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Aims Mixed-species plantations are generally thought to increase soil carbon stocks, but it is unclear whether they can enhance soil water-holding capacity. By quantifying the contribution of rainwater to soil water (CRSW) following three different scales of rainfall events in Pinus massoniana and Schima superba monoculture plantations and a mixed P. massoniana and S. superba plantation, we aimed to examine the variations in CRSW and influencing factors for different plantations. Methods Stable hydrogen isotope compositions of rainwater, soil water and groundwater were analyzed to assess the CRSW of three plantations following three rainfall events in a subtropical monsoon region in China. We further used regression analysis to quantify the relative importance of canopy openness, litter characteristics, soil physical properties and root biomass to the CRSW. Results The CRSW in the P. massoniana monoculture plantation and mixed plantation was higher than that in the S. superba monoculture plantation following the three rainfall events. No significant difference in the CRSW was found between the P. massoniana plantation and the mixed plantation within nine days following the 8.7 mm rainfall event. Furthermore, the CRSW was significantly higher in the mixed plantation than in the two monoculture plantations within 11 days following the 15.3 mm and 36.9 mm rainfall events. The most important factors affecting the CRSW were canopy openness and root biomass after the 8.7 mm rainfall event, whereas root biomass and litter characteristics acted as the primary regulatory factors after the 15.3 mm rainfall event. Under the 36.9 mm rainfall event, dry weight and saturation moisture capacity within the semi-decomposed litter layer had the greatest influence on the CRSW. Conclusion Mixed-species plantations in humid subtropical regions have a higher capacity to intercept and maintain heavy rainfall than their respective monoculture plantations, and thus can enhance their adaptation to extreme rainfall events, as well as after frequent droughts.

Climate change poses a severe threat to biodiversity. Greenhouse gas emissions have accelerated climate warming and significantly impacted species distribution and population dynamics. Zanthoxylum armatum DC. is an ecologically, medicinally, and economically important plant; it is cultivated as an economic crop at large scales in China, and is a valuable medicinal plant in India, Nepal, etc. A precise prediction of the potential distribution areas of Z. armatum will contribute to its protection and determination of its planting areas. In this paper, based on 433 distribution points and 19 climate factors, the MaxEnt model was used to analyze the spatial distribution pattern of Z. armatum between 1970 and 2000, predict its spatial distribution pattern in 2040–2060 (the 2050s) and 2081–2100 (the 2090s), and comprehensively assess the critical climate factors limiting its geographical distribution. The findings are as follows: (1) in the 1970–2000 scenario, the potential suitable distribution areas of Z. armatum include the subtropical monsoon climate regions of Japan, the Korean Peninsula, the south of the Qinling–Huaihe Line of China, and the regions along the southern foot of the Himalayas (India, Bhutan, Nepal, etc.), with an area of 330.54 × 104 km2; (2) the critical climate factors affecting the potential distribution of Z. armatum include temperature (mean diurnal temperature range, mean temperature of the coldest quarter, and temperature seasonality) and annual precipitation; (3) the distribution areas of Z. armatum will shift to higher latitudes and shrink under the three climate change scenarios in the 2050s and 2090s. In the 2090s–SSP585 scenario, the total area of suitable habitat will decrease most markedly, and the decrease rate of the highly suitable areas will reach up to 97.61%; only the region near Delong Town, Nanshan District, Chongqing City, will remain a highly suitable habitat, covering an area of merely 0.08 × 104 km2. These findings suggest that Z. armatum is susceptible to climate change. The border area between Guizhou Province and Chongqing City and the southwest district of Leshan City, Sichuan Province, will be a stable and moderately high potential suitable habitat for Z. armatum in the future. The above regions are recommended to be managed as key protected areas.

The functional resemblance structure, which mainly involved the taxonomic and functional β‐diversity, plays a key role in understanding the assembly process during succession in heterogeneous ecosystems. Systematically comparing the functional resemblance structure is essential for uncovering the successional mechanisms since taxonomic and functional β‐diversity co‐vary. In this study, a series of plots were established among the successional stages in a heterogeneous karst forest. The functional resemblance structure was quantified based on the measured plant functional traits to synchronously compare the changes in taxonomic and functional β‐diversity among the successional stages. The results showed that the taxonomic and functional β‐diversity varied asynchronously across the successional stages, reflecting the changes in functional beta redundancy. In addition, the functional local contribution to β‐diversity was higher in the early successional stage. The functional resemblance structure was dominated by functional beta redundancy, with functioning resilience showing an increasing trend during succession, even in the extremely sensitive karst forests. Furthermore, soil properties mainly determined taxonomic β‐diversity while topography primarily affected the functional dimension. Our findings highlighted the importance of functional beta redundancy in determining the functional resemblance structure and emphasized the necessity of synchronous comparison components of the functional resemblance structure when performing the β‐diversity analyses. This study was conducted in an extremely heterogeneous karst forest ecosystem. We found asynchronous changes in taxonomic and functional dissimilarities along the succession pathway and the functional redundancy dominated the functional resemblance structure.

