Understanding the Ecosystem Services of Riparian Forests: Patterns, Gaps, and Global Trends

Abstract

Riparian forests are usually situated between terrestrial and aquatic systems. They play an essential role in the health of the environment and in providing complex ecosystem services. This is especially essential in arid and semi-arid regions. However, despite these facts, riparian ecosystems are underexplored in the specialty literature. As such, the purpose of this study is to address this gap by synthesizing the current knowledge about riparian forests, using both a bibliometric analysis and a qualitative literature approach. This analysis allowed us to identify six main ecosystem services provided by riparian forests: biodiversity support, carbon sequestration, water quality regulation, slope stability, pollution mitigation, and sociocultural benefits. Furthermore, we have emphasized local challenges (deforestation, agricultural expansion, a lack of policies). Connecting ecological knowledge with a socio-cultural context is the first step in creating a strong foundation for the adequate management of these essential ecosystems, while also supporting their conservation, development and climate resilience.

1. Introduction

The concept of riparian comes from the Latin word riparius, meaning “adjacent to the banks of a river” [1]. This includes the ecological areas that flank rivers, lakes, streams and wetlands, and emphasizes the transition between terrestrial and aquatic ecosystems. Because of this fact, these areas are very rich from a biological perspective, with species that have adapted over time to these changing hydrological conditions [2,3,4,5,6].

Riparian forests have important ecological functions, among which we mention sediment retention, erosion control, nutrient filtration, and water quality control. Furthermore, they offer ecosystem services including carbon sequestration, flood mitigation, and habitat support [7,8,9,10,11]. These aspects are crucial, especially in arid and semi-arid regions [12,13,14,15,16].

However, despite these important aspects, riparian forests and their ecosystem services are still understudied in the specialty literature. Current research studies focus on certain services like carbon storage or on contextual areas, without encompassing the global perspective or using integrative methods [17,18,19,20,21]. Furthermore, many studies have focused on ecosystem services [22,23,24] and forest-related services [25,26,27,28], but missed the perspective of riparian forests as providers of numerous ecosystem services.

This study intends to fulfill that gap by concentrating on synthesizing the ecosystem services provided by riparian forests through a combination of bibliometry and qualitative review. On the one hand, the bibliometric analysis provides scientific trends, geographic context and thematic clusters. On the other hand, the qualitative review allows an in-depth exploration of the types of ecosystem services, contextual challenges and policies.

The need to consolidate this fragmented knowledge and sustain the integration of riparian forest management plans is even more important under the current context of intensifying climate change, shifts in land usage and hydrological changes. This study intends to emphasize the essential ecological functions of riparian forests, but also focuses on policy frameworks, restoration strategies and the future directions needed at a global and interdisciplinary level.

2. Materials and Methods

The present study was developed in two parts: a bibliometric analysis, and a classic literature review. Combined together, these two approaches create a comprehensive view of the scientific research dedicated to forest ecosystem services from riparian areas during the years 1993–2024.

2.1. Bibliometric Analysis

The first stage focused on a bibliometric evaluation of global research trends concerning the ecosystem services provided by riparian forests. Our research used two major scientific databases: the Science Citation Index Expanded (SCI-Expanded) via Web of Science (WOS) and Scopus.

The Web of Science is a platform with over 7100 indexed journals covering more than 150 scientific disciplines. Most importantly, this database goes back to the 1900s. In a similar manner, Scopus offers a wide range of peer-reviewed literature, covering over 16,000 journals, plus conferences, trade publications and books. Both of them are recognized at an international scale for their coverage, reliability and citation capabilities [29]. An interesting comparison between these two systems, realized by Adriaanse and Rensleigh [30], revealed that WOS offered the largest number of citations and the most unique journal coverage, while Scopus provides the least inconsistencies and offers more accuracy. In comparison, a third system (Google Scholar) ranked lower as it had many duplicates and inconsistencies in author names, issue numbers and data.

Our keyword search strategy was created by testing different combinations. Our initial Boolean search string was (“riparian forest” OR “riparian vegetation” OR “riparian zone”) AND (“ecosystem service” OR “ecological function*” OR “environmental benefit*”). We used this search for titles, abstracts and keywords, with a search result focused on the keyword forest ecosystem services in riparian areas. By applying this search system, we reached 361 articles from Web of Science and 345 from Scopus. We then proceeded to filter the duplicates, irrelevant publications, and items that lacked abstracts, reaching a final dataset of 382 relevant entries.

The articles were filtered based on these criteria: (1) peer-reviewed article; (2) includes an abstract; and (3) focuses on riparian forests and their ecosystem services. On the other hand, the articles that were excluded were (1) publications that used keywords in an unrelated context (for example, using the term “champion” in marketing or sports contexts); (2) publications whose terms were used in a non-scientific content (editorial notes, errata); and (3) non-English sources or grey literature (technical reports, NGO publications).

As such, our bibliometric analysis was centered around ten main indicators: (1) Publication types; (2) Research areas; (3) Year of publication; (4) Country of origin; (5) Authors; (6) Institutional affiliations; (7) Language; (8) Journals; (9) Publishers; and (10) Keywords.

The data were processed and structured by using these tools: the Web of Science Core Collection [31], Scopus [32], Microsoft Excel [33], and Geochart [34]. The visualization clusters and mapping were obtained with VOSviewer (version 1.6.20) [35]. To calculate the number of citations, we used the Web of Science database (version 5.35, Clarivate, Philadelphia, PA, USA).

An important note is that some biases may be visible as we excluded non-English and grey literature. This can lead to an underrepresentation of local or regional studies as English-language papers, countries and institutions tend to be more represented in both Web of Science and Scopus. In addition, some works that are relevant might not have been captured in our specific search string as they might have used other terminologies or themes. We acknowledge these limitations and propose this transparency in interpreting the findings of this study.

