Search Results (519)

Tropical forests continue to experience high levels of habitat loss and degradation, with wildfires becoming a frequent component of human-modified landscapes. Here we investigate the response of palm species to the conversion of old-growth forests to successional mosaics, including forest patches burned during wildfires. Palms (≥50 cm height) were recorded once in 2023–2024, across four habitat classes: terra firme old-growth stands, regenerating forest stands associated with slash-and-burn agriculture, old-growth stands burned once and twice, and active cassava fields, in the Tapajós-Arapiuns Extractive Reserve, in the eastern Brazilian Amazon. The flammability of palm leaf litter and forest litter were also examined to assess the potential connections between palm proliferation and wildfires. A total of 10 palm species were recorded in this social forest (including slash-and-burn agriculture and resulting successional mosaics), with positive, negative, and neutral responses to land use. Species richness did not differ among forest habitats, but absolute palm abundance was greatest in disturbed habitats. Only Attalea spectabilis Mart. (curuá) exhibited increased relative abundance across disturbed habitats, including active cassava field. Attalea spectabilis accounted for almost 43% of all stems in the old-growth forest, 89% in regenerating forests, 90% in burned forests, and 79% in crop fields. Disturbed habitats supported a five-to-ten-fold increment in curuá leaves as a measure of habitat flammability. Although curuá litter exhibited lower flame temperature and height, its lower carbon and higher volatile content is expected to be more sensitive to fire ignition and promote the spread of wildfires. The conversion of old-growth forests into social forests promotes the establishment of palm-dominated forests, increasing the potential for a forest transition further fueled by wildfires, with effects on forest resilience and social reproduction still to be understood. Full article

Peatlands store substantial amounts of carbon (C) in the form of peat, but are increasingly threatened by drought and shrub encroachment under climate warming. However, how peat decomposition and its temperature sensitivity (Q₁₀) vary with depth and plant litter input under these stressors remains poorly understood. We incubated peat from two depths with different degrees of decomposition, either alone or incubated with Sphagnum divinum shoots or Betula ovalifolia leaves, under five temperature levels and two moisture conditions in growth chambers. We found that drought and Betula addition increased CO₂ emissions in both peat layers, while Sphagnum affected only shallow peat. Deep peat alone or with Betula exhibited higher Q₁₀ than pure shallow peat. Drought increased the Q₁₀ of both depths’ peat, but this effect disappeared with fresh litter addition. The CO₂ production rate showed a positive but marginal correlation with microbial biomass carbon, and it displayed a rather similar responsive trend to warming as the microbial metabolism quotient. These results indicate that both deep and dry peat are more sensitive to warming, highlighting the importance of keeping deep peat buried and waterlogged to conserve existing carbon storage. Additionally, they further emphasize the necessity of Sphagnum moss recovery following vascular plant encroachment in restoring carbon sink function in peatlands. Full article

The transition zone between the Qinghai–Tibet and Loess Plateaus is an important ecological functional area and carbon (C) reservoir in China. Studying the main drivers of C density changes in forest ecosystems is crucial to enhance the C sink potential of those ecosystems in ecologically fragile regions. In this study, four stand types at different succession stages in the transition zone of Xinglong Mountain were selected as the study objective. The C densities of the ecosystem, vegetation, plant debris, and soil of each stand type were estimated, and the related driving factors were quantified. The results showed that the forest ecosystem C density continuously increased significantly with natural succession (381.23 Mg/hm² to 466.88 Mg/hm²), indicating that the ecosystem has a high potential for C sequestration with progressive forest succession. The increase in ecosystem C density was mainly contributed to by the vegetation C density, which was jointly affected by the vegetation characteristics (C sink, mean diameter at breast height, mean tree height), litter C/N (nitrogen), and surface soil C/N, with factors explaining 95.1% of the variation in vegetation C density, while the net effect of vegetation characteristics was the strongest (13.9%). Overall, this study provides a new insight for understanding the C cycle mechanism in ecologically fragile areas and further improves the theoretical framework for understanding the C sink function of forest ecosystems. Full article

