett. 2001, 4, 379–391. [Google Scholar] [CrossRef]
  31. Kerr, J.T.; Ostrovsky, M. From space to species: Ecological applications for remote sensing. Trends Ecol. Evol. 2003, 18, 299–305. [Google Scholar] [CrossRef]
  32. Turner, W. Sensing biodiversity. Science 2014, 346, 301–302. [Google Scholar] [CrossRef] [PubMed]
  33. Turner, W.; Spector, S.; Gardiner, N. Remote sensing for biodiversity science and conservation. Trends Ecol. Evol. 2003, 18, 306–314. [Google Scholar] [CrossRef]
  34. Ke, Y.H.; Quackenbush, L.J.; Im, J. Synergistic use of QuickBird multispectral imagery and LIDAR data for object-based forest species classification. Remote Sens. Environ. 2010, 114, 1141–1154. [Google Scholar] [CrossRef]
  35. Cross, M.; Scambos, T.; Pacifici, F.; Vargas-Ramirez, O.; Moreno-Sanchez, R.; Marshall, W. Classification of Tropical Forest Tree Species Using Meter-Scale Image Data. Remote Sens. 2019, 11, 1411. [Google Scholar] [CrossRef]
  36. Kokhan, S.; Vostokov, A. Using Vegetative Indices to Quantify Agricultural Crop Characteristics. J. Ecol. Eng. 2020, 21, 120–127. [Google Scholar] [CrossRef]
  37. Fairbanks, D.H.K.; McGwire, K.C. Patterns of floristic richness in vegetation communities of California: Regional scale analysis with multi-temporal NDVI. Glob. Ecol. Biogeogr. 2004, 13, 221–235. [Google Scholar] [CrossRef]
  38. Waring, R.H.; Coops, N.C.; Fan, W.; Nightingale, J.M. MODIS enhanced vegetation index predicts tree species richness across forested ecoregions in the contiguous USA. Remote Sens. Environ. 2006, 103, 218–226. [Google Scholar] [CrossRef]
  39. Carlson, K.M.; Asner, G.P.; Hughes, R.F.; Ostertag, R.; Martin, R.E. Hyperspectral remote sensing of canopy biodiversity in Hawaiian lowland rainforests. Ecosystems 2007, 10, 536–549. [Google Scholar] [CrossRef]
  40. Guo, Q.F. Progress in the application of remote sensing in biodiversity research. Biodiversity 2018, 26, 789–806. [Google Scholar]
  41. Duro, D.; Coops, N.C.; Wulder, M.A.; Han, T. Development of a large area biodiversity monitoring system driven by remote sensing. Prog. Phys. Geogr. Earth Environ. 2007, 31, 235–260. [Google Scholar] [CrossRef]
  42. Breda, N.; Huc, R.; Granier, A.; Dreyer, E. Temperate forest trees and stands under severe drought: A review of ecophysiological responses, adaptation processes and long-term consequences. Ann. For. Sci. 2006, 63, 625–644. [Google Scholar] [CrossRef]
  43. Mwanamwenge, J.; Loss, S.P.; Siddique, K.H.M.; Cocks, P.S. Effect of water stress during floral initiation, flowering and podding on the growth and yield of faba bean (Vicia faba L.). Eur. J. Agron. 1999, 11, 1–11. [Google Scholar] [CrossRef]
  44. Fang, Y.; Xiong, L. General mechanisms of drought response and their application in drought resistance improvement in plants. Cell. Mol. Life Sci. Cmls 2015, 72, 673–689. [Google Scholar] [CrossRef]
  45. Signarbieux, C.; Feller, U. Effects of an extended drought period on physiological properties of grassland species in the field. J. Plant Res. 2012, 125, 251–261. [Google Scholar] [CrossRef] [PubMed]
  46. Yordanov, I.; Velikova, V.; Tsonev, T. Plant responses to drought, acclimation, and stress tolerance. Photosynthetica 2000, 38, 171–186. [Google Scholar] [CrossRef]
  47. Hoekstra, F.A.; Golovina, E.A.; Buitink, J. Mechanisms of plant desiccation tolerance. Trends Plant Sci. 2001, 6, 431–438. [Google Scholar] [CrossRef]
  48. Bohnert, H.J.; Bo, S. Transformation and compatible solutes. Sci. Hortic. 1998, 78, 237–260. [Google Scholar] [CrossRef]
  49. Berriri, S.; Garcia, A.V.; Frey, N.F.D.; Rozhon, W.; Pateyron, S.; Leonhardt, N.; Montillet, J.L.; Leung, J.; Hirt, H.; Colcombet, J. Constitutively Active Mitogen-Activated Protein Kinase Versions Reveal Functions of Arabidopsis MPK4 in Pathogen Defense Signaling. Plant Cell 2012, 24, 4281–4293. [Google Scholar] [CrossRef]
