Search Results (159)

Elm sparse grassland, dominated by Ulmus pumila, serves as a critical ecological barrier in Northern China, yet the specific climatic mechanisms governing its distribution remain poorly quantified, hindering effective restoration. This study employed the Maximum Entropy (MaxEnt) model to disentangle the primary drivers of this ecosystem, specifically addressing whether its distribution is governed by moisture limitation or a stricter thermal regime. Analyzing 94 occurrence records and 13 climatic variables, the model achieved high predictive accuracy (AUC = 0.92) and identified the annual temperature range (ART) as the predominant determinant of macro-distribution (30.1% contribution), surpassing moisture variables such as annual precipitation (19.3%). The results demonstrate that the vegetation is strictly confined to a continental climate envelope with an ART of 46.2~50.7 °C and a coldness index of −70.1~−36.1 °C, while optimal precipitation (313~497 mm) acts as a secondary filter maintaining the open-woodland structure. These findings establish a hierarchical filtering model where a strict thermal regime acts as the primary “gatekeeper” setting absolute geographical boundaries, while moisture availability determines habitat quality within those limits. Consequently, this study advocates for a paradigm shift in ecological engineering—such as the Three-North Shelterbelt Program—from moisture-centric approaches to “climate-smart” restoration that prioritizes specific thermal constraints. Adhering to these precise climatic envelopes is essential to prevent maladaptation and ensure the long-term sustainability of restoration efforts amidst global climate change. Full article

Accelerating aridity and desertification driven by global climate change pose growing threats to dryland forest plantations, making it essential to understand transpiration dynamics across developmental stages for both forest-hydrology theory and the sustainable management of protective shelterbelts. This study compared transpiration characteristics, stomatal conductance (g_s), and water-regulation strategies between a 41-year-old mature stand and a 13-year-old young stand of Mongolian pine (Pinus sylvestris L. var. mongolica Litv.) on the southern margin of Horqin Sandy Land during the 2024 growing season, using thermal-dissipation sap-flow measurements combined with meteorological monitoring and water-potential sampling. Mean individual-tree daily transpiration in the mature stand (2.36 mm·d⁻¹) was approximately 2.6 times that of the young stand (0.90 mm·d⁻¹), yet the young stand showed a disproportionately stronger sap-flow response to small rainfall events. Sap flow in both stands was jointly driven by vapor pressure deficit (VPD) and photosynthetically active radiation, with a near-synchronous lag of ±10 min and tight canopy-atmosphere coupling (decoupling coefficients: 0.177 and 0.256, respectively), indicating transpiration was predominantly governed by stomatal regulation. Stomatal conductance declined with rising VPD in both stands, with a steeper decline in the mature stand. Water-potential analysis revealed pronounced anisohydric behavior in the mature stand (σ = 2.643, R² = 0.765, p < 0.01), and near-strict anisohydric regulation in the young stand (σ = 0.919, R² = 0.105, p > 0.05), indicating high tree-level hydraulic variability and precluding a definitive classification along the iso/anisohydric continuum for this developmental stage. Both g_s and transpiration increased with tree size, contradicting the hydraulic limitation hypothesis. These findings elucidate distinct water-use strategies between the young and mature Mongolian pine stands in this paired design and provide a physiological basis for stage-differentiated, precision water management of dryland shelterbelt plantations. Full article

