ABSTRACT

Understanding species distributions remains central to research in ecology and biogeography. Emphasis is placed on the spatial presence/absence of plants as related to underlying environmental factors; however, distributions result from both abiotic factors and adaptations to the abiotic environment. We analyzed poison ivy (Toxicodendron radicans (L.) Kuntze), which has high intraspecies variability in the plant functional trait of growth habit, to assess implications of plant strategies for spatial distributions. Our objectives were to: 1) determine whether anthropogenic habitats are statistically overrepresented in poison ivy incidence and growth habits (shrub, climbing liana, crawling liana), and 2) model biophysical parameters that constitute preferred poison ivy habitat and the three growth habits. We collected poison ivy field data along a trail-transect with corresponding geospatially indexed parameters, subsequently analyzed using Bayesian spatial modeling. Model results revealed poison ivy preference for human-modified habitat; Developed and Planted/Cultivated land use categories showed the largest marginal posterior probabilities for crawling and climbing lianas. Increasing temperature and elevation preferentially benefit the climbing growth habit. Our results suggest that variability in functional traits may impact species geographic distributions by expanding niche breadth. Incorporation of functional traits may thus advance predictive niche models of species distributions.

摘要

了解物种分布仍然是生态学和生物地理学研究的核心。强调与潜在环境因素相关的植物的空间存在/不存在；然而，分布是由非生物因素和对非生物环境的适应造成的。我们分析了毒藤（Toxicodendron radicans(L.) Kuntze)，它在植物生长习性的功能性状中具有很高的种内变异性，用于评估植物策略对空间分布的影响。我们的目标是：1) 确定人为栖息地在毒藤发生率和生长习性（灌木、攀援藤本植物、爬行藤本植物）中的统计数据是否过多，以及 2) 对构成首选毒藤生境和三种生长习性的生物物理参数进行建模。我们沿着带有相应地理空间索引参数的小径样带收集毒常春藤字段数据，随后使用贝叶斯空间建模进行分析。模型结果显示毒藤偏爱人类改造的栖息地；已开发和种植/耕作的土地利用类别显示出最大的爬行和攀爬藤本植物的边际后验概率。温度和海拔的升高优先有利于攀援的生长习性。我们的研究结果表明，功能性状的变异性可能会通过扩大生态位宽度来影响物种的地理分布。因此，功能性状的结合可能会推进物种分布的预测生态位模型。