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豫东平原聚落景观格局变化   总被引:4,自引:1,他引:3  
杨慧敏  娄帆  李小建  白燕飞 《生态学报》2017,37(16):5313-5323
中国的快速城镇化必然导致聚落景观格局的变化,但目前相关研究对平原地区关注相对较少。文中选取豫东平原地区的开封、商丘、周口市,运用GIS空间分析方法和ENVI遥感影像处理技术,对该地区1972、2015年市域中观尺度上的聚落规模、聚落景观空间变化特征进行分析。结果显示:(1)在聚落发展过程中,1972—2015年聚落斑块数量有所减少,聚落规模逐渐扩张,市域内最大聚落斑块扩张相对更为明显;对聚落斑块扩张强度的分析发现,城市市辖区及周边乡镇聚落扩张强度相对较高。(2)地区内聚落斑块空间分布表现出聚集分布特征,但该时期聚集程度有所减弱;两个年份聚落核密度分布格局大致相似,局部地区存在多核扩散现象,市域尺度上的核密度分布存在地区差异。(3)对斑块形状指数的分析发现,研究区狭长或曲折聚落斑块在空间上分散布局,整体上区域内聚落形状趋于规则。(4)随着距河流、道路距离的增加,聚落斑块总面积和数量有所减少,且道路对聚落分布仅在一定范围内存在较大影响,距中心城市0—6km范围内聚落受中心城区发展辐射影响较大。本文的分析可为平原地区聚落景观的优化布局和聚落用地的集约化发展提供一定的参考。  相似文献   
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Land use changes have profound effects on populations of Neotropical primates, and ongoing climate change is expected to aggravate this scenario. The titi monkeys from eastern Brazil (Callicebus personatus group) have been particularly affected by this process, with four of the five species now allocated to threatened conservation status categories. Here, we estimate the changes in the distribution of these titi monkeys caused by changes in both climate and land use. We also use demographic‐based, functional landscape metrics to assess the magnitude of the change in landscape conditions for the distribution predicted for each species. We built species distribution models (SDMs) based on maximum entropy for current and future conditions (2070), allowing for different global circulation models and contrasting scenarios of glasshouse gas concentrations. We refined the SDMs using a high‐resolution map of habitat remnants. We then calculated habitat availability and connectivity based on home‐range size and the dispersal limitations of the individual, in the context of a predicted loss of 10% of forest cover in the future. The landscape configuration is predicted to be degraded for all species, regardless of the climatic settings. This include reductions in the total cover of forest remnants, patch size and functional connectivity. As the landscape configuration should deteriorate severely in the future for all species, the prevention of further loss of populations will only be achieved through habitat restoration and reconnection to counteract the negative effects for these and several other co‐occurring species.  相似文献   
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Sequencing reduced‐representation libraries of restriction site‐associated DNA (RADseq) to identify single nucleotide polymorphisms (SNPs) is quickly becoming a standard methodology for molecular ecologists. Because of the scale of RADseq data sets, putative loci cannot be assessed individually, making the process of filtering noise and correctly identifying biologically meaningful signal more difficult. Artefacts introduced during library preparation and/or bioinformatic processing of SNP data can create patterns that are incorrectly interpreted as indicative of population structure or natural selection. Therefore, it is crucial to carefully consider types of errors that may be introduced during laboratory work and data processing, and how to minimize, detect and remove these errors. Here, we discuss issues inherent to RADseq methodologies that can result in artefacts during library preparation and locus reconstruction resulting in erroneous SNP calls and, ultimately, genotyping error. Further, we describe steps that can be implemented to create a rigorously filtered data set consisting of markers accurately representing independent loci and compare the effect of different combinations of filters on four RAD data sets. At last, we stress the importance of publishing raw sequence data along with final filtered data sets in addition to detailed documentation of filtering steps and quality control measures.  相似文献   
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Agro-ecosystems constitute essential habitat for many organisms. Agricultural intensification, however, has caused a strong decline of farmland biodiversity. Organic farming (OF) is often presented as a more biodiversity-friendly practice, but the generality of the beneficial effects of OF is debated as the effects appear often species- and context-dependent, and current research has highlighted the need to quantify the relative effects of local- and landscape-scale management on farmland biodiversity. Yet very few studies have investigated the landscape-level effects of OF; that is to say, how the biodiversity of a field is affected by the presence or density of organically farmed fields in the surrounding landscape. We addressed this issue using the metacommunity framework, with weed species richness in winter wheat within an intensively farmed landscape in France as model system. Controlling for the effects of local and landscape structure, we showed that OF leads to higher local weed diversity and that the presence of OF in the landscape is associated with higher local weed biodiversity also for conventionally farmed fields, and may reach a similar biodiversity level to organic fields in field margins. Based on these results, we derive indications for improving the sustainable management of farming systems.  相似文献   
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目录     
《生态学杂志》2019,38(10):0
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肖甜甜  李杨帆  向枝远 《生态学报》2019,39(11):3850-3860
以围填海活动为代表的高强度的人类开发利用方式从根本上改变了海岸带地区的自然属性,区域生态环境发生了深刻变化。定位于我国大陆沿海的围填海区域,通过人机交互目视解译的方法获取我国大陆沿海围填海区域的矢量数据,基于围填海活动影响下海岸带区域的景观类型和生态系统服务变化的评估结果,识别我国海岸带的生态脆弱区和重点保护区,提出围填海区域景观生态红线的划分方法。通过分析可知:(1)围填海区域景观生态红线区呈现出"总体分散、局部集中"的的分布特点;(2)景观生态红线区主要分布在人工湿地和残存自然湿地中。围填海区域是进行海陆统筹研究的关键区域,而景观生态红线作为识别其重要生态功能区,并进行二次保护和抢救性保护的有效手段,将为我国海岸带生态管理提供新思路和新方法。  相似文献   
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