无人机技术在广州南沙区河涌景观特征生态调查中的应用研究进展

在城市化进程逐步加快、社会经济水平趋于高阶的时代,城市生态系统是当前开展交叉学科研究的重要对象,融合了自然科学(如林学、生态学等)和社会科学(如管理学、人文地理学等)领域的思想体系和研究方法。作为一种新兴技术,无人机遥感已在生物学、地理学、信息科学等多个学科领域广泛使用。主要从监测、研究、评估和保护等四个方面简要叙述了无人机技术在林业生态研究和管理中的应用情况,并以广州南沙区河涌景观为例简要分析了无人机技术在珠江三角洲地区城市森林景观中的实际应用。试图为我国城市区域的森林生态、生物多样性与人居环境研究和管理工作提供参考。     

Desferoxamine protects against glucocorticoid-induced osteonecrosis of the femoral head via activating HIF-1α expression

Glucocorticoid-induced osteonecrosis of the femoral head (GIOFH) is one of the most common complications of glucocorticoid administration. By chelating Fe²⁺, desferoxamine (DFO) was reported to be able to activate the HIF-1α/VEGF pathway and promote angiogenesis. In the present study, we examined whether DFO administration could promote angiogenesis and bone repair in GIOFH. GIOFH was induced in rats by methylprednisolone in combination with lipopolysaccharide. Bone repair was assessed by histologic analysis and microcomputed tomography (micro-CT). Vascularization was assessed by Microfil perfusion and micro-CT analysis. Immunohistochemical staining was performed to analyze the expression of HIF-1α, VEGF, and CD31. Our in vivo study revealed that DFO increased HIF-1α/VEGF expression and promoted angiogenesis and osteogenesis in GIOFH. Moreover, our in vitro study revealed that DFO restored dexamethone-induced HIF-1α downregulation and angiogenesis inhibition. Besides, our in vitro study also demonstrated that DFO could protect bone marrow-derived stem cells from dexamethone-induced apoptosis and mitochondrial dysfunction by promoting mitophagy and mitochondrial fission. In summary, our data provided useful information for the development of novel therapeutics for management of GIOFH.     

The ‘pears and lemons’ protein UvPal1 regulates development and virulence of Ustilaginoidea virens

Ustilaginoidea virens is an economically important fungus causing a devastating grain disease, rice false smut. An insertional mutagenesis screen was used to explore biological mechanisms underlying infection process of U. virens. T184, a new mutant was identified, with abnormal conidial morphology and deficient virulence. Analysis of the T-DNA inserted gene UvPal1 in the mutant confirmed it as a putative homologue of a cellular morphogenetic protein in yeast, Pal1, whose function has not been well characterized. Deletion of UvPal1 affected hyphal growth, cell morphology, stress adaptation and virulence. UvPal1 could interact with the endocytic proteins, UvEde1 and UvSla2, but was not required for receptor-mediated endocytosis. A yeast two-hybrid (Y2H) analysis was further carried out to screen the UvPal1-interacting proteins, resulting in the identification of 16 putative interacting proteins. Interestingly, UvPal1 interacted with a septin protein, UvCdc11 in vivo and in vitro, and also affected subcellular localization of UvCdc11 protein. Deletion of the four core septins impaired the growth, morphogenesis, stress response and virulence. Collectively, effects on cell morphology, oxidative stress response and virulence are similar to those of UvPal1, suggesting that UvPal1 physically interacts with UvCdc11 to mediate the septin complex to maintain the cellular morphology and virulence of U. virens.     

Interannual variations and trends in global land surface phenology derived from enhanced vegetation index during 1982–2010

Land surface phenology is widely retrieved from satellite observations at regional and global scales, and its long-term record has been demonstrated to be a valuable tool for reconstructing past climate variations, monitoring the dynamics of terrestrial ecosystems in response to climate impacts, and predicting biological responses to future climate scenarios. This study detected global land surface phenology from the advanced very high resolution radiometer (AVHRR) and the Moderate Resolution Imaging Spectroradiometer (MODIS) data from 1982 to 2010. Based on daily enhanced vegetation index at a spatial resolution of 0.05 degrees, we simulated the seasonal vegetative trajectory for each individual pixel using piecewise logistic models, which was then used to detect the onset of greenness increase (OGI) and the length of vegetation growing season (GSL). Further, both overall interannual variations and pixel-based trends were examined across Koeppen’s climate regions for the periods of 1982–1999 and 2000–2010, respectively. The results show that OGI and GSL varied considerably during 1982–2010 across the globe. Generally, the interannual variation could be more than a month in precipitation-controlled tropical and dry climates while it was mainly less than 15 days in temperature-controlled temperate, cold, and polar climates. OGI, overall, shifted early, and GSL was prolonged from 1982 to 2010 in most climate regions in North America and Asia while the consistently significant trends only occurred in cold climate and polar climate in North America. The overall trends in Europe were generally insignificant. Over South America, late OGI was consistent (particularly from 1982 to 1999) while either positive or negative GSL trends in a climate region were mostly reversed between the periods of 1982–1999 and 2000–2010. In the Northern Hemisphere of Africa, OGI trends were mostly insignificant, but prolonged GSL was evident over individual climate regions during the last 3 decades. OGI mainly showed late trends in the Southern Hemisphere of Africa while GSL was reversed from reduced GSL trends (1982–1999) to prolonged trends (2000–2010). In Australia, GSL exhibited considerable interannual variation, but the consistent trend lacked presence in most regions. Finally, the proportion of pixels with significant trends was less than 1 % in most of climate regions although it could be as large as 10 %.     

Different environmental factors drive tree species diversity along elevation gradients in three climatic zones in Yunnan,southern China

Elevational patterns of tree diversity are well studied worldwide. However, few studies have examined how seedlings respond to elevational gradients and whether their responses vary across climatic zones. In this study, we established three elevational transects in tropical, subtropical and subalpine mountain forests in Yunnan Province, southern China, to examine the responses of tree species and their seedlings to elevational gradients. Within each transect, we calculated species diversity indices and composition of both adult trees and seedlings at different elevations. For both adult trees and seedlings, we found that species diversity decreased with increasing elevation in both tropical and subalpine transects. Species composition showed significant elevational separation within all three transects. Many species had specific elevational preferences, but abundant tree species that occurred at specific elevations tended to have very limited recruitment in the understory. Our results highlight that the major factors that determine elevational distributions of tree species vary across climatic zones. Specifically, we found that the contribution of air temperature to tree species composition increased from tropical to subalpine transects, whereas the contribution of soil moisture decreased across these transects.     

Functional trait space and redundancy of plant communities decrease toward cold temperature at high altitudes in Southwest China

Science China Life Sciences - Plant communities in mountainous areas shift gradually as climatic conditions change with altitude. How trait structure in multivariate space adapts to these varying...