太行山区不同农业景观生境的蜘蛛群落结构特征及其影响因子

为探索太行山区农业景观中不同生境类型对蜘蛛多样性的影响,采用陷阱法对河北省武安市西部太行山区5种类型生境(核桃林、玉米地、苹果-芍药套作园、次生林、绿海花廊景观带)的地表蜘蛛多样性进行调查。通过分析5种类型生境中蜘蛛多样性分布及其与局部生境因子的相关关系,探讨半自然生境对蜘蛛的保护作用。结果表明:人为干扰会显著降低生境中蜘蛛丰富度和多度;增加植被群落结构的复杂程度会使生境中蜘蛛丰富度显著增加,而蜘蛛的多度显著降低;蜘蛛的多度随生境中枯落物厚度的增加而增加。其中核桃林的蜘蛛Shannon-Wiener多样性显著高于其他4种类型生境,核桃林、次生林和绿海花廊的蜘蛛丰富度显著高于苹果-芍药套作园和玉米地,苹果-芍药套作园和绿海花廊的蜘蛛多度显著高于其他3种生境。玉米地、苹果园-芍药套作和绿海花廊中蜘蛛的群落组成具有较高相似性,而核桃林与次生林中蜘蛛群落结构具有较高异质性。地表枯落物厚度是影响当地蜘蛛群落结构的最主要因素。研究区在农业景观与自然景观的过渡区种植核桃林、苹果-芍药套作园和绿海花廊间作板栗,对蜘蛛多样性的保护都有积极作用;不同的生境因子与不同蜘蛛群落的关系不同,如狼蛛偏向人为干扰较大的苹果-芍药套作园和绿海花廊景观带,所以生产管理时要结合特有的生境条件,对相应的蜘蛛进行合理的保护和高效的利用。研究结果对当地的农业景观生境管理和生物多样性保护具有指导意义。     

有机管理对不同农田生境草本植物α、β和γ多样性的影响

有机农业有利于增加农田中的植物多样性,而丰富的植物群落可以为其他动物提供诸如蜜源、寄主、栖息地等多种生态系统服务功能。本研究基于一个有机管理的大面积多生境农场及其附近常规管理的农田区,进行植物调查,对比不同管理措施下大棚菜地、果园、稻田田埂、露天田块及其周边的农田边界等5种生境类型农田草本植物α、β和γ多样性的差异。研究发现,虽然有机管理下所有生境的草本植物物种数和药用草本植物物种数(α多样性)的平均数显著高于常规管理农田,但针对某一具体生境比较发现,有机管理仅显著增加了露天田块和水稻田埂的植物物种数,而对其他生境影响不显著。虽然有机管理农场和常规管理农田区的总体物种组成差异(β多样性)不大,但有机管理下水稻田埂和露天田块的草本植物物种组成显著不同于常规管理下的对应生境。总的植物物种数(γ多样性)在有机管理的农场区和常规管理的农田区间没有显著差异。由此可见本研究中有机管理仅有利于水稻田埂和露天田块的草本植物α多样性和β多样性的增加,而对大棚菜地、农田边界和果园影响不明显,并且有机管理并不能显著地增加该地区的草本植物γ多样性。因此有机农业增加植物多样性并不具有普遍性,需要具体考虑不同生境和不同层次多样性指数的差异。     

