Department of Biology, Lakehead University, Thunder Bay, ON, P7B 5E1, Canada.
Oecologia. 2021 Feb;195(2):469-478. doi: 10.1007/s00442-021-04864-4. Epub 2021 Feb 4.
To understand impacts of post-disturbance assembly mechanisms on the functional diversity (FD) of plant communities, it is necessary to determine how the environment drives their functional trait composition. In the boreal forest, post-fire abiotic filters may control community assembly by selecting plants with specific traits. Ericaceous heaths are characterized by low FD and are thought to be subject to such filters. We hypothesized that soil parameters select for a specific suite of traits and act as a secondary abiotic filter in post-fire ericaceous heath and contribute to the observed reduction of FD. We measured six soil parameters, five functional traits, and plant species abundances in eight post-fire heath and four regenerating forest sites in Eastern Canada. We conducted a combined analysis of RLQ (R-table Linked to Q-table) and fourth-corner methods to examine the links between plant traits and plot-level soil parameters, mediated by species abundances. Only below ground traits were significantly linked to soil variables. Specific root length and ericoid mycorrhizal associations were negatively linked to total soil nitrogen, available ammonium, and pH. Post-fire heath soils favour a specific suite of species traits. Only a portion of the regional species pool possesses the above-mentioned traits, and when they are favoured by habitat conditions, they assemble into a community with low FD. The novelty of our study is here we show how the relationship between traits and soil chemistry can act as a secondary filter and exert community-level trait changes responsible for the low functional diversity observed in heaths.
为了理解干扰后组装机制对植物群落功能多样性（FD）的影响，有必要确定环境如何驱动其功能性状组成。在北方森林中，火灾后的非生物过滤器可能通过选择具有特定特征的植物来控制群落组装。石南灌丛以 FD 低为特征，被认为受到这种过滤器的影响。我们假设土壤参数选择了特定的特征组合，并在火灾后的石南灌丛中充当次要的非生物过滤器，有助于观察到 FD 的降低。我们在加拿大东部的 8 个火灾后的石南灌丛和 4 个再生林地点测量了 6 个土壤参数、5 个功能性状和植物物种丰度。我们通过物种丰度，对 RLQ（R 表与 Q 表相连）和四角分析方法进行了联合分析，以检查植物性状与斑块水平土壤参数之间的联系。只有地下性状与土壤变量有显著联系。比根长和石南菌根结合与总土壤氮、有效铵和 pH 呈负相关。火灾后的石南灌丛土壤有利于特定的物种特征组合。只有一部分区域物种库具有上述特征，当它们受到生境条件的青睐时，它们会组装成一个 FD 低的群落。我们研究的新颖之处在于，我们展示了特征与土壤化学之间的关系如何作为一种二级过滤器，并对负责石南灌丛中观察到的低功能多样性的群落水平特征变化施加影响。
