Deciduous Broad-leaved Forest Research Articles

Analysis of Spatial Differentiation of NDVI and Climate Factors on the Upper Limit of Montane Deciduous Broad-Leaved Forests in the East Monsoon Region of China

The vertical transition zone of mountain vegetation is characterized by high species diversity, and the width of the transition zone may serve as an indirect indicator of climate change. However, research into the differential characteristics of vegetation response to climate changes at the boundary of vertical transition zones has been limited. This study employs MODIS and climate data spanning 2001 to 2018 to investigate spatiotemporal trends in precipitation (PRE), temperature (TMP), radiation (RAD), and Normalized Difference Vegetation Index (NDVI) across nine montane deciduous broad-leaved forests in the eastern monsoon region of China. It explores the time-lag and -accumulation effects of climatic variables on NDVI, quantifying their relative contributions to both its short-term and interannual variations. Results show that, notably, with the Qinling-Daba Mountains as a demarcation, northern regions exhibit significant increases in RAD (0.874–2.047 W m−2/a), whereas southern regions demonstrate notable rises in TMP (0.59–0.73 °C/10a). Areas of lower annual PRE correspond to the most rapid increases in annual average NDVI (5.045 × 10−3/a). NDVI’s lag time and cumulative duration responses to TMP are the shortest (0 and 2~4 periods), while its correlation with RAD is the strongest (0.815–0.975), generally decreasing from higher to lower latitudes. TMP significantly affects NDVI variations, impacting both short-term and interannual trends, with PRE driving short-term fluctuations and RAD dictating long-term shifts. This research provides critical data and a theoretical framework that enhances our understanding of how regional vegetation’s vertical zonation responds to climate change, thereby making a substantial contribution to the study of mountain vegetation’s diverse adaptability to climatic variations.

Analysis of vertical differentiation of vegetation in Taishan World Heritage site based on cloud model

While the forests on Mount Taishan are predominantly man-made, there is a notable vertical variation in vegetation. This study employs the method of cloud model, quantifying uncertainty (fuzziness and randomness) of things. Utilizing digital elevation model (DEM) and vegetation distribution data, we constructed elevation cloud models for Mount Taishan’s deciduous broad-leaved, temperate coniferous, and mixed coniferous-broadleaved forests. Using three numerical features of the cloud model—Expectation (EX), Entropy (EN), and Hyper-entropy (HE)—we quantitatively analyzed the macro regularity and local heterogeneity of Mount Taishan’s forests vertical distribution from the perspective of uncertainty theory. The results indicate: (1) The EX of the core zone elevation of deciduous broad-leaved forest is 716.65 m, temperate coniferous forest is 1053.51 m, and mixed coniferous-broadleaved forest is 1384.09 m. The variation range of the core zone distribution height is smaller in the mixed coniferous-broadleaved forest (EN: 53.74 m) compared to deciduous broad-leaved forest (EN: 99.63 m) and temperate coniferous forest (EN: 121.70 m). (2) The fuzziness and randomness of the distribution height of the lower extension zones of deciduous broad-leaved forest and temperate coniferous forest (EN: 75.15 m, 184.56 m; HE: 24.09 m, 63.54 m) are greater than those of the upper extension zones (EN: 44.75 m, 42.49 m; HE: 14.48 m, 13.23 m). (3) The distribution fuzziness and randomness within temperate coniferous forests exceed those of deciduous broad-leaved forests. Within the core zones, the uncertainty regarding the vertical distribution of vegetation across different aspects remains consistent, which retains the characteristic of man-made forests. However, in transition areas, there is significant disparity, reflecting the adaptive relationship between vegetation and its environment to some extent. In the upper and lower extension zones of deciduous broad-leaved forests, the EX values for the vertical distribution height of mixed coniferous and broad-leaved forests differ significantly from those of deciduous broad-leaved forests (the difference is 22.82–39.15 m), yet closely resemble those of temperate coniferous forests (the difference is 4.79–7.94 m). This suggests a trend wherein deciduous broad-leaved tree species exhibit a proclivity to encroach upon coniferous forest habitats. The elevation cloud model of vertical vegetation zones provides a novel perspective and method for the detailed analysis of Mount Taishan’s vegetation vertical differentiation.

