The Influence of Linear Elements on Plant Species Diversity of Mediterranean Rural Landscapes: Assessment of Different Indices and Statistical Approaches

This paper mainly aims to study the linear element influence on the estimation of vascular plant species diversity in five Mediterranean landscapes modeled as land cover patch mosaics. These landscapes have several core habitats and a different set of linear elements -habitat edges or ecotones, roads or railways, rivers, streams and hedgerows on farm land- whose plant composition were examined. Secondly, it aims to check plant diversity estimation in Mediterranean landscapes using parametric and non-parametric procedures, with two indices: Species richness and Shannon index.Land cover types and landscape linear elements were identified from aerial photographs. Their spatial information was processed using GIS techniques. Field plots were selected using a stratified sampling design according to relieve and tree density of each habitat type. A 50×20 m² multi-scale sampling plot was designed for the core habitats and across the main landscape linear elements. Richness and diversity of plant species were estimated by comparing the observed field data to ICE (Incidence-based Coverage Estimator) and ACE (Abundance-based Coverage Estimator) non-parametric estimators.The species density, percentage of unique species, and alpha diversity per plot were significantly higher (p < 0.05) in linear elements than in core habitats. ICE estimate of number of species was 32% higher than of ACE estimate, which did not differ significantly from the observed values. Accumulated species richness in core habitats together with linear elements, were significantly higher than those recorded only in the core habitats in all the landscapes. Conversely, Shannon diversity index did not show significant differences.     

植物床-沟壕系统的藻类捕获功能

采用原位实验验证植物床．沟壕系统的藻类捕获功能。结果表明：该系统能够有效拦截和捕获源水藻类。在水力梯度驱动下,约35％源水进入高位小沟流经植物床内部根孔结构而汇至低位小沟。低位小沟内叶绿素a（Chl-a）浓度显著低于高位小沟（P=0．0239）,其降低比例为11．1％。以植物床．沟壕系统为结构形式的根孔净化区其出水Chl-a浓度较源水整体下降了27．0％。估算该片根孔净化区捕获藻类鲜生物量约122kg／d。石臼漾湿地共含根孔净化区11片,按供水25万t／d计,估算捕获藻类鲜生物量约1100kg／d。     

北方农牧交错带不同植被保护及恢复措施物种多样性研究

为研究不同生境类型及不同植被恢复方式植物群落结构特征及物种多样性,本文以位于我国西北农牧交错带的宁夏盐池为研究对象,根据不同植被恢复及保护措施特点,在宁夏盐池布设典型样地。样地类型分为:天然草地、退耕还草地、撂荒地、湿地、人工封育草地、流沙地等6种类型。植被调查采用样线和样方相结合的方法,内容包括:植物名称、株数、盖度、高度、生物量(鲜质量)等。运用生态统计学原理,结合BiodiversityPro、MicrocalOrigin等生态学统计软件对不同样地类型植物进行聚类、多样性指数计量等处理、分析。聚类分析表明:不同植被保护及恢复措施下,植物组成、群落结构、主要建群种等都表现出不同特点,不同样地具有各自不同的优势群落、主要建群种等;多样性指数计量结果表明:不同样地间由于生境类型、植被保护及恢复措施等不同造成样地间物种多样性的差异,湿地由于充足的土壤水分条件,无论是丰富度指数还是综合多样性指数都远高于其他样地类型,综合多样性指数D、H分别为12.783、2.915。此外,退耕还草地和天然草地多样性指数也较高,尤其是退耕还草地,D、H分别为11.514和2.696,是农牧交错带一种较为合理的植被恢复措施;多样性较低的是人工封育草地,D、H分别为2.599、1.576。造成人工封育草地物种多样性较低的主要因素一是随着封育时间的延长,优势种的优势地位不断加强、种间竞争等导致部分物种的消失等原因;二是随着封育时间的增加,土壤结皮加厚,水分入渗率和利用率降低从而导致植物群落衰退。     

