Data from: Functional traits associated with the establishment of introduced Phytophthora spp. in Swedish forests

1. Invasive forest pathogens of the genus Phytophthora are threatening ecosystems globally. Phytophthora species are mainly introduced by humans importing infected nursery stock. However, due to the presence of environmental filters, not all introduced Phytophthoras manage to establish and spread. Some Phytophthoras’ ability to overcome these filters may be linked to functional traits. In Northern Europe, the increasing number of reports calls for a better understanding of the invasion process to prevent future outbreaks.
2. We hypothesized that the incidence of invasive Phytophthoras in urban locations would be higher than in remote forests, that there would be a decrease of species richness along the invasion process because of environmental filtering, and that there would be a functional shift among Phytophthora communities between stages of invasion. We compared the species composition of 96 plots from 16 rivers running through areas that constitute a gradient of human influence. We also compared the species composition and functional diversity of Phytophthora communities in 8 nurseries and 14 forests, including anthropogenic and natural forests. Phytophthoras were isolated from river water, soil, and/or plant tissue. Cultures were identified based on the Internal Transcribed Spacer (ITS) region.
3. Three Phytophthoras were detected in all environments (P. cactorum, P. plurivora, and P. cambivora). Their incidence was higher in urban locations than in remote forests, supporting the role of human activity as a driver of invasion. Most of the Phytophthoras detected in forests were detected in nurseries. The Phytophthora community in nurseries was richer and more diverse than in forests, pointing to environmental filtering affecting the establishment. Phytophthora communities in nurseries and forests differed in their functional divergence. Traits associated with establishment were the ability to form asexual survival structures and lower cardinal temperatures for growth.
4. Synthesis and applications. Our findings support the view that human activities act as drivers of Phytophthora invasions, and suggest that Phytophthoras that are able to form asexual structures are more likely to establish in northern Europe. The results increase the capacity to predict the establishment of Phytophthora species in Sweden and expand our understanding of the invasion process of forest pathogens.15-Nov-2017

1. 疫霉属（Phytophthora）入侵性森林病原菌正全球范围内威胁着生态系统。疫霉属物种主要通过人类引种带菌苗木传入。然而，受环境过滤（environmental filters）效应影响，并非所有传入的疫霉都能成功定殖并扩散。部分疫霉克服此类环境过滤的能力可能与其功能性状（functional traits）相关。北欧地区相关报道数量日益增多，亟需深入解析其入侵过程以防范未来疫情暴发。
2. 本研究提出三项假说：入侵疫霉在城市生境的检出率高于偏远森林；受环境过滤效应影响，入侵过程中物种丰富度会逐步降低；疫霉群落的功能性状会随入侵阶段发生转变。我们对流经人类影响梯度区域的16条河流的96个样地的物种组成进行了比较分析；同时对比了8个苗圃与14片森林（包括人工林与天然林）中疫霉群落的物种组成与功能多样性。研究从河水、土壤及/或植物组织中分离得到疫霉，菌株通过内转录间隔区（Internal Transcribed Spacer, ITS）序列进行鉴定。
3. 所有生境中均检出3种疫霉（P. cactorum、P. plurivora及P. cambivora）。它们在城市生境的检出率高于偏远森林，印证了人类活动是入侵驱动因素这一观点。森林中检出的多数疫霉均在苗圃中被检测到。苗圃中的疫霉群落物种丰富度与多样性均高于森林，提示环境过滤效应会影响疫霉的定殖过程。苗圃与森林中的疫霉群落功能分化程度存在显著差异。与定殖相关的功能性状包括形成无性存活结构的能力，以及生长所需的温度临界值更低。
4. 研究总结与应用展望。本研究结果证实人类活动是疫霉入侵的驱动因素，同时表明具备无性结构形成能力的疫霉在北欧更易成功定殖。本研究结果提升了对瑞典境内疫霉物种定殖风险的预测能力，并加深了我们对森林病原菌入侵过程的认知。2017年11月15日