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1.
人工柠条-荒漠草地交错带拟步甲昆虫群落多样性   总被引:2,自引:2,他引:0  
选取宁夏东部盐池县人工柠条灌丛-荒漠草地交错带为研究样地,以距离梯度形式,利用巴氏诱罐法对拟步甲科昆虫群落多样性进行了调查,研究了边缘效应对拟步甲昆虫群落多样性的影响。共采集拟步甲昆虫1405只,分属8属13种。结果表明,克小鳖甲和弯齿琵甲个体数量分别占总个体数的32.74%和43.27%,为该地区的优势种类。拟步甲昆虫在人工柠条灌丛-荒漠草地交错带的分布可分为3种类型,优势种克小鳖甲和弯齿琵甲属于栖息地广布型,但二者并没有表现出十分均匀的适应性,而且他们在各样带的分布呈显著负相关,克小鳖甲的分布趋向于沙生荒漠环境,弯齿琵甲的分布趋向于柠条灌丛;常见种蒙古漠王、小皮鳖甲的分布偏向于喜好荒漠草地;异距琵甲、奥氏真土甲、网目土甲和淡红毛隐甲的分布则偏向于喜好柠条灌丛。拟步甲昆虫丰富度与Shannon-Wiener多样性沿边缘分别向柠条灌丛和荒漠草地内部降低,个体数量总体上沿柠条灌丛、交错带向荒漠草地内部降低,但各样带差异不显著。从季节动态看,荒漠草地和柠条灌丛物种多样性季节变化相似,3种生境拟步甲活动密度季节变化相似。边缘效应强度分析呈现边缘正效应。CCA排序图显示分类地位相近的物种在生态适应上具有趋同性。多元回归分析表明,植被密度影响拟步甲昆虫群落的优势种和个体数量,植被盖度和高度分别影响拟步甲群落的均匀度和丰富度。主坐标分析(PCo A)排序表明人工柠条灌丛-荒漠草地交错带的拟步甲昆虫群落组成与柠条灌丛内部没有明显分化,但趋于向柠条灌丛生境演替。  相似文献   

2.
选取宁夏东部盐池县苜蓿-荒漠草地交错带为研究样地,以距离梯度形式,利用巴氏诱罐法对步甲科昆虫群落多样性进行了调查,共采集步甲昆虫1944头,分属11属22种。结果表明,直角通缘步甲Pterostichus gebleri个体数量占总个体数的67.90%,为该地区的优势种类。物种多样性和均匀度沿苜蓿草地、边缘到荒漠草地依次升高,步甲个体数量沿苜蓿草地、边缘到荒漠草地则依次降低,且显著差异。主成分PCo A排序表明边缘与苜蓿草地和荒漠草地都有部分相似,苜蓿草地内部和荒漠草地间的步甲群落组成差异较大,反映了苜蓿草地内部与荒漠草地内部的群落组成开始明显分化。从季节动态看,苜蓿草地和边缘物种多样性、均匀度季节变化相似,荒漠草地和苜蓿草地的优势度季节变化相似,3种生境步甲物种丰富度、活动密度季节变化相似。边缘效应强度分析呈现边缘正效应。多元回归分析说明植被密度是影响步甲的Shannon-Wiener多样性和优势度,植被密度和植被盖度是影响整个群落步甲和优势种直角通缘步甲活动密度的决定因素。  相似文献   