人工湿地植物床-沟壕系统水质净化效果

嘉兴市石臼漾湿地以仿拟自然界的植物床-沟壕系统为主要结构单元,以人工湿地生态根孔技术为核心净化技术,将河网源水主要水质指标提高了一个类别.为探索该系统以及根孔净化技术的优化途径,于2010年5～10月在湿地内构建了16个并联的植物床-沟壕单元,以正交设计手段研究根孔构筑方式、植物组合和强化介质3种因素对人工湿地植物床-沟壕系统水质净化效果的影响.综合考虑水质净化效果、工程施工难易程度、建设及运行维护成本等情况,推荐人工湿地植物床-沟壕系统的优化途径为:根孔构筑方式采用上、下两层秸秆填埋方式,植物组合优选芦苇+菰,在植物床局部采用适量方解石作为强化介质.比较了中试强化区和大工程区的水质净化效率,结果显示:强化后的植物床-沟壕系统具有进一步提升湿地水质净化效果的潜能,对总氮、总磷、氨氮等水质指标去除率提高幅度约为20%～40%.因此在保证湿地处理水量的前提下,控制大渠过水量、增加植物床-沟壕系统内根孔区的过流量可以发挥该系统更好的水质净化效果.     

Geoecological analysis of the Korea alpine and subalpine plants and lands

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长白山毛赤杨和白桦/沼泽交错带植物多样性分布格局

采用样带网格调查方法和香农-威纳多样性指数分析方法,研究长白山毛赤杨、白桦/沼泽交错带和干扰白桦/沼泽交错带植物多样性水平分布和垂直分布格局。结果表明:①毛赤杨、白桦/沼泽交错群落植物多样性随着交错区环境梯度变化呈现出凸型水平分布格局,其植物多样性指数为相应地段森林群落的1.5倍,沼泽群落的2～3倍。干扰白桦/沼泽交错群落植物多样性随着交错区环境梯度变化呈现出凹型水平分布格局,其植物多样性指数仅相当于相应地段沼泽群落或森林群落的80%左右,仅为毛赤杨、白桦/沼泽交错群落的70%;②毛赤杨、白桦/沼泽交错群落植物多样性呈现“金字塔型”垂直分布格局,其垂直分布格局是草本层(5):灌木层(3):乔木层(1)。而干扰白桦/沼泽交错群落植物多样性垂直分布格局为草本层(5):灌木层(0.4):乔木层(1),并未呈现典型“金字塔型”分布。因此,人为经营活动不仅降低了森林/沼泽交错带植物多样性水平,也改变了其分布格局。     

基于DFSR模型的北方农牧交错区生态系统健康评价 ——以宁夏盐池县为例

以宁夏盐池县为研究区域,基于DFSR模型建立评价指标体系,采用GIS和RS技术辅佐生态系统健康评价,得出盐池县生态系统状况.结果表明,2000年、2002年、2006~2008年,盐池县生态系统健康驱动力分值、状态分值、响应分值及综合分值逐年增加,表明盐池县生态系统健康状况呈上升趋势;2009年生态系统健康驱动力分值和状态分值均增加,但响应分值减少,生态系统健康的综合分值基本上没有改变,表明生态系统的健康状况呈现稳定的状态.     

Spatio-temporal analysis of alpine ecotones: A spatial explicit model targeting altitudinal vegetation shifts

There is general agreement in literature that Alpine vegetation belt ecotones have shown a trend of upward migration in the last few decades. Despite the potential of such shifts as indicators of global change effects in mountain ecosystems, there are relatively few works focused on their assessment in a systematic and spatially explicit way. In this work our aim is to quantify the altitudinal shifts and analyse the spatial pattern dynamics of mountain ecotones. We developed a novel procedure to delineate the current and former state of three characteristic mountain ecotones, which we formalised as forest, tree and tundra lines. Our approach is based on the recognition of altitudinal extreme outposts identified with ecotone locations at a slope scale. The integration of multi-temporal datasets allows the identification and quantification of altitudinal advances and retreats in the outpost locations for a given period. We tested the method in a section of the Italian Alps for the period 1957-2003. Results show a general trend of an increase in altitude for the three ecotones, despite the occurrence of occasional decreases. We estimate decadal altitude increments of 25 m for forest line, 13 m for treeline and 11 m for tundra line. We also identified changes in ecotone spatial morphology between the two dates, with significant implications in connectivity and colonisation dynamics.