The changes in soil organic carbon stock and quality across a subalpine forest successional series

Soil organic carbon (SOC) affects the function of terrestrial ecosystem and plays a vital role in global carbon cycle. Yet, large uncertainty still existed regarding the changes in SOC stock and quality with forest succession. Here, the stock and quality of SOC at 1 m soil profile were investigated across a subalpine forest series, including shrub, deciduous broad-leaved forest, broadleaf-conifer mixed forest, middle-age coniferous forest and mature coniferous forest, which located at southeast of Tibetan Plateau. The results showed that SOC stock ranged from 9.8 to 29.9 kg·m–2, and exhibited a hump-shaped response pattern across the forest successional series. The highest and lowest SOC stock was observed in the mixed forest and shrub forest, respectively. The SOC stock had no significant relationships with soil temperature and litter stock, but was positively correlated with wood debris stock. Meanwhile, the average percentages of polysaccharides, lignins, aromatics and aliphatics based on FTIR spectroscopy were 79.89%, 0.94%, 18.87% and 0.29%, respectively. Furthermore, the percentage of polysaccharides exhibited an increasing pattern across the forest successional series except for the sudden decreasing in the mixed forest, while the proportions of lignins, aromatics and aliphatics exhibited a decreasing pattern across the forest successional series except for the sudden increasing in the mixed forest. Consequently, the humification indices (HIs) were highest in the mixed forest compared to the other four successional stages, which means that the SOC quality in mixed forest was worse than other successional stages. In addition, The SOC stock, recalcitrant fractions and HIs decreased with increasing soil depth, while the polysaccharides exhibited an increasing pattern. These findings demonstrate that the mixed forest had higher SOC stock and worse SOC quality than other successional stages. The high proportion of SOC stock (66% at depth of 20–100 cm) and better SOC quality (lower HIs) indicate that deep soil have tremendous potential to store SOC and needs more attention under global change.

The Nitrogen Cycle of a Cool-Temperate Deciduous Broad-Leaved Forest

The nitrogen (N) cycle, a major biogeochemical cycle in forest ecosystems, notably affects ecosystem multifunctionality. However, the magnitude and role of organic N and the snow season remain uncertain in this cycle. We assessed the N flux and pool data of a temperate deciduous broad-leaved forest to clarify N cycle processes. The results showed that the most important component of the N pool was the soil N pool. The N demand of the site amounted to 139.4 kg N ha−1 year−1 and was divided into tree production (83.8%) and bamboo production (16.2%). We clarified that retranslocation (37.4%), mineralization at a soil depth of 0–5 cm (15.3%), litter leachate (4.6%), throughfall (2.3%), and canopy uptake (0.5%) provided 60.1% of the N demand. In terms of soil at 0–5 cm in depth, the net mineralization rate during the snow season contributed to 30% of the annual mineralization. We concluded that the study site was not N-saturated as a result of a positive N input–output flux budget. More than half of the total N was accounted for by dissolved organic N flowing through several pathways, indicating that organic N plays a vital role in the cycle. The mineralization rate in the soil layer during the snow season is an important link in the N cycle.

Eco-physiological adaptation strategies of dominant tree species in response to canopy and understory simulated nitrogen deposition in a warm temperate forest

Nitrogen (N) is an indispensable element for plant growth and survival. The increased global N deposition due to human activities has aroused attention to forest ecosystems, but most studies have not considered the process of N interception, assimilation, and leaching in forest canopy. To investigate the responses and adaptive strategies of dominant tree species in a warm temperate forest to atmospheric N deposition, this study implemented five treatments: control treatment, canopy simulated low N deposition, canopy simulated high N deposition, understory simulated low N deposition, and understory simulated high N deposition. The morphological and physiological traits and nutrient uptake strategies of three dominant tree species (Liquidambar formosana, Quercus acutissima, and Quercus variabilis) in warm temperate deciduous broad-leaved forest were studied under different forms and levels of stimulated N deposition. The results showed that the specific leaf area (SLA) of the three dominant tree species decreased under high N application. To optimize resource absorption and improve nutrient transport rates, the specific root length (SRL) and specific root area (SRA) of the three tree species tended to decrease, while the average root diameter (ARD) increased. Under canopy N deposition (CAN), the contents of carbon (C), N, total chlorophyll (Tchl), and total amino acids in Q. variabilis leaves were lower than those under understory N deposition (UAN) treatment. Furthermore, principal component analysis (PCA) revealed the differences between different genera (L. formosana and Q. variabilis, L. formosana and Q. acutissima) under various N treatments, and there was no significant difference between the same genus (Q. variabilis and Q. acutissima). The results indicated that the eco-physiological characteristics of different tree species under N deposition treatment were species-specific, and traditional UAN perhaps exaggerated the effect of atmospheric N deposition on tree growth characteristics. Our study considers the retention and redistribution of forest canopy, which is more in accordance with the natural N deposition, and helps us to understand the eco-physiological responses of dominant tree species in forest ecosystem to atmospheric N deposition.

