Effects of cultivation practice on floristic and flowering diversity of spontaneously growing plant species on arable fields

In the past, the floristic diversity of arable fields has been described in terms of species diversity (SD) and their degree of coverage (C), but never in combination with the recording of the actually flowered species (FS) and their flowering intensity (FI) to striking differences in the cultivation methods on arable land. In relation with SD and C, however, FS and FI may provide important additional information on the functional biodiversity of fields. The aim was therefore to investigate the effects of a) conventional, b) organic as well as c) smallholder (never application of herbicides) on the floristic diversity. Using a region in Germany, we investigated SD, C, FS and FI synchronously in a), b) and c), by 356 vegetation surveys (5x5m plots) conducted in spring and summer in 2019 in winter cereals. Statistical tests were used to analyse the differences between a), b) and c). The medians were used to compare the floristic diversity of a), b) and c) and finally relationships of FS and FI to SD were analysed in relation to the cultivation methods. Significant differences in SD, C, FS and FI were found between the a), b) and c) in spring and summer characterised by sharp declines from c) to b) to a). A drastic reduction in floristic diversity from c) 100 to b) 52 to a) 3 was determined. Plants in flower (FS, FI), were very poorly in a), moderately well to well in b) and well to very well represented in c). C) to a) was characterised by an sharp decline, and, from a) to b) by sharp increase in floristic diversity. With current acreage proportions of a) in mind, this would affect, about one-third of land area in Germany, associated with a drastic reduction in functional biodiversity for insects.

过往针对农田植物区系多样性（floristic diversity）的研究，多仅从物种多样性（species diversity, SD）与覆盖度（coverage, C）两个维度展开，却从未结合实际开花物种（flowered species, FS）及其开花强度（flowering intensity, FI）的观测记录，以揭示不同耕地种植方式间的显著差异。不过，相较于仅关注物种多样性与覆盖度，开花物种及其开花强度能够为农田功能多样性（functional biodiversity）提供关键的补充信息。因此本研究旨在探究三种种植模式——a) 常规种植、b) 有机种植以及c) 小农户种植（全程未施用除草剂）——对植物区系多样性的影响。本研究以德国某区域为研究载体，于2019年春季与夏季在冬谷类作物（winter cereals）田中布设356个5×5米样方（plots）开展植被调查（vegetation surveys），同步记录了a、b、c三种种植模式下的物种多样性、覆盖度、开花物种数与开花强度。通过统计学检验方法分析三种种植模式间的差异，并以中位数作为统计量对比三组的植物区系多样性，最终结合种植方式，探究开花物种与开花强度和物种多样性之间的关联机制。研究发现，春季与夏季的物种多样性、覆盖度、开花物种数与开花强度在三组间均存在显著差异，整体呈现出从c组到b组再到a组逐步大幅下降的趋势。具体而言，植物区系多样性从c组的100、b组的52降至a组的3，降幅极为显著。开花植物（FS、FI）在a组中占比极低，在b组中处于中等偏优水平，而在c组中则占比最高且状态极佳。从c组到a组，植物区系多样性呈显著下降趋势；而从a组到b组，植物区系多样性则呈显著上升趋势。考虑到当前德国常规种植（a组）的耕地占比，该种植模式覆盖了德国约三分之一的土地面积，这将导致与之相关的昆虫功能多样性出现大幅下降。