The various vegetation types in the karst landscape have been considered the results of heterogeneous habitats. However, the lack of a comprehensive understanding of regional biodiversity patterns and the underlying ecological processes limits further research on ecological management. This study established forest dynamic plots (FDPs) of the dominant vegetation types (shrubland, SL; mixed tree and shrub forest, MTSF; coniferous forest, CF; coniferous broadleaf mixed forest, CBMF; and broadleaf forest, BF) in the karst landscape and quantified the species diversity patterns and potential ecological processes. The results showed that in terms of diversity patterns, the evenness and species richness of the CF community were significantly lower than other vegetation types, while the BF community had the highest species richness. The other three vegetation types showed no significant variation in species richness and evenness. However, when controlling the number of individuals of FDPs, the rarefied species richness showed significant differences and ranked as BF > SL > MTSF > CBMF > CF, highlighting the importance of considering the impacts of abundance. Additionally, the community assembly of climax communities (CF or BF) was dominated by stochastic processes such as species dispersal or species formation, whereas deterministic processes (habitat filtering) dominated the secondary forests (SL, MTSF, and CBMF). These findings proved that community assembly differs mainly between the climax community and other communities. Hence, it is crucial to consider the biodiversity and of the potential underlying ecological processes together when studying regional ecology and management, particularly in heterogeneous ecosystems.

The biodiversity–ecosystem function (BEF) relationship is the basis for studying the restoration of degraded ecosystems, and the simultaneous assessment of multi-trophic-level biodiversity and ecosystem multifunctionality relationship is more conducive to unravelling the restoration mechanism of degraded ecosystems, especially for degraded forest ecosystems with harsh habitats and infertile soils such as karst. In this study, we evaluated the biodiversity and soil multifunctionality (SMF) of degraded karst forests (scrub, SB; secondary growth forests, SG; old-growth forests, OG) in the Maolan National Nature Reserve, China, using 30 sample plots. Biodiversity and soil multifunctionality (SMF) at three trophic levels (plant–soil fauna–soil microorganisms), were assessed through vegetation surveys and soil sampling. One-way ANOVA showed that SMF increased with natural restoration, but multi-trophic level biodiversity showed different trends. Pearson’s correlation analysis showed a positive correlation between plant species diversity and SMF (p < 0.001), whereas soil fauna and soil microorganisms were negatively correlated with SMF. Structural equation modeling revealed a cascading effect of the multi-trophic level on the stimulation of the SMF during restoration. Only soil microorganisms exhibited a direct driving effect on SMF (p < 0.001), whereas plants indirectly influenced soil microorganisms through soil fauna, which subsequently affected the SMF. Although we observed the negative effects of increased plant diversity on soil fauna and soil microbial diversity in terms of quantitative relationships, the increase in soil fauna species and the evenness of soil microbial function still contributed to SMF restoration. This study revealed the cascading effects of multi-trophic diversity in promoting SMF restoration and emphasized that soil microbes are key to unraveling restoration mechanisms and processes, whereas soil fauna is an important intermediate link.

Grassland ecosystem health is related to global ecological problems, and large areas of grassland are threatened by degradation. Various measures, such as aerial seeding, have been applied to restore degraded grassland ecosystems. However, the effects of these measures remain unclear. In this study, based on the CVOR (condition, vitality, organization, and resilience) model, the entropy method was used to calculate the ecosystem health of aerial seeding restoration sites in the Mu Us sandy grassland, China. Then, the relationship between CVOR value, various indices in the model, and restoration time was measured using correlation analysis. The results show that (1) the vitality criterion layer has the highest weight in the CVOR model; (2) the cautionary hierarchy is the most (40.0%), and the healthy hierarchy is the opposite (10.0%) among all the restoration sites; and (3) 30-year aerial seeding can promote ecosystem health in sandy grasslands. This study demonstrates that aerial seeding is an effective method for restoring degraded grassland ecosystems and can guide future restoration measures and policies for degraded ecosystems.