Interactions between leaf traits and environmental factors help explain the growth of evergreen and deciduous species in a subtropical forest

It is well known that evergreen and deciduous species possess different functional traits and utilize different strategies in growth and adaptation to environments. However, little work has been done to elucidate whether leaf habits mediate the effect of trait-environment interactions on plant performance. In this study, our subjective was to illuminate whether relative growth rate of deciduous and evergreen species is influenced by multiple trait-environment interactions. We conducted measurements on eight leaf traits of 1230 individuals belonging to 25 species in a subtropical evergreen and deciduous broad-leaved mixed forest. Additionally, we collected data on topographic factors, edaphic variables and competition index. Subsequently, we employed generalized linear mixed model to analyze plant relative growth rate, considering high-order trait-environment interactions for both evergreen and deciduous species. We also visualized the effects of these interactions on growth patterns. Our results showed that leaf habits were divided by trait PC1 (41.8%) which was related to leaf lifespan and resource acquisition. Evergreen species tended to have greater interspecific variation compared to deciduous species. Notably, the inclusion of trait-environment interactions significantly improved growth predictions for both leaf habits, although explanatory power of deciduous models was always higher than that of evergreen species. Furthermore, we observed variability in the effects of trait-environment interactions on plant performance varied between leaf habits, leading to different optimal models for each leaf habit, even when they shared similar trait-environment context. These results indicated that difference of life history strategies between leaf habits could be reflected by trait-environment interactions. We emphasized the importance of leaf habits in explaining forest productivity and functions, and future research should focus on the effects of leaf habits on other demographic metrics to understand species coexistence in mixed forests.

Restoring Subtropical Forests: Alleviating P Limitation and Introducing C Limitation Using Evergreen Broad-Leaved Tree Species

Determining which species to utilize for the artificial restoration of subtropical secondary forests has become a focal point in forestry and ecology. To compare the effects of the subtropical secondary forest artificial restoration model on soil microbial nutrient acquisition and limitation, we examined secondary forests (CKs), evergreen coniferous forests (GCPs), evergreen coniferous mixed broad-leaved forests (GCBMs), evergreen mixed broad-leaved forests (GBMs), and natural deciduous broad-leaved mixed forests (DBMs) as research subjects. Among them, GCPs, GCBMs, and GBMs were dominated by the species of the early, middle, and climax stages of subtropical forest succession, respectively. The activities and stoichiometry of β-1,4-glucosidase (BG), β-1,4-N-acetylglucosaminidase (NAG), leucine aminopeptidase (LAP), and acid phosphatase (ACP) in the topsoil were analyzed. The results showed that the forest type significantly affects the activities of BG and LAP rather than NAG or ACP. The BG activity in DBMs was the lowest, while the LAP activity in CKs was significantly higher than that in plantations. Furthermore, the nutrient limitation of microbes was quantitatively analyzed by using the vector analysis of enzyme stoichiometry. The soil microbes in the study area were co-limited by C and P, and the nutrient limitation was in the order of C > P > N. Among the forests, the enzyme stoichiometric ratios in GCPs and DBMs were closest to 1:1:1. From CKs to GBMs, the microbial C limitation was increased, while the P limitation was decreased. The C limitation in DBMs was slightly lower than that in CKs. Overall, the P limitation in evergreen plantations was less than that in CKs. The soil bulk density, C/P, and N/P significantly influenced enzyme activities and stoichiometry. These results suggest that the artificial restoration of subtropical forests using evergreen species alleviated P limitation, while using deciduous broad-leaved species offered potential for alleviating microbial C limitation. Compared with evergreen broad-leaved species, employing pioneer and mid-successional or deciduous broad-leaved species can better achieve balanced microbial nutrient requirements.

