Warm-temperate Deciduous Broad-leaved Forest Research Articles

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.

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.

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.

Effects of topography and stand structure of warm temperate deciduous broad-leaved forest on understory herb diversity in Donglingshan, Beijing

Effects of topography and stand structure of warm temperate deciduous broad-leaved forest on understory herb diversity in Donglingshan, Beijing

Increases in the Methane Uptake of Upland Forest Soil in China Could Significantly Contribute to Climate Change Mitigation

Upland forest soil is an important CH4 sink that plays a key role in climate change mitigation. China features large areas of various types of forest, but spatiotemporal variation in CH4 flux has not yet been clarified. Here, we analyzed variation in CH4 flux and the effects of environmental variables on the CH4 flux of forest in China using in situ observational data. Upland forest soil absorbed CH4 at a rate of 0.24 ± 0.02 g m−2 yr−1. The CH4 uptake rate (0.46 ± 0.10 g m−2 yr−1) of warm temperate deciduous broad-leaved forest was the highest. Soil alkali-hydrolyzable nitrogen was the only factor significantly correlated with CH4 uptake variation among vegetation zones. A break point in CH4 uptake over the study period (from 1997 to 2020) was detected in 2015. CH4 uptake slightly decreased until 2015 and increased after 2015. The mean CH4 uptake of the period after 2015 (0.44 ± 0.07 g m−2 yr−1) was significantly higher than that before 2015 (0.20 ± 0.02 g m−2 yr−1). Atmospheric nitrogen deposition was negatively related to interannual CH4 uptake. Our findings suggest that the CH4 uptake of upland forest soil will continue to increase over the next few decades as China accelerates efforts to achieve its carbon neutrality goal, and this would result in continuous decreases in nitrogen deposition through various pathways.

Shrub layer structure and species diversity of warm temperate deciduous broadleaved forests of the Qinling Mountains Huangguan plot in China

Shrub is an important part of forest ecosystem. Exploring the species composition, structure and spatial distribution of shrub layer can lay an important foundation for further clarifying the mechanisms underlying species coexistence, biodiversity maintenance and community succession. In this study, species composition, spatial distribution, and species diversity of shrub layer were analyzed in 25 hm2 of Huangguan forest plot. A total of 20716 individual shrubs (with 10463 branches) were recorded in the plot, belonging to 54 species, 45 genera, 28 families. The status of dominant species in the shrub layer was not obvious, with all the importance values being less than 10. The diameter structure of shrub layer vegetation was inverted 'J' type. Shrubs showed aggregated distribution in the plot, with obvious altitude differences in spatial distribution. The diameter structure and spatial distribution of the nine shrub species with the largest abundance in the plot were consistent with the overall situation of shrub layer. With increasing altitude, the Shannon diversity index (H) and Simpson dominance index (D) did not change significantly, while the Pielou evenness index (E) decreased. Those indices decreased with the increases of the abundance of dominant species in tree layer, and E increased with the increase of the number of dominant species in sub-tree layer. The indices of H, D, E were significantly negatively correlated with soil total phosphorus (TP). The H index was significantly positively correlated with soil pH, and the E index was significantly positively correlated with soil total potassium. The shrub layer was rich in species, stable in community structure and well regenerated. The species diversity of shrub layer was mainly affected by the number of dominant species in the tree layer, soil pH, and TP.

Changes in the soil nematode community among climate zones do not keep pace with changes in plant communities

