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Shanghai, China

Xu S.,Zhejiang University | Peng Z.,Shanghai Forestry Station | Li Y.,Zhejiang University | Pan S.,Zhejiang University | And 2 more authors.
Life Science Journal | Year: 2013

Self-thinning scaling relationship emerges as a consequence of the trade-off between growth and survival in crowed populations with resource limitations. As an essential link between the organism- and population-level traits of species, it is crucial for predicting ecosystem patterns, dynamics and construction. Despite a long research history, it remains controversial whether the scaling exponent is constant or if it is, what value it takes. The long-term debate always revolves around a dichotomous distinction between the exponent of -3/2 predicted by Euclidean geometry model and -4/3 derived from the fractal network of branching tubes. Evidence emerging recently suggests that the exponent traverses across any single value with the influence caused by biotic and abiotic factors. From a long-term systematic research combined with theoretical analysis, field investigation and experimental observation, our group summarizes that the biotic and abiotic factors are especially noticeable in self-thinning process ascribed to their roles in mediating plant architecture (i.e., allometric growth in height (H) and radius (R)) as well as above- and below-ground allocation, which alters the intensity and pattern of plant interaction (competition and facilitation) and results in variable self-thinning trajectory. To better understand how body mass and density are related in self-thinning process in relation to affecting factors, we describe the self-thinning phenomena, review the theoretical and empirical -3/2 and -4/3 self-thinning rule, discuss the various factors affecting the self-thinning trajectory, analyze the possible mechanism underlying the formation of self-thinning relationship and propose novel directions for future mass-density research. Source

Du B.,Shanghai JiaoTong University | Kang H.,Shanghai JiaoTong University | Kang H.,Key Laboratory of Urban Agriculture South | Pumpanen J.,University of Helsinki | And 9 more authors.
Ecological Research | Year: 2014

Soil organic carbon (SOC) stock in mountain ecosystems is highly heterogeneous because of differences in soil, climate, and vegetation with elevation. Little is known about the spatial distribution and chemical composition of SOC along altitude gradients in subtropical mountain regions, and the controlling factors remain unclear. In this study, we investigated the changes in SOC stock and chemical composition along an elevation gradient (219, 405, 780, and 1268 m a.s.l.) on Lushan Mountain, subtropical China. The results suggested that SOC stocks were significantly higher at high altitude sites (1268 m) than at low altitude ones (219, 405, and 780 m), but the lower altitude sites did not differ significantly. SOC stocks correlated positively with mean annual precipitation but negatively with mean annual temperature and litter C/N ratio. The variations in SOC stocks were related mainly to decreasing temperature and increasing precipitation with altitude, which resulted in decreased litter decomposition at high altitude sites. This effect was also demonstrated by the chemical composition of SOC, which showed lower alkyl C and higher O-alkyl C contents at high altitude sites. These results will improve the understanding of soil C dynamics and enhance predictions of the responses of mountain ecosystem to global warming under climate change. © 2014 The Ecological Society of Japan. Source

Wang Z.,Shanghai JiaoTong University | Shen G.,Shanghai JiaoTong University | Zhu Y.,Shanghai JiaoTong University | Liu C.,Shanghai JiaoTong University | Han Y.,Shanghai Forestry Station
2015 4th International Conference on Agro-Geoinformatics, Agro-Geoinformatics 2015 | Year: 2015