Decrease in Inorganic Nitrogen and Net Nitrogen Transformation Rates with Biochar Application in a Warm-Temperate Broadleaved Forest

Changes in soil nutrient dynamics after biochar application may affect indirect carbon sequestration through changes in plant productivity in forest ecosystems. In the present study, we examined the effects of woody biochar application on soil nitrogen (N) cycling over 8 months in a warm-temperate deciduous broad-leaved forest. Mineral soil samples were collected from the plots treated with different biochar applications (0, 5, and 10 Mg ha−1), and the soil inorganic N concentration was measured. Net mineralization and nitrification rates were determined in each plot using the resin–core method. Soil temperature and water content did not change significantly, but the pH increased significantly following biochar application. Soil inorganic N concentrations (NH4+ and NO3−) and net N transformation rates (mineralization and nitrification rates) were significantly reduced. Microbial biomass and the nitrification ratio (the ratio of nitrification rate to mineralization rate) were unchanged, indicating that the decrease in soil inorganic N concentration was due to the reduced mineralization rate. Adsorption of substrates (from organic matter) by the applied biochar is the most likely reason for the reduction in the N mineralization rate. The results indicate that biochar application does not necessarily stimulate N transformation, which will affect indirect carbon sequestration.

Forest monitoring data of 45 plots across the Japanese archipelago during 1980–2021

AbstractLong‐term monitoring of forest tree communities is a basis for elucidating forest structure and dynamics and for evaluating ecosystem functions such as primary production. Because global climate change is changing forest ecosystems from the local to the global scale, it is essential to document long‐term monitoring data of forests to examine the temporal and geographical trends of forest changes. We report monitoring data of 45 forest plots (average area 0.69 ha; range 0.0325–6.25 ha) at 27 sites in Japan. These plots are situated within 32.38° N to 43.36° N and at elevations ranging from 8 to 2453 m above sea level. The forest plots include both old‐growth and secondary forests, and cover various forest biomes, such as warm‐temperate evergreen forests, temperate deciduous broadleaved forests, and boreal or sub‐alpine coniferous forests. In each plot, all living trees and lianas larger than a certain minimum size (typically 15 cm stem girth at breast height) were repeatedly measured and survival and recruitment of stems were recorded over 5–40 years (average 17.3 years). The data are presented in the format used by the Monitoring Sites 1000 Project in Japan (Ishihara et al. 2011, Ecological Research, 26, 1007–1008) and in the sample‐based Darwin Core format. This dataset expands existing open monitoring data for Japanese forests and thereby facilitates further meta‐analysis of forest community structures and changes in relation to climate change and other drivers. The complete data set for this abstract is available in electronic format in MetaCat in JaLTER at http://db.cger.nies.go.jp/JaLTER/metacat/metacat/ERDP-2024-03.1/jalter-en.

Spatial Distribution and Sustainable Development of Living Woody and Coarse Woody Debris in Warm-Temperate Deciduous Broadleaved Secondary Forests in China.

The investigation into the spatial patterns of living woody (LWD) and coarse woody debris (CWD) in warm-temperate deciduous broadleaved secondary forests serves as a foundational exploration of the mechanisms governing coexistence and mortality in forest ecosystems. The complete spatial randomness null model (CSR) was employed to analyze spatial distribution patterns, with the independent component null model (IC) and canonical correspondence analysis (CCA) utilized to elucidate spatial correlations and topographic influences. All three models were applied to LWD and CWD across various size classes within a 20-hectare plot in the Dongling Mountains. The study's findings indicate that both LWD and CWD predominantly exhibited aggregated patterns, transitioning to a random distribution as the size class increased. Both increasing abundance and maximum diameter at breast height (DBH) also have a significant influence on the distribution of species. Notably, rare species exhibited higher aggregation compared to common and abundant species. The spatial correlation results between LWD and CWD across various size classes predominantly showed positive correlations and uncorrelated patterns within the sampled plots. CCA analysis further revealed that elevation, convexity, slope, and aspect significantly influenced the spatial patterns of LWD and CWD across different size classes. Within the sample site, trees display a tendency to grow and die in clusters. Biotic factors have a more significant influence on species distribution than abiotic factors.

