Assessing habitat loss effects on biodiversity is a major focus of ecological research. The relationship between habitat amount and biodiversity, postulated in the habitat amount hypothesis, is usually assessed at one point in time, which does not account for habitat loss as a temporal process. We examined habitat amount effects at two time periods, 1930s and 2010s, using plant data from three semi-natural habitats: calcareous grassland, heathland and broadleaved woodland, across Dorset, southern England. Woodlands, which changed little in area over the time period, showed minimal effects of habitat amount on species occurrence in both time periods. For grassland and heathland, which had undergone severe losses over the study period, we found the expected positive relationship in the 2010s, but the relationship was negative for these habitats in the 1930s. We explored possible reasons for this result. Total perimeter-to-area ratio (TPAR) showed positive effects in the 1930s for grassland and heathland, suggesting effects of habitat configuration, specifically edge. However, TPAR was highly correlated with habitat amount so this finding is speculative. One possible explanation for the relationships with habitat amount, and the change between the two periods could be the quality of the surrounding matrix. In the 1930s, the landscape was less intensified and was dominated by semi-natural habitats, whereas by the 2010s much had been converted to arable and intensive grasslands. We speculate that species could likely utilise the matrix to a greater degree in the 1930s compared with the 2010s when the matrix was more hostile, thereby decreasing the importance of habitat amount in the 1930s compared with the 2010s. These findings have important implications for conservation, as they show the importance of context (i.e. matrix quality) in determining the relationship between habitat amount and biodiversity.

中文翻译：

---

历史数据揭示了栖息地数量与植物生物多样性的对比关系

评估栖息地丧失对生物多样性的影响是生态学研究的一个主要焦点。栖息地数量假说中假设的栖息地数量和生物多样性之间的关系通常在一个时间点进行评估，这并没有将栖息地丧失视为一个时间过程。我们使用来自三个半自然栖息地的植物数据检查了 1930 年代和 2010 年代两个时间段的栖息地数量影响：英格兰南部多塞特郡的石灰质草地、荒地和阔叶林地。林地面积随时间变化不大，在两个时间段内栖息地数量对物种发生的影响很小。对于在研究期间遭受严重损失的草地和荒地，我们发现 2010 年代预期的正相关关系，但在 1930 年代，这种关系对这些栖息地来说是负面的。我们探讨了造成这一结果的可能原因。总周长面积比 (TPAR) 在 1930 年代对草地和荒地显示出积极影响，表明生境配置的影响，特别是边缘。然而，TPAR 与栖息地数量高度相关，因此这一发现是推测性的。与栖息地数量的关系以及两个时期之间的变化的一种可能解释可能是周围基质的质量。在 1930 年代，景观集约化程度较低，以半自然栖息地为主，而到 2010 年代，大部分地区已转变为可耕种和集约化的草地。我们推测，与 2010 年代矩阵更具敌意时相比，物种可能在 1930 年代更大程度地利用矩阵，与 2010 年代相比，从而降低了 1930 年代栖息地数量的重要性。这些发现对保护具有重要意义，因为它们显示了环境（即矩阵质量）在确定栖息地数量和生物多样性之间关系方面的重要性。