3.
【目的】步甲是主要栖息于地表的种类最丰富的昆虫类群之一,它们对生境的变化更为敏感。分析地形因子对贺兰山步甲昆虫群落物种多样性分布格局的影响,以期揭示步甲昆虫物种多样性分布格局形成和稳定的机制。【方法】2015年7-8月选取贺兰山山地针叶林、山地疏林、山地灌丛、山地草原和浅山荒漠5种生境98个样地,用杯诱法对步甲群落物种组成和多样性进行调查,并采用典范对应分析(CCA)分析物种多样性指数和物种分布与地形因子之间的关系,运用广义可加模型(GAM)拟合不同生境步甲群落多样性指数对海拔梯度的响应曲线,探讨贺兰山步甲群落物种多样性的垂直分布格局。【结果】共采集步甲昆虫21属65种10 989头,其中,直角通缘步甲Pterostichus gebleri和径婪步甲Harpalus salinus为优势种,其个体数量分别占总捕获个体数的44.93%和11.33%。山地疏林生境步甲物种丰富度最高,山地针叶林的步甲Shannon-Wiener多样性指数最高,浅山荒漠的步甲均匀度最高。海拔、坡向、坡度、剖面曲率和地形湿度指数的综合作用对步甲物种多样性分布格局有显著影响。其中,海拔对5种生境的步甲分布影响均显著,且解释力度最高;坡向对山地针叶林和浅山荒漠步甲分布影响显著。步甲总体丰富度和个体数量与海拔呈不对称的单峰曲线关系,Shannon-Wiener多样性指数随海拔呈先递增后保持稳定的变化,均匀度指数与海拔呈"V"型变化趋势。【结论】贺兰山山地步甲物种多样性的分布格局受海拔为主的多种地形因子综合作用的影响。  相似文献   

4.
王建芳  王新谱  李秀敏  刘桂霞 《昆虫学报》2010,53(10):1127-1134
为了探讨土地利用方式对步甲物种多样性的影响及其与环境因子的关系, 于2009年5-10月利用巴氏罐法, 对河北坝上塞北管理区内的灌草丛、马铃薯地、苜蓿地、围封草地、中度放牧草地和重度放牧草地6种生境的步甲进行了系统调查。结果表明: (1)共捕获步甲标本10 804号, 计10属18种, 其中强足通缘步甲Pterostichus fortipes、侧步甲Carabus latreillei和双斑猛步甲Cymindis binotata占优势, 个体数分别占总数的67.5%, 7.53%和7.06%。(2)苜蓿地中的步甲密度、物种丰富度、Margalef丰富度指数、Shannon-Wiener多样性指数和均匀度指数均较高, 其他样地较低。(3)聚类分析结果显示, 不同生境的步甲群落相似性与受干扰强度和土地利用方式一致。(4)步甲主要在6-9月活动, 高峰期为7-8月。各物种在不同土地利用方式生境内的季节变化趋势与不同生境植被生长季节相关, 步甲个体数量随着植物生物量的增加而增加。强足通缘步甲Pterostichus fortipes高峰期大多出现在植物生长旺盛的7月, 仅围封草地内的高峰出现在8月; 双斑猛步甲Cymindis binotata的高峰期出现在8-9月。(5)典范对应分析表明, 土壤含水量、土壤温度、植物盖度、植物生物量及植株高度是影响步甲群落组成的重要环境因子。结论认为, 不同土地利用方式对环境的干扰影响了步甲赖以生存的生境, 进而影响了其物种的组成和数量分布格局。  相似文献   

5.
湿地是介于水体与陆地之间的特殊的生态系统,其中昆虫扮演着重要的角色。通过选取扎龙村、烟筒屯、土木台和育苇场为样地以诱集夜间活动的昆虫为主,对扎龙湿地昆虫群落结构进行了探讨。结果表明:扎龙湿地夜间活动的昆虫分属14目54科139种,以鳞翅目、鞘翅目和双翅目为优势类群。各区域昆虫群落种-多度关系均表现为对数正态分布。物种丰富度为扎龙村>烟筒屯>育苇场>土木台,而群落多样性和均匀度均为烟筒屯>扎龙村>土木台>育苇场,Shannon-Wiener 多样性指数(H') 与均匀度(J')和物种丰富度(S)时间动态关系表现为:烟筒屯Shannon-Wiener 多样性指数(H')与均匀度(J')和物种丰富度(S)均一致;扎龙村和育苇场Shannon-Wiener 多样性指数(H')与均匀度(J')一致,而与物种丰富度(S)弱相关;土木台 Shannon-Wiener 多样性指数(H')与均匀度(J')和物种丰富度(S)均表现为弱相关。研究得出扎龙湿地总体环境质量较好,但局部地区(如土木台)有退化的趋势,并分析造成上述结果的原因。  相似文献   