Patterns and Dominant Driving Factors of Carbon Storage Changes in the Qinghai–Tibet Plateau under Multiple Land Use Change Scenarios

Revealing the spatial–temporal evolution of carbon storage and its driving mechanisms in the Qinghai–Tibet Plateau could provide support for decision making in the protection of regional ecosystems and the achievement of regional dual-carbon goals. In this study, the spatial–temporal evolution of carbon storage in the Qinghai–Tibet Plateau was analyzed under various scenarios using PLUS-InVEST and a gravity center model, and the driving mechanisms of carbon storage were clarified with Geodetector. The results are as follows: (1) During 2000–2020, the areas of coniferous forest, evergreen broad-leaved forest, closed shrub, temperate shrub desert, multi-tree grassland, and grassland showed an increasing trend, while the areas of deciduous broad-leaved forest and mixed forest showed a decreasing trend. (2) During 2030–2060, there was a decreasing trend in the total carbon storage of the Qinghai–Tibet Plateau under three different scenarios. (3) During 2030–2060, the area of the Qinghai–Tibet Plateau was mostly represented by carbon balance (56%), while the areas of carbon sources and carbon sinks showed a scattered distribution. (4) The precipitation and topographic factors with a q value of 0.888 played a dominant role in affecting the spatio-temporal variations in carbon storage in the Qinghai–Tibet Plateau. (5) In future ecological protection and restoration efforts, more high-quality farmlands should be protected and constructed, which could contribute to the achievement of dual-carbon goals. In addition, the hydrothermal conditions should be improved to aid the carbon cycle process in the Qinghai–Tibet Plateau.

The Changes in Soil Microbial Communities and Assembly Processes along Vegetation Succession in a Subtropical Forest

Soil microbes are the primary drivers of the material cycling of the forest ecosystem, and understanding how microbial structure and composition change across succession assists in clarifying the mechanisms behind succession dynamics. However, the response of soil microbial communities and assembly processes to succession is poorly understood in subtropical forests. Thus, through the “space instead of time” and high throughput sequencing method, the dynamics of the soil bacterial and fungal communities and assembly process along the succession were studied, where five succession stages, including Abandoned lands (AL), Deciduous broad-leaved forests (DB), Coniferous forests (CF), Coniferous broad-leaved mixed forests (CB), and Evergreen broad-leaved forests (EB), were selected in a subtropical forest on the western slope of Wuyi Mountain, southern China. The results demonstrated that succession significantly decreased soil bacterial α-diversity but had little effect on fungal α-diversity. The composition of soil bacterial and fungal communities shifted along with the succession stages. LEfSe analysis showed the transition from initial succession microbial communities dominated by Firmicutes, Bacteroidota, Ascomycota, and Chytridiomycota to terminal succession communities dominated by Actinobacteriota and Basidiomycota. Distance-based redundancy analysis (db-RDA) revealed that soil total organic carbon (TOC) was the main factor explaining variability in the structure of soil bacterial communities, and multiple soil environmental factors such as the TOC, soil total nitrogen (TN), C:N ratio, and pH co-regulated the structure of fungi. The null models illustrated that deterministic processes were dominant in the soil bacterial communities, while the stochastic processes contributed significantly to the soil fungal communities during succession. Collectively, our results suggest that different patterns are displayed by the soil bacterial and fungal communities during the succession. These findings enhance our comprehension of the processes that drive the formation and maintenance of soil microbial diversity throughout forest succession.