Revealing the distribution patterns of soil nematode communities among climate zones helps uncover the spatial distribution patterns of belowground biodiversity. The aims of this study were to reveal the spatial distribution patterns of the taxonomic composition, diversity and trophic structure of soil nematode communities among continuous climate zones. Investigations were conducted for five altitudinal vegetation types, i.e., subtropical evergreen broad-leaved forest (SEB), subtropical evergreen and deciduous broad-leaved mixed forest (SEDB), warm temperate deciduous broad-leaved forest (WTDB), mid-temperate coniferous and broad-leaved mixed forest (MTC) and cold temperate coniferous forest (CTC), on the eastern slope of Gongga Mountain from 2014 to 2017. The taxonomic compositions of the soil nematode communities in the SEDB, WTDB, MTC and CTC were similar but differed markedly from that in the SED, with patterns varying among sampling years. Abundances and diversity showed unimodal distribution patterns, with maximum values occurring in the WTDB. The abundances of the four trophic groups varied significantly among the vegetation types. Relative abundances stabilized for bacterivores and plant parasites but declined for fungivores and increased for omnivores-predators from the SEB to the CTC. The ratio of fungivores to bacterivores in the SEB was significantly higher than those in the other vegetation types, implying that the trophic structure and material cycling channels differed among forest types. The spatial distribution of the soil nematode communities was mainly influenced by pH, total K, total P and soil temperature. These findings suggested that the taxonomic composition, abundance, diversity and trophic structure of soil nematode communities vary among climate zones, but the changes in the soil nematode communities among climate zones did not keep pace with those in aboveground plant communities.

Middle Eocene Paleoenvironmental Reconstruction in the Gonjo Basin, Eastern Tibetan Plateau: Evidence From Palynological and Evaporite Records

The early uplift of the Tibetan Plateau (TP) had a profound influence on the paleoenvironment and paleoclimate. However, we still have little information about the link between the paleoclimatic changes and flora ecosystem caused by the uplift. The Eocene fluvial-lacustrine sequences in the Gonjo Basin, eastern TP, provide excellent archives of the paleoecological and paleoclimatic responses to the surface uplift of the TP. In this study, we investigated a section of the middle Eocene Ranmugou Formation (47.8–>44 Ma) and used the sporomorphs assemblages, sedimentology, and geochemistry of the evaporites to reconstruct the paleoclimate and paleovegetation. The palynological assemblages and coexistence analysis reveal that the middle Eocene ecosystem in the Gonjo Basin was dominated by warm and humid temperate deciduous broad-leaved forests. The 87Sr/86Sr ratios (0.709942–0.710062) of all of the gypsum samples are higher than those of contemporaneous seawater, while the δ34S values (10.3–11.0%) are much lower, indicating a lacustrine environment. Combined with published palynological and paleoelevation data for eastern Tibetan lacustrine basins, we infer that the paleoenvironment changed from warm and humid deciduous broad-leaved forests during 47.8–>44 Ma, to cool and arid temperate forest during 44–40 Ma in the Gonjo Basin, and to arid and cool steppe-desert vegetation in the late Eocene Nangqian Basin. The changes in the paleoclimate and vegetation were primarily driven by the surface uplift of the Central Watershed Mountain, the high topography of which blocked the moisture from the Asian Eocene monsoon.

The first complete chloroplast genome of Tetradium daniellii (Benn.) T. G. Hartley

Tetradium daniellii (Benn.) T. G. Hartley is an important medicinal, ornamental, and timber tree species and belongs to genus Tetradium in family of Rutaceae. It is widely distributed in warm temperate deciduous broad-leaved forest areas in northern China, Korean Peninsula and Japan. In this study, we sequenced its sample and determined complete chloroplast genome. The CP genome of T. daniellii has a circle structure with the length 158,446 bp, includes a small single copy region (17, 972 bp), a large single copy (86, 478 bp) and two inverted repeats (26,998 bp). There were 131 genes, which included 86 protein-coding genes, 8 rRNA and 37 tRNA, and overall GC content covered by 38.3%. The gene trnK-UUU, rps16, trnG-UCC, atpF, rpoC1, trnL-UAA, trnV-UAC, petB, petD, rpl16, rpl2, ndhB, trnI-GAU, trnA-UGC and ndhA contained an intron; gene clpP, ycf3 contained 2 introns. The phylogenetic result showed that T. daniellii had the closest relationship with Tetradium ruticarpum (NC_052830).

