Contrasting beetle assemblage responses to cultivated farmlands and native woodlands in a dynamic agricultural landscape

Seasonal differences in beetle assemblages in woodland remnants compared with four adjoining farmland uses in a highly modified agricultural landscape in eleven sites in the Lachlan River Catchment, New South Wales, Australia. We used a split-plot sampling design where each remnant patch was matched with the four different farmland matrix types. We sampled beetles along a 400 m transect from 200 m in each patch out into 200 m in each of the four adjoining farmland matrix types. We then sampled beetles with a pair of pitfall traps located at each end of the transect: 200 m inside the remnant patch and 200 m in the adjoining farmland matrix. Individual traps from each pair were placed on either side of a drift fence (60 cm long x 10 cm high) to help direct arthropods into the trap. Traps were plastic jars (6.5 cm diameter, 250 ml) dug into the ground with the rim level with the soil surface, filled with 100 ml of preservative (1:3 glycol – water mixture, and a drop of detergent to reduce surface tension). We sampled from the same pitfall trap locations during two distinct periods of the cropping cycle: spring when crops were at peak flowering, and summer after crop harvest (stubble retained). A total of 88 pairs of traps (11 replicate sites x 4 transects x 2 trap pairs) were opened for 14 days during spring (October–November 2014) and summer (January–February 2015).

本研究针对澳大利亚新南威尔士州拉克兰河流域（Lachlan River Catchment）11个地点的高度改造农业景观，探究林地残余斑块与四种相邻农田利用方式下甲虫群落的季节差异。我们采用裂区抽样设计（split-plot sampling design），将每个残余斑块与四种不同的农田基质类型配对。沿400米样线（transect）进行甲虫采样：样线从每个斑块内200米延伸至四种相邻农田基质类型中各200米处。随后，在样线两端各设置一对陷阱诱捕器（pitfall traps）：一端位于残余斑块内200米处，另一端位于相邻农田基质内200米处。每对诱捕器中的单个陷阱分别放置在漂移围栏（drift fence，长60厘米×高10厘米）两侧，以引导节肢动物进入陷阱。陷阱为塑料罐（直径6.5厘米，容量250毫升），埋入地下使其边缘与土壤表面齐平，内装100毫升防腐剂（1:3乙二醇-水混合物，并加入一滴洗涤剂以降低表面张力）。我们在作物周期的两个不同时期于相同陷阱诱捕器位置采样：作物盛花期的春季，以及作物收获后（留茬）的夏季。2014年10月至11月的春季和2015年1月至2月的夏季期间，共88对陷阱（11个重复地点×4条样线×2对陷阱）开放14天。