Carbon Allocation to Leaves and Its Controlling Factors and Impacts on Gross Primary Productivity in Forest Ecosystems of Northeast China

Carbon allocation in forest ecosystems is essential for the optimization of growth. However, remote-sensing-based research on the estimation of carbon allocation in forests is inadequate. This article considers forests in northeastern China as the research area and uses leaf area index (LAI) data combined with random forest and structural equation modelling methods to study the spatiotemporal distribution characteristics and driving factors of carbon allocation to leaves (ΔLAI) in deciduous broad-leaved forests (DBF), deciduous coniferous forests (DNF), and mixed forests (MF) during the green-up period (GUP) at a monthly scale during April, May, June, and July from 2001 to 2021, and clarifies the impact of leaf carbon allocation on gross primary productivity (GPP). The ΔLAI was the highest in DBF in April and in DNF and MF in May. The ΔLAI in April with an increasing trend year by year in DBF and MF, and the ΔLAI in May with an increasing trend in DNF. Among all the direct and indirect relationships that affect ΔLAI, temperature (TEM) has the highest path coefficient for DBF’s ΔLAI in April (−1.213) and the start of the season (SOS) has the highest path coefficient for DNF (−1.186) and MF (0.815). ΔLAI in the GUP has a significant positive impact on the GPP. In the MF, the higher ΔLAI in May was most conducive to an increase in GPP. During the critical period, that is April and May, carbon allocation to leaves effectively improves the carbon sequestration capacity of forestland. This information is of great value for the development and validation of terrestrial ecosystem models.

Geographical distribution and potential distribution prediction of thirteen species of Citrus L. in China.

Using DIVA-GIS software to study the spatial accumulation of Citrus species, an important economic crop in China. Draw the distribution maps of Citrus to concerning altitude and vegetation, and use DIVA-GIS' Bioclim ecological model and maximum information entropy model Maxent software to estimate the potential distribution areas of various Citrus species. The results show that the Citrus genus is located in the south of Qinling Mountains, mainly in the southwest of China and the coast of southeastern China. Sichuan and Chongqing are the most densely distributed regions of Citrus. The distribution of Citrus is closely related to the vegetation type and altitude. The vegetation types in the distribution area is evergreen broad-leaved forest, evergreen shrub, deciduous broad-leaved forest, mixed-leaf forest coverage area, deciduous coniferous forest, farmland, trees, other vegetation coverage, and evergreen coniferous forest. The current potential distribution area of Citrus is mainly in Guizhou, Hubei, Hunan, Guangdong, Guangxi, Yunnan,Sichuan, Chongqing, and other provinces and municipalities and their borders, while the potential distribution area in the future moves northward and enter Henan and southern Gansu. At the same time, climate warming changes the distribution of suitable areas of Citrus, which makes the suitable areas of C. sinensis Osbeck, C. reticulata Blanco, and other crops greatly increased. Planning the planting area will effectively improve the yield and quality in the future. Planning presents new challenges.

First Account of the Breeding Biology of Indian Blue Robin (Larvivora brunnea) in Southwest China.

Breeding biology lies at the core of life history research on birds, and it provides important information for avian conservation. We discovered one nest of the Indian Blue Robin (Larvivora brunnea) on 28 May 2021, at the Laojun mountains in Lijiang, northwestern Yunnan, China. Field observation was combined with the use of a GoPro camera for video shooting to quantitatively study the incubation and brooding behavior. We also conducted measurements of the eggs and nestlings on site and inspected the nesting materials used. A bowl-shaped nest with four eggs was located at 2830 m in the evergreen deciduous broad-leaved forest. All eggs were successfully incubated and two nestlings fledged on 22 June 2021, resulting in a total breeding success of 50%. Only the female bird incubated the eggs and brooded the nestlings. The incubation period was at least 13 days and the nestling period was 13 days. As incubation progressed, the incubation bout duration decreased. During the incubation period, the nesting time of the female bird shows a declining trend as incubation progresses. Both parents participated in feeding the nestling, and the frequency of parental supply increased with the maturity of the nestling.

Effects of urban green spaces landscape pattern on carbon sink among urban ecological function areas at the appropriate scale: A case study in Xi’an