不同施肥措施对德州市农田土壤生物学性状的影响

[目的]探讨不同施肥措施对山东省德州市农田土壤生物学性状的作用效果,为农田土壤的培肥与农作物的合理种植提供理论依据。[方法]通过连续3a的大田试验,研究CK(对照,不施肥)、CF(尿素提供100%的氮)、CM(牛粪提供100%的氮)和CM+CF(牛粪和尿素各提供50%的氮)等处理对德州市农田土壤养分、微生物数量、微生物多样性、活性有机碳及碳库管理指数的影响。[结果]与CF处理相比,CM+CF处理显著提高了农田土壤碱解氮、速效磷、速效钾含量和部分微量元素的有效性,降低了pH值;明显增加了土壤微生物数量与微生物量碳、氮含量,其中细菌数分别较CK,CF和CM处理显著增加91.22%,65.47%和17.11%;同时,CM+CF处理的微生物多样性指数最高,并与微生物总量的变化趋势一致,而CF与CK处理的微生物多样性指数与微生物总量的变化趋势不一致。此外,CM+CF处理的低活性有机碳含量和碳库管理指数亦显著高于其他处理,其中碳库管理指数比CK,CF和CM处理高出69.52,67.84,38.61。与CM+CF处理相比,CM处理对农田土壤的影响效果较小。[结论]牛粪与化肥配施能显著改善德州市农田土壤的生物学性状,有利于提升土壤肥力和增强供肥性。     

稻蟹共作与常规稻田蜘蛛群落组成及多样性分析

稻蟹共作是一种新型的稻田生态种养殖技术,对推动生态农业发展具有重要意义。目前对稻田蜘蛛的研究仅限于常规稻田,而关于稻蟹共作系统蜘蛛方面的研究尚少见报道。本试验旨在研究稻蟹共作田与常规稻田中蜘蛛群落的组成及多样性特点,探索稻蟹共作田蜘蛛的发生特点,为进一步研究稻蟹共作系统生物多样性特征奠定基础。试验采用吸虫器抽吸法,系统调查了盘锦稻蟹共作田和常规稻田蜘蛛物种组成,并分析了蜘蛛群落多样性特点。结果表明：这两类稻田共调查11科31种蜘蛛,狼蛛科（Lycosidae）、皿蛛科（Linyphiidae）和园蛛科（Araneidae）数量最多,占总蛛数70%;稻蟹共作田蜘蛛个体数量显著高于常规稻田。2类稻田蜘蛛优势种均为草间钻头蛛（Hylyphantes graminicola）和拟水狼蛛（Pirata subpiraticus）。多样性指数表明,6月初蜘蛛Shannon-Wiener多样性指数最低,8-9月蜘蛛群落最高;而均匀度指数、丰富度指数总体与其呈正相关,优势度指数与其呈负相关;2类稻田蜘蛛群落多样性特点基本一致。研究结果表明稻蟹共作田和常规稻田蜘蛛种类和多样性特点没有显著差异,但蜘蛛个体数量有显著差异,即稻蟹共作田蜘蛛个体数量显著高于常规稻田。     

基于Meta-analysis研究不同管理措施对中国农田土壤剖面有机碳的影响

深入理解土壤剖面深层有机碳的含量和变化（Soil Organic Carbon, SOC）对于准确估算农田土壤碳库具有重要意义，因此，探讨不同农田管理措施对剖面SOC的影响程度至关重要。本研究收集了1980-2019年间国内外已发表有关中国农田管理措施对剖面SOC影响的文献，利用Meta-analysis整合分析不同农田管理措施对我国农田土壤剖面SOC变化的影响。结果表明，不同耕作条件下，NTS对土壤剖面SOC的提升速率显著大于CT，年变化率达36.1%，深层土壤（<20 cm）SOC也明显增加约7%-31%，增加了深层土壤碳的输入量；与不施肥相比，不同施肥措施均能显著提高剖面SOC含量，其中MNPK处理对耕层（0-20 cm）SOC增长速率最大，约为0.52 g/(kg·yr)；常年水田耕作形成的淹水厌氧环境，可有效减缓有机物质的矿化分解、增加表层（0-20 cm）SOC累积，年增长率达24.84%；随耕作年限增加，表层土壤碳随耕作输入深层土壤，深层（<20 cm）SOC固定量增加约2.17%-20.29%。不同农田管理措施比较分析结果显示，MNPK、NTS和水田耕作通过保护土壤结构稳定、维持土壤环境不被破坏、增加土壤碳输入等手段，均可达到抑制SOC矿化分解和提升土壤固碳量的效果，其中，NTS对剖面SOC的年提升率达11%-36%，在管理措施中表现最佳，可广泛推广。     

