Finding “hidden” effects of nonnative plant invasion

In my post-doc work on how colonisation and diversification of plant lineages can have a legacy effect on extant plant communities, we previously showed that understanding evolutionary priority effects is necessary to predict the structure and function of pristine ecological communities. In a paper just published in New Phytologist, we tested whether anthropogenically-driven changes in available habitat and mass immigration (i.e. non-native invasion) eliminate the role of evolutionary priority effects in community assembly. We advanced the theory that radiating lineages can monopolize niche space by showing that evolutionary drivers of community assembly also operate in new habitat created by anthropogenic disturbance. However, we also demonstrated that non-native invasion can erase the otherwise strong role of evolutionary priority effects in shaping native community composition. This work is important and timely because it indicates that effects of human-induced global change on community assembly extend beyond purely ecological dynamics to the ecological consequences of plant radiations.

Burns lab paper out in Oecologia

Our newest paper from our common garden experiment testing whether plant-induced soil heterogeneity promotes plant species coexistence is out in the April issue of Oecologia. In this paper we show that soil heterogeneity increases per capita biomass of invaders  (i.e. the disadvantaged species in a competing pair). By using a reciprocal invasion among species pairs in our experimental design, this indicates mutual invasibility by this species pair, which is a criterion for stable coexistence. Moreover, we unlock the “black box” of mechanistic drivers of plant-soil feedbacks by measuring the spatial arrangement in both biotic and abiotic soil properties within our experimentally-created soil treatments. We show that soil biota (bacteria and fungi) and phosphorous may be important drivers of the reproductive biomass response to the spatial arrangement of plant-soil feedbacks.

This paper wouldn’t have been possible without the outstanding work of Ph.D. student, Jennifer Murphy, and undergraduate student, Angela Kaczowka, along with many other students of the Burns lab who assisted with experimental set-up and data collection over the 4 years of the experiment.

Our paper is Editor’s Choice in Journal of Ecology

Our paper on evolutionary priority effects in New Zealand forests has been selected as the Editor’s Choice article in the upcoming issue of Journal of Ecology — the editors wrote this great blog post summarising our findings and the implications for our understanding of ecological communities. And one of my co-authors and one of our lab’s PhD students kindly supplied me with useful (and attractive!) photos to include in the blog post.

Evolutionary drivers of assembly in NZ forests

Our paper showing an evolutionary legacy of community assembly in New Zealand forests, an evolutionarily older and more structurally complex ecosystem than investigated to date, is now in early view online at the Journal of Ecology. We have shown that evolutionary priority effects — where early-arriving ancestral taxa diversify and preempt niche space, precluding later arrivals from dominating new habitats — shape extant communities of both pteridophytes and angiosperms. These physiologically-contrasting taxonomic groups exhibit different responses to precipitation gradients, however. Evolutionary priority effects in pteridophyte communities become stronger with increasing precipitation, as predicted by the hypothesis that competition has a greater role in structuring communities in benign or resource-rich environments (i.e. the Stress Gradient Hypothesis). Angiosperms show a different pattern, with stronger priority effects in the drier eastern portion of the mountain range we sampled, suggesting that environmental drivers other than precipitation may be more important in structuring angiosperm communities. Our work thus advances current understanding by showing a remarkable consistency of clade age effects on community dominance across different ecological conditions — more structurally complex ecosystems and longer evolutionary timescales, as well as across physiologically-contrasting taxonomic groups.

Delving into taxonomy – in the marine realm

I’ve recently had the opportunity to expand my academic horizons by assisting a Ph.D. student (who has now completed his degree!) with statistical analysis of morphological data from two purported species of New Zealand brachiopods, which are shelled marine animals in their own phylum that is closely related to the molluscs. Though we were unable to statistically distinguish the species based on morphometrics, enzyme analysis indicated that they should remain separated. Moreover, we confirmed that morphological differences between brachiopod species in other genera range from very small to quite large. It’s been quite a novel experience for this plant community ecologist to have a hand in taxonomic research, and on marine animals at that!

NZES Conference 2015

Last week the 2015 New Zealand Ecological Society conference was held at the University of Canterbury in Christchurch, and I presented a poster on my work in collaboration with Dr. Barbara J. Anderson that shows evolutionary priority effects occur with similar strength in secondary as well as primary grasslands in NZ. This suggests that evolutionary priority effects can persist through major environmental disturbance, providing further support for previous work in our group that has found evolutionary priority effects to occur in alpine and forest ecosystems in NZ.

The conference had a great opening session focusing on non-governmental conservation efforts, with brief talks given by leaders of several local and regional initiatives throughout NZ to enhance biodiversity value and sustainability in the lands they cherish — from Northland to Cape Kidnappers to northwest Nelson. These talks were followed up by a Massey University professor and the Director-General of the Department of Conservation, and finally a keynote address from Dr. Peter Kareiva of The Nature Conservancy, all highlighting different initiatives and examples of successful, often innovative, approaches to integrate conservation goals with social and economic concerns. It’s becoming increasingly evident that successful conservation of biodiversity requires explicit consideration of human needs, values, and involvement, rather than the false notion that humans are entirely separate from nature. This may be stating the obvious, but it is often overlooked as we become absorbed in what every other organism is doing!

UPDATE:

A colleague just tuned me in to the fact that myself and another colleague feature in some of the photos taken from the NZES conference poster session! Check out the conference’s Facebook page and photo album.

Botany colloquium and Botanical Society talks — all in one month!

It seems that neat events are often clustered (perhaps a spatio-temporal analysis is in order to back up my anecdote…), and that certainly happened this month when I was invited to speak at two events. On 9 October, the Botany department at the University of Otago here in Dunedin hosted its annual post-graduate colloquium, at which I was invited to give the guest research talk. And the following Wednesday I was the invited speaker for the monthly seminar series of the Botanical Society of Otago, a great organisation with excellent field trips in which I’ve often taken part. Both were excellent opportunities to present my current research to local botanical enthusiasts (many of whom are much more familiar with the NZ flora than me!), and I had many stimulating discussions about the eco-evolutionary dynamics in NZ plant communities with them as a result. Dunedin is certainly a great place to be a plant ecologist!