中国温带典型森林植物比叶面积的空间格局及其影响因素

比叶面积（SLA）能够反映植物自身生长对策、对光能的捕获能力、对外界环境变化的适应和对可利用资源的分配策略，对植物的生境适应状况和群落的自然演替程度也起到重要的指示作用。为了深入了解温带森林植物SLA随空间变化的变异特征及其影响因素，跨越1200 km选取中国东北部12个典型温带森林（寒温带兴安落叶松林、温带红松针阔混交林和暖温带落叶阔叶栎林），通过对样地内物种进行系统性的调查，分析了植物SLA在空间上的变化规律及环境因素的影响效应。结果显示：中国温带森林植物SLA范围为2.02-99.65 m²/kg（均值为34.18 m²/kg），其中乔木SLA范围为2.02-58.74 m²/kg（均值为21.32 m²/kg），灌木SLA范围为2.88-99.65 m²/kg（均值为31.60 m²/kg），草本SLA范围为4.66-98.53 m²/kg（均值为38.75 m²/kg）。SLA在不同森林类型之间差异显著，具体表现为：温带红松针阔混交林 > 暖温带落叶阔叶栎林 > 寒温带兴安落叶松林。SLA受到气候因素和土壤因素的影响，其中随着年均降水、土壤碳氮含量的增加显著增加；随着年均温度、紫外辐射、光合有效辐射，呈先增加后降低的趋势；随着土壤碳氮比的增加显著降低。以上结果揭示了温带森林SLA的空间变异规律，可以为将来区域乃至全球尺度下植物功能性状研究提供理论支撑。;Specific leaf area (SLA) can reflect plant growth strategies, the ability to capture light energy, adaptation to changing environments, and allocation strategies of available resources. SLA critically plays an important role in indicating plant adaptation to their habitat and the degree of community succession as well. SLA is a complex of plant leaf area and weight, and is defined as the ratio of single leaf area to its dry weight. The current research on SLA in temperate forests mostly focused on the spatial variation of dominant species or just a certain tree, and the vertical variation among forests. However, the systematic investigation of the entire community was rarely carried out. This research was conducted in the northeast of China in which covered three forest types. These types were respectively cold-temperate Larix gmelinii forests, temperate broad-leaved Korean pine mixed forests and warm-temperate deciduous broad-leaved Oak forests. This study selected 12 typical temperate forests spanning 1200 km, and performed a systematic survey to explore the spatial patterns and influencing factors of plant SLA. The results showed that the SLA of China's temperate forest plants ranged from 2.02 to 99.65 m²/kg (mean, 34.18 m²/kg). Specifically, the SLA range was 2.02-58.74 m²/kg for trees (mean, 21.32 m²/kg), 2.88-99.65 m²/kg for shrubs (mean, 31.60 m²/kg), and 4.66-98.53 m²/kg for herbs (mean, 38.75 m²/kg). Plant SLA significantly differed among different forest types, with the greatest SLA in temperate broad-leaved Korean pine mixed forest, followed by warm-temperate deciduous broad-leaved Oak forest and cold-temperate Larix gmelinii forest. Significant latitudinal pattern of plant SLA was observed. As latitude increased, SLA initially increased and then decreased. SLA was found to be affected by both climatic and soil factors. SLA increased significantly with the increasing mean annual precipitation, soil carbon content, and soil nitrogen content. However, with the increase of mean annual temperature, ultraviolet radiation, and photosynthetically active radiation, SLA first increased, followed by a decline. Moreover, it decreased significantly as the soil carbon to nitrogen ratio increased. In summary, this study reveals the spatial variation of SLA in temperate forests, and it can not only provide a new perspective for the study on the response of different forest ecosystems to global change, but also provide an important theoretical basis for the development of the adaptive management of natural forests in China. Moreover, it also provides a theoretical support for future studies on plant functional traits at the regional and global scales.

