Woody flora as a predictor of vascular plant richness: An insight in Italy

A key problem in quantifying biodiversity is whether it is possible to infer the overall diversity using suitable data subsets. The aim of this article, based on the updated data on the native woody flora of Italy, is to evaluate the reliability of such data as a predictor of vascular plant richness at a medium scale represented by the 20 administrative regions. Woody taxa were divided in trees, shrubs and lianas. We used stepwise multiple regression and principal component analysis to analyse the correlation between environmental heterogeneity, vascular plant units (species and subspecies) richness and woody units’ richness. Woody flora of Italy consists of 61 families, 133 genera, 469 species and 509 units. Shrubs constitute 74% of the woody flora, trees and lianas of 23% and 3%, respectively. Both stepwise multiple regression analysis and two principal component analyses strongly suggest that woody units, and trees in particular, are correlated with total vascular plant richness, at all hierarchical taxonomical levels. The environmental heterogeneity has been demonstrated to be much more important than the area for the biodiversity of Italian regions. Woody flora, as a surrogate of total flora, is extremely useful for rapid assessments of overall vascular plant diversity that may be exploited for monitoring purposes.

量化生物多样性的核心难题之一，是能否通过适宜的数据子集推断整体物种多样性。本文基于意大利本土木本植物区系的最新更新数据，旨在评估以该国20个行政区为中等尺度代表时，此类数据作为维管植物（vascular plant）丰富度预测因子的可靠性。木本类群被划分为乔木、灌木与藤本三类。我们采用逐步多元回归（stepwise multiple regression）与主成分分析（principal component analysis），探究环境异质性、维管植物单元（物种及亚种）丰富度与木本单元丰富度之间的相关性。意大利木本植物区系包含61科、133属、469个物种，总计509个植物单元。其中灌木占木本区系的74%，乔木与藤本分别占23%与3%。逐步多元回归分析与两次主成分分析均有力表明，在所有分类学层级下，木本单元（尤其是乔木）与总维管植物丰富度存在显著相关性。研究证实，对于意大利各行政区的生物多样性而言，环境异质性的重要性远高于面积因素。木本植物区系作为总植物区系的替代指标，在快速评估整体维管植物多样性方面极具应用价值，可用于生物多样性监测工作。