Farmland shelterbelts are important linear vegetation infrastructures in oasis agricultural landscapes. Their accurate extraction is essential for shelterbelt inventory and farmland management, but remains challenging because shelterbelts are narrow, elongated, locally discontinuous, and spectrally similar to croplands, orchards, roadside vegetation, bare soil, and irrigation-related features. This study developed a GF-2-based deep learning workflow for farmland shelterbelt extraction in the 11th Regiment of Alar City, Xinjiang, China. Four representative semantic segmentation models, namely U-Net, U-Net with scSE attention, U-Net++, and DeepLabV3+, were trained and evaluated using four-band GF-2 optical imagery under a unified experimental setting. Model performance was assessed using Precision, Recall, F1-score, Intersection over Union (IoU), overall accuracy, and Kappa coefficient. Patch-level statistical comparison and visual interpretation were further conducted to examine performance differences, shelterbelt continuity, boundary integrity, omission errors, and background confusion. The results showed that U-Net achieved the best overall performance, with a Precision of 94.58%, Recall of 94.77%, F1-score of 94.67%, IoU of 89.88%, overall accuracy of 99.71%, and Kappa coefficient of 0.9452. Compared with U-Net with scSE attention, U-Net++, and DeepLabV3+, U-Net better preserved the continuity and boundary integrity of narrow shelterbelts in regular field-boundary networks. The other models showed varying degrees of omission, boundary fragmentation, or confusion with spectrally similar agricultural objects. The best-performing U-Net model was then applied to the complete study area, and the extracted shelterbelt area was approximately 6.5 km², accounting for about 4.37% of the cultivated land area. These results indicate that GF-2 optical imagery combined with semantic segmentation can support fine-scale farmland shelterbelt mapping in oasis agricultural landscapes. They also show that model evaluation for narrow linear vegetation features should consider not only pixel-level accuracy but also spatial continuity, boundary integrity, and typical error patterns. The proposed workflow provides a practical reference for GF-2-based farmland shelterbelt inventory, high-resolution linear vegetation mapping, and shelterbelt monitoring in arid oasis agricultural landscapes. Full article

Coastal sandy ecosystems face compounded abiotic stresses, including nutrient-poor soils, strong winds, and salt spray, making vegetation restoration highly challenging. Plant functional traits are key indicators of adaptive strategies under environmental stress, yet systematic studies on leaf, twig, and root functional traits of bamboo stands under different silvicultural regimes in coastal sandy land remain scarce. This study examined six stand types on Dongshan Island, Fujian Province: monospecific stands of Bambusa oldhamii Munro, Phyllostachys nidularia f. farcata Wen, and Bambusa tuldoides ‘Swolleninternode’, and their corresponding mixed stands with Casuarina equisetifolia L. (bamboo-to-C. equisetifolia ratio 7:3). Eighteen morphological and structural indices spanning three organ categories, leaf morphology (leaf area, specific leaf area [SLA], leaf tissue density [LTD], etc.), twig structure (wood density, dry matter content, etc.), and root morphology (specific root length [SRL], specific root surface area [SRA], root tissue density [RTD], etc.), were measured and analysed using Pearson correlation and principal component analysis (PCA). Results: (1) Coefficients of variation (CV) for leaf and twig traits ranged from 11.29% to 74.61%; leaf area (CV = 74.61%) and twig wood density (CV = 71.91%) were most variable, indicating high phenotypic plasticity of bamboo in coastal sandy environments. (2) Twig wood density in monospecific stands of B. oldhamii (0.346 g cm⁻³) was significantly higher than in all other stands (p < 0.05), reflecting a conservative water-transport strategy; mixed stands of B. oldhamii had significantly higher SRL and SRA than other stands (p < 0.05), indicating stronger root resource-acquisition capacity. (3) PCA revealed that leaf area, leaf volume, SLA, LTD, SRL, average root diameter, total root volume, total root surface area, and twig wood density (TWD) were the key traits distinguishing stands under different silvicultural regimes; monospecific stands scored higher overall than mixed stands, reflecting superior leaf, twig, and root functional coordination. Different silvicultural regimes significantly shape the functional adaptive strategies of bamboo in coastal sandy land. Bamboo plants integrate leaf, twig, and root traits in a coordinated, resource-conservative manner to withstand coastal stresses. These findings provide a theoretical basis for bamboo species selection and mixed-stand configuration in coastal shelterbelt management. Full article