Perennial ryegrass (Lolium perenne), an important forage and turfgrass species, can establish a mutualistic symbiosis with the fungal endophyte Epichloë festucae var. lolii. Although the physiological and ecological impacts of endophyte infection on ryegrass have been extensively investigated, the response of the soil microbial community and nitrogen-cycling gene to this relationship has received much less attention. The present study emphasized abundance and diversity variation in the AOB-amoA, nirK and nosZ functional genes in the rhizosphere soil of the endophyte–ryegrass symbiosis following litter addition. We sampled four times: at T₀ (prior to first litter addition), T₁ (post 120 d of 1st litter addition), T₂ (post 120 d of 2nd litter addition) and T₃ (post 120 d of 3rd litter addition) times. Real-time fluorescence quantitative PCR (qPCR) and PCR amplification and sequencing were used to characterize the abundance and diversity of the AOB-amoA, nirK and nosZ genes in rhizosphere soils of endophyte-infected (E+) plants and endophyte-free (E−) plants. A significant enhancement of total Phosphorus (P), Soil Organic Carbon (SOC), Ammonium ion (NH₄⁺) and Nitrate ion (NO₃⁻) contents in the rhizosphere soil was recorded in endophyte-infected plants at different sampling times compared to endophyte-free plants (p ≤ 0.05). The absolute abundance of the AOB-amoA gene at T₀ and T₁ times was higher, as was the absolute abundance of the nosZ gene at T₀, T₁ and T₃ times in the E+ plant rhizophere soils relative to E− plant rhizosphere soils. A significant change in relative abundance of the AOB-amoA and nosZ genes in the host rhizophere soils of endophyte-infected plants at T₁ and T₃ times was observed. The experiment failed to show any significant alteration in abundance and diversity of the nirK gene, and diversity of the AOB-amoA and nosZ genes. Analysis of the abundance and diversity of the nirK gene indicated that changes in soil properties accounted for approximately 70.38% of the variation along the first axis and 16.69% along the second axis, and soil NH₄⁺ (p = 0.002, 50.4%) and soil C/P ratio (p = 0.012, 15.8%) had a strong effect. The changes in community abundance and diversity of the AOB-amoA and nosZ genes were mainly related to soil pH, N/P ratio and NH₄⁺ content. The results demonstrate that the existence of tripartite interactions among the foliar endophyte E. festucae var. Lolii, L. perenne and soil nitrogen-cycling gene has important implications for reducing soil losses on N. Full article

Urban forests provide essential ecosystem services, including improving soil health, sequestering carbon (C), and supporting biodiversity. However, the effects of anthropogenic litter and root management on soil biogeochemical processes in urban environments remain poorly understood. This study applied the Detritus Inputs and Removal Treatment (DIRT) framework to examine how aboveground and belowground organic inputs influence soil organic carbon (SOC), total nitrogen (TN), soil water content (SWC), and enzymatic activities in subtropical urban camphor tree forests in China. Six treatments were implemented: litter removal (LR), litter addition (LA), root exclusion (RE), combined litter and root removal (LR + RE), combined litter addition and root exclusion (LA + RE), and an undisturbed litter control (LC). The results showed that the LA treatment significantly enhanced SOC, TN, SWC, and key soil enzyme activities (protease, catalase, and urease) compared to the LC, highlighting the crucial role of litter in enhancing soil fertility and microbial functioning. These elevated enzyme activities suggest intensified microbial nutrient cycling and metabolic activity in response to organic matter inputs. In contrast, the combined LR + RE treatment reduced SOC and enzyme activities but unexpectedly increased TN, indicating disrupted nutrient cycling, possibly due to accelerated microbial nitrogen mineralization and decomposition of existing soil organic matter in the absence of fresh carbon inputs. The LA treatment also showed the highest carbon-to-nitrogen (C:N) ratio, reflecting a carbon-enriched environment that may favor long-term carbon stabilization. Additionally, SWC was most improved under the LA + RE treatment, suggesting its potential for enhancing soil moisture retention in urban settings. These findings underscore the complementary roles of litter and root inputs in maintaining soil health and biogeochemical balance in urban forests. The study provides insights into enzyme-mediated soil processes under varying organic input regimes and highlights the value of targeted organic matter management to enhance urban ecosystem services. Full article