设施种植模式对土壤细菌多样性及群落结构的影响

为了研究有机和常规设施种植模式及轮作对土壤细菌多样性和群落结构的影响,本研究采用Illumina平台Hiseq 2500高通量测序技术,于2016年6月(作物处于收获期)对北京市顺义区不同设施种植模式(分别为有机设施种植模式和常规设施种植模式下的叶菜连作、茄果连作和叶茄轮作)下土壤细菌进行16S r RNA测序。测序质控后共获得17 278个操作分类单元(operational taxonomic units,OTUs),共计318 851条有效序列。比较不同种植模式和轮作下土壤细菌多样性、细菌群落结构组成、相对丰度及土壤理化性质与细菌群落多样性关系的差异性。结果表明:土壤微生物群落结构在有机和常规设施种植模式下差异明显,有机设施种植土壤细菌多样性高于常规设施种植;有机设施种植下轮作与连作土壤细菌群落结构表现出明显差异,而常规设施种植下,两者没有明显差异;有机种植模式下,轮作土壤细菌群落多样性高于连作土壤;设施种植土壤细菌群落主要属于鞘氨醇单胞菌属(Sphingomonas,5.05%)和芽孢杆菌属(Bacillus,4.84%),相对丰度大于0.5%的共有14个属。有机设施种植土壤含有较多促进植物生长、有机质分解的细菌,常规设施种植土壤中降解化学杀虫剂、防治土壤病害、促进硝化过程的细菌较多。RDA分析结果显示土壤细菌群落主要受全磷、速效磷、有机质的影响。Tumebacillus、Candidatus Solibacter和Acidothermus都是分解有机质、利用碳源的细菌属,与土壤有机质含量呈正相关关系。由此可见,设施条件下,有机和常规种植土壤微生物群落结构的差异性主要源于肥料使用、有害生物防治措施和管理方式的不同。有机设施种植模式下,轮作更有利于发挥其改良土壤营养循环和防治土壤病虫害的作用。上述结果为在微生物水平上研究设施条件下不同种植模式的土壤生态质量差异提供了参考。     

近地层臭氧浓度升高对稻田土壤微生物群落功能多样性的影响

利用中国臭氧FACE(Free-Air O3 Concentration Enrichment,开放式空气臭氧浓度增高)试验平台,研究了近地层臭氧浓度升高条件下,2009年和2010年的稻田土壤微生物功能多样性的响应规律。结果发现,1.5倍当前臭氧浓度下稻田土壤水溶性有机碳含量从100.0～110.9μg g-1降低至81.3～94.5μg g-1。臭氧浓度升高下BIOLOG平均吸光值(AWCD)有低于对照的趋势。多样性指数结果表明,臭氧浓度升高50%对稻田土壤微生物丰富度、优势度及均一度无显著影响。2010年碳源底物利用的主成分分析显示,1.5倍当前臭氧浓度下稻田土壤微生物对碳源底物的利用方式发生变化。本研究揭示近地层臭氧浓度升高可能对稻田土壤微生物产生积累效应,并通过微生物碳源底物有效性的改变最终影响土壤微生物的功能多样性。     

长期施肥对旱作区农田土壤细菌群落组成和多样性的影响

为阐明长期有机、无机施肥对旱作区土壤细菌群落组成及多样性的影响机制,以农田土壤生态系统为研究对象,采用单因素随机区组设计,利用长期定位试验(11年)和高通量测序的方法,研究了不施肥(对照,T0)、单施化肥(T1)、化肥配施羊粪有机肥(T2)和化肥配施生物有机肥(T3)对土壤的影响,分析了处理间土壤细菌群落组成及多样性的差异,探究了驱动土壤细菌群落组成及多样性变化的主要土壤环境因子。结果表明:与T0相比,羊粪有机肥、生物有机肥与化肥配施能显著提高土壤全氮、全磷、有机质、碱解氮、有效磷和铵态氮的含量,其中T2处理效果最显著(P<0.05)。各施肥处理下土壤放线菌门(Actinobacteria)、变形菌门(Proteobacteria)、绿弯菌门(Chloroflexi) 细菌为优势菌门;羊粪有机肥、生物有机肥与化肥配施处理降低了土壤放线菌门的相对丰度,增加了绿弯菌门、拟杆菌门和厚壁菌门的相对丰度,T2处理与T0处理间有显著差异(P<0.05)。与T1处理相比,羊粪有机肥、生物有机肥与化肥配合施用使土壤硝化螺旋菌门的相对丰度显著降低。类诺卡氏菌属(Nocardioides)、KD4-96和Subgroup_6为土壤细菌群落的优势菌属。T2处理较T3处理更显著地降低了土壤类诺卡氏菌属(41.15%)、芽球菌属(41.67%)和红杆菌属(27.45%)的相对丰度。与T0处理相比,T2处理更显著增加了细菌群落物种数、群落辛普森指数、香农指数和Chao1 指数(P<0.05)。冗余分析表明,土壤有机质(P=0.001)、pH(P=0.003)是驱动土壤细菌群落组成及多样性变化的主要因素。土壤pH以及有机质含量高低对驱动旱作区土壤细菌群落组成以及土壤细菌多样性变化均产生直接效应。因此,化肥与羊粪有机肥相结合的长期施肥管理是优化旱作区区域农田养分管理、提升土壤肥力的有效途径。     

作物多样性种植对农田害虫及天敌的影响

作物多样性种植在中国有着古老而悠久的历史,在现代农业生产中仍发挥着重要作用。近几年,利用多样性种植控制虫害成为全世界农业研究的热点之一。作物多样性种植直接影响农田害虫的发生、危害、行为。许多研究表明,农作物多样性种植,害虫数量和危害程度都有不同程度的减轻。但也有一些研究表明,作物多样性种植不仅不能减轻害虫的危害程度,甚至还会加重其危害程度。多样性种植不仅影响天敌昆虫数量,而且影响其寄生率或捕食率,并通过影响其定向行为、搜索行为、转移行为等影响其活动能力。本文总结了近年来作物多样性种植对农田害虫及天敌的影响方面的研究结果,并讨论了该领域研究的前景及目前存在的问题。本文还介绍了作物多样性种植对昆虫影响机制的7种假说(物理阻隔假说、视动反应假说、寄主植物气味掩盖假说、驱避性化学物质假说、植物气味组成改变假说、天敌假说、资源密度假说)和1种理论(适宜性/非适宜性降落理论),这些假说和理论在一定程度上能够阐明多样性种植对昆虫的影响机理,但是没有一种假说或理论能够全面阐明多样性种植控制害虫的生态机制。     

三种不同种植模式对土壤细菌群落多样性的影响

采用变性梯度凝胶电泳(DGGE )技术,研究了不同种植模式对土壤细菌群落多样性的影响。结果表明,不同种植模式下DGGE图谱条带的数量及亮度有较大区别,且有几条特征性条带发生了明显的变化。0—15 cm土层细菌群落的丰富度、多样性指数及均匀度指数均表现为:“菜稻菜模式”（RVCs） “休闲轮作模式”（FRCs） “蔬菜连作模式”（VCCs）;15—30 cm土层细菌群落的丰富度、多样性指数及均匀度指数均表现为:FRCs RVCs VCCs。UPGMC聚类分析表明,RVCs 处理的细菌群落结构相似性较低。主成分分析表明,对各主成分起分异作用的主要是 RVCs和FRCs;与主成分因子1 正相关程度较高的种植模式为:RVCs和VCCs,与主成分因子2 正相关程度较高的是 FRCs。可见,水稻土细菌群落多样性与种植模式密切相关,这些变化对土壤细菌群落有重要的调节作用。     

有机管理对不同土地利用方式下土壤质量的影响

许多研究发现有机管理可以改善农田土壤质量,但是否不同土地利用方式下都存在此结论尚未明确。为探究有机管理对不同土地利用方式土壤质量的影响,本研究基于一个多土地利用方式的有机管理农场及其附近常规管理农田进行土壤质量调查,对比不同管理措施及大棚菜地、果园、露天菜地、农田边界、稻田田埂5种土地利用方式下农田土壤质量的差异,并对不同管理措施下农田土壤养分含量、重金属含量、动物数量共计20个指标进行方差分析和主成分分析。研究发现虽然总体上(综合5种土地利用方式的均值)有机管理的土壤pH显著高于常规农田;但针对一种土地利用方式,只有露天菜地和农田边界的土壤pH显著提高。总体上有机管理下土壤全磷、全钾、有效磷含量显著降低,但露天菜地土壤有机质和全氮含量均显著高于常规管理农田。有机管理在总体上显著降低了土壤Cr、Cu、Ni、Zn含量;但针对一种土地利用方式,只显著降低了大棚菜地土壤Cr、Ni、Zn含量,果园和稻田田埂土壤Cu含量,露天菜地和农田边界土壤Zn含量。有机管理虽然总体上均显著增加了土壤中蜘蛛目、倍足纲、步甲、蚯蚓的数量;但针对一种土地利用方式,只显著增加了露天菜地地表蜘蛛目、倍足纲、步甲,稻田田埂地表步甲、土壤蚯蚓以及果园倍足纲数量。主成分分析结果表明,不同管理方式下土壤质量差异明显,有机管理下蜘蛛目、倍足纲、步甲和蚯蚓等土壤动物较多,土壤pH较高,土壤P含量较低,重金属Cu、Pb、Zn、Cr含量较低,但并非在所有土地利用方式下都成立。由此可见,有机管理虽然总体上可以改善土壤质量,但受具体管理措施、人为投入品数量和有机种植时间等因素影响,并非在所有土地利用方式下效果都显著,且在不同土地利用方式下显著改善的指标也各不相同,因此需要针对不同土地利用方式和不同指标采取针对性的改善措施。     

Changes in agricultural management drive the diversity of Burkholderia species isolated from soil on PCAT medium

In order to assess the diversity of culturable Burkholderia populations in rhizosphere and bulk soil and to evaluate how different agricultural management regimes and land use history affect this diversity, four treatments were evaluated: permanent grassland; grassland converted into maize monoculture; arable land and arable land converted into grassland. Burkholderia isolates obtained on PCAT medium were grouped in 47 clusters using 16S ribosomal RNA gene based PCR-DGGE combined with BOX genomic fingerprinting (DGGE-BOX). The distribution of the isolates in the DGGE-BOX clusters was used to calculate the Shannon diversity index per treatment. Interestingly, we observed that the Burkholderia diversity was affected by changes in the agricultural management, since the highest diversity was observed in permanent grassland and in continuous arable land. In addition, the diversity tended to be higher in the rhizosphere than in the corresponding bulk soil. The use of species abundance models indicated that rhizosphere communities had more even distributions than communities collected from the bulk soil. Identification of isolates revealed that only 2% of these belonged to the B. cepacia complex and that the majority was assigned to either (1) new Burkholderia species or (2) Burkholderia species that had originally been isolated from soil. Isolates classified as B. hospita, B. caledonica and Burkholderia sp. ‘LMG 22934’ and ‘LMG 22936’ were found mainly in the arable land, while isolates belonging to Burkholderia sp. ‘LMG 22929’ and B. phytofirmans were associated with the grassland area. Another potentially new Burkholderia species, ‘LMG 22932’, was found in both areas, in close association with the maize rhizosphere.     

不同利用方式下红壤微生物生物量及代谢功能多样性的变化

研究了不同农林利用方式下红壤微生物生物量和代谢功能多样性等土壤质量指标的变化.结果表明:不同利用方式对土壤质量各指标造成了显著的影响;稻田的微生物生物量碳、氮最高,林地和草地微生物生物量次之,旱地的微生物生物量碳、氮最低(分别是稻田利用方式的4.3% 和 13.7%);稻田的微生物代谢功能多样性最高,旱地、林地和草地的细菌代谢功能多样性较低,旱地的真菌代谢功能多样性最低;微生物生物量和代谢功能多样性可以作为反映土壤质量变化的早期敏感的指标,用来衡量管理措施的改变对土壤质量造成的影响.     

Functional aspects of soil animal diversity in agricultural grasslands

There has been recent interest in the characterization of soil biodiversity and its function in agricultural grasslands. Much of the interest has come from the need to develop grassland management strategies directed at manipulating the soil biota to encourage a greater reliance on ecosystem self-regulation. This review summarises information on selected groups of soil animals in grasslands, the factors influencing their abundance, diversity and community structure and their relationships to the functioning and stability of grassland ecosystems. Observations on the impacts of agricultural managements on populations and communities of soil fauna and their interactions confirm that high input, intensively managed systems tend to promote low diversity while lower input systems conserve diversity. It is also evident that high input systems favour bacterial-pathways of decomposition, dominated by labile substrates and opportunistic, bacterial-feeding fauna. In contrast, low-input systems favour fungal-pathways with a more heterogeneous habitat and resource leading to domination by more persistent fungal-feeding fauna. In view of this, we suggest that low input grassland farming systems are optimal for increasing soil biotic diversity and hence self-regulation of ecosystem function. Research is needed to test the hypothesis that soil biodiversity is positively associated with stability, and to elucidate relationships between productivity, community integrity and functioning of soil biotic communities.     

Discriminating the effects of agricultural land management practices on soil fungal communities

The structure of fungal communities was examined in soil subjected to 5 years of different agricultural land management and tomato production practices. Length heterogeneity polymerase chain reaction (LH-PCR) of fungal rDNA internal transcribed spacer-1 (ITS-1) regions was used to create genomic fingerprints of the soil fungal communities. Three years after initiation of land management practices, univariate analysis of genetic diversity failed to detect differences among soil fungal communities in plots managed organically, conventionally or maintained free of vegetation by continuous tillage (disk fallow). Genetic diversity was significantly higher in plots maintained as a perennial pasture grass (Paspalum notatum var Argentine bahiagrass) or as an undisturbed weed fallow. The composition of soil fungal communities within organic, pasture grass or disk fallow plots were separated into unique clusters by non-parametric multivariate analysis of their Bray-Curtis similarity matrices, computed from the relative abundance of ITS-1 amplicons, while the composition of communities within disk fallow and conventional plots could not be distinguished from each other. Diversity of soil fungal communities was significantly reduced following the cultivation of tomato in year four when compared to the diversity in plots where tomato was not cultivated. Divergence in the composition of soil fungal communities was observed following the cultivation of tomato under all land management regimes except organic, where communities continued to remained clustered based upon similarities among their ITS-1 amplicons. Divergence in the composition of fungal communities became more pronounced following two major hurricanes (Francis and Jeanne, September 2004) except for communities in the organic and pasture grass plots. Following the completion of a second tomato crop in year 5, genetic diversity and richness was similar under all land management regimes except the pasture grass, where it remained significantly higher. By contrast, following two consecutive years of tomato production, unique but mutually similar compositions of fungal communities were detected only in plots subjected to the organic land management regime. This was supported by observations that fungal communities were dominated by a 341 bp rDNA amplicon fragment in all land management regimes except the organic. Cloning and sequencing indicated that the 341 bp fragment generated by LH-PCR had a sequencing size of 343 bp, which was most closely related to Fusarium oxysporum. Thus, land management practices that disturb or disrupt soil fungal communities will significantly reduce their diversity. However, the composition of soil fungal communities is more strongly influenced by land management practices and communities within an organically management system were more resistant to anthropogenic and meteorological disturbances.     

