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Habitat preferences of some neophytes with a reference to habitat disturbances

Myśliwy M.

Polish Journal of Ecology

2014

Vol. 62, nr 3

509--526

The spread of species far from their native range is an important component of global changes. Investigating the ability of alien plants to invade different habitats is one of the most important approaches in the analysis of biological invasion mechanisms. The study was based on floristic research carried out in 1998–2002 in the north-western part of Poland. The habitats sampled were classified according to the EUNIS classification. A dataset of 2638 naturalized neophyte records was compiled based on a total of 2132 floristic lists. Species entries were supplemented with data on taxonomic position (family), origin, frequency, life form and number of habitats a particular species colonises. Ordination analyses showed the level of disturbance in individual habitats to be important in species-habitats relationships. Some of the species (e.g. Chamomilla suaveolens, Galinsoga parviflora, Veronica persica) occurred mainly in man-made, heavily disturbed habitats, while others (e.g. Impatiens parviflora, Padus serotina, Quercus rubra) were present primarily in natural habitats, less affected by humans. The species with the broadest habitat ranges identified included, i.a. Conyza canadensis, Impatiens parviflora, Epilobium ciliatum, and Oxalis fontana. Most of them, however, had different “core” habitats. Some species, e.g. Juncus tenuis, Elodea canadensis, Veronica persica were associated with one or a few habitats. The ability of species to invade numerous habitat types did not depend on their invasive status. The most successful aliens are those which spread dynamically along forest paths as well as those penetrating forest communities. The phytocoenotic role of each naturalized neophyte in plant communities requires a detailed study.Each individual habitat supports well-established alien species whose traits fit its characteristics and the disturbance intensity. Analysis of alien species traits, local distribution, habitat preferences and range makes it possible to reliably assess potentially successful invaders.

Effects of environmental variation and spatial distance on the beta diversity of woody plant functional groups in a tropical forest

Zhang Z., Zang R., Wang L., Wang G., Zhang J.

Polish Journal of Ecology

2012

Vol. 60, nr 3

525-533

Tropical forests are among the most complex ecosystems on Earth. The high alpha-diversity of tropical forests has been amply documented, however, beta diversity, equally important for us to understand the mechanism of biodiversity maintenance, has seldom been studied. The main current hypotheses about the origin of beta diversity are as follows: (1) species composition is uniform over large areas; (2) species composition fluctuates in a random, auto-correlated way emphasizing spatially limited dispersal; (3) species composition is related to environmental conditions. Testing these hypotheses is important to understand ecosystem function and to manage ecosystems effectively. In this study, we quantified the relative influence of environmental variation and spatial distance on the beta diversity of woody plant functional groups in a tropical forest of Hainan Island, China. Floristic and environmental data were collected from 135 grid-sample plots. We classified woody plant functional groups based on frequency, growth forms and successional status, respectively. To see whether environmental variation and spatial distance influence beta diversity, the simple and partial Mantel tests, in conjunction with linear and spline regression models were performed. The results showed that environmental heterogeneity and spatial distance were the primary determinants of pair-wise species composition differences between plots in the study area. Common, tree and climax species were more sensitive than the others to changes in environmental heterogeneity and spatial distance. Except for rare, pioneer and shrub species, the others had apparently negative relationship between spatial distance and similarity. The distance decay of similarity was determined by joint influences of spatial distance and spatially-structured environmental variables. Spatial distance had the clearest effect on beta diversity at distances <15 km and with the increase in spatial distance, beta diversity was gradually controlled by environmental heterogeneity. This study provides further support for neutral theory and environmental control hypothesis as opposed to uniformly distributed hypothesis.