Phyllosphere microorganisms interact with host plants to regulate growth, promote nutrient uptake and enhance stress tolerance with host specificity, while arbuscular mycorrhizal fungi facilitate plant nutrient absorption and stress adaptation. Current poplar microbial studies mostly focus on hermaphroditic species, with limited research on dioecious poplars. This study selected four poplar species commonly hybridized with Populuscathayana and Populus deltoides in the Xinmin area of Liaoning Province as research subjects: two female plants, DM-9-18 and DX-08-01, and two male plants, 2111 and Qingshan poplar. We performed MiSeq high-throughput sequencing targeting bacterial 16S rRNA, fungal ITS, and arbuscular mycorrhizal fungal (AMF) marker genes from poplar phyllosphere, coupled with chemical quantification of leaf, root and rhizosphere soil, to disentangle clone- and sex-associated divergence in microbial assemblages and their core environmental drivers. No significant gender differences were observed in leaf and rhizosphere nutrient levels and microbial α diversity, whereas male poplars had higher rhizosphere soil nutrients. Male and female poplars genotypes harbored distinct microbial ASVs. The dominant phyllosphere microbes and arbuscular mycorrhizal fungi exhibited gender-specific abundance variations, and nutrient content was the key factor shaping microbial communities. This study clarifies microbial community differences among the four selected hybrid poplar clones. While the experimental design confounds sex with host genotype, the observed patterns provide insights into potential sex-related variations. Our results advance the mechanistic understanding of how dioecious poplar genotype and sexual phenotype jointly filter leaf and root-associated microbial symbionts, with applied implications for hybrid poplar breeding and shelterbelt microbial regulation. Full article

The Taklimakan Desert Highway shelterbelt is the world’s largest ecological protection system established along a highway in a shifting desert environment and plays a critical role in mitigating wind-blown sand hazards and ensuring transportation safety. However, its long-term stability and protective capacity after more than two decades of operation remain insufficiently understood. In this study, Landsat imagery from 2005 to 2025 was used to monitor the long-term evolution of the shelterbelt along the Middle Section (~180 km) of the Taklimakan Desert Highway. A Random Forest classifier was employed to extract shelterbelt distribution, and classification results were validated using high-resolution Google Earth imagery and unmanned aerial vehicle observations. To quantify shelterbelt condition, a Shelterbelt Stability Index (SSI) was developed by integrating fractional vegetation cover (FVC), connectivity index (CI), percentage of landscape (PLAND), and perimeter-area fractal dimension (FRAC). The shelterbelt experienced initial seedling decline from 2005 to 2011, followed by progressive restoration during 2011–2020 and finally entered a stable saturated stage after 2020. Affected by saline water drip irrigation, wind-sand erosion and pipeline clogging, the overall vegetation condition deteriorated continuously before 2011. After targeted irrigation regulation, optimization of planting patterns and replanting measures were implemented; the degradation trend was reversed, contributing to the sustained improvement of vegetation thereafter. Significant spatial heterogeneity was observed along the highway, with certain sections maintaining high continuity and vegetation coverage, while others exhibited fragmentation, local discontinuities, area shrinkage, and increasing structural complexity. The proposed SSI effectively captured long-term structural dynamics and identified vulnerable sections subject to degradation. This study provides new insights into the life-cycle evolution of desert highway shelterbelts and offers scientific support for the sustainable management of ecological protection systems in arid environments. Full article

Ecological stoichiometric ratios of soil provide insights into the interactions and limitations among elements. This study examined the nutrient characteristics K, N, and P stoichiometric ratios in the soils collected from three distinct shelter forests (Casuarina equisetifolia, secondary forest, and Cocos nucifera) in a tropical coastal region of Hainan Province, China. Significant differences were observed among forest types in terms of stoichiometric ratios and nutrient levels in soil (p < 0.05). This may be related to the high species diversity in secondary forests and the complex composition of litter. soil nutrient levels in the secondary forest were higher than those in C. equisetifolia and C. nucifera. The effects of soil nutrient factors on soil ecological stoichiometric ratios differed across shelterbelt types. Soil organic matter, total potassium, available potassium, and ammonium nitrogen content substantially influenced the N:P, K:P, and N:K ratios (Q² > 0.5). Soil TN content was highly significantly positively correlated with N:P, N:K, in C. equisetifolia and C. nucifera (p < 0.01), whereas in the secondary forest, it was highly significantly positively correlated with SOM and NH₄⁺-N (p < 0.01). These results reflecting the complexity of nutrient cycling as well as the interdependence and mutual regulation between vegetation and soil in coastal shelter forest ecosystems. Full article