2.2. Traditional Literature Review

In the second phase, a traditional literature review was conducted using the refined dataset of 382 selected articles. This in-depth qualitative assessment allowed for the thematic categorization of the research into six major areas: (1) Ecosystem services provided by riparian forests; (2) Carbon sequestration in riparian forests; (3) Riparian forests and water quality regulation; (4) Contributions of riparian forests to slope stability; (5) National and regional perspectives on riparian forest conditions and management; and (6) Degradation and loss of ecosystem services in riparian forests.

An overview of the complete methodological framework is illustrated in Figure 1.

3. Results

3.1. A Bibliometric Review

We inventoried a total of 382 publications related to forest ecosystem services in riparian areas. The majority of these are research articles (337, or 88%), followed by reviews (20, or 5%), book chapters (13, or 4%), and conference proceedings (12, or 3%) (Figure 2).

The research areas into which the published articles can be classified are diverse. Out of a total of 19 research areas, the ones with the highest share are as follows: Environmental Sciences & Ecology (85 articles); Forestry (42 articles), Biodiversity & Conservation-Environmental Sciences & Ecology (41 articles); Environmental Sciences & Ecology—Water Resources (14 articles) and Agriculture (10 articles).

The number of published articles has increased over time, with the highest number recorded in 2021 (49 articles) (Figure 3).

Authors from 72 countries have published articles on this topic. The most well-represented countries by the number of articles are the USA, Brazil, and Germany, while by total link strength they are the USA, England, Germany, Brazil, and Canada (Figure 4).

According to the analysis conducted with the VOSviewer software (version 1.6.20), the countries of origin of the authors of articles on this topic can be grouped into seven clusters, among which four clusters contain a larger number of constituent countries. Cluster 1 includes countries from North and South America: USA, Canada, Mexico, Brazil, Argentina, Chile, and Costa Rica. Cluster 2 mainly includes countries from Asia and Australia: China, Indonesia, and Australia. Two European countries can be added to this: the Netherlands (located very close to Indonesia in the graph—likely due to historical ties as Indonesia is a former colony, with scientific collaborations possibly being maintained) and Germany (positioned centrally in the graph, with numerous connections to all other clusters except the American one). Cluster 3 includes only European countries: United Kingdom, France, Portugal, Spain, and Austria. Cluster 4 includes three European countries (Italy, Greece, and Denmark) plus Colombia, which interestingly does not belong to the American cluster. However, it is represented by only a small number of articles (2), which is not representative (Figure 5).

The articles have been published in 183 journals. The most well-represented journals are as follows: Ecological Indicators, Forest Ecology and Management, and Science of the Total Environment and Forests (Figure 6).

In these articles, the most frequently used keywords are as follows: ecosystem services, conservation, biodiversity and forest.

Based on their connections, keywords can be grouped into several clusters, the most important being as follows: Cluster 1: ecosystem, forest, indicators, land use, quality, riparian forest, stream water quality (keywords related to ecosystem services and their indicators); Cluster 2: agriculture, biodiversity, conservation, corridors, disturbance, diversity, urbanization (keywords mainly related to disturbance and the domains affected by it); Cluster 3: benefits, climate change, dynamics, flood-plain, forest management, riparian forests, vegetations (keywords related to the influences exerted on riparian forests), (Figure 7).

Regarding the evolution of keyword usage over time, we can identify three periods: between 2015 and 2017, the most frequently used keywords were vegetation, riparian, forests, landscape, patterns, and disturbance; in the period 2017–2019, they were ecosystem services, management, conservation, rivers, and diversity; and in the period 2019–2021, they were climate change, services, urbanization, biodiversity conservation (Figure 8).

The institutions to which the authors of these articles belong, ranked by importance, are as follows: Universidade de Sao Paulo (9 articles); Chinese Academy of Sciences (8 articles); United States Department of Agriculture (USDA), (8 articles); and Universidad Nacional Autonoma de Mexico (5 articles).

The top publishers publishing these articles are dominated by the four major publishers: Elsevier (99 articles), Springer Nature (51 articles), Wiley (42 articles) and MDPI (33 articles).

3.2. Literature Review

3.2.1. Ecosystem Services Provided by Forests from Riparian Areas

From the large number of ecosystem services offered by riparian forests, those that have a direct description in the articles published so far are presented in

Table 1. Some of the ecosystem services provided by riparian forests (extracted from the literature).

