PBG05 Response of bird abundance to the Patch-Burn Grazing experiment at Konza Prairie

‘PBG’ datasets are associated with a long-term, large-scale study that is addressing the effects of fire-grazing interactions in the context of a Patch-Burn Grazing management system designed to promote grassland heterogeneity.  Effects of patch-burn grazing management on plant and animal diversity and the nature and variety of wildlife habitat are being assessed in two replicate management units, each consisting of three pastures (watersheds) designated C03A/C03B/C03C and C3SA/C3SB/C3SC.  In each patch-burn grazing unit, one watershed is burned and two that are left unburned in a given year.  The burning treatments are rotated annually so that each pasture is burned every third year. Each patch-burn grazing unit is paired with an annually-burned pasture for comparison with traditional grazing systems (C01A and C1SB). All grazing units are stocked with cow/calf pairs from approximately 1 May until 1 Oct at a stocking density equal to 3.2 ha per cow/calf. To examine the impact of patch burning and grazing in all 8 units, we monitor changes in plant species composition, residual biomass, grassland bird populations, insect populations, small mammal populations, soil nutrients, and stream water quality1 (1C3SA/C3SB/C3SC unit only).  The KSU Department of Animal Science monitors cattle performance, including weight gain and body condition to assess the economic feasibility of using patch-burn management on a widespread basis. This data set focuses on variation in avian abundance, diversity, and nesting activity between patch-burned and uniformly-burned pastures at Konza Prairie Biological Station.  Three watershed units (C3A, C3B, C3C) constitute “patches†that are alternately burned in a 3-year rotation within a single, fenced pasture (i.e., patch-burn grazing).  Two additional watersheds serve as controls:  a grazed, annually/uniformly-burned watershed (C1A) and an ungrazed, annually/uniformly-burned watershed (1D).  Eight, 300-m line transects were established in each watershed from which observers record the numbers of individuals per bird species and the perpendicular distance of individual birds from each transect.  Three visits are made to each watershed between the last week in May through the end of June, where two “core†transects per watershed are sampled each visit.  Six additional transects per watershed are sampled, but only once in a given year (two peripheral transects are sampled per watershed, per visit).  The survey data will allow estimates of relative abundance, absolute density (determined from distance sampling), and species composition and diversity among the patch-burned and control watersheds.  Vegetation structure is sampled along survey transects to characterize management-specific variation in physical attributes of avian habitat.  Nest data are collected through systematic searches of nests throughout watersheds or from inclusion of nests found haphazardly by observers.  Nest data are being analyzed for variation in daily nest survival and levels of brood parasitism of various species among the watershed units.

"PBG"数据集关联于一项长期大规模研究，旨在探究斑块火烧放牧（Patch-Burn Grazing）管理体系下火-放牧交互作用对草原异质性提升的影响。该研究在两个重复管理单元中评估斑块火烧放牧管理对动植物多样性以及野生动物栖息地的性质与类型的影响，每个管理单元包含3个牧场（集水区），分别命名为C03A/C03B/C03C与C3SA/C3SB/C3SC。在每个斑块火烧放牧单元中，每年会对1个集水区实施火烧，其余2个集水区不进行火烧；火烧处理每年轮换，确保每个牧场每3年被火烧一次。
每个斑块火烧放牧单元均搭配一个年度火烧牧场，以与传统放牧系统进行对照（对应对照牧场为C01A与C1SB）。所有放牧单元均在每年5月1日至10月1日期间放养带犊母牛对，放牧密度为每3.2公顷对应1头母牛与牛犊。
为探究斑块火烧与放牧对全部8个实验单元的影响，研究人员监测了以下指标的变化：植物物种组成、残留生物量、草原鸟类种群、昆虫种群、小型哺乳动物种群、土壤养分，以及仅在C3SA/C3SB/C3SC集水区开展的河流水质监测。堪萨斯州立大学（Kansas State University，KSU）动物科学系则监测牛只生长性能，包括增重与体况，以评估斑块火烧放牧管理大规模应用的经济可行性。
本数据集聚焦于康扎草原生物站（Konza Prairie Biological Station）内斑块火烧牧场与均匀火烧牧场之间的鸟类丰度、多样性及筑巢活动差异。3个集水区单元（C3A、C3B、C3C）构成"斑块"，在单个围栏牧场内以3年轮换周期交替进行火烧（即斑块火烧放牧模式）。另有2个集水区作为对照：1个为放牧+年度/均匀火烧集水区（C1A），另1个为不放牧+年度/均匀火烧集水区（1D）。
每个集水区内设置8条300米长的样线，研究人员通过每条样线记录对应区域内各鸟类物种的个体数量，以及个体与该样线的垂直距离。每年5月最后一周至6月底期间，研究人员会对每个集水区开展3次调查，每次调查采样该集水区内的2条"核心"样线。每个集水区另有6条额外样线，其中每条仅在当年被采样1次（注：每次调查会采样该集水区内的2条外围样线）。本次调查数据可用于估算斑块火烧与对照集水区之间的相对丰度、基于距离抽样法得出的绝对密度，以及物种组成与多样性。
研究人员还沿调查样线采样植被结构，以表征不同管理方式下鸟类栖息地物理属性的差异。筑巢数据通过两种方式收集：一是对集水区内的巢穴进行系统性搜寻，二是纳入研究人员偶然发现的巢穴。目前正对筑巢数据进行分析，以探究不同集水区单元内各物种的每日巢存活率与巢寄生水平的差异。