6.
采用陷阱诱捕法和网捕法于2016年7月-8月对宁夏温性草原13种不同草原型的甲虫种类和数量分布进行了调查,共获得甲虫标本1591号,分属于10科58种,其中直角通缘步甲Pterostichus gebleri(Dejean)、麻步甲Carabus brandti brandti Faldermann、短翅伪葬步甲Pseudotaphoxenus brevipennis Semenov、甘肃大步甲Carabus gansuensis gansuensis Semenov、暗星步甲Calosoma(Charmosta)lugens Chaudoir和蒙古伪葬步甲Pseudotaphoxenus mongolicus(Jedlicka)为优势种,个体数量分别占总个体数的23.69%、9.68%、9.05%、8.61%、8.30%和6.28%。在种类分布上,固原官厅乡三等长芒草Stipa bungeana Trin.型、同心郭大湾村二等大针茅S.grandis P.Smirn.长芒草型、同心张家塬乡四等大针茅长芒草型、彭阳罗洼乡三等百里香Thymus mongolicus Ronn长芒草型及彭阳孟塬乡四等铁杆蒿Artemisia sacrorum Ledeb.长芒草型等地种类和数量均较多;多样性分析表明,海原月亮山四等苔草Carex.spp.、杂类草Miscellaneous grass型集中性概率指数最大,同心张家山村二等大针茅长芒草型多样性指数和均匀性指数均最大,固原官厅乡三等长芒草型的丰富度指数最高;群落相似性分析显示,固原三营镇三等长芒草大针茅型与同心张家塬乡四等大针茅长芒草型、同心郭大湾村二等大针茅长芒草型相似性系数最高;昆虫对生境指示作用分析表明,胸圆高鳖甲Hypsosoma rotundicolle Fairmaire和弯齿琵甲Blaps(Blaps)femoralis femoralis(Fischer von Waldheim)分别可作为彭阳孟塬乡四等铁杆蒿长芒草型和海原嵩川乡三等苔草杂类草型的指示类群。  相似文献   

7.
冀卫荣  胡俊杰  李友莲 《生态学报》2008,28(8):3721-3728
在山西庞泉沟国家自然保护区华北落叶松不同林龄的人工林和天然林内,利用巴氏罐诱法,对其地表甲虫大步甲属Carabus物种进行了系统的调查,结果表明: (1)共获得大步甲属标本1290号,分属于10种,9种是该保护区的新记录种类,其中C. canaliculatus沟步甲、C. crassesculptus粗皱步甲、C. manifestus罕丽步甲、C. vladimirskyi长叶步甲为优势种,肩步甲C. hummeli、刻翅步甲C. sculptipennis、粒步甲C. granulatus为常见种. (2)不同林地物种丰富度S、多样性H′、优势度D、个体数量N存在显著差异,均匀度J不存在显著差异;S、H′、D、J在人工林25年生林地最高;N在天然林20~30年生林地最多;β多样性人工林5年生林地最高.(3) 4种优势种季节性变化总体上是沟步甲的盛发期为7月和8月份;粗皱步甲的高峰期为7月份;罕丽步甲7月、5月、9月份和6月份发生数量多,8月份稀有;长叶步甲8月份和9月份为盛发期;不同物种在不同林地出现的高峰期是不一致的.(4)物种相似性分析结果是天然林35~45a和60~80a,人工林25a和天然林5~8a极相似,其余为中等不相似和中等相似.(5)生境相似性分析的结果是天然林35~45a和60~80a相似性最高,人工林5年生与天然林20~30a、35~45a生境相似性差异逐渐增大.(6)生境指示种分析的结果是粗皱步甲、罕丽步甲为广布种,肩步甲仅在天然林35~45a和60~80a生的林地采集到,其中在天然林35~45a林地生境物种指示值高达96.73.  相似文献   