  50. Zhang, A.; Zhang, J.; Ye, N.H.; Cao, J.M.; Tan, M.P.; Zhang, J.H.; Jiang, M.Y. ZmMPK5 is required for the NADPH oxidase-mediated self-propagation of apoplastic H2O2 in brassinosteroid-induced antioxidant defence in leaves of maize. J. Exp. Bot. 2010, 61, 4399–4411. [Google Scholar] [CrossRef]
  51. Lichtenthaler, H.K.; Buschmann, C.; Doll, M. Photosynthetic activity, chloroplast ultrastructure, and leaf characteristics of high-light and low-light plants and of sun and shade leaves. Photosynth. Res. 1981, 2, 115–141. [Google Scholar] [CrossRef]
  52. Clauw, P.; Coppens, F.; De Beuf, K. Leaf Responses to Mild Drought Stress in Natural Variants of Arabidopsis. Plant Physiol. 2015, 168, 1180. [Google Scholar] [CrossRef]
  53. Fanizza, G.; Ricciardi, L. Influence of drought stress on shoot, leaf growth, leaf water potential, stomatal resistance in wine grape genotypes (Vitis vinifera L.). Vitis 1990, 29, 371. [Google Scholar]
  54. Comas, L.H.; Becker, S.R.; Cruz, V.V.; Byrne, P.F.; Dierig, D.A. Root traits contributing to plant productivity under drought. Front. Plant Sci. 2013, 4, 442. [Google Scholar] [CrossRef] [PubMed]
  55. Ullah, A.; Sun, H.; Hakim; Yang, X.Y.; Zhang, X.L. A novel cotton WRKY gene, GhWRKY6-like, improves salt tolerance by activating the ABA signaling pathway and scavenging of reactive oxygen species. Physiol. Plant. 2018, 162, 439–454. [Google Scholar] [CrossRef] [PubMed]
  56. Stael, S.; Wurzinger, B.; Mair, A.; Mehlmer, N.; Vothknecht, U.C.; Teige, M. Plant organellar calcium signalling: An emerging field. J. Exp. Bot. 2012, 63, 1525–1542. [Google Scholar] [CrossRef]
  57. Tanveer, M. 24-Epibrassinolide; an active brassinolide and its role in salt stress tolerance in plants: A review. Plant Physiol. Biochem. 2018, 130, 69–79. [Google Scholar] [CrossRef]
  58. Lennon, J.T.; den Hollander, F.; Wilke-Berenguer, M.; Blath, J. Principles of seed banks and the emergence of complexity from dormancy. Nat. Commun. 2021, 12, 4807. [Google Scholar] [CrossRef]
  59. Treep, J.; de Jager, M.; Bartumeus, F.; Soons, M.B. Seed dispersal as a search strategy: Dynamic and fragmented landscapes select for multi-scale movement strategies in plants. Mov. Ecol. 2021, 9, 4. [Google Scholar] [CrossRef]
  60. Wang, N.; Zhao, M.; Li, Q.; Liu, X.; Song, H.; Peng, X.; Wang, H.; Yang, N.; Fan, P.; Wang, R.; et al. Effects of defoliation modalities on plant growth, leaf traits, and carbohydrate allocation in Amorpha fruticosa L. and Robinia pseudoacacia L. seedlings. Ann. For. Sci. 2020, 77, 53. [Google Scholar] [CrossRef]
  61. Jentsch, A.; Kreyling, J.; Elmer, M.; Gellesch, E.; Beierkuhnlein, C. Climate Extremes Initiate Ecosystem-Regulating Functions While Maintaining Productivity; Wiley-Blackwell: Hoboken, NJ, USA, 2011. [Google Scholar]
  62. Arfin Khan, M.A.S.; Grant, K.; Beierkuhnlein, C.; Kreyling, J.; Jentsch, A. Climatic extremes lead to species-specific legume facilitation in an experimental temperate grassland. Plant Soil 2014, 379, 161–175. [Google Scholar] [CrossRef]
  63. de Dios, V.R.; Weltzin, J.F.; Sun, W.; Huxman, T.E.; Williams, D.G. Transitions from grassland to savanna under drought through passive facilitation by grasses. J. Veg. Sci. 2014, 25, 937–946. [Google Scholar] [CrossRef]
  64. Keeley, J.E. Trace Gas Emissions and Smoke-Induced Seed Germination. J. Veg. Sci. 1997, 276, 1248–1250. [Google Scholar] [CrossRef]
  65. Cipriotti, P.A.; Flombaum, P.; Sala, O.E.; Aguiar, M.R. Does drought control emergence and survival of grass seedlings in semi-arid rangelands?: An example with a Patagonian species. J. Arid Environ. 2008, 72, 162–174. [Google Scholar] [CrossRef]