The land-use conversion of Masson pine forests to tea fields is extensively practiced across subtropical China, primarily driven by its economic benefit. However, the effects of this conversion on soil fungal communities and functional guilds are poorly understood. Herein, a field experiment was conducted in a Masson pine forest (F), a 5-year-old tea plantation without (FT-CK) fertilization or with (FT-N), and a 30-year-old tea plantation (FT-O) to assess the impact of Masson pine forest-to-tea conversion on soil fungal abundance, community structure, and functional guilds by using qPCR and high-throughput sequencing. Compared to F, fungal abundance significantly decreased by 95%, 68%, and 79% in FT-CK, FT-N, and FT-O, respectively, probably caused by the decreased total nitrogen content and habitat disruption. Fungal alpha diversity significantly increased in FT-N and FT-O compared to FT-CK. FT-O presented the highest percentages of Mortierella among treatments, which favours soil organic carbon accumulation. FUNGuild-based predictions showed that FT-CK and FT-N had higher relative abundances of plant pathogens than F and FT-O. FT-O presented the highest percentages of litter and soil saprotrophs but exhibited the lowest percentages of ectomycorrhizal fungi among treatments, likely driven by increased soil organic carbon, total nitrogen, and total phosphorus content. Our findings demonstrate that Masson pine forest-to-tea conversion significantly degrades soil fungal community and function, highlighting the urgent need for soil management strategies (e.g., organic amendments) to enhance soil health in tea agroecosystems. Full article

Acid deposition, a major environmental issue causing soil acidification and microbial suppression, impacts forest nutrient cycling. Meanwhile, nitrogen (N) fertilization is widely applied in subtropical forests, yet its interaction with acid deposition on litter decomposition is unclear. We conducted a field experiment using two common tree species, Cunninghamia lanceolata and Cinnamomum camphora, and applied three acid deposition levels (0, 0.25, and 0.50 g H⁺ m⁻² month⁻¹) and four N fertilization levels (0, 3, 6, and 9 g N m⁻² year⁻¹) in a factorial design. Our results showed that acid deposition alone significantly reduced litter decomposition rates, with maximum mass loss decreasing by 23.6% for Cunninghamia and 36.3% for Cinnamomum (p < 0.05). Urea fertilization alone also suppressed decomposition, reducing maximum mass loss by 27.3% for Cunninghamia and 37.3% for Cinnamomum (p < 0.05). However, when combined, urea fertilization mitigated the suppressive effect of acid deposition, particularly under severe acid conditions, where maximum mass loss increased by 18.5% for Cunninghamia and 43.1% for Cinnamomum (p < 0.05). Acid deposition reduced microbial respiration and enzyme activities related to carbon cycling, while urea fertilization showed both positive and negative effects depending on the acid levels (p < 0.05). Urea can enhance the litter layer’s acid-buffering capacity, offering potential management insights for acid deposition-affected forests. Further research on microbial mechanisms across ecosystems is recommended. Full article

What is the potential impact on carbon storage of the native and introduced tree species commonly associated with coffee in the central Peruvian Amazon? Coffee is a pivotal crop within the Peruvian economy. Nevertheless, the establishment of new plantations—driven by the subsistence needs of smallholder farmers—has led to expansion into forested areas. Given the significance of this crop and the demonstrated ecosystem benefits of agroforestry systems (AFSs), the aim of this study was to evaluate the influence of native and introduced shade tree species on carbon storage in coffee plantations. This study was observational and exhibited characteristics of an unbalanced incomplete block design. Agroforestry systems (AFSs) with shade tree species such as Inga, Retrophyllum rospigliosii, Eucalyptus and Pinus, and three unshaded coffee plantations, were included in this study. The total carbon stored in each AFS was higher than in unshaded coffee plantations. Soil contributed between 47% and 91% to total carbon storage, shade trees (24–46%), coffee (2–7%), leaf litter (0.6–1.9%) and shrubs and herbaceous plants (0.02–0.3%). The AFS with R. rospigliosii achieved the highest carbon storage with 190.38 Mg ha⁻¹, highlighting the compatibility of this species with coffee plantations, as well as its positive effect on climate change mitigation in deforested areas. Full article