8.
兴安落叶松林是大兴安岭地区代表性的植被类型,其生物多样性具有独特性。步甲是森林生态系统环境和多样性的指示性物种,以及认识环境变化和生物多样性特征的关键物种。为研究大兴安岭地区兴安落叶松林步甲群落多样性的时间动态,分析步甲群落对时间变化的响应规律,于2019年5月下旬-8月下旬步甲活跃期,利用陷阱诱捕法在兴安落叶松林5个样地中采集步甲标本共15属34种1149头,其中大兴安岭地区地理新纪录物种7种,中国地理新纪录物种6种。研究结果表明,通缘步甲属(Pterostichus)和大步甲属(Carabus)物种丰富度最高;通缘步甲属未定种5(Pterostichus eximius)为极优势物种,对时间变化最敏感。兴安落叶松林小生境类型的多样化和步甲休眠期的选择是步甲群落个体数和物种数随时间变化呈双峰模式的主要因素,最高峰均出现在6月下旬;多样性与均匀度指数均在7月上旬达高峰期,8月下旬多样性下降而均匀度上升,各指数之间相关性较低。步甲群落在6月下旬到7月下旬对环境具有较高的适应度;群落结构在环境条件相对稳定的6月下旬到7月下旬和8月上旬到8月下旬均表现为极相似(I>0.75)。物种取食特征和生活史策略的多样化使步甲群落各指数随时间变化具有显著差异,而物种取食特征和生活史策略受环境因子的综合影响较大。稳定的森林环境条件下,步甲活跃期更长,群落结构相似度更高。该结果为步甲群落时间动态研究奠定了一定的理论基础,为大兴安岭地区地下生物多样性的保护和管理策略制定提供了一定的理论和数据依据。  相似文献   

9.
田中平  庄丽  李建贵 《生态学报》2012,32(4):1151-1162
针对伊犁河谷北坡山地的植物多样性和土壤因子沿海拔的分布方式进行研究。对研究地海拔1000-2200m植物和环境特征进行调查,选取群落样地总数为44个,共调查到植物种155种,其中乔木7种、灌木18种、草本130种,调查到的群落类型完全涵盖了研究区所有沿海拔上升的群落类型。通过NLFS高级模拟显示总的物种丰富度、Simpson指数、Shannon-Wiener多样性指数、Pielou均匀度指数都与海拔呈现先升高后降低,再升高的一个特殊分布格局。出现了两个较高的物种丰富度地带,其中一个是低山荒漠到落叶阔叶林,另一个是山地草原到针叶林带。土壤养分和盐分也表现出了类似多样性的分布格局。通过PCA和相关分析表明,环境因子控制着物种丰富度和它的分布方式。水分在低海拔比较重要,在高海拔温度比较重要,而由于逆温层的作用,在较高海拔的针叶林带物种多样性出现了上升。物种丰富度与土壤总盐呈现显著负相关关系(r=-0.343),与土壤全盐也呈现显著负相关关系(r=-0.341)。Simpson指数与土壤pH值呈现显著负相关关系(r=-0.465)。Shannon-Wiener指数与土壤电导率呈现显著负相关关系(r=-0.367)。Pielou均匀度指数与土壤电导率呈现极显著负相关关系(r=-0.477),总之,多样性指数和土样盐分表现出了强相关性。这个研究为伊犁河谷植被与植物资源的保护和利用提供重要的科学依据,为河谷区山地植被与环境关系提供基础科学理论,为山地退化植被的修复提供参考案例和可借鉴的基础性数据。  相似文献   