Cur. No.	Ecosystem Service	Region	Citing Article
	Biodiversity
1	Biodiversity	general	Cole et al., 2020 [36]
	Plant biodiversity
2	Tree species	Benin; Philippines	Kinnoumè et al., 2024 [37]; Pasion et al., 2021 [38];
3	The amount and the potential role of dead wood	Italy	Tabacchi et al., 2000 [39]
	Animal biodiversity
4	Invertebrates	Malaysia	Gray et al., 2016 [40]
5	Ichthyofauna	Brazil	Collier et al., 2019 [41]
6	Bees and wasps	Brazil	de Araújo et al., 2018 [42]
7	Leaf-litter ants	Mexico	García-Martínez et al., 2017 [43]
8	Lepidoptera	Philippines	Guadalquiver et al., 2019 [44]
9	Amphibians	Brazil	Almeida et al., 2020 [45]
10	Reptiles	Philippine	Sanguila, 2020 [46]
11	Birds	Mexico; Brazil	Hernández-Dávila et al., 2021 [47]
12	Buts	Swaziland	Monadjem and Reside, 2008 [48]
	Soil
13	Improve soil permeability	general	Cole et al., 2020 [36]
14	Soil penetration resistance	Brazil	Murta et al., 2022 [49]
	Carbon sequestration
15	Carbon sequestration	Brazil	Garrastazú et al., 2015 [13]
16	Greenhouse gas production	USA	Jacinthe et al., 2015 [50]
	Sediments retention
17	Retain sediments	Brazil	Cordeiro et al., 2020 [51]
18	Trapping suspended sediment	USA	Kidd et al., 2105 [52]
	Water
19	Moderating aquatic temperatures	general	Cole et al., 2020 [36]
20	Water quality	Latvia; Italy; Costa Rica	Saklaurs et al., 2022 [53]; Tabacchi et al., 2000 [39]; Brumberg et al., 2021 [54]
21	Watercourse shading	Brazil	de Sosa et al., 2018 [55]
22	Transpiration of trees	USA	Hernandez-Santana et al., 2011 [56]
	Land use
23	Hydrological impacts of land-use and land-cover change	Mexico	Ávila-García et al., 2020 [57]
24	Connectivity across agricultural landscapes	Spain	de la Fuente et al., 2018 [58]
25	Impacts of land use policies on ecosystem services	USA	Benez-Secanho et al., 2021 [59]
26	Effects of land use, cover, and protection	Canada	Hanna et al., 2020 [60]
	Pollution
27	Intercept and remove pollutants	general	Cole et al., 2020 [36]
28	Filters for nonpoint-source pollution	USA	Lowrance, 1998 [61]
	Social and recreation
29	Recreational sites for humans	USA	Patten, 1998 [62]
30	Social and recreational values	Belgium	Rodewald and Bakermans, 2006 [63]
31	Economic benefits	USA, Sweden	Anderson and Poage, 2014 [64]; Bakx et al., 2024 [65]
	Biomass carbon sequestration		Dybala et al., 2019 [66], Aishan et al., 2018 [67]
32	Nature-based solutions	Mexic	Mendez Estrella et al., 2017 [68]; Lidman, F. et al., 2014 [69]
33	Ecosystem service bundles	England	Broadmeadow S. et al., 2004 [70]

.

3.2.2. Carbon Sequestration of Riparian Forests

The findings indicate that land-use changes favoring improved agricultural practices, the establishment of secondary forests, and especially the implementation of stricter land-use restrictions significantly enhance carbon sequestration. In contrast, relaxing riparian zone regulations is associated with a considerable risk of carbon loss. Notably, reducing buffer zone widths can lead to land conversion into agricultural or pasture uses, diminishing the carbon sequestration capacity and undermining other ecosystem services [13].

Model simulations suggest that establishing riparian forests can more than triple the baseline carbon stock of unforested soils. At maturity, riparian forests typically store between 68 and 158 Mg C/ha in biomass, with the highest carbon stocks found in warmer and wetter climatic conditions. Active reforestation efforts, such as planting, greatly accelerate biomass carbon accumulation—early growth rates were observed to be more than twice as high compared to naturally regenerating forests [66].

In the arid inland river basins of Northwest China, desert riparian forests play a crucial role in both regional environmental stability and the regulation of the global carbon cycle. Biomass productivity in these ecosystems is significantly influenced by proximity to water sources. A strong inverse correlation was found between biomass productivity and both distance from the river and groundwater depth. Approximately 64% of total biomass was concentrated within 200 m of the river, where groundwater availability supports vegetation growth. Beyond 800 m, both biomass and carbon storage decline sharply [67].

In Mexico, riparian ecosystems were found to store approximately 93 t C/ha—about 1.5 times greater than oak forests, which store an estimated 65 t C/ha. The productivity of riparian ecosystems was comparable to that of highly productive land uses, such as agriculture and oak forest, and exceeded the productivity observed in other regional ecosystems [68].

3.2.3. Riparian Forests and Water Quality Regulation

The water quality within riparian zones is closely linked to the composition and structure of ground vegetation, which is, in turn, influenced by stand density, total yield, and species composition. Effective riparian forest management requires site-specific approaches, as dominant tree species and stand characteristics (such as age and productivity) vary across landscapes. For instance, integrating Betula pubescens Ehrh. into coniferous stands has been shown to enhance litterfall quality and provide essential shading for streams during summer, helping to regulate stream temperatures [53].

Forest understory vegetation and woody plant components contribute significantly to water quality through the retention of nutrients and the sequestration of organic matter [69]. Nutrient uptake in riparian zones occurs via plant root systems interacting with water flow through the soil, as well as through microbial assimilation and sorption processes [70,71]. Riparian areas with tree-dominated vegetation—particularly those with deep-rooted plant communities—demonstrate greater effectiveness in removing nitrogen and phosphorus compared to areas dominated by shrubs or grasses [72].

Tree species, particularly those from the Salicaceae family, have been extensively studied for their capacity to accumulate environmental pollutants over extended periods. Their expansive root systems, efficient nutrient uptake, and rapid growth make them especially valuable for nutrient filtering in riparian contexts [73,74].

Riparian forested wetlands further improve downstream water quality by trapping suspended sediments and associated nutrients from surface runoff. The alternating hydrologic conditions (wet and dry periods) induced by water flow into adjacent wetlands also influence site productivity and nutrient cycling dynamics [52].

Due to their physical connectivity between aquatic systems and terrestrial catchments, riparian ecosystems play a pivotal role in regulating hydrological and ecological processes. They reduce sediment transport, provide organic inputs to aquatic systems, stabilize stream banks, and help structure both aquatic and terrestrial communities. Additionally, riparian buffer strips serve to moderate the solar radiation reaching water bodies; the removal of riparian vegetation can result in elevated water temperatures and the consequent deterioration of water quality [75].