The Southern Jiangsu hills region is located within the Yangtze River Delta Ecological Barrier. Soil erosion poses a threat to the development of commercial forests and the water quality of Lake Taihu, making it urgent to quantify the mechanisms by which vegetation and rainfall regulate slope erosion. This study established five standard runoff plots in Zhangzhu, Yixing, and continuously monitored runoff and soil loss from 2022 to 2023. By combining Random Forest modeling, partial least squares structural equation modeling (PLS-SEM), and moderation effect analysis, the study assessed the contributions of various driving factors under different rainfall types. The results indicate that the peach orchard (PEA + GRA) is an optimal ecological model, achieving runoff and sediment reduction rates of over 54.09% and 70.19%, respectively. Rainfall is the dominant factor driving runoff (r = 0.75), while the maximum 30 min rainfall intensity (I₃₀) is the dominant factor driving soil loss (r = 0.82). Furthermore, during low- to moderate-intensity rainfall events, vegetation attributes primarily govern hydrological responses; however, during extreme Type III rainstorms (24 h rainfall exceeding 50 mm), rainfall volume becomes the decisive factor. Moderation analysis further reveals that vegetation height and cover exert significant moderating effects on the initial transition phase from rainfall to runoff. These findings provide evidence-based guidance for optimal soil and water conservation strategy selection in subtropical hilly landscapes. Full article

Ecosystem water use efficiency (WUE) is a key indicator of carbon–water coupling in ecosystems under climate change. While WUE responses to meteorological droughts are well-documented, the influence of different soil layers on WUE across vegetation types in water-limited regions remains unclear. Based on ERA5-Land soil moisture and MODIS vegetation products, this study investigates the spatiotemporal variations in soil moisture indices (SSMI) across three soil layers and their synchronous, lagged, and cumulative associations with WUE and resilience in the Three-North Shelterbelt Forest Program (TNSFP) region from 2001 to 2022. Our results showed that while the shallow and middle layers exhibited general wetting trends, the deep soil layer (100–289 cm) underwent continuous depletion in 56.01% of the study area. WUE showed weak synchronous responses to soil moisture drought across all layers, with no significant threshold effect. However, the lag and cumulative associations increased with soil depth, from 3–6 months in shallow layers to 9–12 months in deep layers, suggesting that deep-layer soil moisture may reflect longer-term ecohydrological stress and delayed ecosystem responses. Ecological resilience (R_d) differed by vegetation type. Grasslands were resilient to shallow drought but vulnerable to deep moisture deficits, while forests maintained stability under deep stress. These findings emphasize the importance of aligning vegetation configuration with soil water availability in restoration efforts, providing critical insights for sustainable water resource management and forest rehabilitation. Full article

(1) Background: The diversity and compositional structure of a soil’s microbial community play important roles in the function of the whole soil environment, making them important indicators of soil quality. Poplars grow rapidly, have broad adaptability, strong resistance, and significant ecological benefits, making them the primary timber species in northern China. This study aims to explore the differences and similarities among soil microbial communities of different poplar varieties by investigating the effects of soil factors on various poplar species, as well as the composition and diversity of their soil microbiomes, which holds practical significance. (2) Methods: In this experiment, soil samples from four different poplar varieties (YA: Populus × euramericana ‘102’; YB: Populus × euramericana ‘Guariento’; YC: Populus cathayana × canadensis ‘Xinlin 1’; YD: Populus × liaoningensis) were selected for the determination of their microbial communities, soil chemical properties and enzyme activities. (3) Results: Significant differences (p < 0.05) were observed among the four poplar varieties in ammonium nitrogen (NH₄⁺-N), nitrate nitrogen (NO₃⁻-N), total nitrogen (TN), total carbon (TC), total phosphorus (TP), available phosphorus (AP), invertase (INV), amylase (AMY), urease (URE), neutral phosphatase (NEP) and N-acetyl-β-D-glucosaminidase (NAG). Additionally, strong correlations were observed between soil factors and microorganisms, particularly with TP, AP, NEP and URE. (4) Conclusions: Soil chemical properties and enzyme activities significantly affect both poplar growth and microbial community structure, though the impacts vary. There are both similarities and differences in the composition and diversity of soil microbial communities across different poplar varieties. Full article