10.
云南西北部地区地表甲虫的物种多样性   总被引:26,自引:4,他引:22       下载免费PDF全文
共调查了云南西北部地区的中甸大雪山、中甸碧塔海、德钦白芒雪山、丽江石鼓镇、玉龙雪山保护区和永胜县6个小区域。采用巴氏罐诱法研究不同生境下地表甲虫物种多样性的变化。其结果:①共采集甲虫标本2852号,分属16个科,以隐翅虫数量最多,占41.3%;步甲次之,占25.9%;金龟、象甲、拟步甲的数量各占5%以上;其他11科合计占13%;②甲虫群落的物种多样性分析表明:农业活动频繁的永胜县,个体数量和丰富度较低;游牧业和旅游业频繁的中甸碧塔海多样性指数和丰富度较低;其他4个区域多样性指数、均量和丰富度较低;游牧业和旅游业频繁的中甸碧塔海多样性指数和丰富度较低;其他4个区域多样性指数、均匀度指数、丰富度以及个体数量比较均匀。除永胜县外,其他地区甲虫群落间相似性系数随空间距离的增大而降低。③比较针叶林、阔叶林、混交林、灌丛和草甸等5种生境,所有甲虫、步甲、金龟数量在针叶林和草甸生境内较高;隐翅虫数量在针叶林和阔叶林内较高;象甲在阔叶林内数量较高;拟步甲在灌丛内数量较高;但只有步甲和隐翅虫差异显著。④物种的个体数量、丰富度和多样性指数随海拔高度不同,其变化趋势相似。在1500-2000m呈下降趋势;在2500-3000m和3500-4000m分别形成2个峰值。均匀度指数的变化趋势则与之相反。以上结果表明,空间距离和生境类型影响云南西北部地区地表甲虫群落的物种多样性和相似性,频繁的农牧业和旅游业活动,对保持地表甲虫物种多样性的自然分布规律产生一定影响。  相似文献   

11.
内蒙古锡林河流域羊草草原15种植物热值特征   总被引:1,自引:0,他引:1  
通过对生物量约占羊草草原生物量80%的15种主要野生植物地上植株进行分种取样,测定其热值(美国PARR6300型氧弹式热量计进行热值测定)、灰分(干灰化法测定)、矿质元素(iCAP6000型电感耦合等离子体发射光谱仪测定)同时对各项指标的相关性进行分析来探讨内蒙古锡林河流域羊草草原主要植物作为生物燃料供给料的潜力及植物热值对灰分和矿质元素含量的响应情况。结果表明:15种野生植物热值范围为16.19 MJ/kg(木地肤)到20.99 MJ/kg(小叶锦鸡儿),15种植物热值平均值为18.76 MJ/kg,该值高于全世界陆生植物平均热值。15种植物热值高低顺序为:小叶锦鸡儿>早熟禾>大针茅>冰草>羽茅>羊草>中华隐子草>变蒿>芨芨草>菊叶萎陵菜>大籽蒿>冷蒿>狗尾草>银灰旋复花>木地肤。15种野生植物灰分范围20.25%(银灰旋复花)到3.62%(芨芨草),15种植物灰分含量存在显著差异(P<0.05),其高低顺序为银灰旋复花>木地肤>冷蒿>大籽蒿>菊叶萎凌菜>狗尾草>冰草>羊草>早熟禾>中华隐子草>变蒿>羽茅>小叶锦鸡儿>大针茅>芨芨草。Pearson’s相关分析表明热值与灰分之间存在极显著负相关关系(P<0.01),热值和碳之间存在极显著正相关关系(P<0.01),矿质元素与热值之间没有一致的相关关系。内蒙古羊草草原植物热值普遍高于能源植物柳枝稷的热值,这也说明该地区植物具有作为能源植物的潜力。  相似文献   