Species composition and community structure of warm temperate deciduous broadleaved forests in Huangguan of Qinling Mountains, China

The Qinling Mountain is a natural boundary between warm temperate zone and subtropical zone. While the China Forest Biodiversity Monitoring Network (CForBio) have basically covered most of the climate regions in China, few plots were located in the climate transition zone. Following the field protocol of CForBio and the Center for Tropical Forest Science (CTFS), a 25 hm2(500 m×500 m) forest plot was established in Huangguan Nature Reserve in Shaanxi Province, China, in 2019. In this study, we analyzed species composition, flora characteristics, diameter class structure, and spatial distribution patterns of dominant tree species based on the data of all woody species with a diameter at breast height (DBH) ≥1 cm. The results showed that there were 75137 woody individuals with DBH ≥1 cm in the plot (95679 when including branching individuals), belonging to 121 species, 83 genera and 44 families. The flora type at the genera level was mainly temperate, accounting for 71.1% of the total genera, and mixed with some tropical components. The dominant species in the community were obvious, with the number of individuals in the top 5 species exceeding 40% of the total number of individuals, the number of individuals in the top 50 species accounting for 95% of the total number of individuals, and the number of individuals in the remaining 61 species being less than 5% of the total. The diameter distribution of all woody indivi-duals in the plot was inverted 'J' type. Spatial distribution patterns varied across the four most abundant species with importance value >5. The degree of aggregation within species decreased with the increases of scales, while the spatial distribution of different species was affected by environmental heterogeneity. Warm-temperate deciduous broadleaved forest in Qinling Mountains had abundant species, stable community structure and good regeneration, reflecting the typical characteristics of the transition from warm temperate zone to subtropical zone. Environmental heterogeneity might be an important factor affecting the spatial distribution of tree species in the plot.

Impacts of Heat and Drought on Gross Primary Productivity in China

Heat and drought stress, which often occur together, are the main environmental factors limiting the survival and growth of vegetation. Studies on the response of gross primary production (GPP) to extreme climate events such as heat and drought are highly significant for the identification of ecologically vulnerable regions, ecological risk assessments, and ecological environmental protection. We got 1982–2017 climatic data from the University of East Anglia Climatic Research Unit, Norwich, England, and GPP data from National Earth System Science Data Sharing Service Platform, Beijing, China. Using Theil–Sen median trend analysis and the Mann–Kendall test, we analyzed trends in temperature and the standardized precipitation/standardized precipitation evapotranspiration indices in the eight vegetation regions of China. Additionally, the response of GPP to the single and combined impacts of heat and drought were analyzed using multidimensional copula functions, and GPP reduction probabilities were estimated under different drought levels and heat intensities. The results showed that the probability of a drastic GPP reduction increases with increasing drought levels and heat intensities. The combined impacts of heat and drought on vegetation productivity is greater than the impacts of either drought or heat alone and presents a nonlinear superposition of the two extremes. The impact of heat on GPP is not evident when the drought level is high. The temperate grassland and warm temperate deciduous broad-leaved forest regions are the most sensitive regions to drought and heat in China. This study provides a scientific basis for the comprehensive evaluation of the risk of GPP reduction under the single and combined impacts of heat stress and drought stress.

Coarse woody debris features of a warm temperate deciduous broad-leaved forest, northern China

Stocking and structural composition of a deciduous broad-leaved forest were determined to predict coarse woody debris quantity by quantifying the empirical relationships between these two attributes. The most ecologically significant families by stem density were Salicaceae, Betulaceae, Fagaceae, and Aceraceae. Populus davidiana was the most dominant species followed by Betula dahurica, Quercus mongolica, and Acer mono. The four species accounted for 69.5% of total stems. Numerous small-diameter species characterized the coarse woody debris showing a reversed J-shaped distribution. The coarse debris of P. davidiana, B. dahurica, and Q. mongolica mainly comprised the 10–20 cm size class, whereas A. mono debris was mainly in the 5–10 cm size class. The spatial patterns of different size classes of coarse woody debris were analyzed using the g-function to determine the size of the tree at its death. The results indicate that the spatial patterns at the 0–50 m scale shifted gradually from an aggregated to a random pattern. For some species, the larger coarse debris might change from an aggregated to a random distribution more easily. Given the importance of coarse woody debris in forest ecosystems, its composition and patterns can improve understanding of community structure and dynamics. The aggregation pattern might be due to density dependence and self-thinning effects, as well as by succession and mortality. The four dominant species across the different size classes showed distinct aggregated distribution features at different spatial scales. This suggests a correlation between the dominant species population, size class, and aggregated distribution of coarse woody debris.