Urban forest biomass is a major store of carbon and thus plays an important role in the regional and global carbon cycle. In this paper, the estimating method of urban forest biomass based on the field inventory data, remote sensing data and spatial analysis was explored. The spatiotemporal dynamics of urban forest biomass in Shanghai, China between 2005 and 2012 were analyzed. The results show that (1) The density and amount of forest biomass in Shanghai maintained a steady increase between 2005 and 2012. The mean biomass density across Shanghai increased from 34.82 tlha in 2005 to 37.12 tlha in 201 2,and the amount raised from 3.02 m illion tons (Tg) in 2005 and 3. 14Tg in 2008 to 3.42Tg in 2012. Of which, the forest biomass increased annually by 0.04 Tg from 2005 to 2008 and 0.07 Tg from 2008 to 2012. The mostly fraction (94 %) of total forest biomass was in the suburban areas and only 6% in the urban areas, which were in accordance with their area proportions to the total Shanghai area ,that was respectively 95.44'Yoand 4.56%. (2) The higher forest biomass density areas concentrated mostly in the urban areas such as the northern Pudong New District and Huangpu District, where there are higher tree planting density , mature trees and elder forests. S uburban districts such as Qingpu District and Jiading District presented the lower forest biomass density, because the landuse types in these areas consisted mainly of industrial and agricultural land and forests are mostly younger managed. The spatial distribution of forest biomass displayed a tendency of high density in northeast area and low in southwest area.(3) The total forest biomass and average biomass density in the urban and suburban areas presented different change traces over the past two periods of 2005-2008 and 2008-2012. in the urban areas , the total biomass and average biomass density decreased slightly from 2005 to 2008, and increased gradually from 2008 to 2012, whereas the associated value both rose continuously in the suburban areas between 2005 and 2012. This dynamics tendency showed a consistency with the forest change. it was concluded that the urban forest biomass keeps rising stably and modified constantly in the spatial distribution as well with the rapid development of economy and modernization in Shanghai. More emphasis on the harmonious development of economy, social and ecology should be put to make great support to comprehend the regional and global carbon cycle. © 2015 IEEE. Source

Ma C.,Shanghai JiaoTong University | Shen G.,Shanghai JiaoTong University | Shen G.,Key Laboratory of Urban Agriculture South | Zhi Y.,Key Laboratory of Urban Agriculture South | And 2 more authors.
2014 The 3rd International Conference on Agro-Geoinformatics, Agro-Geoinformatics 2014 | Year: 2014

The spectral reflectance features of saline soils changing with salt content and the concentrations of salt ions were studied based on microbial remediation process for the salinized soil. In response to the variations of soil salt content during the remediation process, the spectral response range of salt ions and associated inversion models were analyzed and constructed by adjusting sampling intervals. The results showed there were a positive correlation between the degree of salinity of soil including the salt content of soils and the concentrations of ions contained in salts and the corresponding spectral reflectance of soils although the sensitivity levels varied with different salt ions. The sensitive spectral band of salt content, the concentrations of Mg2+, Cl- and Na+ was respectively 1447-1608nm, 1350-1461nm, 1336-1461nm and 1471-1561nm, and all R2 of their associated inversion models were greater than 0.86. © 2014 IEEE. Source

Wang Z.-J.,Shanghai JiaoTong University | Shen G.-R.,Shanghai JiaoTong University | Shen G.-R.,Key Laboratory of Urban Agriculture South | Zhu Y.,Shanghai JiaoTong University | And 4 more authors.
Chinese Journal of Ecology | Year: 2016

Estimation of urban forest leaf biomass at regional scale plays a significant role in understanding plant growth, carbon assimilation processes and forest ecosystems. In this study, an urban forest leaf biomass estimation method which combined regression analysis and spatial analysis in Shanghai, China was explored. Based on the measured data of leaf biomass from June 2011 to June 2012 and a variety of remote sensing data, an analysis of the distribution characteristics of urban forest leaf biomass was also carried out. The results showed that (1) The higher leaf biomass densities concentrated mainly in the urban areas like Jing’ an District and the Huangpu District, while suburban localities like Songjiang District and Jinshan District presented lower biomass densities, which were around 4 to 10 and 1 to 6 t • hm-2, respectively. (2) The density and the amount of urban forest leaf biomass in Shanghai were 2.55 t • hm-2 and 300.81x103 t, respectively. The overall leaf biomass was also found to be distributed mainly in the suburban areas with a fraction of 94.16%, whereas the urban areas shared a little fraction of 5.84%. Among the administrative districts of Shanghai, Chongming County and Pudong New District owned the highest and second highest leaf biomass, altogether reaching 34.82% of the total, however, Jing’ an District occupied only 0.11%, which was in accordance with its area proportion. (3) The root-mean-square error (RMSE), mean absolute error (MAE) and mean relative error (MRE) of the regression-IDW model for urban forest leaf biomass in this study were respectively 0. 81%, 0.62% and 29.33%, which were decreased by 58.46%, 48.76% and 48.71% respectively than those of the original simple regression model and by 47.74%, 38% and 49.24% respectively than those of the spatial analysis method. The combination of spatial analysis and regression analysis provided a quick, convenient and efficient method for estimating the urban forest leaf biomass and monitoring upscaled forest inventory data at a regional scale. © 2016, editorial Board of Chinese Journal of Ecology. All Rights Reserved. Source

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