Arbuscular mycorrhizal fungi (AMF) are the key symbiotic microorganisms in sandy poplar plantations, regulating vegetation restoration and nutrient cycling. This study aims to investigate the impact of biogas slurry (BS) application on the community structure of AMF in the rhizosphere soil of poplar forests, in order to support the sustainable management of the forest. This study focused on poplar plantations in the sandy areas of Northeast China. High-throughput sequencing technology was utilized to examine the community structure and diversity characteristics of AMF while measuring the physical and chemical characteristics of the soil. The application of BS increased the nutritional status of poplar rhizosphere soil and changed its physical and chemical characteristics, according to the findings. Paraglomus and Glomus dominated the AMF community. The application of BS increased the relative abundance of Glomus in the 0–20 cm and 20–40 cm soil strata. The primary determinants of changes in the dominant AMF populations of poplar were TP, AP, TN, NO₃⁻-N, and pH. To conclude, BS application together with soil depth regulates AMF community composition within sandy poplar plantations. BS amendment ameliorates soil nutrient conditions, increasing subsurface AMF diversity and the relative abundance of vital functional genera. Three core hypotheses were tested: (1) BS application elevates soil carbon, nitrogen and phosphorus concentrations. (2) Biogas slurry and soil depth jointly alter AMF richness and composition. (3) BS-induced shifts in soil nutrients are significantly correlated with AMF community assemblage. Full article

Continuous sap-flow monitoring is a key approach for understanding water-use strategies of shelterbelt species in semi-arid sandy lands. This study investigated two tree species (Populus alba var. pyramidalis Bge. and Pinus sylvestris var. mongholica Litv.) and two shrub species (Salix psammophila C. Wang & C. Y. Yang and Atraphaxis bracteata Losinsk.) in the Zhanggutai region, southern Horqin Sandy Land. Sap flow, environmental variables, and precipitation were continuously measured during the 2019–2020 growing seasons. Stomatal conductance (g_s) and its sensitivity to vapor pressure deficit (VPD) were evaluated. Precipitation dropped from 302.3 mm in 2019 to 106.3 mm in 2020. Daily sap flow peaked mid-season and declined by 21.9%–29.2% during 2020. VPD and solar radiation were primary drivers with narrow response lags. Trees exhibited higher g_s and stronger stomatal sensitivity than shrubs, showing steeper declines as VPD rose, which indicates key drought adaptation and protective mechanisms. Conversely, shrubs maintained a moderate and more stable g_s profile throughout the growing season. In 2020, soil water deficits may force stomatal closure, causing a pronounced drop in baseline g_s and a subsequent decline in sensitivity across all species. This widespread environmental decoupling indicates a critical shift from an atmospheric demand-limited regime during the wet year to a supply-limited regime during the drought year. Overall, trees demonstrated more pronounced stand-scale hydroclimatic sensitivity than shrubs. Given the persistent water consumption by shrubs, our results suggest tree species may offer advantages in later forest restoration stages. Nevertheless, further studies integrating biomass growth and ecosystem water balance are needed to optimize sustainable shelterbelt management. Full article

Bamboo forests are formed by the interlacing of multiple ramet systems. However, the interaction relationships between ramet systems remain unclear. To determine the effects of initial planting density on the construction of ramet systems in typical monopodial bamboos, and to clarify the differentiation rules of underground clonal architecture for bamboo species with different culm diameters, in this study, we selected large-diameter species Phyllostachys edulis and small-diameter species Phyllostachys praecox as study species. A pot experiment with root restriction was conducted using three density gradients of low, medium, and high. Rhizome morphology, underground bud bank dynamics, branching types, and the spatial distribution of the ramet systems were determined. The results showed that density significantly affected rhizome elongation, node allocation, the ratio of dormant buds to germinated buds, and branching hierarchy distribution of ramet systems, with pronounced differences between species. In P. edulis, longer rhizomes, higher dormant bud accumulation, and the branching hierarchies concentrated in low-to-moderate grades were observed at low density. In contrast, rhizome growth and branching were significantly inhibited with increasing density. For P. precox, multistage rhizome extension, higher sprouting activity, and wider branching distribution in the middle and posterior segments of the rhizomes occurred under low- and medium-density conditions. Under high density, however, the peak of dormant buds shifted backward, and a sprouting compensation effect occurred. The initial density reshaped the spatial architecture of ramet systems by altering the intensity of underground competition and preferentially inhibiting the development of new branches and high-grade rhizomes. This study focused on monopodial bamboos during the early establishment stage of mother bamboo development. First, it explored density-driven effects governing ramet system formation. Second, it elucidated contrasting clonal trade-off responses between large- and small-diameter bamboo species. The results will supplement theories on the population construction of woody clonal plants. In addition, they can guide rational close planting and targeted regulation of ramet systems in artificial bamboo stands. Full article