  66. Nadeem, S.M.; Ahmad, M.; Zahir, Z.A.; Javaid, A.; Ashraf, M. The role of mycorrhizae and plant growth promoting rhizobacteria (PGPR) in improving crop productivity under stressful environments. Biotechnol. Adv. 2014, 32, 429–448. [Google Scholar] [CrossRef] [PubMed]
  67. Kemp, P.R. Ecology of Soil Seed Banks; Elsevier: Amsterdam, The Netherlands, 1989. [Google Scholar]
  68. Kayes, L.J.; Tinker, D.B. Forest structure and regeneration following a mountain pine beetle epidemic in southeastern Wyoming. For. Ecol. Manag. 2012, 263, 57–66. [Google Scholar] [CrossRef]
  69. Yu, F.; Wang, D. Seed dispersal by small rodents favors oak over pine regeneration in the pine-oak forests of the Qinling mountains, China. Scand. J. For. Res. 2013, 28, 540–549. [Google Scholar] [CrossRef]
  70. Mező-Kricsfalusy, G.; Kricsfalusy, V. Population biology of plants. Popul. Biol. Plants 1977, 67. [Google Scholar]
  71. Prichard, S.J.; Hessburg, P.F.; Hagmann, R.K. Adapting western North American forests to climate change and wildfires: Ten common questions. Ecol. Appl. 2021, 31, e02433. [Google Scholar] [CrossRef]
  72. McDermid, S.S.; Cook, B.I.; De Kauwe, M.G.; Mankin, J.; Smerdon, J.E.; Williams, A.P.; Seager, R.; Puma, M.J.; Aleinov, I.; Kelley, M.; et al. Disentangling the Regional Climate Impacts of Competing Vegetation Responses to Elevated Atmospheric CO2. J. Geophys. Res.-Atmos. 2021, 126, e2020JD034108. [Google Scholar] [CrossRef]
  73. Lauvaux, C.A.; Skinner, C.N.; Taylor, A.H. High severity fire and mixed conifer forest-chaparral dynamics in the southern Cascade Range, USA. For. Ecol. Manag. 2016, 363, 74–85. [Google Scholar] [CrossRef]
  74. Fairman, T.A.; Bennett, L.T.; Nitschke, C.R. Short-interval wildfires increase likelihood of resprouting failure in fire-tolerant trees. J. Environ. Manag. 2019, 231, 59–65. [Google Scholar] [CrossRef]
  75. Allen, C.D.; Breshears, D.D.; McDowell, N.G. On underestimation of global vulnerability to tree mortality and forest die-off from hotter drought in the Anthropocene. Ecosphere 2015, 6, 1–55. [Google Scholar] [CrossRef]
  76. Aussenac, G. Influence des changements climatiques sur les peuplements forestiers et le cycle de l’eau. La Houille Blanche 2002, 88, 90–95. [Google Scholar] [CrossRef]
  77. Dai, A. Increasing drought under global warming in observations and models. Nat. Clim. Chang. 2013, 3, 52–58. [Google Scholar] [CrossRef]
  78. Fay, P.A.; Carlisle, J.D.; Knapp, A.K.; Blair, J.M.; Collins, S.L. Altering Rainfall Timing and Quantity in a Mesic Grassland Ecosystem: Design and Performance of Rainfall Manipulation Shelters. Ecosystems 2000, 3, 308–319. [Google Scholar] [CrossRef]
  79. Hooper, D.U.; Chapin, F.S.; Ewel, J.J. Effects of biodiversity on ecosystem functioning:A consensus of current knowledge. Ecol. Monogr. 2005, 75, 3–35. [Google Scholar] [CrossRef]
  80. Forrester, D.I.; Theiveyanathan, S.; Collopy, J.J.; Marcar, N.E. Enhanced water use efficiency in a mixed Eucalyptus globulus and Acacia mearnsii plantation. For. Ecol. Manag. 2010, 259, 1761–1770. [Google Scholar] [CrossRef]
  81. Kunert, N.; Schwendenmann, L.; Potvin, C.; Hölscher, D. Tree diversity enhances tree transpiration in a Panamanian forest plantation. J. Appl. Ecol. 2012, 49, 135–144. [Google Scholar] [CrossRef]
  82. Haberstroh, S.; Werner, C. The role of species interactions for forest resilience to drought. Plant Biol. 2022, 24, 1098–1107. [Google Scholar] [CrossRef]
  83. Grossiord, C.; Granier, A.; Ratcliffe, S.; Bouriaud, O.; Bruelheide, H.; Checko, E.; Forrester, D.I.; Dawud, S.M.; Finer, L.; Pollastrini, M.; et al. Tree diversity does not always improve resistance of forest ecosystems to drought. Proc. Natl. Acad. Sci. USA 2014, 111, 14812–14815. [Google Scholar] [CrossRef] [PubMed]