Canopy gaps are a prevalent disturbance form in forest ecosystems that promote forest regeneration and succession by modifying the heterogeneity of the microenvironment. However, a significant knowledge gap exists in comprehending the global-scale impact of canopy gaps on soil nutrient properties, which is related to forest management and conservation tactics. In this study, 518 paired observations derived from 31 peer-reviewed articles were meta-analyzed to evaluate the overall response of soil nutrient properties to canopy gaps. The results showed that canopy gaps increased NO3−–N (+ 22.20%) and MBP (+ 194.17%). The canopy gap decreased the content of TN, MBC, and C:P ratio by 9.27%, 19.58%, and 19.25%, respectively. The size of canopy gaps significantly reduced SOC (−14.37%), MBC (−27.45%), TN (−11.98%), NH4+–N (−65.26%), C:N (−15.77%, −16.02%) and C:P ratio (−28.92%), but significantly increases NO3−–N (+ 37.25%). Hence, it is advisable to establish a critical gap size that caters to the specific soil fertility requirements of various regions for the optimal release of soil nutrients. These findings hold substantial significance for optimizing canopy gap management, comprehensively understanding the impact of canopy gaps on soil nutrient properties, and facilitating decision-making to assess soil fertility following canopy gap disturbances.

Human-induced environmental changes threaten the functional stability of natural forest ecosystems. Understanding the dominant factors influencing both functional space and stability in extremely heterogeneous environments is crucial for elucidating the stability of heterogeneous forest ecosystems. Here, 30 forest dynamic plots were established along the successional pathway in Maolan National Nature Reserve in Southwest China. By measuring 15,725 stems across 286 distinct species’ six key plant functional traits, we constructed the key plant functional traits for functional space and quantified functional redundancy (FR) and functional vulnerability (FV) to represent functional stability, and we further utilized the line model and multiple linear regression model to explore the key biotic/abiotic indicators influencing functional stability along the successional pathway of degraded karst forests. Additionally, as the successional pathway unfolded, the contribution of the six plant traits to the overall functional space increased, from 59.85% to 66.64%. These traits included specific leaf area (SLA), leaf dry matter content (LDMC), leaf thickness (LT) and leaf nitrogen content (LNC), which played a crucial role in driving functional space. With the increasing species richness (FR), functional entities (p < 0.001) and FR (p < 0.001) increased, while FV (p < 0.01) decreased. The results also demonstrated a higher FR in degraded karst forests (FR > 2). However, over 51% of FEs consisted of a single species, with the majority of species clustered into a few functional entities (FEs), indicating an elevated level of FV in karst forests. Soil nutrient availability significantly influences the ecosystem’s functional stability, explaining 87% of FR variability and 100% of FV variability. Finally, the rich SR of karst forests could provide sufficient insurance effects; soil pH and available potassium (AK) enhance resilience, and exchangeable calcium (Eca), total phosphorus (TP) and total potassium (TK) indicate the resistance of functional stability in degraded karst forests. This study highlights the complex mechanisms of functional stability in extreme habitat conditions, thereby deepening our understanding of ecosystem function maintenance.

(1) Background: Forest gaps play an important role in promoting forest regeneration and facilitating the forest growth cycle. Since the 1980s, forest gaps have been widely studied by forestry scientists. The purpose of this study was to review the global literature from 1980 to 2021, based on the scientific database Web of Science Core Collection, and to summarize the research hotspots and the trends of the forest gaps. (2) Method: A bibliometric analysis was performed using the visual analytic software CiteSpace to quantify the description of annual publications, collaboration analysis of authors, institutions and countries, co-citation analysis of cited journals, cited authors, and cited references. The keyword co-occurrence, burst, and time zone were also analyzed by the software. (3) Results: The results show that the volume of annual publications is increasing. Dr. Harald Bugmann is the author with the most published works. The most active institution is the American Forest Service. The United States, Canada, and China are the three most productive countries. “Ecology” is the most cited journal. The results indicate that the hotspot in the forest gap research has shifted, and the effects of forest environmental changes caused by forest gaps under climate change have received more attention from scientists. In the future, more attention may be paid to the role of forest gaps on near-natural forest management patterns, the effect of forest gaps on forest sustainable development, and the way to study forest gaps using lidar technology. (4) Conclusion: Our results can help to understand emerging trends in forest gap research to inform forest ecology and management.