China's national nature reserve network shows great imbalances in conserving the country's mega-diverse vegetation

The National Nature Reserve (NNR) network forms a central element in China's governmental strategy to conserve the country's vast biodiversity and its varied ecosystems. Nonetheless, the effectiveness of the existing NNR network in protecting China's highly diverse habitats and the fauna and flora they contain has remained unclear. Here, we analyze how comprehensively the existing NNR network protects China's vegetation diversity, identifying potential gaps to inform future NNR designations. Covering ~15.7% of China's land area, the existing nature reserve network contains 18 main vegetation types and 26 sub-types. All main vegetation types are also contained in the National-level Nature Reserves (NNRs), but to highly differing degrees. NNRs cover ~24.0% of China's grasslands, but only ~3.3% of the country's monsoon forests. With regards to main vegetation regions, about 41.4% of the Qinghai-Xizang Plateau is covered by NNRs, in contrast to only ~4.6% of the region representing warm-temperate deciduous broad-leaved forests. In five main vegetation regions, NNRs cover <10% of the area and are scattered across a highly fragmented network, leading for example to China's highly biodiverse subtropical evergreen broad-leaved forests being conserved only in small, isolated NNRs. NNRs also greatly vary in the number of vegetation types they individually comprise, with only 64 NNRs (18.9%) individually containing >50% of the vegetation types in their respective region. Overall, NNR size increases and fragmentation decreases from China's south-east to its western provinces. The resulting, extremely uneven distribution of NNRs across China limits their effectiveness in protection the country's plant diversity treasure trove. The country's NNR network therefore needs significant adjustments to effectively conserve China's valuable natural resources for future generations.

模拟穿透雨减少对锐齿栎(Quercus aliena var. acuteserrata)树干液流密度的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 模拟穿透雨减少对锐齿栎(Quercus aliena var. acuteserrata)树干液流密度的影响 DOI: 10.5846/stxb201903060423 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国际竹藤中心基本科研业务费专项基金项目（1632018002，1632018004，1632017016）；国家重点研发计划（2018YFC0507301） Effects of manipulated throughfall reduction on sap flux density of Quercus aliena var. acuteserrata Author: Affiliation: Fund Project: International Bamboo and Rattan Center"s special funds for basic research and operation fees;National Key R&D Program 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:降水格局变化是全球气候变化的重要特征之一，未来气候变化下，较为频繁和严峻的干旱将威胁地球中纬度部分地区的森林，但森林植被如何响应季节性干旱胁迫及其机制尚不清楚。北亚热带-暖温带过渡区分布着以锐齿栎（Quercus aliena var. acuteserrata）为优势树种的落叶阔叶林，研究其水分蒸腾代谢过程对干旱的响应是评估气候变化对过渡区天然落叶阔叶林生态系统水碳影响的关键科学问题。在典型的锐齿栎天然林中通过开展模拟穿透雨减少大型野外实验，采用Granier热扩散式探针技术监测锐齿栎树干液流密度的动态变化，研究了不同径级锐齿栎树干液流密度对模拟干旱的响应规律。结果表明：（1）穿透雨减少对树干液流密度的影响呈现季节变异。在7月份，林内穿透雨减少显著降低了锐齿栎的树干液流密度，但生长季后期的10月份林内穿透雨减少反而使锐齿栎树干液流密度显著升高。（2）不同径级的锐齿栎树干液流密度在生长季内对干旱有不同的响应，特别是小径级的树干液流密度与其他径级有较多的不同。小径级的锐齿栎树干液流密度在5、7月份表现为减雨样地显著小于对照样地，在9、10月份则表现为减雨样地显著大于对照样地。中径级的锐齿栎树干液流密度在5、10月份表现为减雨样地显著大于对照样地，在7月份则表现为减雨样地极显著小于对照样地。大径级的锐齿栎树干液流密度在6、7月份表现为减雨样地显著小于对照样地，在10月份则表现为减雨样地显著大于对照样地。 Abstract:The change in precipitation pattern is one of the characteristics of global climate change. Some regions at mid-latitude might experience more frequent and severe drought. However, it is unclear how the precipitation change will affect the forest vegetation in those regions. Amongst, Quercus aliena var. acuteserrata is the dominant canopy tree species of deciduous broad-leaved forests in the warm temperate zone of middle China. Understanding the evapotranspiration responses of Q. aliena to drought induced by climate change is crucial to elucidate carbon-water coupling process. In order to explore the warm-temperate deciduous broad-leaved forest response to precipitation change, a manipulated throughfall reduction experiment was conducted in Baotianman National Nature Reserve since 2013. The Granier thermal diffusion probe (TDP) was used to measure the dynamic change of sap flux density of Q. aliena. The results showed that the throughfall reduction had significant effects on the sap flux density (Js) during the growing season. Firstly, the throughfall reduction significantly reduced the sap flux density of Q. aliena in July. However, in the late growing season (October), the throughfall reduction increased the sap flux density of Q. aliena significantly. Therefore, the sap flux density of Q. aliena differently responded to the throughfall reduction among months during the growing season. Secondly, the sap flux density of Q. aliena of different tree sizes showed different responses to drought during the growing season, especially the small trees (diameter at breast height, DBH≤21 cm) was different from that of medium (21 cm 参考文献 相似文献 引证文献