(1) Background: Understanding how forest management practices regulate hydrological cycles is critical for sustainable water resource management and addressing global water crises. However, the effects of light-felling (selective thinning) on hydrological processes in temperate mixed forests remain poorly understood. This study comprehensively evaluated the impacts of light-felling intensity levels on three hydrological layers (canopy, litter, and soil) in mid-rotation Korean pine (Pinus koraiensis) forests managed under the “planting conifer and preserving broadleaved trees” (PCPBT) system on Changbai Mountain, China. (2) Methods: Hydrological processes—including canopy interception, throughfall, stemflow, litter interception, soil water absorption, runoff, and evapotranspiration—were measured across five light-felling intensity levels (control, low, medium, heavy, and clear-cutting) during the growing season. The stand structure and precipitation characteristics were analyzed to elucidate the driving mechanisms. (3) Results: (1) Low and heavy light-felling significantly increased the canopy interception by 18.9%~57.0% (p < 0.05), while medium-intensity light-felling reduced it by 20.6%. The throughfall was significantly decreased 10.7% at low intensity but increased 5.3% at medium intensity. The stemflow rates declined by 15.8%~42.7% across all treatments. (2) The litter interception was reduced by 22.1% under heavy-intensity light-felling (p < 0.05). (3) The soil runoff rates decreased by 56.3%, 16.1%, and 6.5% under the low, heavy, and clear-cutting intensity levels, respectively, although increased by 27.1% under medium-intensity activity (p < 0.05). (4) The monthly hydrological dynamics shifted from bimodal (control) to unimodal patterns under most treatments. (5) The canopy processes were primarily driven by precipitation, while litter interception was influenced by throughfall and tree diversity. The soil processes correlated strongly with throughfall. (4) Conclusions: Low and heavy light-felling led to enhanced canopy interception and reduced soil runoff and mitigated flood risks, whereas medium-intensity light-felling supports water supply during droughts by increasing the throughfall and runoff. These findings provide critical insights for balancing carbon sequestration and hydrological regulation in forest management. Full article

Headwater streams serve as a crucial link between forest and downstream aquatic ecosystems and also act as crucial agents in carbon (C) and nutrient storage and flux. These aquatic systems play a pivotal role in regulating biogeochemical cycles. Plant litter is an important contributor of nutrients to headwater streams, having significant impacts on downstream ecosystems. However, current research predominantly focuses on the dynamics of plant litter C and nutrients such as nitrogen and phosphorus, and we know little about those of nutrients such as sodium (Na). In this study, we conducted a comprehensive evaluation of the annual dynamics of plant litter Na storage within a subtropical headwater stream. This study took place over a period of one year, from March 2021 to February 2022. Our results showed that (1) the average annual concentration and storage of litter Na was 538.6 mg/kg and 2957.6 mg/m², respectively, and litter Na storage exhibited a declining trend from stream source to mouth, while demonstrating significantly higher values during the rainy season compared to the dry season; (2) plant litter type had significant impacts on Na concentration and storage, with leaf, twig, and fine woody debris accounting for the majority of litter Na storage; and (3) hydrological (precipitation, discharge) and physicochemical (water temperature, flow velocity, pH, dissolved oxygen, alkalinity) factors jointly affected Na storage patterns. Overall, the results of this study clearly reveal the dynamic characteristics of Na storage in plant litter in a subtropical forest headwater stream, which contributes to a more comprehensive understanding of the role of headwater streams in nutrient cycling and the dynamic changes of nutrients along with hydrological processes. This research will enhance our predictive understanding of nutrient cycling at the watershed scale. Full article

Little information is available about the ecosystem carbon (C) storage among coniferous and broadleaved plantations with similar stand ages in North China. The aim of the present research was to estimate the C storages of the components of plants, litter, and soil in two coniferous plantations (Pinus tabulaeformis and Larix principis-rupprechtii) and two broadleaved plantations (Betula platyphylla and Populus davidiana) on Yanshan Mountain, North China. Allometric equations of diameter at breast height (DBH) and height (H) were used to quantify the biomass of the tree organs. The C storage of trees, herbs, litter, and soil were estimated based on the measured C contents. The C storage varied from 24.0 to 51.9 Mg ha⁻¹, 0.3 to 0.7 Mg ha⁻¹, and 1.9 to 4.0 Mg ha⁻¹ in the tree, herbs, and litter layers, respectively. The ecosystem C storages were as follows: B. platyphylla (164.1 Mg ha⁻¹) > P. davidiana (150.4 Mg ha⁻¹) > L. principis-rupprechtii (122.3 Mg ha⁻¹) > P. tabulaeformis (106.7 Mg ha⁻¹), 65.7%–75.6% of which was stored in the soil layer. Broadleaf plantations stored higher C than coniferous plantations in this study. These results indicate that ecosystem C storage varied among various plantation types, and broadleaf plantations had considerable ecosystem C sequestration potential with even-aged plantation stands. Full article