Most remote-sensing assessments within China’s large-scale forestry engineering regions have relied primarily on greenness indicators, leaving productivity recovery and remaining restoration potential insufficiently characterized. Here, we assessed vegetation greenness and productivity recovery status, together with habitat-constrained remaining recovery potentials, within China’s Eight Forestry Engineering Regions from 2001 to 2025 using long-term Normalized Difference Vegetation Index (NDVI) and net primary productivity (NPP) datasets and climatic, topographic, and soil variables. Both NDVI and NPP increased significantly across all regions, with overall trends of 0.0029 yr⁻¹ and 3.38 g C m⁻² yr⁻¹ per year, respectively. The middle Yellow River shelterbelt region showed the strongest increasing trend, with 94.4% and 98.4% of vegetated pixels exhibiting significant increases in NDVI and NPP, respectively. The sliding-window similar-habitat model revealed that most regions have already approached their habitat-constrained potential states, though substantial remaining potential persisted in parts of the Three-north shelterbelt program and ecotonal areas. Greenness and productivity recovery potentials were positively correlated (Pearson r = 0.637), yet 14.0% of the vegetated area exhibited low greenness but high-productivity remaining potential, indicating that apparent greening does not necessarily translate into equivalent productivity recovery. These findings highlight the importance of jointly evaluating vegetation structural and functional recovery using greenness and productivity indicators. They also provide a scientific basis for differentiated restoration assessment and management within China’s large-scale forestry engineering regions. Full article

In the extremely arid Gobi environment, it remains unclear whether afforestation with saxaul (Haloxylon ammodendron) is an effective ecological restoration strategy or whether it may trigger ecological risks under severe water limitation. This study examined saxaul shelterbelts of different ages across precipitation gradients (0–50, 50–100, and 100–150 mm·yr⁻¹) in the Alxa Gobi based on 48 plots. It systematically assessed the effects of precipitation on stand growth, soil particle-size distribution, and nutrient dynamics inside and outside plantations, and used partial least squares path modeling (PLS-PM) to analyze the coupling mechanisms among precipitation, soil, and plant growth. The results showed that precipitation was the key factor controlling the survival and growth of saxaul, while planting density further regulated survival rates within different precipitation zones. Plant height, crown width, and basal diameter generally showed better performance in higher-precipitation zones, although differences among plantation ages may have been influenced by variation in initial planting density. Among the three precipitation zones, plants in the 100–150 mm zone exhibited the best growth performance. In low-precipitation areas (≤50 mm), the growth of saxaul was strongly limited, and afforestation disturbance was associated with disruption of the surface gravel layer, soil coarsening, and inadequate nutrient accumulation. In contrast, in medium- and high-precipitation areas (50–150 mm), saxaul plantations established at appropriate densities are more conducive to the accumulation of fine soil particles and nutrient enrichment. Correlation heatmaps and PLS-PM results further showed that precipitation gradient, soil texture, soil fertility, and plant growth were closely coupled. Moreover, the associations between soil and vegetation variables were stronger inside the shelterbelts than outside the shelterbelts, indicating that more pronounced local soil–vegetation feedbacks may have been formed after the establishment of artificial Haloxylon ammodendron stands. Overall, the suitability of saxaul plantations in the Alxa Gobi showed clear precipitation-dependent differentiation, with approximately 50 mm representing a practical lower limit for saxaul plantation establishment. Large-scale saxaul plantations is not recommended in areas with precipitation ≤ 50 mm, where low-disturbance restoration focused on gravel-layer protection should be prioritized; in contrast, areas receiving 50–150 mm precipitation are more suitable for plantation establishment under appropriate density control. These findings provide a scientific basis for sustainable afforestation, regional allocation, and low-disturbance management in extremely arid Gobi regions under the principle of matching vegetation restoration to water availability and site conditions. Full article