Our research focuses on the population dynamics of plants and how they are influenced by impacts of natural disturbances and global environmental change. We are particularly interested in the interactive effects of fire, grazing and drought in grasslands and woodlands in southern Australia, and how climate change, fragmentation and shrub encroachment affect ecosystems.

Wednesday, 20 January 2016

Lab Publications in 2015

Here's a list of publications that the Morgan Plant Ecology Lab has been associated with in 2015. I'm happy to provide PDF copies if you can't access them (email me at J.Morgan@latrobe.edu.au).

NutNet papers (global studies on bottom-up vs. top-down regulation of diversity in grasslands)

Fay et al. (2015) Grassland productivity limited by multiple nutrients. Nature Plants 10.1038/nplants.2015.80
Seabloom et al. (2015) Plant species’ origin predicts dominance and response to nutrient enrichment and herbivores in global grasslands. Nature CommunicationsVolume: 6, 7710, DOI:doi:10.1038/ncomms8710

Stevens et al. (2015) Anthropogenic nitrogen deposition predicts local grassland primary production worldwide. Ecology 96, 1459-1465.

Alpine ecology and conservation

Mark et al. (2015) Ecological responses to 52 years of experimental snow manipulation in high-alpine cushionfield, Old Man Range, south central New Zealand. Arctic, Antarctic, and Alpine Research 47, 751-772.
Williams et al. (2015) An International Union for the Conservation of Nature Red List ecosystems risk assessment for alpine snow patch herbfields, south-eastern Australia. Austral Ecology 40, 433–443.

Grassy ecosystems coexistence and change

Cross et al. (2015) A plant strategy approach to understand multidecadal change in community assembly processes in Australian grassy woodlands. Journal of Ecology, 103, 1300–1307.
O'Loughlin et al. (2015) The rise and fall of Leptospermum laevigatum: plant community change associated with the invasion and senescence of a range-expanding native species. Applied Vegetation Science 18, 323–331.

Wong et al. (2015) The incorporation of fungal to bacterial ratios and plant ecosystem effect traits into a state-and-transition model of land-use change in semi-arid grasslands. Agriculture, Ecosystems and Environment 210, 11-19.

Plant ecology

Meehan et al. (2015) Premature opening and dimorphism in Hakea decurrens (Proteaceae) follicles: a bet-hedging regeneration strategy? The Victorian Naturalist 132, 139-146.

And of course, there was the launch of the book Land of Sweeping Plains by Nick Williams, Adrian Marshall & John Morgan (CSIRO Publishing), a synthesis of 40 yrs of temperate grassland ecology, restoration and conservation.

Friday, 15 January 2016

The perils of wild seed harvesting - an update

I just had to share this post: The Promise and Peril of Wild Seed Harvesting

In a previous post, I raised some concern about the impact of harvesting seed for restoration from wild populations (in particular, from rare plants in small populations).

Justin Meissen and collaborators have just published an awesome paper called " Risks of overharvesting seed from native tallgrass prairies" in Restoration Ecology - see the abstract here.

They found evidence that some short-lived and non-clonal plants were negatively affected by seed harvesting for prairie restoration. They classified these species 'harvest-negative'. While the scales of wild harvesting for prairie restoration seems extraordinary, I'm sure that intensive harvesting of key species from small grassland remnants is just as damaging to their persistence here in southern Australia. All the more reason to move to seed production areas to produce the billions of propagules necessary for landscape-scale restoration.

Thursday, 14 January 2016

Cracking open the relationship between biological diversity and ecosystem productivity solves a long-standing riddle

Biodiversity has been hypothesized to be of critical importance for the stability of natural ecosystems and their abilities to provide positive benefits such as oxygen production, soil genesis, and water detoxification to plant and animal communities, as well as to human society. Many of the efforts of conservation agencies around the world are driven by the assumption that this hypothesis is true. Elucidating this connection, and the processes that underpin it, is important on many levels such as anticipating how ecological communities may change (a) in response to anthropogenic perturbations (i.e. changes to the abiotic environment), (b) the introduction of new species or (c) the loss of established ones. While theoretical studies have supported this claim, scientists have struggled for the last half-century to clearly isolate such an effect in the real world. Indeed, a comprehensive, mechanistic understanding of the relationship between biodiversity and ecosystem productivity remains elusive. 

The fundamental mechanisms underlying global productivity-diversity patterns
have been debated by ecologists for decades. Methodological advances are now permitting a glimpse at the processes that lie behind surface patterns.
I was lucky enough to be part of a paper just published in Nature by Jim Grace et al. where we argue that the interplay between these factors is more fully understood when both are placed in a rich network of cause-and-effect pathways, as opposed to being regarded as entities engaged in an isolated back-and-forth.

We considered data generated by the Nutrient Network, a global scientific cooperative that examined 40+ grass-dominated plant communities from across the planet. Indeed, we used data from over a thousand grassland plots spanning five continents.
Location of the NutNet study sites across the world

Several interesting results emerged:
1.  the rate of biomass production increases with the number of species found at a site (its species richness). This effect holds steady across the observed variation in species richness, instead of saturating in communities with greater richness, as a generation of experimental and theoretical work has suggested that it may.
2. with increasing accumulated above-ground biomass (live plant tissue and dead litter)  species richness declines.  We think this provides evidence that competition between species — primarily for light — is an important force in determining why communities contain as many species as they do. Competition seemed to be influential regardless of how productive a community was, contrary to the historical suggestion that competition is a stronger structuring force in more-productive communities.

These results show that you cannot have sustainable, productive ecosystems without maintaining biodiversity in the landscape. Indeed, as Debra Willard, Coordinator for the USGS Climate Research & Development Program, put it: “These results suggest that if climate change leads to reduced species or genetic diversity, which is a real possibility, that then could lead to a reduced capacity for ecosystems to respond to additional stresses.”

One of the Australian NutNet sites, from Western Australia

Further information: Grace et al. (2016) Integrative modelling reveals mechanisms linking productivity and plant species richness. Nature doi:10.1038/nature16524