Department of Life Sciences, University of Trieste, via Giorgieri 10-34100, Trieste, Italy.
Sci Total Environ. 2012 Apr 1;421-422:197-202. doi: 10.1016/j.scitotenv.2012.01.051. Epub 2012 Feb 16.
The responses of lichens to habitat changes caused by invasive trees are poorly understood. Invasive forest trees may impact epiphytic lichens by altering both substrate and stand conditions. Previous research has demonstrated that black locust invasion, associated with intensive exploitation of native oak forests, led to dramatic shifts in lichen composition. However, it is not clear if, along with stand aging, black locust formations regain forest species. The main aim of this study was to test whether the succession of black locust stands promotes a lichen succession leading to assemblages in mature black locust stands which are similar to those of native forests. To test the influence of macro-environmental conditions, we performed the study in two bioclimatically different areas of Italy. The epiphytic lichen biota of native oak and chestnut stands was compared with that of black locust stands of different successional stages. In both regions we did not find a lichen succession in black locust stands of different age, and mature black-locust stands did not recover the diversity of epiphytic species, which are lost by the replacement of the native forests by black locust. The absence of this pattern may be caused by factors related to the management of black locust stands, and to bark features. The different bioclimatic conditions between the two study areas may explain differences in the lichen biota of native forests, while that of black locust stands tend to be similar between regions, suggesting that forest habitat changes associated with the spread of black locust could decrease lichen diversity among bioclimatically different regions.
外来树种入侵导致的生境变化对地衣的影响还不太清楚。入侵性森林树木可能会通过改变基质和林分条件来影响附生地衣。先前的研究表明，与对本地栎树林的集约化开发有关的黑荆入侵导致了地衣组成的剧烈变化。然而，目前还不清楚随着林分的老化，黑荆林分是否会恢复森林物种。本研究的主要目的是检验黑荆林分的演替是否会促进地衣演替，从而使黑荆成熟林分中的地衣组合与本地森林相似。为了检验宏观环境条件的影响，我们在意大利两个生物气候不同的地区进行了研究。我们比较了本地栎树和栗树林分中的附生地衣生物群与不同演替阶段的黑荆林分中的地衣生物群。在两个地区，我们都没有发现黑荆林分随年龄变化的地衣演替，成熟的黑荆林分也没有恢复附生地衣物种的多样性，这些物种因本地森林被黑荆取代而丢失。这种模式的缺失可能是由于与黑荆林分管理和树皮特征有关的因素造成的。两个研究区之间不同的生物气候条件可能解释了本地森林地衣生物群的差异，而黑荆林分的地衣生物群在不同地区之间往往相似，这表明与黑荆传播相关的森林生境变化可能会降低生物气候不同地区的地衣多样性。
