Understanding plant invasions through traits
The ability to characterize successful invasive species is a necessity for forecasting potential threats. Species traits are a useful framework for characterizing invasiveness, as they are measurable proxies for mechanisms involved in resource acquisition, dispersal and reproduction, indicating how an organism interacts with others and its surrounding environment. Furthermore, species traits represent a taxon-independent approach that can serve as a connector between population processes, community-level processes and environmental gradients.
In our research program, we employ a traits-based framework to understand and forecast invasion dynamics, from establishment to impacts to adaptation to climate change.
Our first foray into forecasting invasive success...
Using a comprehensive set of 45 traits, we performed a case study of invasive traits displayed by exotic woody plants in the United States (U.S.) by comparing 63 invasive and 794 non-invasive exotic woody plant species naturalized across the country.
Through a combination of multivariate and machine-learning methods, we were able to identify six key traits that can consistently predict invasiveness of exotic woody species across the United States. Read the full story here.
But what defines invasive success?
Distribution of two invasive plant species, Australian pine and Tree-of-Heaven, in the United States. One species succeeds in the "range size" dimension, while the other does not.
Multiple dimensions of invasiveness
Recent efforts have recognized that invasiveness cannot be adequately represented in a unidimensional binary, but rather by multiple aspects of demographic and ecological success (e.g., range size, local abundance, spread rate, impact) that should be explored separately.
Our work aims to build upon previous hypotheses to evaluate the potential mechanisms driving success in different dimensions. To achieve this, we will test the relationship between species traits—as proxies for these mechanisms—and the invasive range size, local abundance and spread rate of over 900 invasive plant species in the United States.
We are also working on exploring the species traits associated with responsiveness to climate change. Stay tuned!
What about belowground traits?
The role of invasive root traits
To fully comprehend the dynamics of invasive plants and provide informed management strategies, it is essential to investigate their belowground effects. However, because most studies have concentrated on aboveground traits, there is surprisingly little knowledge about what is happening below ground. This is particularly striking, given that plant roots account for roughly half of plant biomass and play a crucial role in shaping ecosystems.
In collaboration with Dr. Matt McCary from Rice University, we collected data on microbial composition, and plant species and their cover for 377 plots from NEON.
We found that invasive and native plants exhibit distinct root traits, with invasive species typically having more fine roots, while native plants possess higher root tissue density. Additionally, we discovered that soil microbial communities in heavily invaded ecosystems were more homogeneous in composition across different ecosystem types and geographical regions compared to those in areas dominated by native plants.
Read the full story here, and stay tuned for new findings.