Keith Sally A, Newton Adrian C, Morecroft Michael D, Bealey Clive E, Bullock James M
Centre for Conservation Ecology and Environmental Change, C232, School of Conservation Sciences, Talbot Campus, University of Bournemouth, Fern Barrow, Poole BH12 5BB, UK.
Proc Biol Sci. 2009 Oct 7;276(1672):3539-44. doi: 10.1098/rspb.2009.0938. Epub 2009 Jul 22.
Taxonomic homogenization (TH) is the increasing similarity of the species composition of ecological communities over time. Such homogenization represents a form of biodiversity loss and can result from local species turnover. Evidence for TH is limited, reflecting a lack of suitable historical datasets, and previous analyses have generated contrasting conclusions. We present an analysis of woodland patches across a southern English county (Dorset) in which we quantified 70 years of change in the composition of vascular plant communities. We tested the hypotheses that over this time patches decreased in species richness, homogenized, or shifted towards novel communities. Although mean species richness at the patch scale did not change, we found increased similarity in species composition among woodlands over time. We concluded that the woodlands have undergone TH without experiencing declines in local diversity or shifts towards novel communities. Analysis of species characteristics suggested that these changes were not driven by non-native species invasions or climate change, but instead reflected reorganization of the native plant communities in response to eutrophication and increasingly shaded conditions. These analyses provide, to our knowledge, the first direct evidence of TH in the UK and highlight the potential importance of this phenomenon as a contributor to biodiversity loss.
分类同质化（TH）是指生态群落的物种组成随时间推移而日益相似的现象。这种同质化代表了生物多样性丧失的一种形式，可能是由当地物种更替导致的。TH的证据有限，这反映出缺乏合适的历史数据集，并且之前的分析得出了相互矛盾的结论。我们对英格兰南部一个郡（多塞特郡）的林地斑块进行了分析，在其中量化了70年间维管植物群落组成的变化。我们检验了以下假设：在这段时间里，斑块的物种丰富度下降、同质化或转向新的群落。虽然斑块尺度上的平均物种丰富度没有变化，但我们发现随着时间的推移，林地之间的物种组成相似度增加。我们得出结论，这些林地经历了分类同质化，却没有出现当地多样性下降或转向新群落的情况。对物种特征的分析表明，这些变化并非由外来物种入侵或气候变化驱动，而是反映了本地植物群落因富营养化和遮荫条件增加而发生的重组。据我们所知，这些分析提供了英国分类同质化的首个直接证据，并凸显了这一现象作为生物多样性丧失促成因素的潜在重要性。