  84. Pourbabae, H.; Rahimi, V.; Adel, M.N. Effects of drought on plant species diversity and productivity in the Oak forests of Western Iran. Ecol. Balk. 2014, 6, 61–71. [Google Scholar]
  85. Brandao, D.O.; Barata, L.E.S.; Nobre, C.A. The Effects of Environmental Changes on Plant Species and Forest Dependent Communities in the Amazon Region. Forests 2022, 13, 466. [Google Scholar] [CrossRef]
  86. Ciríaco, E.; Albuquerque, M.B.D.; Dias, A. Drought and Its Consequences to Plants—From Individual to Ecosystem. In Responses of Organisms to Water Stress; IntechOpen: London, UK, 2013. [Google Scholar]
  87. Barnard, R.L.; Osborne, C.A.; Firestone, M.K. Responses of soil bacterial and fungal communities to extreme desiccation and rewetting. ISME J. 2013, 7, 2229–2241. [Google Scholar] [CrossRef]
  88. Aubry-Kientz, M.; Rossi, V. A joint individual-based model coupling growth and mortality reveals that tree vigor is a key component of tropical forest dynamics. Ecol. Evol. 2015, 5, 2457–2465. [Google Scholar] [CrossRef] [PubMed]
  89. Papamichael, I.; Voukkali, I.; Zorpas, A.A. Mediterranean: Main environmental issues and concerns. Euro-Mediterr J. Environ. 2022, 7, 477–481. [Google Scholar] [CrossRef]
  90. Allen, C.D.; Breshears, D.D. Drought-induced shift of a forest–woodland ecotone: Rapid landscape response to climate variation. Proc. Natl. Acad. Sci. USA 1998, 95, 14839–14842. [Google Scholar] [CrossRef]
  91. Cheng, H.; Sinha, A.; Cruz, F.W. Climate change patterns in Amazonia and biodiversity. Nat. Commun. 2013, 4, 1411. [Google Scholar] [CrossRef]
  92. Liiri, M.; Setl, H.; Haimi, J.; Fritze, P.H. Relationship between soil microarthropod species diversity and plant growth does not change when the system is disturbed. Oikos 2002, 96, 137–149. [Google Scholar] [CrossRef]
  93. Mulder, C.; Uliassi, D.D.; Doak, D.F. Physical stress and diversity-productivity relationships: The role of positive interactions. Proc. Natl. Acad. Sci. USA 2001, 98, 6704–6708. [Google Scholar] [CrossRef]
  94. Réjou-Méchain, M.; Tymen, B.; Blanc, L.; Fauset, S.; Chave, J. Using repeated small-footprint LiDAR acquisitions to infer spatial and temporal variations of a high-biomass Neotropical forest. Remote. Sens. Environ. 2015, 169, 93–101. [Google Scholar] [CrossRef]
  95. Lindh, M.; Zhang, L.; Falster, D. Plant diversity and drought: The role of deep roots. Ecol. Model. 2014, 290, 85–93. [Google Scholar] [CrossRef]
  96. Jonard, M.; Andre, F.; Dambrine, E.; Ponette, Q.; Ulrich, E. Temporal trends in the foliar nutritional status of the French, Walloon and Luxembourg broad-leaved plots of forest monitoring. Ann. For. Sci. 2009, 66, 412. [Google Scholar] [CrossRef]
  97. Peterken, G.F.; Mountford, E.P. Effects of drought on beech in Lady Park Wood, an unmanaged mixed deciduous woodland. For. Int. J. For. Res. 1996, 69, 125–136. [Google Scholar] [CrossRef]
  98. Emperaire, G.; Laming-Emperaire, A. La grotte du Mylodon (Patagonie occidentale). J. Soc. Am. 1954, 43, 214–220. [Google Scholar] [CrossRef]
  99. Thuiller, W. Large-scale environmental correlates of forest tree distributions in Catalonia (NE Spain). Glob. Ecol. Biogeogr. 2010, 12, 313–325. [Google Scholar] [CrossRef]
  100. Landmann, G. Role of Climate, Stand Dynamics and Past Management in Forest Declines: A Review of Ten Years of Field Ecology in France; Springer: Berlin/Heidelberg, Germany, 1993. [Google Scholar]
  101. Convey, P. Impacts of climate change on biota in the Arctic and Antarctic. In Proceedings of the 96th ESA Annual Convention, Austin, TX, USA, 7–12 August 2011. [Google Scholar]