The transformation of degraded stands represents an essential strategy for enhancing stand productivity and optimizing site adaptability. This study examined four typical monoculture forest stands transformed from underperforming Platycladus orientalis (PO) forests in the limestone area of Xuzhou, China: Acer pictum subsp. mono (AP), Pistacia chinensis (PC), Ligustrum lucidum (LL), and Firmiana simplex (FS). The contents of carbon (C), nitrogen (N), and phosphorus (P), along with the C:N:P stoichiometric ratios, were analyzed in plants (leaves and fine roots), litter, and soil. The relationships among these components and their main influencing factors were explored. The results indicated that FS leaves contained higher levels of N and P, whereas LL litter presented significantly elevated C:N and N:P ratios in comparison with those of the other forest stands (p < 0.05). With the exception of FS, leaves displayed lower P than fine roots, which presented pronounced P enrichment. The soil C, N, and P contents decreased with depth, with both the forest stand and depth significantly impacting the soil stoichiometry (p < 0.01). Redundancy analysis identified available potassium, total nitrogen, and microbial biomass carbon in the soil as key factors influencing the stoichiometric characteristics of the leaf–fine root–litter continuum. Collectively, the leaf N:P ratios (>16) and low soil P contents indicate that plantation growth was primarily constrained by P limitation. In response, AP, PC, and LL allocate more P to fine roots to adapt to the environment. Full article

Boreal forests have historically been regarded as some of the largest terrestrial carbon (C) sinks. However, increased soil organic matter (SOM) decomposition due to forest harvesting and post-harvest silviculture (e.g., site preparation, planting, and managing for competing vegetation) may exacerbate the effects of climate warming and shift boreal forests from being C sinks to C sources. We used an established stand-scale, fully replicated, experimental study to identify how two levels of forest management (harvesting = Harvest Only, and harvesting with post-harvest silviculture = Harvest Plus) influence SOC dynamics at three boreal forest sites varying in soil texture. Each site was surveyed for forest floor (litter and F/H horizons) and mineral soils pre-harvest (0) and 5, 14, and 20 years post-harvest. We predicted that sites harvested and left to revegetate naturally would have the lowest SOC stocks after 20 years, as sites that were planted and managed for competing vegetation would recover faster and contribute to a larger nutrient pool, and that the sand-dominated site would have the largest SOC losses following harvest due to the inherently lower ability of sand soils to chemically and/or physically protect SOC from decomposition following harvest. Over a 20-year period, both forest management treatments generally resulted in reduced total (litter, F/H, and mineral horizon) SOC stocks compared with the control: the Harvest Only treatment reduced overall SOC stocks by 15% at the silt-dominated site and 31% at the clay-dominated site but increased overall SOC stocks by 4% at the sand-dominated site, whereas the Harvest Plus treatment reduced overall SOC stocks by 32% at the sand- and silt-dominated sites and 5% at the clay-dominated site. This suggests that harvesting and leaving plots to revegetate naturally on sand-dominated sites and harvesting followed by post-harvest silviculture on clay-dominated sites may minimize total SOC losses at similar sites, though a full replicated field experiment is needed to test this hypothesis. Most treatment effects in this study were observed only in the second decade post-harvest (14 and 20 years post-harvest), highlighting the importance of long-term field experiments on the effects of forest harvesting and post-harvest silviculture. This research improves our understanding of the relationship between C dynamics, forest management, and soil texture, which is integral for developing sustainable management strategies that optimize C sequestration and contribute to the resilience of boreal forest ecosystems in the face of climate change. Full article

