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In order to explain the difference of survival response of plants at different levels in evergreen broad-leaved forest to the Phyllostachys edulis expansion from the perspective of ecological stoichiometry homeostasis, this study used the method of space-time substitution, a typical P. edulis evergreen broad-leaved forest interface including P. edulis forest, P. edulis broad-leaved mixed forest and evergreen broad-leaved forest was selected in Jinggangshan National Nature Reserve, Jiangxi Province. The N and P contents of soil and leaves of P. edulis, broad-leaved trees, shrubs and herbaceous layer plants in each forest were compared and analyzed. The results were as follows:(1)From bamboo forest to evergreen broad-leaved forest, the soil N content and N:P increased, while soil P content decreased; the leaf P contents of tree species(Machilus thunbergii, Alniphyllum fortunei and Daphniphyllum macropodum)decreased and the N:P increased. Unlike the trees, the leaf N and P stoichiometric characteristics of plants both in shrub and herbaceous layers showed no significant change, except the shrub tree Lindera erythrocarpa.(2)The soil N:P was positively correlated with the leaf N:P of trees, negatively correlated with that of shrubs and had no correlation with that of herbaceous plants, respectively.(3)The leaf N and P contents and N:P for P. edulis remained stable. In conclusion, P. edulis expansion changes plant leaf N and P stoichiometric characteristics by altering the soil N and P stoichiometric characteristics. Shrubs and herbaceous plants are less affected, however, it causes the imbalance of plant N and P stoichiometric characteristics of tree layer plants, which may be an important reason for the survival of tree species in evergreen broad-leaved forest. [ABSTRACT FROM AUTHOR]

In order to better apply the light energy utilization model in subtropical evergreen coniferous forest areas, take Qianyanzhou, Taihe County, Jiangxi Province as an example, using satellite remote sensing data（GLASS LAI leaf area index product data set） from 2003 to 2005, MODIS surface reflectance product data set（MOD09 A1） and MODIS GPP product（MOD17 A2）) and China Terrestrial Ecosystem Flux Research Network（ChinaFLUX） the flux observation data of evergreen coniferous forests in Qianyanzhou, fraction of absorbed photosynthetically active radiation（FPAR）, 7 kinds of moisture limitation factors（fθ） and 3 kinds of temperature limitation factors（ft） in the 13 different energy efficiency models were reconstructed. A better model combination was obtained by comparing the coefficient of determination and the root mean square error（RMSE） of the flux station observations with the estimated values of 273 model combinations. At the same time, the optimization model was used to estimate gross primary productivity（GPP） and conduct sensitivity analysis. The results showed that the optimal model combination obtained by optimizing: the photosynthetically active radiation absorption ratio expressed in EVI, the moisture influence factor fθ-3 PG in the 3 PG model, and the temperature influence factor ft-TEM in the TEM model（R²=0.86, RMSE=0.47 μmol/m²·s） had the best simulation effect. The GPP simulation values of the optimized model were better than MODIS terrestrial level four standard data products（MOD17 A2）. Sensitivity analysis resultsshowed that the maximum light quantum efficiency αmax,enhanced vegetation index（ EVI） and photosynthetically active radiation（ PAR） were the direct linear variables of the model and had the greatest impact. Other parameters were determined by the order from big to small was light and minimum temperature Tmin,photosynthetic optimum temperature Topt,monthly average temperature T,and photosynthetic maximum temperature Tmax. Therefore,the optimization model in this paper had strong practical significance and was of great significance to further improve the accuracy of GPP estimation. [ABSTRACT FROM AUTHOR]

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Copyright of Forest Research is the property of Forest Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Forest Research is the property of Forest Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)