Life’s tough. And a tough living situation can really hold an organism back. When your home is fragmented and there’s hunger, growth is going to be impacted. It’s going to be hard to reach that full potential.
Plants these days have to cope with highly modified homes. We are talking habitat loss, increased isolation, declining habitat size, increased edge effects – all the calling cards of fragmentation. But wait there’s more! These changes also interact with those hungry vertebrates – so there are herbivory pressures too.
Head therapist Brad, along with his colleagues, wanted to understand how the top-down pressure of herbivory, and the bottom-up pressure of fragmentation impacted on the growth of a number of common species. So out at the Wog Wog Fragmentation Experiment, he created some ‘safe places’ (read: herbivore exclusion areas), put the plants in the ground, and kept track of how they were doing.
What came out of the group sessions was that different species were dealing with different issues. Cassinia growth was heavily influenced by herbivory, and not at all by fragmentation (despite there being less hungry mammals in fragmented forest). Other species were less palatable and so herbivory wasn’t an issue, but growth was lower in fragments.
The take home message being that different plants will deal with these interacting pressures differently, but luckily in this system, no one is having to deal with both.
For the actual science of this story, you should definitely read the paper and contact the authors if you have any questions.
Farmilo BJ, Morgan JW & Nimmo DG (2016) Plant growth in a fragmented forest is a consequence of top-down and bottom-up processes, but not their interaction. Journal of Plant Ecology DOI:10.1093/jp3/rtw067.
K!E#22 by Luke S. O’Loughlin