Dynamic effects of ground-layer plant communities on beetles in a fragmented farming landscape

Seasonal differences in beetle assemblages and the vegetation community in woodland remnants compared with four adjoining farmland uses. Study area was a highly modified agricultural landscape in eleven sites in the Lachlan River Catchment, New South Wales, Australia. \n\nSeasonal differences in beetle assemblages and the vegetation community in woodland remnants compared with four adjoining farmland uses. Study area was a highly modified agricultural landscape in eleven sites in the Lachlan River Catchment, New South Wales, Australia. Our survey design consisted of four 400 m transects running from inside each patch out into the adjoining farmland. We sampled beetles and vegetation at three locations along each transect: 200 m inside the patch, 200 m inside the farmland, and 0 m at the patch-farmland boundary. \n\nWe sampled from the same trap location during two distinct periods in terms of plant phenology and agronomic practices in farmland: spring when crops and spring-active species were at peak growth, and summer when crops have been harvested (stubble retained; fine woody debris treatment applied) and summer-active species at peak growth. Each sampling location comprised a pair of pitfall traps, consisting of 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). 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. We opened a total of 132 pairs of traps (11 replicate sites x 4 transects x 3 trap pairs) for 14 days during spring (October–November 2014) and summer (January–February 2015).\n\nDuring beetle sampling in spring and summer, the same observer (KN) recorded: (1) six vegetation structural variables (vegetation height and cover of litter, native forb, native grass, exotic perennial grasses, exotic annual forbs and grasses) within a 20 × 10 m plot centred around the sampling location (Table 1); and (2) the composition of all plant species from five 1 × 1 m quadrats placed randomly within each 20 × 10 m plot. Plant species composition data were pooled from these quadrats for each sampling location.\n\nOur survey design consisted of four 400 m transects running from inside each patch out into the adjoining farmland. We sampled beetles and vegetation at three locations along each transect: 200 m inside the patch, 200 m inside the farmland, and 0 m at the patch-farmland boundary. 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).

本研究聚焦澳大利亚新南威尔士州（New South Wales）拉克兰河流域（Lachlan River Catchment）11个样地，旨在对比残存林地（woodland remnants）与四种毗邻农田利用类型（adjoining farmland uses）中甲虫群落（beetle assemblages）及植被群落（vegetation community）的季节差异。研究区域为一处经过高度改造的农业景观。

本研究聚焦澳大利亚新南威尔士州拉克兰河流域11个样地，旨在对比残存林地与四种毗邻农田利用类型中甲虫群落及植被群落的季节差异。研究区域为一处经过高度改造的农业景观。本研究的调查设计（survey design）为：从每个林地斑块（patch）内部向外延伸布设4条长400米的样带（transect），直至毗邻农田区域。沿每条样带设置3个采样点（sampling location）：斑块内部200米处、农田内部200米处，以及斑块与农田的交界带（patch-farmland boundary，0米处）。

本次采样依据农田的植物物候（plant phenology）与农艺措施（agronomic practices），分为两个截然不同的时段：春季，此时作物与春季活跃物种（spring-active species）处于生长高峰期（peak growth）；夏季，此时作物已收获（保留田间残茬（stubble retained）且施加了细木质残体处理（fine woody debris treatment）），夏季活跃物种处于生长高峰期。每个采样点设置一组巴氏诱捕器（pitfall traps），由直径6.5厘米、容积250毫升的塑料广口瓶（plastic jars）制成，将其埋入土壤中，罐口与地面齐平，瓶内注入100毫升保存液（preservative），配比为体积比1:3的乙二醇-水溶液（glycol–water mixture），并添加1滴洗涤剂以降低表面张力（surface tension）。每组诱捕器的两个单瓶分别置于导虫围栏（drift fence，长60厘米、高10厘米）两侧，以引导节肢动物（arthropods）进入诱捕器。本研究共布设132组诱捕器（11个重复样地（replicate sites）×4条样带×3组诱捕器），分别于2014年10-11月（春季）和2015年1-2月（夏季）开展为期14天的采样。

在春、夏两季的甲虫采样期间，由同一观察者（KN）完成两项记录：(1) 以采样点为中心的20×10米样地内的6项植被结构变量（vegetation structural variables），包括植被高度以及枯落物、本地非禾本草本植物（native forb）、本地禾草（native grass）、外来多年生禾草（exotic perennial grasses）、外来一年生非禾本草本植物与禾草（exotic annual forbs and grasses）的盖度，详见表1；(2) 在每个20×10米样地内随机设置的5个1×1米样方（quadrats）中，采集所有植物物种的组成数据（plant species composition）。每个采样点的植物物种组成数据由对应样方的采集结果合并得到。

本研究的调查设计为：从每个林地斑块内部向外延伸布设4条长400米的样带，直至毗邻农田区域。沿每条样带设置3个采样点：斑块内部200米处、农田内部200米处，以及斑块与农田的交界带（0米处）。每组诱捕器的两个单瓶分别置于导虫围栏（长60厘米、高10厘米）两侧，以引导节肢动物进入诱捕器。诱捕器由直径6.5厘米、容积250毫升的塑料广口瓶制成，将其埋入土壤中，罐口与地面齐平，瓶内注入100毫升保存液（体积比1:3的乙二醇-水溶液，添加1滴洗涤剂以降低表面张力）。本次采样选取了作物生长周期内的两个典型时段：春季（作物处于盛花期）与作物收获后仍保留田间残茬的夏季。