At appropriate scales, optimizing landscape pattern in urban green spaces is shown to augment carbon sink. However, existing research primarily concentrates on regional or city-wide areas, often overlooking the nuanced effects of landscape pattern on carbon sink within specialized urban ecological function areas. Focusing on the city of Xi'an and emphasizing the forest within green spaces as the principal subject, this study investigated the spatial interplay between forest landscape pattern and carbon sink across the Ecological Control Area, the Urban Ecological Construction Buffer Area, and the Tsinling Mountains Ecological Protection Area. Grounded in field surveys, this study employed GF1-WFV remote sensing imagery to ascertain the 2021 land-use data in Xi'an and further classified forests into five distinct types: deciduous broad-leaved forest, evergreen coniferous forest, evergreen broad-leaved forest, coniferous and broad-leaved mixed forest, and evergreen-deciduous broad-leaved mixed forest. Employing the Carnegie-Ames-Stanford Approach model and landscape metrics methods, the study evaluated the carbon sink and landscape pattern at multi-scale. Through semi-variance analyses, we discerned the appropriate grid scales. Finally, multiple linear stepwise regression model elucidated the significant landscape metrics, while geographically weighted regression model were employed to scrutinize spatial relationships. Our findings suggested that grid scales of 5 km for the Ecological Control Area, 3 km for the Urban Ecological Construction Buffer Area, and 6 km for the Tsinling Mountains Ecological Protection Area are most appropriate for effective management and planning. Metrics related to area, edge, and fragmentation were pivotal in enhancing carbon sink, and their influence was spatially variable. This study furnished an in-depth analysis of how landscape pattern and carbon sink interact spatially within various urban ecological function areas at appropriate grid scales, thereby providing a scientific framework for the sustainable planning and management of green spaces.

Forest Canopy Structures and Bamboo Rhizome Internodes Impact the Appearance Quality of Bamboo Shoots

Bamboo shoots are a healthy vegetable with significant commercial value, and their appearance quality is a key factor influencing consumer preference and market pricing. Their growth characteristics—after being unearthed, they maintain basal diameter while rapidly growing in height—affect the taste and nutritional quality. However, little attention has been given to the impact of bamboo forest management on shoot appearance. Therefore, this study addressed this research gap through a comprehensive investigation across three types of bamboo forests: evergreen broad-leaved forest (EBF), evergreen deciduous broad-leaved mixed forest (MBF), and pure bamboo forest (PBF). In addition, we further assessed factors that potentially affect the appearance quality of bamboo shoots, including canopy structures, understory light factors and understory soil factors, mother bamboo factors, and shoot internal factors (pigments and cells). The basal diameters of shoots in PBF and MBF were 1.89 cm and 1.97 cm, respectively, which were significantly larger than those in EBF by 0.27 cm and 0.35 cm, respectively. The linear mixed effect model identified the number of bamboo rhizome internodes and the chlorophyll a content as primary factors influencing basal diameter thickening and elongation growth of shoots, respectively. In addition, increasing the bamboo canopy and mean leaf angle reduced the chlorophyll a content and increased the carotenoid content, thereby benefiting the improvement in or maintenance of the taste and quality of shoots. This study highlighted that increasing the number of bamboo rhizome internodes, bamboo canopy, and mean leaf angle is helpful to improve the appearance quality of shoots. These findings offer a scientific foundation for bamboo forest management, contributing to both ecological sustainability and economic benefits.

Vertical biome shifts and climate changes since the last glacial maximum in the southeastern margin of the Tibetan plateau, Southwest China

Since the last glacial maximum (LGM), global warming has significantly influenced the intricate dynamics of vegetation on the southeastern margin of the Tibetan Plateau in southwest (SW) China. However, the responses of montane vegetation to glacial-interglacial climate changes have received less attention than those of modern alpine vegetation belts. Here, we present a continuous pollen record from the lake Caohai area of Guizhou Province and a quantitative reconstruction of the region's biome and climate changes over the past 21 ka. Our findings demonstrate that the study area was encompassed by evergreen sclerophyll Quercus forest during the LGM, which subsequently transitioned to deciduous broadleaved forest around 15.8 ka, shortly after the termination of the last glacial period. During the early Holocene, the deciduous forest underwent a transformation and gave way to evergreen broadleaved forest around 10.3 ka. The abundance of evergreen subtropical elements peaked between 9 and 5 ka, coinciding with the Holocene thermal maximum (HTM). This was followed by the return of deciduous taxa after the 4 ka in the late Holocene. However, anthropogenic impacts on local vegetation became apparent only from about 2 ka. The pollen-based biome reconstruction features clear vertical shifts that correspond to the modern vegetation belts at different elevations, with a maximum vertical movement of about 1000 m between the last glacial and the Holocene. Statistical analysis of pollen data reveals that principal components can serve as reliable climate indicators, consistent with climate simulations using the TraCE model. Both proxy and model results demonstrate that forest ecosystems undergo transformation when thermal and moisture conditions exceed bioclimatic thresholds, emphasizing the crucial role of climate boundaries in driving biome succession. Our findings unveil an extended cold and dry period during the LGM, with the lowest precipitation observed during the last glacial termination due to intense North Atlantic cooling and weak overturning circulation. The strong agreement between the transition from sclerophyll to deciduous forests and increasing temperatures suggests that deglacial warming primarily drove vertical biome shifts after the LGM in the southeastern margin of the Tibetan Plateau. Conversely, forest succession during the Holocene, which align with variations in fire intensity, were predominantly triggered by summer monsoon changes. The quantitative reconstructions of both biomes and climates presented in this study provide novel insights into temporal relationships between climate dynamics and ecosystem changes in SW China.