地形及土壤多样性与耕地动态变化的相关分析

本文以河南豫北、豫中和豫南3个典型样区为研究对象,运用地统计学方法,从多样性、相关性角度定量分析了地形、土壤的多样性特征及其与耕地变化(2001年、2007年和2017年)面积的空间分布多样性特征的关系,以期为耕地资源动态变化的驱动力分析及合理利用提供新的研究角度。研究表明:1)豫北和豫中样区的地形构成组分多样性呈现出均匀性,豫南样区表现为相对单一性;各研究区的地形空间分布多样性为平原丘陵山地。2)豫南的土壤构成组分最为均匀且丰富,豫中的土壤构成组分相对单一;各研究区的典型土壤各异但总体上分布皆较均匀,各样区的土壤空间分布多样性的显著差异与地形条件密切相关。3)研究尺度影响地形、土壤空间分布多样性特征的表达, 3 km×3 km网格是相对适宜的研究尺度。4)地形和土壤的空间分布多样性指数与耕地变化面积空间分布都具有明显的相关性,其中地形中平原相关性较大,达0.95左右;各样区典型土壤如豫南的水稻土,豫中、豫北的褐土以及豫北的潮土的相关性更为明显,达0.9以上。综合来看,典型样区的地形、土壤因子的构成组分多样性及空间分布格局有显著差别;在不同网格尺度下,耕地的变化面积与地形、土壤因子的空间分布多样性指数密切相关。     

科尔沁沙地土地利用变化对大型土壤节肢动物群落影响

土地利用类型是地球表层系统最突出的景观标志,不仅可以客观地展示地球表面特征空间格局的活动,还反映着地球表面景观的时空动态过程[1-2].由于土地利用变化与人类活动和全球气候变化密切相关,对生物多样性消长、生态环境演变、生态安全水平以及人类可持续性发展有着重要影响,因而其研究已成为当今全球变化研究的前沿和热点课题[1,3].     

Responses of birds of different biogeographic origins and habitat requirements to agricultural land abandonment in northern Spain

Agricultural land-use changes in Europe have taken two opposing directions: towards agricultural intensification or land abandonment. While in the Mediterranean region land abandonment is a main cause of avian diversity decline, in northern Europe species diversity often increases with successional age. We examined the hypothesis that the biogeographic origin of the avifauna determines whether abandonment brings conservation benefits or detriment by studying the bird community of agricultural land in northern Spain, at the boundary of the Mediterranean and Eurosiberian regions. Using a successional gradient, we examined landscape-scale effects of agricultural abandonment on birds during the breeding and non-breeding seasons.The trend in avian diversity with successional stage differed little between Mediterranean and Eurosiberian species in winter. In the spring, however, there was an increase in diversity with stage in abandonment for Eurosiberian birds but not for Mediterranean species. Analysis of individual species showed a preference among Eurosiberian birds for more wooded habitats whereas Mediterranean birds preferred open areas and shrubland.The introduction of agricultural policies to geo-political units that do not coincide with eco-regions cannot be assumed to bring uniform conservation benefits. In the Mediterranean region, agricultural mosaics of low intensity cultivation maintain the highest diversity of priority bird species. Agricultural land abandonment should not be assumed to benefit conservation.     

Patterns of species diversity in rural herbaceous communities under different management regimes, Chiba, central Japan

The patterns of plant species diversity in herbaceous vegetation subjected to various human activities were studied in most of the landscape elements in a rural area of Chiba, central Japan. Twenty-eight transects were sampled in four types of human management-regime (cultivation, trampling, mowing, and abandonment) and were grouped into seven vegetation types using TWINSPAN and DCA analyses. The DCA axis 1 arranged all the transects into a successional order along which biomass and the degree of succession increased. Accumulated number of species increased in a stepwise pattern along the DCA axis 1, in which the dominant plant life-forms were replaced from annuals, to perennials and perennials/tree-saplings depending on different management regimes. The unique species which were confined to a certain management regime, were identified in each site. It is suggested that the coexistence of various successional communities under different human management regimes enhance regional species diversity through maintaining these unique species. Among four types of management regime, mowing sites (especially traditional verge meadows) had most abundant unique, rare species specially adapted to regular cutting. It is suggested that maintaining such traditional mown sites is important to conserve the unique biodiversity of the studied area.