Topography Affects Tree Species Distribution and Biomass Variation in a Warm Temperate, Secondary Forest

A thorough understanding of carbon storage patterns in forest ecosystems is crucial for forest management to slow the rate of climate change. Here, we explored fine-scale biomass spatial patterns in a secondary warm temperate deciduous broad-leaved forest in north China. A 20-ha plot was established and classified by topographic features into ridge, valley, gentle slope, and steep slope habitats. Total tree biomass varied from 103.8 Mg/ha on the gentle slope habitats to 117.4 Mg/ha on the ridge habitats, with an average biomass of 109.6 Mg/ha across the entire plot. A few species produced the majority of the biomass, with five species contributing 78.4% of the total tree biomass. These five species included Quercus mongolica Fisch. ex Ledeb (41.7 Mg/ha, 38.1%), Betula dahurica Pall. (19.8 Mg/ha, 18.0%), Acer mono Maxim. (12.6 Mg/ha, 11.5%), Betula platyphylla Suk. (7.0 Mg/ha, 6.4%), and Populus davidiana Dode. (4.8 Mg/ha, 4.4%). The five species were also associated with certain habitats; for example, Q. mongolica was positively associated with the ridge habitat and A. mono was positively associated with the valley habitat. Results from this work document the variability in forest biomass across a warm temperate forest ecosystem of north China, with implications for managing and accounting forest carbon.

Precipitation mediates the temporal dynamics of net primary productivity and precipitation use efficiency in China’s northern and southern forests