12.
选取宁夏荒漠草原人为灌丛地转变过程中的两种优势种沙芦草(Agropyron mongolicum)和柠条锦鸡儿(Caragana korshinskii)为对象,利用不同浓度PEG条件下的种子萌发特性来探究其在干旱胁迫下植被更新萌发特征,结果表明:柠条锦鸡儿平均初始萌发时间早于沙芦草14 h,且柠条锦鸡儿吸水率低于沙芦草,分别为201.21%、293.43%;柠条锦鸡儿和沙芦草种子萌发率和萌发速率均随渗透势的升高呈先上升后下降趋势,且均在-0.02 MPa时萌发率最高,分别为28.67%、44.67%,在-1.2 MPa时最低,分别为6.67%、1.33%;两者萌发速率均在-0.02 MPa时达到最大,分别为12.84%、9.52%,且柠条锦鸡儿起始萌发天数少于沙芦草1-4 d;通过S型生长曲线和线性模型模拟种子萌发水势和萌发率关系,分析得出柠条锦鸡儿萌发水势阈值范围为-0.3--0.86 MPa、沙芦草为-0.3--0.65 MPa,灌木柠条锦鸡儿种子萌发水势阈值范围低于多年生禾草沙芦草。以上结果表明灌丛引入下的荒漠草原在未来干旱条件下,其灌丛柠条锦鸡儿种子在植被更新中较沙芦草更具萌发优势。  相似文献   

13.
This paper studied the occurrence of carabid beetles (Coleoptera: Carabidae) in the forest edge, the adjacent forest interior, and the surrounding grassland in southwestern China. Beetles were collected with pitfall traps along five replicated transects. Forest species rarely penetrated into the grassland from the forest interior, and the grassland specialists were not found in the forest interior. The forest edge hosted additional species from the adjacent grassland that increased its overall species richness. Nearly all forest species (23 of 24 species) and grassland species (13 of 15 species) can be found in the forest edge. Carabids of the forest edge were more similar to those of the forest interior than to those of the grassland by ordination and cluster analysis. Based on the specificity and fidelity, carabids can be distinguished into five species groups: habitat generalists, grassland-associated species, forest generalists, forest specialists, and edge-associated species. Multiple linear regression analysis showed that canopy cover and/or shrub cover were the most important factors in determining the richness, abundance, and diversity of carabids. The forest edge may serve as a transition zone for dispersal and re-colonization of carabid beetles from adjacent habitats and therefore is important for natural conservation.  相似文献   

14.
We investigated the effects of hydromorphological restoration measures (mainly the removal of bank fixations) on riparian mesohabitats, vegetation and carabid beetles by comparing 24 restored to nearby non-restored floodplain sections in Germany. Mesohabitats were recorded along ten equally-spaced transects, plant communities and riparian plant and carabid beetle species along three transects per section. Based on 18 indices including habitat and species diversity, taxonomic diversity and functional indices we compared the frequency and magnitude of changes following restoration, both for the overall dataset and for each site individually. Riparian habitat diversity doubled in restored sections compared to non-restored sections. The numbers of vegetation units and plant and carabid beetle species richness also doubled in restored sections, whereas changes in Shannon diversity were most pronounced for mesohabitats and riparian plants. Taxonomic diversity of carabid beetles decreased in restored sections reflecting post restoration dominance of riparian Bembidion species. Stress-tolerant pioneers of plant and especially carabid species benefit strongly from the re-establishment of open sand and gravel bars, while hygrophilous species, which also include non-riparian species, did not respond to restoration. We conclude that restoring river hydromorphology has almost generally positive effects on riparian habitats and riparian biodiversity. Riparian biota are thus well-suited indicators for the effects of hydromorphological restoration.  相似文献   