  102. Thomas, F.M.; Blank, R.; Hartmann, G. Abiotic and biotic factors and their interactions as causes of oak decline in Central Europe. For. Pathol. 2010, 32, 277–307. [Google Scholar] [CrossRef]
  103. Gutschick, V.P.; Bassirirad, H. Extreme Events as Shaping Physiology, Ecology, and Evolution of Plants: Toward a Unified Definition and Evaluation of Their Consequences; Wiley/Blackwell: Hoboken, NJ, USA, 2003. [Google Scholar]
  104. Aguirre-Gutiérrez, J.; Malhi, Y.; Lewis, S.L.; Fauset, S.; Adu-Bredu, S.; Affum-Baffoe, K.; Baker, T.R.; Gvozdevaite, A.; Hubau, W.; Moore, S.; et al. Long-term droughts may drive drier tropical forests towards increased functional, taxonomic and phylogenetic homogeneity. Nat. Commun. 2020, 11, 3346. [Google Scholar] [CrossRef] [PubMed]
  105. Anderegg, W.R.L.; Trugman, A.T.; Badgley, G.; Konings, A.G.; Shaw, J. Divergent forest sensitivity to repeated extreme droughts. Nat. Clim. Change 2020, 10, 1091–1095. [Google Scholar] [CrossRef]
  106. Ackerly, D.D. Community assembly, niche conservatism, and adaptive evolution in changing environments. Int. J. Plant Sci. 2003, 164, S165–S184. [Google Scholar] [CrossRef]
  107. Li, C.; Barclay, H.; Roitberg, B.; Lalonde, R. Ecology and Prediction of Compensatory Growth: From Theory to Application in Forestry. Front. Plant Sci. 2021, 12, 655417. [Google Scholar] [CrossRef]
Water 15 03486 g001
Figure 1. The conceptual map outlines how precipitation deficits translate into plant physiological damage and ultimately potential plant mortality, thus affecting forest plant diversity. Large arrows indicate transitions from one box to another and are discussed in the text, while small arrows indicate impacts on the large arrows.
Figure 1. The conceptual map outlines how precipitation deficits translate into plant physiological damage and ultimately potential plant mortality, thus affecting forest plant diversity. Large arrows indicate transitions from one box to another and are discussed in the text, while small arrows indicate impacts on the large arrows.
Water 15 03486 g001
Table 1. Mechanisms of drought resistance and resilience.
Table 1. Mechanisms of drought resistance and resilience.
OrganismMechanismsSpecific ReactionReferences
IndividualMorpho-physiological response mechanismsStomatal closure[52]
Changing leaf structure and reducing shape[53]
Development of longer and more dense root systems[54]
Biochemical and molecular AdaptationsCompound changes in cell membrane composition[49]
Production of endogenous level of hormones[55]
Calcium signaling induced drought resistance[56]
External strategies to enhance drought resistanceExogenous application of substances[57]
Seed bank[58]
Seed dispersal[59]
Prompt defoliation[60]
CommunityPlant interactionsCompetitive effect[61]
Species specificity[62]
Passive promotion[63]
The introduction of more drought-tolerant species[64]
Community interactionsAnimal–plant interactions[65]
Plant Microbe Interactions[66]
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Zhang, T.-Y.; Di, D.-R.; Liao, X.-L.; Shi, W.-Y. Response of Forest Plant Diversity to Drought: A Review. Water 2023, 15, 3486. https://doi.org/10.3390/w15193486

AMA Style

Zhang T-Y, Di D-R, Liao X-L, Shi W-Y. Response of Forest Plant Diversity to Drought: A Review. Water. 2023; 15(19):3486. https://doi.org/10.3390/w15193486

Chicago/Turabian Style

Zhang, Tian-Ye, Dong-Rui Di, Xing-Liang Liao, and Wei-Yu Shi. 2023. "Response of Forest Plant Diversity to Drought: A Review" Water 15, no. 19: 3486. https://doi.org/10.3390/w15193486

APA Style

Zhang, T.-Y., Di, D.-R., Liao, X.-L., & Shi, W.-Y. (2023). Response of Forest Plant Diversity to Drought: A Review. Water, 15(19), 3486. https://doi.org/10.3390/w15193486

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop