贵州赤水桫椤国家级自然保护区鸟兽多样性红外相机初步监测

红外相机监测是了解野生动物多样性和威胁因素的重要手段。本研究采用网格法和分层抽样调查法, 在贵州赤水桫椤国家级自然保护区内选取20个监测位点布设红外相机, 对区内鸟兽物种多样性进行监测。2015年8月至2017年8月, 红外相机累计工作6,370个工作日, 共拍摄45,953张照片, 独立有效照片1,936张。准确鉴定出兽类4目8科19种, 鸟类4目11科28种, 其中, 国家II级重点保护野生动物7种。相对丰富度指数(RAI)排前五位的兽类依次是毛冠鹿(Elaphodus cephalophus)、鼬獾(Melogale moschata)、藏酋猴(Macaca thibetana)、小麂(Muntiacus reevesi)和野猪(Sus scrofa); 鸟类依次是紫啸鸫(Myophonus caeruleus)、红腹角雉(Tragopan temminckii)、灰胸竹鸡(Bambusicola thoracicus)、黑喉噪鹛(Garrulax chinensis)和棕颈钩嘴鹛(Pomatorhinus ruficollis)。物种积累曲线结果表明, 兽类稀疏化曲线在300天后趋于稳定, 表明监测取样已较充分, 而鸟类监测物种数随时间积累依旧保持增长趋势。     

四川老河沟保护地2011-2015年野生动物红外相机监测数据集

红外相机技术目前已成为调查、记录陆生大中型兽类和地栖鸟类的最有效方法之一, 为自然保护地的生物多样性编目、野生动物本底调查提供了可靠的数据基础。老河沟保护地位于四川省平武县, 地处岷山山脉中段, 面积110 km², 是大熊猫(Ailuropoda melanoleuca)、川金丝猴(Rhinopithecus roxellana)、红喉雉鹑(Tetraophasis obscurus)等珍稀濒危野生动物的自然栖息地。本文汇总、整理了老河沟保护地2011-2015年的红外相机监测记录, 提供了完整的红外相机监测数据集。数据集包括红外相机有效位点130个, 海拔跨度1,317-3,265 m, 总有效相机工作日10,185 d。红外相机拍摄记录159,694条, 其中兽类记录91,839条, 独立有效照片3,017张, 包括分属5目15科的野生兽类28种; 鸟类记录37,775条, 独立有效照片1,311张, 包括分属7目19科的野生鸟类60种; 两栖类记录8条, 独立有效照片2张, 包括1目1科1种; 家畜记录47条, 独立有效照片5张。     

千岛湖栖息地片段化对大山雀营巢资源利用的影响

为了解栖息地片段化对次级洞巢鸟营巢资源利用的影响, 我们于2008年2-8月, 在千岛湖地区选取21个岛屿, 采用悬挂人工巢箱方法进行大山雀(Parus major)招引实验。通过测定岛屿面积、岛屿隔离度、捕食者活动率、人工巢箱周围植被盖度和人工巢箱巢向等5种参数, 分析大山雀人工巢箱利用与上述参数间的关系。实验期间, 共悬挂443个人工巢箱, 其中有72个(16.3%)被大山雀利用。大山雀倾向于选择捕食者活动率低、植被盖度低、巢口向东或向南的人工巢箱; 岛屿面积和隔离度对大山雀利用人工巢箱不存在显著的直接影响, 但岛屿面积可通过影响捕食者的活动率, 对大山雀利用人工巢箱产生间接影响。因此, 我们认为在栖息地片段化后, 应更多关注对洞巢鸟营巢资源利用有直接影响的栖息地特征因素, 以及片段化效应的间接影响。     

千岛湖栖息地片段化效应对鸟类巢捕食风险的影响

为了解栖息地片段化对鸟类巢捕食风险的影响,我们于2010年4-8月,在千岛湖地区选取16个岛屿,分别在岛屿边缘和内部区域用放置鸡蛋(大型卵)和鹌鹑(Coturnix japonica)蛋(小型卵)的方法进行人工模拟地面巢试验,研究不同体积大小鸟卵的巢捕食率及其差异,分析巢捕食率与岛屿面积、隔离度、形状指数和植物物种丰富...     

利用红外相机监测四川大相岭自然保护区鸟兽物种多样性

红外相机调查技术已成为地栖兽类与鸟类物种多样性研究的重要手段之一, 2017年10月至2018年10月, 我们在四川大相岭自然保护区布设167台红外相机进行生物多样性监测。红外相机累计工作6,738个工作日, 共获得独立有效照片3,317张, 其中野生兽类2,673张、野生鸟类644张。鉴定出野生兽类5目14科23种, 野生鸟类5目11科33种。国家一级重点保护野生动物有3种, 即大熊猫(Ailuropoda melanoleuca)、四川羚牛(Budorcas tibetanus)和林麝(Moschus berezovskii); 国家二级重点保护野生动物有10种, 分别是藏酋猴(Macaca thibetana)、黑熊(Ursus thibetanus)、小熊猫(Ailurus fulgens)、黄喉貂(Martes flavigula)、中华鬣羚(Capricornis milneedwardsii)、水鹿(Cervus equinus)、血雉(Ithaginis cruentus)、白腹锦鸡(Chrysolophus amherstiae)、白鹇(Lophura nycthemera)和红腹角雉(Tragopan temminckii)。其中, 属于《中国脊椎动物红色名录》中极危的有1种, 即林麝, 易危的有9种, 近危的有10种; 被IUCN红色名录评估为濒危的有2种, 易危的有5种, 近危的有3种; 被CITES附录I收录的有4种, 附录II收录的有6种。新记录物种7种, 分别是灰鼯鼠(Petaurista xanthotis)、水鹿、黄颈啄木鸟(Dendrocopos darjellensis)、星鸦(Nucifraga caryocatactes)、白眉鸫(Turdus obscurus)、蓝短翅鸫(Brachypteryx montana)和红翅噪鹛(Trochalopteron formosum)。物种相对丰富度最高的3种动物分别是毛冠鹿(Elaphodus cephalophus, RAI = 125.26)、藏酋猴(RAI = 64.71)和红腹角雉(RAI = 43.34)。本次监测初步掌握了四川大相岭自然保护区内大中型兽类和林下活动鸟类的种类组成和相对多度, 为野生动物的研究与保护管理提供了参考依据。     

贵州梵净山国家级自然保护区鸟兽红外相机监测

红外相机监测是了解野生动物多样性现状、动态变化和面临威胁的重要手段。本研究采用网格抽样调查法, 在贵州梵净山国家级自然保护区内选取2个监测样区共40个监测位点布设红外相机, 对区内兽类和鸟类物种进行监测调查。2017年4月至2018年12月间, 红外相机累积监测14,808个相机工作日, 共收集有效照片14,119张, 独立有效物种照片3,199张。共鉴定野生动物9目22科61种, 其中兽类26种, 隶属于4目12科; 鸟类35种, 隶属于5目10科。记录到国家I级重点保护野生动物2种: 黔金丝猴(Rhinopithecus brelichi)和白颈长尾雉(Syrmaticus ellioti), 国家II级重点保护野生动物9种; 被IUCN红色名录评估为濒危(EN)的1种、易危(VU)的5种、近危(NT)的8种。物种的相对多度指数(relative abundance index, RAI)分析结果显示, 藏酋猴(Macaca thibetana, RAI = 28.23)、毛冠鹿(Elaphodus cephalophus, RAI = 15.46)、野猪(Sus scrofa, RAI = 11.82)、小麂(Muntiacus reevesi, RAI = 9.05)、黔金丝猴(RAI = 7.70)为相对多度最高的5种兽类; 紫啸鸫(Myophonus insularis, RAI = 10.33)、红腹角雉(Tragopan temminckii, RAI = 9.59)、红腹锦鸡(Chrysolophus pictus, RAI = 6.96)、白颈长尾雉(RAI = 3.71)、勺鸡(Pucrasia macrolopha, RAI = 1.55)为相对多度最高的5种鸟类。另外, 红外相机还监测到较多的家畜活动(RAI = 11.14)和人为活动(RAI = 12.90), 保护区管理部门仍需采取相应管理措施, 进一步提高周边居民的保护意识, 促进保护区与社区的协调发展。     

红外相机技术监测效率分析——以陕西佛坪北部山区鸟兽监测为例

利用红外相机对陕西汉中市佛坪县北部山区3个监测样地内的大型兽类和地栖鸟类进行了初步调查和监测,分析了在该区域利用红外相机监测的效率、相机数量和相机工作日与物种数量间的关系以及物种的最佳拍摄地点。结果表明:59台红外相机共拍摄到物种独立照片22 089张,鉴定出野生动物40种,其中,国家一级重点保护野生动物5种,国家二级重点保护野生动物8种。当相机数量增加到54台时拍摄到了本次记录的全部40种野生动物,当单台相机工作日达到140 d时,监测物种数趋于饱和。不同物种的最佳拍摄地点受季节和海拔的双重影响,表现出一定的规律性。综上所述,现有的红外相机布设方法,能够有效地对大型兽类和地栖鸟类进行监测调查,但对于其他啮齿类和树栖鸟类,还应该从物种的体型、生活习性、栖息环境,红外相机布设的位点选择、布设时间、相机参数设置等方面,重新考虑监测方法。此研究不仅积累了监测样地的本底资料,也为红外相机在该区野生动物保护的应用提供了可借鉴的基础资料。     

千岛湖岛屿小型兽类群落的多样性

2007 年秋季和2008 年春季,选取千岛湖地区14 个岛屿和2 个半岛作为样地,采用夹夜法进行小型兽类群落组成调查。两季度共布夹20 400 个,捕获小型兽类1 141 只,隶属2 目3 科9 属13 种,啮齿目(Rodentia)鼠科(Muridae)10 种和仓鼠科(Cricetidae)1 种,食虫目(Insectivora)鼩鼱科(Soricidae)2 种。利用以上结果分析其群落多样性,结果显示:14 个岛屿小型兽类群落春、秋两季的多样性指数、均匀度指数和优势度指数均呈现极显著差异且优势种发生变化;对可能影响岛屿小型兽类群落多样性的岛屿面积、距最近陆地距离、距最近大岛距离和植物丰富度等因素进行逐步回归分析,发现只有植物丰富度对小型兽类群落的物种丰富度有显著影响;对16 个样地按照物种组成比进行聚类,许源半岛样地与14 个岛屿聚为一类,姚家半岛样地单独归为一类,相似性指数比较结果亦显示姚家半岛样地与其它样地的相似性指数偏低。结论:景观破碎化导致千岛湖岛屿小型兽类群落的稳定性下降,物种多样性季节变化强烈;随岛屿面积的增加,小型兽类物种丰富度并非总是增加的,而是出现反复,呈现明显的小岛效应;14 个岛屿的物种与许源半岛样地物种构成比接近,推断在水库未形成前属同一生境。     

运用红外相机调查云南巍山青华绿孔雀自然保护区的鸟兽多样性

2016年10月至2017年9月, 作者在云南巍山青华绿孔雀自然保护区的核心区和缓冲区的28个监测位点布设红外相机, 累计监测6,377台日, 共获得独立有效照片1,692张, 其中兽类563张, 鸟类1,129张。鉴定出71种鸟类和兽类, 其中兽类13种, 分属5目11科; 鸟类58种, 分属9目23科。国家一级重点保护动物有2种, 即黑颈长尾雉(Syrmaticus humiae)和林麝(Moschus berezovskii); 国家二级重点保护动物有7种, 分别是黄喉貂(Martes flavigula)、松雀鹰(Accipiter virgatus)、普通鵟(Buteo japonicus)、白腹锦鸡(Chrysolophus amherstiae)、白鹇(Lophuar nycthemera)、领角鸮(Otus lettia)和灰林鸮(Strix aluco)。在《中国脊椎动物红色名录》中, 1种被评估为极危, 3种被评估为易危。CITES附录I收录的有1种, 附录II收录的有7种。物种相对丰富度最高的是黑领噪鹛(Garrulax pectoralis, 5.68), 其次是赤腹松鼠(Callosciurus erythraeus, 2.81)、赤麂(Muntiacus muntjak, 1.68)。本次物种调查结果可反映本保护区大、中型兽类和地栖性鸟类本底, 为保护区管理和野生动物长期监测提供了数据。     

基于红外相机技术的江西马头山国家级自然保护区兽类和鸟类物种多样性监测初报

江西马头山国家级自然保护区地处武夷山中段,为了进一步掌握该保护区野生动物资源现状,于2016年1月至2018年12月在保护区垂直等高线布设了50台红外相机,对区内兽类和鸟类物种多样性连续监测了34 551个相机工作日,共获得独立有效照片2 534张,其中兽类1 724张,鸟类810张。共鉴定出野生兽类5目10科13种,鸟类7目12科30种,其中包括10种国家II级重点保护动物：猕猴（Macaca mulatta）、中华鬣羚（Capricornis mil-needwardsii）、亚洲黑熊（Ursus thibetanus）、白鹇（Lophura nycthemera）、蛇雕（Spilornis cheela）、松雀鹰（Accipiter vir-gatus）、赤腹鹰（A.soloensis）、领鸺鹠（Glaucidium brodiei）、白眉山鹧鸪（Arborophila gingica）和红头咬鹃（Harpacteserythrocephalus）。白眉山鹧鸪、黄嘴栗啄木鸟（Blythipicus pyrrhotis）和白眉鸫（Turdus obscurus）是保护区的物种新纪录。拍摄率最高的3个物种依次是小麂（Muntiacus reevesi）、白鹇和野猪（Sus scrofa）。马头山国家级自然保护区有待增加相机数量,扩大监测范围,以更好地开展野生动物监测。     

八大公山自然保护区地栖性小兽多样性初步研究

湖南省八大公山自然保护区自1982年设立以来, 尚未进行过兽类资源的深入研究。为此, 作者于2012年9–10月, 采用笼捕法、陷阱法和红外相机法等对保护区内森林动态永久监测样地及周边常见植被类型中的地栖性小型兽类多样性进行了初步研究。共捕获小型兽类12种, 其中啮齿目8种, 食虫目4种。结合以往记录, 该保护区现已记录的小型兽类有20种, 而本次调查新增分布记录物种6种, 即黑腹绒鼠(Eothenomys melanogaster)、猪尾鼠(Typhlomys cinereus)、中华姬鼠(Apodemus draco)、四川短尾鼩(Anourosorex squamipes)、灰黑齿鼩鼱(Blarinella griselda)和藏鼩鼱(Sorex thibetanus)。陷阱法所捕获个体的体重显著小于笼捕法。此外, 不同生境类型对小兽多样性有重要影响。建议综合采用多种调查方法对整个保护区兽类多样性资源进行深入监测与研究。     

A preliminary study of the biodiversity of ground-dwelling small mammals in Badagongshan National Nature Reserve,Hunan Province

Little is known about the diversity patterns of mammals in the Badagongshan National Nature Reserve, Hunan Province, although the reserve was established in 1982. During September and October of 2012, the diversity of ground-dwelling small mammals was investigated using live traps, pitfalls and camera traps in a permanent forest dynamics plot and other nearby vegetation types. We captured 12 species of ground-dwelling small mammals, including eight species of Rodentia and four species of Insectivora. Presently, there are 20 species of ground-dwelling small mammals recorded in the Badagongshan National Nature Reserve, including six new species recorded in this study, i.e., Eothenomys melanogaster, Typhlomys cinereus, Apodemus draco, Anourosorex squamipes, Blarinella griselda, and Sorex thibetanus. The body mass of the individuals captured by live traps was much larger than that of the individuals captured by pitfall traps. Our study also indicates that the diversity patterns of ground-dwelling small mammals are affected by the habitat types. Therefore, we recommend that a combination of different methods be used to effectively monitor mammal diversity in the Badagongshan National Nature Reserve.     

利用红外相机技术对四川王朗国家级自然保护区野生动物物种多样性的初步调查

本研究以四川王朗国家级自然保护区为研究区域, 利用红外相机对保护区内的主要野生动物进行了初步调查, 分析了该区域的物种多样性现状、相机数量和相机工作日与物种数量间的关系以及物种的相对丰富度。结果表明: 42台红外相机共拍摄到物种独立照片1,793张, 鉴定出野生动物25种, 包括大熊猫(Ailuropoda melanoleuca)、四川羚牛(Budorcas tibetanus)和黄喉雉鹑(Tetraophasis szechenyii) 3种国家一级重点保护野生动物, 黑熊(Ursus thibetanus)、黄喉貂(Martes flavigula)、中华鬣羚(Capricornis milneedwardsii)、中华斑羚(Naemorhedus griseus)等8种国家二级重点保护野生动物。在相机数量增加到23台的时候拍摄到了本次记录的全部25种野生动物, 并且在单台相机工作日达到180天时, 物种数达到饱和。保护区内物种相对丰富度最高的是血雉(Ithaginis cruentus)(29.28)和毛冠鹿(Elaphodus cephalophus)(15.78); 大熊猫的相对丰富度为8.09; 红腹角雉(Tragopan temminckii)、中华鬣羚和黄喉雉鹑的相对丰富度在2-5之间; 中华斑羚、勺鸡(Pucrasia macrolopha)、黑熊、四川羚牛和蓝马鸡(Crossoptilon auritum)的相对丰富度最低, 不到1。综上所述, 红外相机能够有效地对野生动物资源进行监测调查, 对于相对丰富度较低的物种需要投入更多的精力, 这些物种的栖息地保护对于自然保护区的发展至关重要。     

Even the Smallest Non-Crop Habitat Islands Could Be Beneficial: Distribution of Carabid Beetles and Spiders in Agricultural Landscape

Carabid beetles and ground-dwelling spiders inhabiting agroecosystems are beneficial organisms with a potential to control pest species. Intensification of agricultural management and reduction of areas covered by non-crop vegetation during recent decades in some areas has led to many potentially serious environmental problems including a decline in the diversity and abundance of beneficial arthropods in agricultural landscapes. This study investigated carabid beetle and spider assemblages in non-crop habitat islands of various sizes (50 to 18,000 square metres) within one large field, as well as the arable land within the field, using pitfall traps in two consecutive sampling periods (spring to early summer and peak summer). The non-crop habitat islands situated inside arable land hosted many unique ground-dwelling arthropod species that were not present within the surrounding arable land. Even the smallest non-crop habitat islands with areas of tens of square metres were inhabited by assemblages substantially different from these inhabiting arable land and thus enhanced the biodiversity of agricultural landscapes. The non-crop habitat area substantially affected the activity density, recorded species richness and recorded species composition of carabid and ground-dwelling spider assemblages; however, the effects were weakened when species specialised to non-crop habitats species were analysed separately. Interestingly, recorded species richness of spiders increased with non-crop habitat area, whereas recorded species richness of carabid beetles exhibited an opposite trend. There was substantial temporal variation in the spatial distribution of ground-dwelling arthropods, and contrasting patterns were observed for particular taxa (carabid beetles and spiders). In general, local environmental conditions (i.e., non-crop habitat island tree cover, shrub cover, grass cover and litter depth) were better determinants of arthropod assemblages than non-crop habitat island size, indicating that the creation of quite small but diversified (e.g., differing in vegetation cover) non-crop habitat islands could be the most efficient tool for the maintenance and enhancement of diversity of ground-dwelling carabids and spiders in agricultural landscapes.     

Efficient sampling of ground-dwelling arthropods using pitfall traps in arid steppes

Pitfall trapping is probably the most frequently used method for sampling ground-dwelling arthropods. While the capture of specimens in pitfall traps largely depends on the number of individuals in the sampled area, trap design and trapping effort for a given environment, can also affect sampling success. The aim of this study was to determine the best pitfall trapping design for collecting ground-dwelling arthropods in the wind-blown and cold arid steppe areas of Patagonia. We tested four designs of traps, six types of preservative and different times of activation as well as the quantity of traps. Both preservation attributes and sampling efficiency differed between different trap designs and fluids compared. We conclude that in order to obtain reliable data on the structure of a community of ground-dwelling arthropods in Patagonia, at least three pitfall traps per experimental unit are required. In addition, traps should be opened for a minimum of 10 days filled with 300 ml of 30% ethylene glycol. We also suggested the use of a simple trap design (i. e. without funnel or roof). We believe these findings will contribute to more appropriate sampling of the ground dwelling fauna of Patagonia as well as other arid areas, leading to more reliable diversity studies.     

Can demographic parameters be estimated from capture-recapture data on small grids? A test with forest rodents

This preliminary study proposes small trapping grids as an alternative to traditional large grids for the simultaneous monitoring of several rodent populations by capture--recapture. Monthly trapping sessions of wood mouse Apodemus sylvaticus (Linnaeus, 1758) and bank vole Clethrionomys glareolus (Schreber, 1780) were carried on over a small area (0.015 ha, 21 traps). The coherence of demographic parameter estimates on such small grids with those obtained on classical large grids was checked by performing two trapping sessions on a larger grid (0.9 ha, 110 traps, 10 m mesh) surrounding the small grid. We compared the two grid designs on the basis of sex ratio upon first capture, trap saturation rate, minimum number alive (MNA), monthly survival, and trappability. These demographic parameters proved to be non-biased by the trapped area, even though the precision was lower on the small grid. Small grids seem therefore to give the same picture of population dynamics as classical large grids except for parameters sensitive to an edge effect (eg density). By decreasing significantly the trapping effort, small grids will be of particular interest whenever the simultaneous operation of several trapping grids is needed (eg to compare different environmental conditions).     

利用红外相机对四川白水河国家级自然保护区鸟兽资源的初步调查

2017年5月至2018年5月, 我们在四川白水河国家级自然保护区内设置红外相机对地面活动鸟兽进行了初步调查。布设在24个位点的24台相机累计工作3,832天, 共获得可识别物种的独立有效照片535张。经鉴定, 兽类有4目10科17种, 鸟类有2目4科10种。其中, 国家I级重点保护野生动物5种, 国家II级重点保护野生动物8种, 中国豪猪(Hystrix hodgsoni)、宝兴歌鸫(Turdus mupinensis)和黑顶噪鹛(Trochalopteron affine)为保护区新记录种, 而大熊猫(Ailuropoda melanoleuca)为汶川地震后首次拍到。兽类中, 花面狸(Paguma larvata)、黄喉貂(Martes flavigula)和中华斑羚(Naemorhedus griseus) 3种动物的独立有效照片总数占全部兽类独立有效照片数的50.2%。鸟类中, 血雉(Ithaginis cruentus)和红腹角雉(Tragopan temminckii)的独立有效照片总数占全部鸟类独立有效照片数的91.6%。本研究为白水河国家级自然保护区野生动物资源管理和保护提供了参考依据。     

荒漠草原“土岛”生境群落物种共存机制

经过长期破碎化, 荒漠草原原生硬质灰钙土斑块散布在广大沙化土地中, 形成类似“土岛”的土被结构。为揭示土岛生境的群落物种共存机制, 2016年在宁夏盐池县皖记沟村选取大(200-300 m²)、中(约100 m²)、小(约50 m²)土岛各3个开展调查, 采用Jaccard相异系数、物种生态位宽度和生态位重叠度、零模型、Meta分析, 综合计算和分析土岛内部与外部植物群落相似性、物种生态位宽度和生态位重叠、物种共存格局及其影响因子。研究发现, (1)随着破碎化加剧, 土岛内部植物多样性整体呈现下降趋势, 群落优势种从短花针茅(Stipa breviflora)转变为猪毛蒿(Artemisia scoparia)和短花针茅共优种, 土岛内外群落相似性增加。(2)土岛内外绝大多数物种生态位重叠较小, 生态位重叠在土岛内呈集中分布, 而土岛外则呈均匀发散分布。(3)环境过滤为主的生态过程决定了土岛生境群落物种的共存格局, 随着土岛面积减小, 环境因子对群落物种共存的调控强度降低, 关键性环境因子由土壤细砂粒和黏粒转变为粗砂粒, 显著性竞争物种共存格局在小岛出现。综上所述, 土岛生境对于维持草原物种具有重要作用, 环境过滤主导了荒漠草原物种共存格局。随着生境破碎化加剧或土岛面积减小, 物种共存格局及其调控因子发生转变。保护面积在200 m²以上的大土岛对于恢复荒漠草原区草原成分种和其物种多样性机制都十分必要。     

Dung beetle assemblages on tropical land‐bridge islands: small island effect and vulnerable species

Aim Using dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae) in a tropical land‐bridge island system, we test for the small island effect (SIE) in the species–area relationship and evaluate its effects on species richness and community composition. We also examine the determinants of species richness across island size and investigate the traits of dung beetle species in relation to their local extinction vulnerability following forest fragmentation. Location Lake Kenyir, a hydroelectric reservoir in north‐eastern Peninsular Malaysia. Methods We sampled dung beetles using human dung baited pitfall traps on 24 land‐bridge islands and three mainland sites. We used regression tree analyses to test for the SIE, as well as species traits related to local rarity, as an indication of extinction vulnerability. We employed generalized linear models (GLMs) to examine determinants for species richness at different scales and compared the results with those from conventional linear and breakpoint regressions. Community analyses included non‐metric multidimensional scaling, partial Mantel tests, nestedness analysis and abundance spectra. Results Regression tree analysis revealed an area threshold at 35.8 ha indicating an SIE. Tree basal area was the most important predictor of species richness on small islands (<35.8 ha). Results from GLMs supported these findings, with isolation and edge index also being important for small islands. The SIE also manifested in patterns of dung beetle community composition where communities on small islands (<35.8 ha) departed from those on the mainland and larger islands, and were highly variable with no significant nestedness, probably as a result of unexpected species occurrences on several small islands. The communities exhibited a low degree of spatial autocorrelation, suggesting that dispersal limitation plays a part in structuring dung beetle assemblages. Species with lower baseline density and an inability to forage on the forest edge were found to be rarer among sites and hence more prone to local extinction. Main conclusions We highlight the stochastic nature of dung beetle community composition on small islands and argue that this results in reduced ecosystem functionality. A better understanding of the minimum fragment size required for retaining functional ecological communities will be important for effective conservation management and the maintenance of tropical forest ecosystem stability.     

河西走廊中部戈壁地表甲虫群落动态变化及其影响因素

地表甲虫是戈壁主要的地表昆虫类群, 但我们对其种属组成和活动节律的认识还很有限。2018-2020年1-12月我们利用陷阱法对河西走廊中部典型砾质戈壁地表甲虫种类及数量进行了连续观测, 并测定了该区降水和温度。本文研究发现: (1)戈壁地表甲虫由步甲科、叶甲科、象甲科、粪金龟科和拟步甲科5科21种组成, 阿小鳖甲(Microdera kraatzi alashanica)、戈壁琵甲(Blaps gobiensis)和波笨粪金龟(Lethrus potanini)是优势地表甲虫种; (2)戈壁地表甲虫活动节律存在明显年季变异, 地表甲虫的活动期在3-10月, 地表甲虫活动密度的最大值出现在4-7月, 而物种丰富度的最大值均在5月出现; (3)降水增多的2019年地表甲虫的活动密度明显增加, 且2019年地表甲虫物种丰富度和多样性指数显著高于2018年; (4)地表甲虫的取食类型和个体大小影响它们的活动节律, 降水增多的年份提高了植食性的象甲科和部分拟步甲科的活动密度, 而一些拟步甲科的活动密度对降水的响应存在一定的滞后性; (5)降水和温度变化强烈影响地表甲虫活动节律, 地表甲虫的个体数和物种数与月降水量和月平均温度呈显著的二次曲线和指数关系, 植食性和捕食性甲虫对降水及温度变化响应较腐食性甲虫敏感, 大甲虫对降水变化的响应较中甲虫和小甲虫敏感。总之, 降水及温度变化影响了戈壁地表甲虫的活动节律, 而不同地表甲虫种对二者的响应因其生理生态特征不同而异, 从而影响了地表甲虫群落动态变化规律。