3.2.4. Influences of Riparian Forests on Slope Stability

Vegetation is a fundamental component in maintaining slope stability within riparian ecosystems, contributing through both mechanical and hydrological mechanisms [76,77]. Mechanically, root systems bind soil particles, enhancing structural integrity and resistance to erosion. Hydrologically, vegetation influences the soil moisture content through evapotranspiration and transpiration, reducing pore water pressure and contributing to slope stability [70].

Shrubs and trees are particularly effective in stabilizing slopes compared to herbaceous vegetation, due to their deeper and more extensive root systems, which provide stronger reinforcement against soil displacement and landslides. This root reinforcement anchors above-ground biomass and lowers the likelihood of shear failure at the ecosystem scale [78,79].

The role of vegetation in enhancing slope stability is not only species-dependent but also context-specific, particularly in relation to topography. Topographical variations—such as the slope gradient, elevation, and aspect—can influence the effectiveness of riparian buffer zones. For example, elevation was found to follow the same spatial pattern as riparian width and exhibited a complex relationship with ecological indicators: it was negatively associated with habitat quality and the presence of exotic species, but positively correlated with vegetation regeneration [80].

These findings highlight the need for integrated riparian management strategies that account for both vegetative structure and topographic variability. Effective buffer zone planning should consider plant species with strong root systems as well as the local terrain, as both significantly influence erosion control, slope resilience, and the overall stability of riparian landscapes.

3.2.5. National Perspectives on Riparian Forest Conditions and Management

Riparian forest ecosystems from all over the world are under a series of pressures and challenges, all depending on policy frameworks, ecological priorities and the socioeconomic and cultural context. As such, we have focused on finding country-specific examples and then grouping them into thematic categories that emphasize patterns in their conditions, threats and conservation strategies.

Policy Frameworks, Buffers and Regulations

A number of countries have already developed policy frameworks that help define and manage riparian areas. However, their implementation and precision vary, depending on the country. For example, Aquatic Buffer Zones (ABZs) from Ireland have been mandated since 1991 in order to supply conifers during afforestation or replantation. These areas, ranging from 10 to 25 m, are usually left alone so that native vegetation can take over [81]. A similar case is found in the United Kingdom, where riparian buffers are used to address land pollution or offer ecosystems services. However, the lack of a standardized width for these buffers poses certain limits, especially from an ecological perspective. As such, fixed buffers are more effective in removing pollution, while variable buffers are better for supporting denitrification. Research only confirms the need to design buffers based on the specific case, and then validate it directly on the field [55]. Another example can be found in the United States, where the Northwest Forest Plan (NWFP) moved away from timber production and focused more on preserving the ecosystem. As such, more than 1 million riparian hectares were used to support ecological functions. And what is still more important is that the effectiveness of these buffers is still monitored, through the Density Management and Riparian Buffer Study (DMS) [64]. One last example comes from Brazil, where the Forest Code (BFC) requires the protection and restoration of riparian areas. However, a clear guideline regarding their location around small streams leaves room for uncertainties. This only requires a clearer guideline, as well as a focus on small areas as well [82].

Restoration and Rehabilitation Initiatives

Restoration programs are already in use in many countries that deal with ecological degradation. For example, since 2000, China has put in place a series of initiatives (the Integrated Water Resource Management of the Tarim River Basin, the Ecological Water Diversion Project (EWDP)) that focus on the regenerative role of riparian forests. Further studies have focused on the response of groundwater and the rehabilitation of the physiological traits of forests [83,84]. Another program from China, the Grain for Green Program (GGP), focuses on soil erosion and promotes afforestation, especially on slopes and riparian farmlands. Over time, these actions proved to improve soil functions, purify water and mitigate floods [85,86,87,88]. Moving to another country, the native riparian forests from the Koiliaris watershed in Greece have been restored and proved to be the most effective natural solution to reversing soil degradation and desertification [89]. On the other hand, riparian forests from Poland are deteriorating, with only 46% having a good conservation status. This situation has been caused by lower precipitation, the influence of humans, a lack of forest management initiatives and the spread of invasive species [90].

Governance and Implementation Challenges

Although legal frameworks are in place in many countries, there are still challenges that impact the effective management of these riparian forests. For example, Kenya has instituted policies such as the Environment Management and Coordination Act (EMCA) and Water Resources Management Rules (WRMR). However, their implementation has been fragmented because of overlapping mandates and confusing laws. This situation is commonly found in southeastern semiarid regions that have been affected by deforestation in order to make place for agriculture or human settlements [91,92]. For example, Tanzania has similar problems and lacks conservation practices that can improve the management of riparian areas. This is especially true considering that riparian vegetation is crucial in sustaining water flow [93].

Ecosystem Services and Community Dependence

Numerous communities depend on riparian forests for their livelihoods as well as ecosystem services. For example, the riparian ecosystem in the Bangladesh delta is threatened by monsoon erosion, freshwater loss and salinity intrusions. Climate change only accentuates these vulnerabilities as sea levels increase. In this context, the restoration of mangroves is essential in improving ecosystem resilience and impending environmental risks [94]. Another example can be found in Mexico, where the Río Grande de Comitán–Lagos de Montebello proves that forests are responsible for improving fog, evapotranspiration and water yield. This must be studied further in order to adapt current strategies to local conditions [57]. Communities from the native Nothofagus dombeyi forests in Chile value these forests as they play an essential role in water flow and quality [95]. The tugai forests of Central Asia are another example of the impact of riparian forests on ecosystems, erosion, biodiversity and migratory birds [96,97,98]. One last example is from Botswana, where the riparian vegetation from the Okavango Delta is praised and used by local communities in construction, transportation (traditional mekoro canoes) or products such as palm beverages. This only underscores the interdependence of ecology and humanity [99,100,101,102].

3.2.6. Degradation and Loss of Ecosystem Services in Riparian Forests

Riparian forests worldwide are under increasing threat from anthropogenic activities, which have led to significant degradation and the consequent loss of critical ecosystem services. One of the most impactful drivers is the construction of dams for hydroelectric power, which inundates riverbanks and leads to the destruction of riparian biotic communities [42] (de Araujo).

In addition to damming, widespread land-use changes—particularly from agriculture, industrial expansion, and urban encroachment—have made riparian zones some of the most heavily degraded ecosystems globally [103,104]. Poorly managed forestry operations, especially in timber-producing regions, further exacerbate this degradation. Logging in riparian and adjacent upland areas can disrupt key ecosystem functions, particularly in zones characterized by high groundwater (GW) discharge. These areas often have sensitive soils and strong hydrological connectivity with upland regions, increasing their vulnerability. Therefore, forestry planning must integrate enhanced riparian buffer zone management, particularly in GW discharge hotspots, to safeguard these ecosystems [105].

In Brazil, the continuous conversion of riparian forests into agricultural land has resulted in both vegetative degradation and negative alterations to soil characteristics and ecosystem functions. Forest degradation significantly reduces soil carbon, phosphorus, cation exchange capacity, silt content, porosity, and water infiltration capacity. Vegetation structure—particularly tree height, basal area, and herbaceous biomass—proves to be a reliable proxy for monitoring soil-related ecosystem services such as water regulation, erosion control, and nutrient cycling. This relationship offers a strategic approach to monitoring and modeling riparian forest services at broader spatial scales, aiding restoration and conservation efforts [106].

In the rural Peruvian Amazon, the deforestation of riparian zones has direct social implications. Given the region’s dependence on aquatic resources, such ecological disturbances pose substantial risks to local community health and well-being [107].

Hydrological alterations also pose significant challenges. In hyper-arid regions such as the floodplains of Populus euphratica, decreasing water availability—driven by intensive agricultural irrigation—threatens the long-term regeneration of forest species and undermines the overall structure and functioning of these ecosystems [108].

Empirical studies further illustrate the ecological consequences of riparian deforestation. A comparative analysis of 16 stream reaches in eastern North America revealed that deforestation leads to channel narrowing, which decreases stream habitat availability and impairs in-stream processing of organic matter and pollutants. In contrast, forested reaches support higher biodiversity, greater organic matter breakdown, and more efficient nutrient uptake. These findings emphasize that riparian vegetation enhances not only channel morphology but also the functional integrity of aquatic ecosystems [17].

Across the western United States, riparian systems have been extensively modified by urban development, dam construction, groundwater extraction, overgrazing, and the introduction of invasive species. These disruptions, combined with land-use changes within watersheds, have fundamentally altered riparian biotic communities [62].

In Central Asia, particularly in Xinjiang and the Tarim Basin, growing demands for water-intensive cash crops such as cotton have intensified pressures on riparian ecosystems. Overextraction of water has led to declining groundwater levels and extensive salinization, resulting in significant losses of ecosystem services and the degradation of poplar-dominated floodplain forests [109,110].

In northeastern China (Altai Prefecture), riparian forest health has been severely compromised by long-term inappropriate land use and large-scale hydrological projects. Reservoir management and water diversion activities have disrupted natural flow regimes essential for riparian regeneration. Mining activities have further accelerated soil erosion, and conflicting agricultural and pastoral land-use demands have impeded forest recovery. These cumulative impacts have led to significant declines in vegetation structure and habitat quality [111,112,113,114].

4. Discussion

4.1. Bibliometric Review

Unsurprisingly, research articles dominate the body of literature on this topic. However, what stands out is the relatively high number of review papers, which highlights the complexity and breadth of the subject. This diversity allows for more comprehensive, synthesis-based analyses. The wide array of research areas these publications span is also evident. There are several review articles directly related to our topic. For example, Gundersen et al. [4] provide a review of the ecosystem services offered by riparian forests in Nordic countries, focusing on water protection, terrestrial biodiversity, carbon storage, and greenhouse gas dynamics. Similarly, Vidal-Abarca Gutierrez and Suarez Alonso [115] examine the ecosystem services provided by rivers and riparian zones in Spain.

One country that stands out due to the high volume of published research and contributing researchers is Brazil. This can be attributed to the presence of one of the world’s largest river systems, namely the Amazon. However, riparian ecosystems in Brazil have faced significant pressures from human activities and shifting environmental policies [13]. Studies show that land use and land cover changes in tropical riparian zones critically impact ecosystem services tied to soil carbon and nitrogen cycles [116,117]. However, the data on subtropical riparian systems remain limited, particularly in the southern part of the Atlantic Forest Biome.

The journals in which these articles have been published mainly fall under two broad scientific domains: Environmental Sciences (e.g., Science of the Total Environment, Ecological Indicators, Journal of Environmental Management) and Forestry (e.g., Forest Ecology and Management, Forests, Frontiers in Forest and Global Change). Frequently used keywords such as ecosystem services, conservation, biodiversity, and forest also align with these categories. In recent years, however, there has been a noticeable shift toward keywords that reflect current global concerns, including climate change, urbanization, and biodiversity conservation.

Among the most frequently used keywords, we mention ecosystem services, conservation, biodiversity, and forest. However, recent years have shifted the focus towards keywords that are more aligned with global concerns such as climate change, urbanization, and biodiversity conservation. This fact emphasizes the interest of researchers in studying riparian forests under a broader socio-environmental and political context. As riparian forests play an essential role in carbon sequestration, climate regulation and adaptive strategies, it is normal to see a growth of studies focused on the climate change approach. Furthermore, studies have started to explore more how riparian forests can be a buffer against climate disruptions such as floods and droughts. The reverse also applies, where studies focus on the effects of climate changes on riparian biodiversity and ecosystem functioning. In a similar manner, urbanization keywords are more prevalent, highlighting the impact of urban expansion on riparian areas and landscapes. Numerous studies focus on the degradation and fragmentation of riparian forests because of urban developments. Here, the reverse also applies, with many studies focusing on how riparian forests can positively affect urban spaces, due to stormwater mitigation, heat reduction, and the creation of recreational spaces. We can also note the preponderance of biodiversity conservation keywords, sustaining the need to protect species from riparian forests. Many studies focus on the need to preserve these habitats because of their ecological value, but also because of their impact of human societies. All these emerging keywords sustain the need to continue and even extend the studies on riparian ecosystems. More importantly, rather than focusing only on their ecological role, studies must embrace an interdisciplinary approach, integrating both social, political and cultural contexts. Only through this method can we address these global challenges.

4.2. Literature Review

4.2.1. Ecosystem Services Provided by Forests from Riparian Areas

Riparian forests are essential providers of ecosystem services that have both an ecological and societal impact. By analyzing the literature, we have synthesized their role in sequestrating carbon, regulating water, stabilizing slopes and supporting biodiversity. Through this, we can emphasize patterns and trends, as well as identify key priorities in their research and regulation.

Riparian forests are similar to carbon sinks, having important sequestration advantages. These are also recognized by reforestation works and buffer policies [13]. These effects are even more accentuated in secondary areas or forests that are regulated by strict land usage. As such, the reduction in buffer widths can be linked to decreases in carbon storage as land-use conversions increase.

In Central Asia, particularly in Xinjiang and the Tarim Basin, growing demands for water-intensive cash crops such as cotton have intensified pressures on riparian ecosystems. Overextraction of water has led to declining groundwater levels and extensive salinization, resulting in significant losses of ecosystem services and the degradation of poplar-dominated floodplain forests [109,110].

In northeastern China (Altai Prefecture), riparian forest health has been severely compromised by long-term inappropriate land use and large-scale hydrological projects. Reservoir management and water diversion activities have disrupted natural flow regimes essential for riparian regeneration. Mining activities have further accelerated soil erosion, and conflicting agricultural and pastoral land-use demands have impeded forest recovery. These cumulative impacts have led to significant declines in vegetation structure and habitat quality [111,112,113,114].

The potential for sequestration depends on the climate, succession stage and proximity to water. For example, biomass from arid regions decreases significantly beyond 800 m as river water and groundwater become more limited [67]. In contrast, restoration (especially through active planting) increases carbon in the early stages, compared to passive regeneration [66]. This is complemented by the hydrological conditions of riparian areas (such as high soil moisture and nutrients), with essential effects on the development of biomass [118,119,120]. Sometimes, this can place riparian species even above their upland counterparts [121,122]. But, we must ascertain that this depends on local conditions and variables, as many studies have shown that there are no significant differences between some temperate areas [123,124].

These findings only sustain the need to include riparian areas in climate strategies and national policies, with a special focus on degraded and arid locations. These policies should focus on restoration, as well as on buffer zones and their standards based on the local hydrological context.

Riparian forests play a special role in filtering sediments, stopping pollutants and regulating nutrient flows [39,125]. A dense, layered vegetation impacts runoff and improves the capture of sediments. Furthermore, the rich microbial soils of riparian forests play a role in denitrification. However, the mobility of phosphorus can sometimes increase [75,126].

Some species with deep roots (Salix, Populus) play an essential role in the cycle of nutrients and the stabilization of soils [127,128]. Another crucial role in the buffer of nutrients is played by riparian wetlands as their flood–dry cycles influence biological and chemical transformations [52,129]. These processes are essential in mitigating non-point source pollution, particularly in agricultural landscapes, where runoff contributes to eutrophication and sedimentation [130].

A great example is the usage of riparian forests in agricultural areas that are affected by nutrient runoff and eutrophication (such as the US Midwest, China or India). Here, the restoration of riparian forests can be a valuable solution for reaching local and national water quality targets. The physical presence of trees improves infiltration, enhances soil porosity and permeability, and contributes to greater water retention [131,132].

Slope Stability and Erosion Control

Riparian ecosystems also play an essential role in stabilizing slopes because of their complex roots that can hold soils together, increase strength and reduce moisture levels [40,77]. The risk of erosion is determined by the slope angle, the intensity of land usage and the vegetation present [51]. In this context, trees are crucial because of their deeper roots [78,79]. In this context, restoration plans should integrate root architecture and data when planning riparian forests as they can improve and control erosion. This is specially applicable to vulnerable landscapes such as the Andean foothills or the Southeast Asian watersheds.

Biodiversity and Habitat Connectivity

Riparian forests include a diverse range of plants and animals, especially in fragmented landscapes [133,134,135]. Furthermore, they support and sustain rare and endangered species [136,137]. Studies report higher abundances of native plant species, woodland beetles, insectivorous mammals, and bats in riparian woodlands compared to open buffers [138,139,140]. Through leaf litter and deadwood, they also improve these habitats [141,142,143]. An important difference is between deciduous systems, which support invertebrate biomass, and coniferous ones [144].

In addition, these forests promote gene flow and the migration of species [145,146,147], which is especially important in areas that are affected by climate changes or urban developments [148,149].

As such, when creating policies for riparian forests, these should take into account both their conservation and connectivity. Riparian forests must be included in landscape planning as they are a core element of their infrastructure.

