作者机构：
[李艳琼; 景宜然] College of Life Science and Technology, Central South University of Forestry and Technology, Changsha, 410004, China;National Engineering Laboratory for Applied Technology of Forestry & Ecology in South China, Changsha, 410004, China;[邓东华; 易昌晏] Shaoyang Bureau of Forestry, Shaoyang, 422100, China;[黄志宏; 邓湘雯; 项文化; 方晰] College of Life Science and Technology, Central South University of Forestry and Technology, Changsha, 410004, China, National Engineering Laboratory for Applied Technology of Forestry & Ecology in South China, Changsha, 410004, China
通讯机构：
[Deng, X.-W.] C;College of Life Science and Technology, China
作者机构：
[Yuan, Wenping; Zhang, Haicheng; Chen, Yang; Cai, Wenwen; Liu, Dan; Dong, Wenjie] Beijing Normal Univ, State Key Lab Earth Surface Proc & Resource Ecol, Beijing 100875, Peoples R China.;[Yuan, Wenping] Chinese Acad Sci, State Key Lab Cryospher Sci, Cold & Arid Reg Environm & Engn Res Inst, Lanzhou 730000, Gansu, Peoples R China.;[Zhao, Zhonghui; Xiang, Wenhua; Liu, Shuguang] Cent South Univ Forestry & Technol, Natl Engn Lab Appl Technol Forestry & Ecol South, Changsha 410004, Hunan, Peoples R China.;[Yu, Guirui; He, Honglin] Chinese Acad Sci, Key Lab Ecosyst Network Observat & Modeling, Synth Res Ctr Chinese Ecosyst Res Network, Inst Geog Sci & Nat Resources Res, Beijing 100101, Peoples R China.;[Chen, Zhuoqi] Beijing Normal Univ, Coll Global Change & Earth Syst Sci, Beijing 100875, Peoples R China.
通讯机构：
[Yuan, Wenping] B;Beijing Normal Univ, State Key Lab Earth Surface Proc & Resource Ecol, Beijing 100875, Peoples R China.
摘要：
Increasing heatwave and drought events can potentially alter the carbon cycle. Few studies have investigated the impacts of hundred-year return heatwaves and droughts, as those events are rare. In the summer of 2013, southern China experienced its strongest drought and heatwave on record for the past 113 years. We show that the record-breaking heatwave and drought lasted two months (from July to August), significantly reduced the satellite-based vegetation index and gross primary production, substantially altered the regional carbon cycle, and produced the largest negative crop yield anomaly since 1960. The event resulted in a net reduction of 101.54 Tg C in carbon sequestration in the region during these two months, which was 39-53% of the annual net carbon sink of China's terrestrial ecosystems (190-260 Tg C yr(-1)). Moreover, model experiments showed that heatwaves and droughts consistently decreased ecosystem vegetation primary production but had opposite impacts on ecosystem respiration (TER), with increased TER by 6.78 +/- 2.15% and decreased TER by 15.34 +/- 3.57% assuming only changed temperature and precipitation, respectively. In light of increasing frequency and severity of future heatwaves and droughts, our study highlights the importance of accounting for the impacts of heatwaves and droughts in assessing the carbon sequestration in terrestrial ecosystems.
摘要：
Chinese subtropical forests contain a diversity of tree species and exhibit a high carbon (C) sequestration capacity, but biomass and C stock assessments in subtropical secondary forests remain uncertain because of a limited availability of allometric equations and an uncertain applicability of existing allometric equations that have not been tested for these forests. We developed allometric equations for important coniferous (Pinus massoniana), deciduous broadleaved (Alniphyllum fortunei, Choerospondias axillaris, Liquidambar formosana) and evergreen broadleaved (Cyclobalanopsis glauca, Litsea rotundifolia, Schima superba) species. A total of 70 trees (10 trees for each species) with diameters at breast height (D) ranging from 2.6 to 50.9 cm were destructively harvested and dissected into tree components (stem, branch, leaf and coarse root). Species-specific equations using D alone as the predictor variable fitted the data well (p < 0.0053 and R
2 > 0.72) for each tree component. Including height (H) in the form of D
2
H only improved the regression fit for A. fortunei and L. rotundifolia. The relationships of branch, leaf and root biomass against D varied among tree species. General equations for functional groups and all species combined showed comparable bias for stem, aboveground and total tree biomass to species-specific equations. We recommend the general equations of multiple species to estimate forest biomass at regional scales and also to estimate stem, aboveground and total tree biomass for each species when species-specific allometric equations are not available at a given site. For branch, leaf and root biomass, species-specific equations are preferred, even though this requires biomass data for additional tree species.
关键词：
Koelreuteria paniculata;Lateral fine root development;Manganese mine wastes;Phytoremediation;Seedling biomass
摘要：
The planting of trees on mine wastelands is an effective, long-term technique for phytoremediation of heavy metal-contaminated wastes. In this study, a pot experiment with seedlings of Koelreuteria paniculata under six treatments of local mine wastes was designed to determine the major constraints on tree establishment and to evaluate the feasibility of planting K. paniculata on manganese mine wastelands. Results showed that K. paniculata grew well in mine tailings, and also under a regime of equal amounts of mine tailings and soil provided in adjacent halves of pots. In contrast, mine sludge did not favor survival and growth because its clay texture limited fine root development. The bio-concentration factor and the translocation factor were mostly less than 1, indicating a low phytoextraction potential for K. paniculata. K. paniculata is suited to restore manganese mine sludge by mixing the mine sludge with local mine tailings or soil.
作者机构：
[田大伦; 方晰; 李斌; 项文化; 闫文德] 中南林业科技大学,生命科学与技术学院,长沙410004;[李斌] 国家林业局,北京100714;[田大伦; 方晰; 项文化; 闫文德] 南方林业生态应用技术国家工程实验室,长沙410004;Division of Science, College of Arts and Sciences, Governors State University, University Park, Illinois 60484(USA);湖南省邵阳县林业局,邵阳,422100
通讯机构：
College of Life science and technology, Central South University of Forestry and Technology, Changsha, China
摘要：
Tree diameter at breast height (dbh) and height are the most important variables used in forest inventory and management as well as forest carbon-stock estimation. In order to identify the key stand variables that influence the tree height-dbh relationship and to develop and validate a suit of models for predicting tree height, data from 5961 tree samples aged from 6 years to 53 years and collected from 80 Chinese-fir plantation plots were used to fit 39 models, including 33 nonlinear models and 6 linear models, were developed and evaluated into two groups. The results showed that composite models performed better in height estimate than one-independent-variable models. Nonlinear composite Model 34 and linear composite Model 6 were recommended for predicting tree height in Chinese fir plantations with a dbh range between 4 cm and 40 cm when the dbh data for each tree and the quadratic mean dbh of the stand (Dq) and mean height of the stand (Hm) were available. Moreover, Hm could be estimated by using the formula Hm = 11.707 x l n(Dq)-18.032. Clearly, Dq was the primary stand variable that influenced the height-dbh relationship. The parameters of the models varied according to stand age and site. The inappropriate application of provincial or regional height-dbh models for predicting small tree height at local scale may result in larger uncertainties. The method and the recommended models developed in this study were statistically reliable for applications in growth and yield estimation for even-aged Chinese-fir plantation in Huitong and Changsha. The models could be extended to other regions and to other tree species only after verification in subtropical China.