15.
The effects of vegetation types and environmental factors on carabid beetle (Coleoptera: Carabidae) communities were studied. Carabid beetles were collected using pitfall traps (total 2844 trapping days) and seven microenvironmental factors were measured in four vegetation types: grassland, natural evergreen coniferous forest (Pinus densiflora), deciduous broad-leaved natural forest (Quercus crispula, Betula platyphylla, Alnus japonica, or Fagus crenata), and deciduous coniferous plantation (Larix kaempferi) in cool temperate Japan. These four vegetation types provided a novel comparison between natural forests and plantations because the vast majority of related studies have investigated only deciduous broad-leaved natural forests and evergreen coniferous plantations. PERMANOVA indicated that vegetation types affected carabid community composition. Ordination plots showed that community composition differed greatly between grassland and forest vegetation types, but that community composition in the plantation forest overlapped with that of natural forest types. Characteristics differentiating the grassland included a high proportion of winged species and a low mean carabid body weight. Among the examined environmental factors, litter depth, soil water content, and depth of the soil A-horizon had large effects on carabid communities. These results suggest that the effect of afforestation on carabid communities in cool temperate Japan might be insignificant compared with the effects of cover types (deciduous vs. evergreen) and microenvironmental factors.  相似文献   

16.
False indigo (Amorpha fruticosa L.) is an invasive exotic plant introduced to Europe in the early eighteenth century. Its spread has been rapid, particularly in disturbed wetland habitats, where it forms dense impermeable monospecific stands and modifies habitat conditions. The impact of A. fruticosa on native plant communities has been well analyzed, however knowledge concerning the possible effects on soil invertebrates and particularly carabid beetles is completely lacking. This study analyzed the impact of an A. fruticosa invasion on carabid beetles and other soil invertebrates. Soil fauna was sampled by pitfall traps at natural habitats, initially colonized by A. fruticosa, and habitats largely invaded by A. fruticosa. In total 2,613 carabid beetles belonging to 50 species and 72,166 soil invertebrates were collected. The invasion of A. fruticosa strongly affected the carabid beetle species composition, which clearly differed between all studied sites. Widespread euritopic carabid beetle species showed positive responses to A. fruticosa invasion, while the activity density of open habitat species strongly declined. Mean individual biomass was significantly higher at invaded sites due to increased incidence of large carabids (genus Carabus Linné, 1758). Carabid beetle activity density and abundance of soil invertebrates were considerably higher at invaded sites than in natural sites. Conversely, the impact of A. fruticosa on carabid beetle species richness and diversity was less pronounced, most likely due to immigration from adjacent habitats. Changes in carabid beetle species composition and abundance of soil invertebrates were most likely due to changes in vegetation structure and microclimate. The results suggest that A. fruticosa invasion considerably affected carabid beetles, an insect group that is only indirectly related to plant composition. Therefore, severe future changes can be expected in invertebrate groups that are closely related to plant composition, since A. fruticosa cannot be completely removed from the habitat and covers relatively large areas.  相似文献   

17.
Diversity patterns of amphipods, carabid beetles and ants were investigated in five naturally-fragmented Afromontane forest remnants, and in the surrounding grassland matrix. Forests were architecturally similar. In contrast, grasslands surrounding these forests are subject to great differences in anthropogenic impacts. Consequently, transition from forest to grassland ranged from being abrupt (heavy disturbance) to gradual (little disturbance). Significantly different mean numbers of carabid individuals and species were captured between sites and multivariate analyses showed clear separation in carabid assemblage-structure with level of disturbance. Carabids were, furthermore, significantly more diverse in forests, compared to grasslands. Ants, however, were equally species rich between sites but were significantly more abundant and species rich in grasslands than forests. Amphipods, represented here by a single species, Talistroides africana, was significantly less abundant at highly disturbed sites and significantly more abundant in forests than grasslands. Results support the hypothesis that the dynamics of remnants are influenced by their surrounding landscape. Here, the dynamics of amphipods and carabids (predominantly forest taxa) were influenced by different disturbance regimes in grasslands surrounding these forests. Epigaeic ants, a predominantly grassland taxon here, also showed significant differences in assemblage-composition between sites with varying disturbance. Conserving Afromontane grasslands should be of prime concern because this will include the protection of forest/grassland ecotones and forest remnants.  相似文献   

