校园绿地是城市绿地中的重要组成部分,为了研究城市绿地对热环境的调控功能,以东南大学四牌楼校区的校园绿地作为研究对象,采用无人机热红外拍摄提取地表温度数据,并结合实地调查确定绿地中植物的种类、冠幅,结合公式完成对绿地绿量及绿量密度的计算,通过函数回归的方法分析绿量密度与地表温度的关系。结果表明,绿地的地表温度与绿量密度呈对数函数关系,绿量密度存在大小阈值。当绿量密度≤小阈值(≤4.08 m³/m²)时,单位面积绿量与温度呈显著负相关性,绿量的增加会起到显著的降温效果;当绿量密度处于大小阈值之间(4.08 m³/m²,16.32 m³/m²)时,单位面积绿量与温度仍有负相关性,但绿量的增加使降温效果有所下降;当绿量密度≥大阈值(≥16.32 m³/m²)时,绿地自身的温度特性相对稳定,受绿量增加的影响较小。

生态系统对环境的净化服务是其向人类提供的重要服务功能之一.了解生态系统的净化机理及其价值,对自然资源的保护及其可持续利用有着十分重要的作用.本文讨论了生态系统的净化服务的机理,提出了生态系统净化类型.在此基础上,运用经济学和环境经济学原理,探讨了生态系统的净化价值评估方法,以我国森林生态系统为例,对生态系统的净化价值进行了估算.

Metagenomics and 16S pyrosequencing have enabled the study of ecosystem structure and dynamics to great depth and accuracy. Co-occurrence and correlation patterns found in these data sets are increasingly used for the prediction of species interactions in environments ranging from the oceans to the human microbiome. In addition, parallelized co-culture assays and combinatorial labelling experiments allow high-throughput discovery of cooperative and competitive relationships between species. In this Review, we describe how these techniques are opening the way towards global ecosystem network prediction and the development of ecosystem-wide dynamic models.

近年来，紫花苜蓿（Medicago sativa L.）和黄花苜蓿（Medicago falcata L.）被广泛选作补播材料，用于修复退化草地。尽管研究表明二者的植物学特征存在差异，但鲜有人关注它们是否会通过不同的方式影响退化草地的生产力。为了探究二者对退化草地的修复效果是否存在差异，并确定影响补播地生产力的限制因素，本研究选取黄花苜蓿和紫花苜蓿作为补播种对退化草甸草原进行了补播，并在隔年对草地植被、土壤理化性质和微生物量进行监测。结果表明，两种苜蓿都可以显著增加退化草地生产力并改善土壤健康状况。然而，紫花苜蓿通过增加土壤铵态氮改变植被群落结构，其补播样地生产力也由土壤速效养分影响；黄花苜蓿通过增加土壤速效磷含量改变植被群落结构，其补播样地生产力由植被群落结构和土壤微生物量共同影响。初步结果表明，黄花苜蓿更适宜在养分贫瘠的退化草地进行补播。此外在选择紫花苜蓿补播时，可以适当施肥以提高补播成功率。

Land use/Land cover (LULC) changes as a result of policy planning influence ecosystem structures, processes, and functions, which are the basis for providing a wide range of ecosystem services (ES). There is an increasing consensus about the importance of integrating ES into ecological policy but quantifying the potential impacts of different policy on ES has proven difficult. We designed a remote sensing, geographic information system and scenario analysis-based approach to estimate and analyze the relationship between ES (soil conservation and carbon sequestration) and ecological policy designed to improve human welfare in the Chongqing municipality in the upper reaches of the Three Gorges Reservoir Area, China; a densely populated, highly modified watershed with serious soil erosion and flood hazard. Three alternative scenarios in 2050 were modeled for the Three Gorges Reservoir Area watershed. The model GEOMOD was used to predict future LULC changes due to policy planning. The ES models (Universal Soil Loss Equation model and Carnegie-Ames-Stanford Approach model) were designed to inform decisions, with an aim to align economic forces with conservation. We examine policy effectiveness by comparing scenarios for 2050 (Scenario1: Maintain current policy with no considerations of ES; Scenario2: Integrate ES into policy planning; Scenario3: Integrate ES into policy planning in view of the need of local people). Scenario-based LULC change analysis revealed that if the current afforestation policy continues (scenario 1), total ES would be further increased in 2050 due to expansion of forest cover. However, by targeting policy to improve ES provision (scenarios 2 and 3), ecological risks of soil loss can be significantly reduced and carbon sequestration enhanced. Scenario 3, thus, provided the best future environmental development scenario considering the need of local people in each region for ES. This scenario will theoretically help the Three Gorges Dam to harvest more ecological benefits through improvements in soil conservation and carbon sequestration. This study highlights the observation that including ES in policy planning and has a great potential to generate opportunities to maximize ES. This study highlights that including ES in policy planning has a great potential to generate opportunities to maximize ES. Hence, there is a need to encourage proper implementation of ecological policy to maintain and improve ES.

This paper describes a protocol effective at extracting high yields of high-purity microbial community DNA from humified soils. DNA was extracted from soil by lysozyme, SDS and freeze-thaw lysis, precipitated and then subjected to a double caesium chloride density gradient centrifugation stage before concentrating and washing. Evaluation using three soils yielded up to 30 micrograms DNA g-1 dry soil, with absorbance ratios at 260:230 nm and 260:280 nm of 1.6-2.0. The DNA extracted from the three soils was digested by four restriction enzymes and a 16S rDNA eubacterial product was amplified by PCR. These tests indicated that the DNA obtained by the protocol was sufficiently pure for molecular biological analysis.

Chimeric DNA sequences often form during polymerase chain reaction amplification, especially when sequencing single regions (e.g. 16S rRNA or fungal Internal Transcribed Spacer) to assess diversity or compare populations. Undetected chimeras may be misinterpreted as novel species, causing inflated estimates of diversity and spurious inferences of differences between populations. Detection and removal of chimeras is therefore of critical importance in such experiments.We describe UCHIME, a new program that detects chimeric sequences with two or more segments. UCHIME either uses a database of chimera-free sequences or detects chimeras de novo by exploiting abundance data. UCHIME has better sensitivity than ChimeraSlayer (previously the most sensitive database method), especially with short, noisy sequences. In testing on artificial bacterial communities with known composition, UCHIME de novo sensitivity is shown to be comparable to Perseus. UCHIME is >100× faster than Perseus and >1000× faster than ChimeraSlayer.robert@drive5.comSource, binaries and data: http://drive5.com/uchime.Supplementary data are available at Bioinformatics online.

鞘氨醇单胞菌(Sphingosinomonas)是一类革兰氏阴性菌,对芳香化合物和多环芳烃具有较强的降解能力。不少研究表明,鞘氨醇单胞菌对重金属具有降解能力,相关功能基因的表达过程也有发现,但其降解机理和完整降解过程尚未探明。文章归纳了鞘氨醇单胞菌的研究现状,总结了鞘氨醇单胞菌对重金属污染的修复效果,分析了其修复过程中的影响因素及其促进植物生长的作用机制,探讨了鞘氨醇单胞菌在重金属污染土壤修复中的关键基因和作用机理,可为进一步开发利用鞘氨醇单胞菌修复环境污染提供思路和依据。