4.2.2. National Perspectives on Riparian Forest Conditions and Management

The comparative analysis of riparian forest management across countries reveals both shared challenges and context-specific strategies that reflect diverse ecological conditions, governance structures, and societal priorities. A recurring theme is the recognition of riparian forests as multifunctional systems that deliver a broad suite of ecosystem services (ES), from water purification and erosion control to biodiversity support and cultural values. Despite this, the conservation status and management of these forests vary widely.

Several European countries, such as Poland, the United Kingdom, and Ireland, have made progress in integrating ES into forest policy and planning, yet practical implementation gaps remain. In Poland, the unfavorable conservation status of nearly half the monitored riparian hardwood stands underscores the pressure exerted by hydrological alterations, invasive species, and unsustainable land use. This situation highlights the need for more adaptive and ecologically informed management approaches that account for altered flood regimes and declining groundwater levels. Conversely, in the UK and Ireland, policy frameworks have begun to emphasize riparian buffers and aquatic buffer zones, respectively, as tools to safeguard ES. However, the lack of standardized criteria for buffer design—particularly in terms of width and service-specific optimization—indicates a critical knowledge gap that must be addressed through field-based validation and service-targeted planning [55,82].

Southern European and Mediterranean countries, such as Greece, also illustrate how historical land degradation and ongoing agricultural pressures necessitate nature-based solutions. The restoration of riparian forests in areas like the Koiliaris watershed demonstrates that reestablishing native vegetation can significantly enhance ecological resilience and mitigate desertification. This aligns with the broader EU Biodiversity Strategy 2020 objectives, which emphasize the role of ES in informing management practices and conserving multifunctional landscapes [150,151].

In Asia, large-scale ecological restoration programs exemplify how targeted government initiatives can reverse ecological decline. In China, programs such as the Ecological Water Diversion Project (EWDP) and Grain for Green (GGP) reflect a comprehensive approach to the rehabilitation of riparian zones through afforestation, hydrological rebalancing, and service enhancement. These efforts demonstrate a strategic alignment of riparian forest restoration with national development and climate mitigation goals, especially in fragile arid regions like the Tarim Basin. Similarly, the tugai forests of Central Asia are recognized for their vital ES, though their continued degradation underscores the need for stronger protection mechanisms across national boundaries. In Bangladesh, the convergence of climate-related stressors and transboundary water issues has intensified the vulnerability of riparian and mangrove ecosystems. Restoration strategies, particularly for mangroves, are being increasingly adopted as frontline defenses against sea-level rise, salinity intrusion, and storm surges, highlighting the direct link between ecological restoration and human adaptation.

In the Americas, forest policies have increasingly shifted from production to conservation-oriented paradigms. The United States’ Northwest Forest Plan (NWFP) and associated studies like the DMS reflect an evidence-based approach to riparian buffer management, aiming to balance habitat preservation with broader ES goals. Meanwhile, Mexico and Brazil present contrasting challenges: in Mexico, the ecosystem–water nexus is emphasized in watershed management, although strategies remain locally contingent; in Brazil, regulatory ambiguity under the Forest Code complicates enforcement, particularly for small stream riparian zones whose cumulative importance is often underappreciated.

In South America, particularly in Chile, the acknowledgment of ES by local communities provides a strong socioecological foundation for riparian forest protection. This bottom-up valuation is key to successful, enduring conservation outcomes, especially where institutional enforcement is limited.

In Sub-Saharan Africa, structural governance challenges persist. Tanzania and Kenya both illustrate how fragmented policies and institutional overlap hinder coherent riparian management. In Kenya, although legislation exists, implementation suffers due to regulatory fragmentation and land use pressure. In Botswana, the traditional dependence on riparian resources within the Okavango Delta exemplifies how ecosystem health is directly tied to local livelihoods, making the protection of riparian vegetation a socio-economic imperative as well as an ecological one.

Overall, these national case studies affirm the growing recognition of riparian forests as integral to sustainable land and water management. Recent forest planning frameworks increasingly account for ecosystem multifunctionality, as noted by Frank et al. [150], offering a path toward better conservation outcomes. To bridge the gap between policy intent and ecological reality, riparian forest management must be grounded in service-specific, site-appropriate strategies that are co-developed with local stakeholders. Elevating riparian zones within national biodiversity and climate strategies—while clarifying regulatory standards and fostering cross-sectoral collaboration—can unlock their full potential as providers of critical ecosystem services.

4.2.3. Degradation and Loss of Ecosystem Services in Riparian Forests

However, despite of all these advantages, riparian forests are one of the most endangered ecosystems at a global scale [152,153,154]. The main pressures are posed by land conversion (towards agriculture and urban development), river regulations (such as dams) and certain forestry operations.

A good example comes from dam-induced changes [103,104]. These can significantly alter floodplain connectivity, with a visible impact on the regeneration of forests and the delivery of their services [105]. Arid regions are especially targeted, such as Populus euphratica zones [108]. On the other hand, agricultural practices in Brazil and deforestation in the Amazon have a degrading effect on ecosystem services. They affect the cycle of nutrients, infiltration processes and the overall biodiversity [106,107]. As for deforestation, cuttings from temperate forests have proved to disrupt groundwater and the overall structure of forests [155,156,157,158,159].

These cumulative disturbances illustrate the fragility of riparian systems under combined pressures from hydrological alteration and land-use change. As floodplain vegetation becomes increasingly threatened by drought and altered flow regimes, even early successional stages (seedlings and saplings) are at risk of mortality, compromising long-term forest regeneration [160,161,162].

The degradation of riparian buffer strips and associated forest cover also directly impacts water quality and yield at the catchment level. Mismanagement of water resources, including uncoordinated reservoir operations and unsustainable irrigation, further exacerbates these effects. As noted byJunk Hunter, and Kroes [163,164,165] disturbances that alter the hydrologic regime of riparian forested wetlands not only disrupt their structure but also their functional capacity to provide ecosystem services—ranging from flood attenuation and sediment retention to nutrient filtering and biodiversity support.