Reducing the use of chemical inputs (fertilizers, pesticides) in agriculture while maintaining crop productivity is the main challenge facing sub-Saharan African family farming systems. The use of effective microorganisms (EM) is among the various innovative approaches for minimizing chemical inputs and the environmental impact of agricultural production and protecting soil health while enhancing crop yields and improving food security. This study sought to characterize the microbial biodiversity of local beneficial microorganisms (BMs) products from locally fermented forest litter and investigate their ability to enhance tomato plant growth and development. Beneficial microorganisms (BMs) were obtained by anaerobic fermentation of forest litter collected in four agroecological regions of Senegal mixed with sugarcane molasses and various types of carbon sources (groundnut shells, millet stovers, and rice bran in different proportions). The microbial community composition was analyzed using next-generation rDNA sequencing, and their effects on tomato growth traits were tested in greenhouse experiments. Results show that regardless of the litter geographical collection site, the dominant bacterial taxa in the BMs belonged to the phyla Firmicutes (27.75–97.06%) and Proteobacteria (2.93–72.24%). Within these groups, the most prevalent classes were Bacilli (14.41–89.82%), α-proteobacteria (2.83–72.09%), and Clostridia (0.024–13.34%). Key genera included Lactobacillus (13–65.83%), Acetobacter (8.91–72.09%), Sporolactobacillus (1.40–43.35%), and Clostridium (0.08–13.34%). Fungal taxa were dominated by the classes Leotiomycetes and Sordariomycetes, with a prevalence of the acidophilic genus Acidea. Although microbial diversity is relatively uniform across samples, the relative abundance of microbial taxa is influenced by the litter’s origin. This is illustrated by the PCoA analysis, which clusters microbial communities based on their litter source. Greenhouse experiments revealed that five BMs (DK-M, DK-G, DK-GM, NB-R, and NB-M) significantly (p < 0.05) enhanced tomato growth traits, including plant height (+10.75% for DK-G and +9.44% for NB-R), root length (+56.84–62.20%), root volume (+84.32–97.35%), root surface area (+53.16–56.72%), and both fresh and dry shoot biomass when compared to untreated controls. This study revealed that forest-fermented litter products (BMs), produced using litter collected from various regions in Senegal, contain beneficial microorganisms known as plant growth-promoting microorganisms (PGPMs), which enhanced tomato growth. These findings highlight the potential of locally produced BMs as an agroecological alternative to inorganic inputs, particularly within Senegal’s family farming systems. Full article

Understanding the complex interplay among altitudinal gradients, tree species diversity, structural attributes, and soil carbon (C) is critical for effective coniferous forest management and climate change mitigation. This study addresses a knowledge gap by investigating the effects of altitudinal gradient on coniferous tree diversity, biomass, carbon stock, regeneration, and soil organic carbon storage (SOCs) in the understudied temperate forests of the Hindu-Kush Kalam Valley. Using 120 sample plots 20 × 20 m (400 m²) each via a field inventory approach across five altitudinal gradients [E1 (2000–2200 m)–E5 (2801–3000 m)], we comprehensively analyzed tree structure, composition, and SOCs. A total of four coniferous tree species and 2172 individuals were investigated for this study. Our findings reveal that elevation indirectly influences species diversity, SOCs, and forest regeneration. Notably, tree height has a positive relationship with altitudinal gradients, while tree carbon stock exhibits an inverse relationship. Forest disturbance was high in the middle elevation gradients E2–E4, with high deforestation rate at E1 and E2. Cedrus deodara, the dominant species, showed the highest deforestation rate at lower elevations (R² = 0.72; p < 0.05) and regeneration ability (R² = 0.77; p < 0.05), which declined with increasing elevation. Middle elevations had the highest litter carbon stock and SOCs values emphasizing the critical role of elevation gradients in carbon sink and species distribution. The regeneration status and number of trees per ha in Kalam Valley forests showed a significant decline with increasing elevation (p < 0.05), with Cedrus deodara recording the highest regeneration rate at E1 and Abies pindrow the lowest at E5. The PCA revealed that altitudinal gradients factor dominate variability via PCA1, while the Shannon and Simpson Indices drives PCA2, highlighting ecological diversity’s independent role in shaping distinct yet complementary vegetative and ecological perspectives. This study reveals how altitudinal gradients shape forest structure and carbon sequestration, offering critical insights for biodiversity conservation and climate-resilient forest management. Full article