18.
禁牧条件下不同类型草地群落结构特征   总被引:2,自引:0,他引:2  
利用幂乘方法则模型探讨了鄂尔多斯3种不同类型草地在禁牧情况下的群落结构特征,包括物种组成、物种多样性、生物量和空间分布规律。结果表明:幂乘方法则在解析鄂尔多斯不同类型草地的空间异质性时具有很好的吻合性;羊草(Leymuschinensis)草地、芨芨草(Achnatherum splendens)草地和油蒿(Artemisia ordosica)灌丛草地均比随机分布呈现了较强的空间异质性,群落整体的空间异质性指数表现为油蒿灌丛草地>羊草草地>芨芨草草地;群落整体的物种多样性指数为油蒿灌丛草地>羊草草地>芨芨草草地;L-样方(50cm×50cm)内的平均物种数和物种多样性指数均表现为羊草草地极显著地高于油蒿灌丛草地,油蒿灌丛草地又极显著地高于芨芨草草地(P<0.001);L-样方内的平均生物量表现为油蒿灌丛草地极显著地高于芨芨草草地(P<0.001),而羊草草地与油蒿灌丛草地以及芨芨草草地之间没有显著性差异;这3种类型的草地其L-样方内的平均生物量和物种多样性指数都随着群落整体空间异质性指数的增大而增大。  相似文献   

19.
The sodium regulation of carnivorous carabid beetles of the genus Cypholoba and herbivorous tenebrionid beetles of the species Phrynocolus petrosus from dry savannah in East Africa was investigated while the beetles went through dehydration in the laboratory. In both species the water loss took place mainly at the expense of the extracellular fluid, and in both species the loss of extracellular water was accompanied by a loss of extracellular sodium. In the carabid beetles the sodium removed from the extracellular fluid was excreted from the body, while in the tenebrionids sodium was kept within the body. It is proposed that the different manners in which the two species handle their sodium reflect differences in their access to dietary water and sodium.  相似文献   

20.
Semi-natural grasslands are key habitats for biodiversity conservation in Central Europe. Shrub encroachment is one of the most threatening drivers of grassland degradation and affects soil properties, microclimate, and vegetation with possible impacts on higher trophic levels. We aimed to analyse the impact of shrub encroachment with broom (Cytisus scoparius) on carabid beetle diversity, species composition, and functional traits. In a field study on dry grasslands on the island of Hiddensee (Germany) we studied 15 sites along a gradient of increasing broom encroachment and classified them into three dry grassland types with low, medium, and high shrub cover. Our results provide evidence that shrub encroachment initially has positive effects on species richness and activity densities of dry grassland carabids. Carabid species composition differed among differently shrub-covered dry grassland types, and sites with low and high shrub cover were each characterised by unique carabid assemblages. The species composition of sites with a medium shrub biomass had a transitional character and contained species which are typical for open dry grassland, but also shared species with sites with a high shrub cover. Among functional trait parameters investigated, especially the body size of carabid beetles was related to environmental parameters associated with shrub encroachment. Body size was positively correlated to shrub biomass and soil humidity, but negatively to temperature. Eurytopy values of carabids were related to high litter cover, i.e. habitat generalist (eurytopic) species mainly occurred in densely shrub-encroached sites. In order to preserve unique carabid assemblages of open dry grasslands with stenotopic and smaller species, it is most important to prevent a shrub encroachment higher than about 60% cover. For management we suggest extensive grazing (by cattle, sheep or horses) to prevent shrub encroachment on dry grasslands. In areas with high shrub cover additionally the use of goats or mechanical removal of shrubs might be necessary.  相似文献   

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