Community structure and species composition of typical Quercus variabilis natural secondary forest at the northern foothills of the Qinling Mountains, China

We investigated species composition and community structure of a typical Quercus variabilis natural secondary forest in the northern foothills of the Qinling Mountains, within the dynamic monitoring plot of deciduous broad-leaved forest at the Louguantai experimental forest farm in Zhouzhi County, Shaanxi Province. The results showed that there were 3162 individual woody plants with diameter at breast height ≥1 cm in the plot, which were belonged to 42 species, 36 genera, and 25 families. The community genus's areal type was dominated by the temperate component, which accounted for 44.4%, and followed by the tropical component. The community was dominated by several tree species. The top three species with respect to importance value were Q. variabilis, Pinus tabuliformis, and Quercus aliena, with the sum of their importance value being 64.7%. The average DBH of all woody plants was 7.58 cm. The distribution of all individuals and dominant species in the tree layer was approximately normal, with more medium-size individuals. The community structure was stable. The community was poorly renewed, with a trend of population decline. Biodiversity indices varied considerably among different plots, being lower than those of subtropical broad-leaved evergreen forests. There was a significant correlation between community species distribution and environmental factors. Soil and topography explained 42.4% of the variation in community distribution. Altitude and soil alkali hydrolysable nitrogen had a significant effect on community distribution. Altitude, soil total phosphorus, and organic matter content significantly affected the species diversity of Q. variabilis communities. The stronger adaptability of Q. variabilis populations allowed them to become dominant in low-nutrient environments, which limited species diversity in the community.

Monsoon influence on plant diversity in northern Indochina: Evidence from the late Miocene Yen Bai flora, northern Vietnam

Indochina, as a global biodiversity hotspot, offers the potential for understanding the evolution of biodiversity. However, the historical narrative of plant diversity in this region remains enigmatic due to limited fossil records. Here, we report a newly discovered megafossil flora from the late Miocene of the Yen Bai Basin, northern Vietnam. This megafossil flora suggests that the late Miocene vegetation in northern Vietnam comprised mixed tropical evergreen and deciduous broadleaved forest components mainly characterized by Fabaceae, Fagaceae, and Lauraceae bearing strong resemblance to the modern vegetation in northern Vietnam. Paleoclimate reconstruction for this plant fossil assemblage using the Coexistence Approach indicates a mean annual temperature (MAT) of 18.5–23.0 °C and a mean annual precipitation (MAP) of 1183.1–2078.5 mm. Similarly, employing the Climate-Leaf Analysis Multivariate Program yields an MAT of 21.3 ± 2.3 °C and a growing season precipitation (GSP) of 1328.6 ± 606.0 mm. The length of the growing season was about eleven months. Overall these results indicate a modern-like warm and humid tropical monsoon climate in northern Vietnam during the late Miocene. Climatic comparison of the Yen Bai with other fossil floras in northern Vietnam and southern China reveals the relative stability of temperature seasonality since the middle Eocene but obvious long-term variation in precipitation seasonality, particularly in respect of precipitation during the three consecutive driest months (X3.DRY). This suggests the Asian monsoon in northern Vietnam underwent important changes from the middle Eocene to the late Miocene, and intensified significantly during the middle and late Miocene. Our results show the modernization of plant diversity in northern Indochina had its origin in the Paleogene and further developed in the late Miocene, and was linked to the evolution of the Asian monsoon mainly in terms of changes in dry season precipitation.