作者机构：
[Mengxiao Yu; Xin Xiong; Xiangping Tan; Qi Deng; Junhua Yan] Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China;University of Chinese Academy of Sciences, Beijing, China;[Ying-Ping Wang] CSIRO Oceans and Atmosphere, PMB 1, Aspendale, Australia;[Xi Fang; Jinlei Chen] Faculty of Life Science and Technology, Central South University of Forestry and Technology, Changsha, China;[Shuo Zhang; Nannan Cao; Pingping Xu] Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China<&wdkj&>University of Chinese Academy of Sciences, Beijing, China
通讯机构：
[Qi Deng; Junhua Yan] K;Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China<&wdkj&>Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
摘要：
Changes in litter quality (carbon:nitrogen, C:N) and above-ground biomass (AGB) following vegetation restoration significantly impact soil physicochemical properties, yet their effects on soil microbial metabolic limitations remain unclear. We measured litter quality, AGB, soil physicochemical properties, and extracellular enzyme activity (EEA) along a vegetation restoration gradient (7, 14, 49, 70 years, and nearly climax evergreen broadleaved forests) in southern China. We also evaluated soil microbial metabolic limitations by a vector analysis of the EEA. Results revealed the soil microbial metabolisms were co-limited by C and phosphorus (P). The microbial C limitation initially decreased (before 14 years) and then increased, while the microbial P limitation initially increased (before 49 years) and then decreased. Partial least squares path modeling (PLS-PM) showed that the microbial C limitation was mainly attributed to microbial C use efficiency induced by litter quality, suggesting that microorganisms may transfer cellular energy between microbial growth and C-acquiring enzyme production. The microbial P limitation was primarily correlated with AGB-driven change in soil elements and their stoichiometry, highlighting the importance of nutrient stoichiometry and balance in microbial metabolism. The shifts between microbial C and P limitations and the strong connections of plant-soil-microbe processes during vegetation restoration revealed here will provide us with helpful information for optimal management to achieve forest restoration success.
摘要：
Vegetation restoration affects the stability of soil organic carbon (SOC) by changing the composition of soil carbon pools, including active carbon (C-a), the labile pool of SOC; slow carbon (C-s), the physically stabilized pool of SOC; and resistant carbon (C-r), the chemically stabilized pool of SOC. The aims of this study were to determine how SOC pools changed during restoration of a subtropical forest and to what extent vegetation characteristics and soil properties affected the changes in SOC pools. Soil samples were collected to 40 cm in four plant communities along a restoration chronosequence: scrub-grassland (4-5 years), shrubs (10-12 years), coniferous and broadleaved mixed forest (45-46 years), and evergreen broadleaved forest (90-91 years). Laboratory incubations were used to measure CO2 production during SOC mineralization, and acid hydrolysis was used to measure C-r. The CO2 production and C-r data were fitted to a three-component first-order kinetic model to determine the C-a and C-s. Pearson's correlations, stepwise multiple line regressions, and variation partitioning analysis were used to determine the key factors that affected SOC pools. The results showed that vegetation restoration increased the contents of SOC from 1.67 to 47.6 g kg(-1), C a from 0.03 to 0.35 g kg(-1), C, from 1.32 to 24.5 g kg(-1), and C-r from 0.33 to 22.8 g kg(-1). During vegetation restoration, the increase in SOC was primarily due to carbon (C) stored in stable pools (i.e., C-s or C-r), and the portion of C-r in total SOC increased markedly from 18.5 to 56.3%. Fine root biomass was the primary driver that controlled SOC pools during vegetation restoration. The C/N ratio of litter had a greater effect on C-a and C-s than that of other factors, whereas the soil clay content contributed secondarily to C-r. The results suggest that vegetation restoration increases not only the amounts of SOC, C-a, C-s, and C-r but also the stability of the SOC pool in subtropical soil. The relatively rapid increases in C-s and C-r following vegetation restoration played a crucial role in C sequestration. Therefore, strong measures to preserve natural forests and facilitate vegetation restoration should be the primary approach to increase long-term soil C sequestration in this region.
期刊：
Ecology and Evolution,2019年9(9):5338-5347 ISSN：2045-7758
通讯作者：
Deng, Xiangwen
作者机构：
[Ouyang, Shuai; Xiang, Wenhua; Yan, Wende; Wu, Anchi; Fang, Xi; Deng, Xiangwen] Cent South Univ Forestry & Technol, Fac Life Sci & Technol, Changsha, Hunan, Peoples R China.;[Ouyang, Shuai; Xiang, Wenhua; Yan, Wende; Wu, Anchi; Fang, Xi; Deng, Xiangwen] Natl Engn Lab Appl Technol Forestry & Ecol South, Changsha, Hunan, Peoples R China.;[Ouyang, Shuai; Xiang, Wenhua; Yan, Wende; Wu, Anchi; Fang, Xi; Deng, Xiangwen] Huitong Natl Stn Sci Observat & Res Chinese Fir P, Huitong, Peoples R China.;[He, Honglin] Chinese Acad Sci, Inst Geog Sci & Nat Resources Res, Key Lab Ecosyst Network Observat & Modeling, Beijing, Peoples R China.;[Ren, Xiaoli; He, Honglin] Chinese Acad Sci, Grad Univ, Beijing, Peoples R China.
通讯机构：
[Deng, Xiangwen] C;Cent South Univ Forestry & Technol, Fac Life Sci & Technol, Changsha, Hunan, Peoples R China.
关键词：
community structure;neutral theory model;niche model;secondary forests;spatial scaling;species abundance distributions
摘要：
To quantify and assess the processes underlying community assembly and driving tree species abundance distributions(SADs) with spatial scale variation in two typical subtropical secondary forests in Dashanchong state-owned forest farm, two 1-ha permanent study plots (100-m x 100-m) were established. We selected four diversity indices including species richness, Shannon-Wiener, Simpson and Pielou, and relative importance values to quantify community assembly and biodiversity. Empirical cumulative distribution and species accumulation curves were utilized to describe the SADs of two forests communities trees. Three types of models, including statistic model (lognormal and logseries model), niche model (broken-stick, niche preemption, and Zipf-Mandelbrodt model), and neutral theory model, were estimated by the fitted SADs. Simulation effects were tested by Akaike's information criterion (AIC) and Kolmogorov-Smirnov test. Results found that the Fagaceae and Anacardiaceae families were their respective dominance family in the evergreen broad-leaved and deciduous mixed communities. According to original data and random sampling predictions, the SADs were hump-shaped for intermediate abundance classes, peaking between 8 and 32 in the evergreen broad-leaved community, but this maximum increased with size of total sampled area size in the deciduous mixed community. All niche models could only explain SADs patterns at smaller spatial scales. However, both the neutral theory and purely statistical models were suitable for explaining the SADs for secondary forest communities when the sampling plot exceeded 40 m. The results showed the SADs indicated a clear directional trend toward convergence and similar predominating ecological processes in two typical subtropical secondary forests. The neutral process gradually replaced the niche process in importance and become the main mechanism for determining SADs of forest trees as the sampling scale expanded. Thus, we can preliminarily conclude that neutral processes had a major effect on biodiversity patterns in these two subtropical secondary forests but exclude possible contributions of other processes.