AbstractKey messagePrecipitation mediates the dynamic of net primary productivity and precipitation use efficiency across the North-South Transect forests of China, which may result from an increase of productivity in warm temperate deciduous broad-leaved forests or a decrease of precipitation use efficiency in temperate coniferous broad-leaved mixed forests.ContextPrecipitation use efficiency (PUE), the ratio of net primary productivity (NPP) to annual precipitation, is one of the key factors that can clarify the response of forest ecosystem carbon and water cycles to ongoing climate change.AimsTo investigate large-scale patterns of NPP and PUE, and to determine how NPP and PUE would respond to climate and soil variables across the North-South Transect forests (TNSTF) of China.MethodsWe revealed the spatial pattern dynamics of NPP and PUE in the TNSTF from 2000 to 2010 employing MOD17 NPP data and further explored the responses of NPP and PUE to environment factors across the TNSTF. Additionally, the temporal dynamics of NPP and PUE in different forest types and their dependencies on climate variation were investigated.ResultsThe results indicated that NPP increased from 2000 to 2010 in most regions across the TNSTF. The spatial distribution pattern of NPP was mainly correlated with climate factors in the TNSTF rather than soil properties. Spatially, an increased trend of PUE (2000–2010) was found in the south and decreased PUE was revealed in the north of the TNSTF. In addition, the spatial distribution of PUE in the TNSTF was associated with both climate and soil factors. For different forests, only the NPP in warm temperate deciduous broad-leaved forests significantly increased (2000–2010, R2 = 0.33, P < 0.05) due to the increase in precipitation (R2 = 0.82, P < 0.0005). Moreover, only the PUE in temperate coniferous broad-leaved mixed forests presented a significantly decreasing trend (2000–2010, R2 = 0.38, P < 0.05), which was significantly negatively correlated with precipitation (R2 = 0.80, P < 0.0005).ConclusionOur findings demonstrated that climate governed the spatial distribution of NPP; in addition to the climate, soil properties also played an important role in shaping the spatial distribution of PUE. Our findings highlight that the dynamics of precipitation rather than those of temperature mediated the variations in NPP and PUE in forests across the TNSTF.

Species spatial distributions in a warm-temperate deciduous broad-leaved forest in China

Spatial distribution is fundamental for understanding species coexistence mechanisms in forest communities. Here we comprehensively explored fine-scale spatial patterns of tree species in a secondary warm-temperate deciduous broad-leaved forest community in north China. Aggregated distribution patterns were predominant. Species functional traits had no significant effects on their spatial patterns. The aggregation intensity decreased with increasing DBH and abundance. The multivariate linear stepwise regression showed that abundance and maximum DBH were correlated with the aggregation intensity. Our results partially confirm that species attributes (abundance, DBH) and habitat heterogeneity may primarily contribute to spatial patterns and species coexistence in this secondary forest.

Response of the water use efficiency of natural vegetation to drought in Northeast China

Drought has become a problem that is universally faced by global terrestrial ecosystems. Northeast China is located in a region sensitive to global climate changes, and one of the main impacts of climate changes in Northeast China is manifested as drought in growing seasons. This study analyzes the spatio-temporal evolution law of the water use efficiency (WUE) of the main natural vegetation (i.e., cold-temperate coniferous forests, temperate pine-broad-leaved mixed forests, warm-temperate deciduous broad-leaved forests, and grasslands) in Northeast China based on public MODIS data products, including MCD12Q1, MOD15A2H, MOD16A2, and MOD17A3H, and meteorological data from 2002 to 2013. The influence of drought events on the WUE of different vegetation types and their response to drought events are also investigated. The study findings are as follows: (1) drought in Northeast China frequently occurs in the regions stretching from 114.55°E to 120.90°E, and the percentage of drought area among the forests is lower than that among the grasslands during these years; (2) the annual average WUE of the natural vegetation ranges from 0.82 to 1.08 C/kg−1H2O, and the WUE of forests (0.82 to 1.08 C/kg−1H2O) is universally higher than that of grasslands (0.84 to 0.99 C/kg−1H2O; (3) in 2008, the regions where the WUE in drought conditions is higher than that in normal water conditions account for 86.11% of the study area, and a significant linear positive correlation is found between the WUE in drought conditions and the WUE in normal water conditions, whereas the degree of drought does not influence the WUE of the natural vegetation in an obviously linear manner; and (4) the WUE for the cold-temperate coniferous forests and temperate pine-broad-leaved mixed forests with a high ET or low NPP is more likely to rise in drought conditions; the WUE for the grasslands with a low Evapotranspiration (ET), Net Primary Production (NPP), and Leaf Area Index (LAI) is more likely to rise in drought conditions; and the ET, NPP, and LAI have no significant influence on the WUE for the warm-temperate deciduous broad-leaved forests in drought conditions. This study contributes to improving the evaluation of the influence of drought on natural ecosystems.

北京东灵山暖温带落叶阔叶林枯立木与活立木空间分布格局

北京东灵山暖温带落叶阔叶林枯立木与活立木空间分布格局