As such, management practices should include integrated strategies that take into account all these aspects (hydrological integrity, land usage, species recovery threshold). This emphasizes the need to restore natural flood regimes and to include riparian forests in local and national policies. A high level of genetic diversity and a maximum caution to the transfer of forest reproductive materials is also needed [166,167,168]. In particular, statistical and numerical methods are still widely used [169,170].

In summary, the degradation of riparian forests across diverse global contexts underscores the critical need for integrated, adaptive management that reconciles ecological function with human demands. Protection and restoration strategies must account for the unique vulnerabilities of RFs to hydrological change, land-use pressure, and climate variability. Emphasizing riparian zones as dynamic ecological corridors—rather than static buffer strips—may help shift the management paradigm toward a more holistic, process-oriented approach capable of safeguarding their ecosystem service potential in the future.

While this review provides a comprehensive synthesis of the current state of knowledge on forest ecosystem services in riparian areas, several gaps and limitations must be acknowledged. The bibliometric analysis, though robust, is inherently constrained by the search terms and databases used. By focusing primarily on Web of Science and Scopus and using the phrase “forest ecosystem services in riparian areas” as the core search term, some relevant studies—particularly those published in non-indexed regional journals or in grey literature (e.g., government and NGO reports)—may have been overlooked. As a result, there may be a geographic or linguistic bias in the literature base, with English-language publications and research from countries with greater scientific visibility being disproportionately represented. The ecological heterogeneity of riparian zones poses challenges for generalization. Riparian forests vary widely in structure, function, and management across climatic zones, hydrological regimes, and socio-political contexts. Although we included a range of case studies, our ability to offer globally applicable recommendations is limited by the context-specific nature of many findings. The dynamic and often rapidly changing policy environments surrounding land use and forest management in many countries mean that some of the policy insights reviewed here may already be in flux. Continuous updates and adaptive research frameworks are therefore necessary to ensure that conclusions remain relevant in light of evolving environmental and governance challenges.

Despite growing academic and policy interest in riparian forest ecosystem services, several key areas remain underexplored and present promising opportunities for future research. For regional data gaps and understudied ecosystems, while substantial work has been performed in regions such as North America, Europe, and Brazil, there remains a notable lack of research from subtropical, semi-arid, and developing regions—particularly in parts of Africa, Central Asia, and Southeast Asia. Future studies should prioritize these areas to develop a more globally representative understanding of riparian ecosystem services. Regarding the quantification of ecosystem service trade-offs, more research is needed to assess the trade-offs between the different ecosystem services provided by riparian forests. For example, maximizing carbon sequestration may conflict with biodiversity conservation or water yield. Regarding the integration of social–ecological frameworks, riparian forest research must increasingly consider the social dimensions of ecosystem services. Understanding local perceptions, community dependencies, and cultural values can improve conservation outcomes. Participatory mapping, stakeholder engagement, and socio-economic valuation studies are necessary to inform equitable and effective management practices.

4.2.4. Gaps, Research Needs, and Future Directions

Although our synthesis is broad, there are still some areas that can be addressed in the future:

Underrepresented regions and ecosystem types. Most of the studies come from North America, Europe, and Brazil, while subtropical, semi-arid and tropical regions (Sahel—Africa, Tarim River Basin—Central Asia, Mekong and Salween basins—Southeast Asia) are clearly understudied. Future studies should be devoted to these areas.

Neglected ecosystem services. Most of the studies have focused solely on carbon and water-related services. Some aspects that should be considered by future studies include biodiversity trade-offs, the cultural values of riparian forests, and their complex services (including medicinal plants, fisheries).

Research agendas and methods. More research is needed regarding the methods used in these studies. Some examples include field validation, social and ecological assessments, trade-off modelling, participatory mapping and stakeholder involvement.

Conceptual and policy frameworks. Riparian areas can be grouped based on their ecological status (intact, degraded, recovering), dominant ecosystem services (hydrological, carbon, biodiversity) and socio-political context (high governance capacity, contested land). This approach can be an effective tool in restoring and protecting these areas, while also being adapted to regional contexts.

5. Conclusions

Our review reinforces the complex importance of riparian forests as providers of diverse ecosystem services, especially under growing climate change and environmental pressures. By synthesizing data from almost 400 peer-reviewed studies covering three decades, we have documented a growth in academic and policy interest regarding these ecosystems.

Our study shows that riparian forests are essential for biodiversity conservation, carbon sequestration, water quality enhancement, and slope stabilization. Most importantly, we emphasize the complex interactions between biophysical factors (such as vegetation type, hydrology, soil properties) and socio-political factors (land-use policy, management regulations and institutional frameworks).

Despite a widespread recognition of their value, riparian forests remain among the most vulnerable ecosystems. Pressures such as deforestation, hydrology alterations, agricultural expansion and weak regulations have triggered their degradation. Furthermore, the absence of specific management strategies and standards undermines their conservation and restoration.

Our analysis points to several pressing needs: (1) the better integration of ecosystem frameworks into riparian management policies; (2) better research in understudied regions such as subtropical and semi-arid ones; (3) adopting a cross-disciplinary approach that connects scientific findings with policies and local; and (4) developing targeted restorations that reflect the ecological conditions and community needs.

In conclusion, riparian forests should not be viewed as marginal landscapes but recognized as resilient and essential for both natural ecosystems and local communities. Protecting and enhancing their uniqueness should be a priority at a global level, especially under climatic changes and intensifying land-usage. The research and governance communities should work together to make them more visible and valuable.