摘要
Agricultural landscapes are essential for the conservation of biodiversity. Nevertheless, a negative trend continues to be observed in many rural areas for the most prominent indicator species group, the farmland birds. However, clear cause-effect relationships are rarely reported and sometimes difficult to deduce, especially from monitoring data which are based only on the detection of species and counts of the numbers of individuals. Because the identification of habitat preferences is a precondition for farmland bird biodiversity conservation efforts, a monitoring scheme for the simultaneous collection and analysis of bird and land use data was developed and tested. In order to assign the occurrence of bird species to land characteristics at various spatial scales and different land use and crop types, we applied a hierarchical structured sampling design. The spatial scales were ‘agricultural landscape', ‘agricultural landscape types', ‘field crops and other habitats' and ‘vegetation structures'. These scales were integrated with a novel concept, the ‘habitat matrix'(HM). This method was applied to farmland breeding bird abundances on 29 plots, each 1 km2 in size, by the use of the territory mapping method. The same plots were enlarged by a 100 m buffer and the sizes and location of habitats documented. Vegetation height, coverage and density were also recorded for all crop fields in the study area. We propose that this monitoring method facilitates the identification of scale dependent relationships between farmland bird habitat characteristics and bird abundance. This is demonstrated by the farmland bird species Corn Bunting(Emberiza calandra), Skylark(Alauda arvensis), and Whinchat(Saxicola rubetra). The breeding territories of these species reveal large differences within the various spatial scales ‘agricultural landscape', ‘agricultural landscape types' and ‘field crops'. Throughout the breeding season the abundances varied, dependent on the field crop and the development of vegetation structures(height, coverage, and density). HM-analysis led to the identification of specific habitat configurations preferred by individual bird species within the agricultural landscape. These findings indicate that the methodology has the potential to design monitoring schemes for the identification of cause-and-effects of landscape configuration, land use and land use changes on the habitat suitability and abundance of farmland birds.
农田景观在生物多样性保护中发挥着重要作用,很多农田地区最重要的指示性鸟类物种的数量已呈下降趋势。然而,有关二者间确切的因果关系却鲜有报道,有时也难下定论,特别是目前的监测数据只是基于鸟种调查和个体计数。鉴于确定栖息地偏好是保护农田鸟类的前提,我们设计并验证了一套可同步搜集和分析鸟类及土地利用数据的监测方案。为了能在不同空间尺度、不同的土地利用方式及作物种类水平上将鸟类种类与土地特征相关联,我们采用了层次结构取样设计。将空间尺度分为"农田景观"、"农田景观类型"、"农作物及其他栖息地"和"植被结构"。这些尺度合为一个新的概念,即"栖息地矩阵(HM)"。利用领域标图方法,我们在29块1 km2的样地上监测了繁殖鸟类的丰富度。在这些样地周边分别增加100 m宽的缓冲带,并记录栖息地的大小和位置以及研究区域内所有耕地上植被的高度、盖度和密度。这一监测方案便于分析农田鸟类栖息地特征与鸟类丰富度之间在空间尺度上的关系。我们以黍鹀(Emberiza calandra)、云雀(Alauda arvensis)和草原石鵖(Saxicola rubetra)3种农田鸟类为例进行了验证。结果表明,这3种鸟类的繁殖领域在"农田景观"、"农田景观类型"和"农作物"尺度上有较大不同。在整个繁殖季内,鸟类丰富度因作物种类和植被发育情况(高度、盖度及密度)的不同而发生变化。栖息地矩阵分析可以用于分析农田景观中某一鸟种偏好的栖息地的详细状况。综上所述,这一套方法在设计分析景观配置、土地利用方式及土地利用变化与农田鸟类栖息地适宜度及鸟类丰富度间关系的监测方案上具有很大的潜力。
基金
Funding from the German Federal Ministry of Food,Agriculture and Consumer Protection(BMELV)
