Wednesday, 29 January 2014
Importantly, we think we've seen an interaction between climate drying and fragmentation as it affects plant species density. Brad's work lays the foundation for understanding how pine forest harvesting (which is due to occur soon) then subsequently affects patterns and processes in these forests.
You can check out his Research Blog here: http://wogwogfragmentationexperiment.blogspot.com.au/
It tracks his progress over the years, and provides some neat tips about undertaking a PhD.
Here's the Executive Summary of his thesis:
Virtually all of Earth’s ecosystems have been dramatically transformed via human actions leading to irreversible biodiversity losses. Global extinctions are expected to result as species richness declines towards an equilibrium determined by the amount of remaining habitat. This thesis uses the Wog Wog Habitat Fragmentation Experiment (the second longest running experiment of its kind) in temperate south-eastern Australia to investigate how patterns of plant species density vary with size of forest fragments (0.25, 0.88 and 3.06 ha), as well as identifying factors which may influence vegetation dynamics within a plantation landscape. Species density in small fragments was higher than continuous forest for both total and common species at small spatial scales. This finding contradicts much of the fragmentation literature suggesting that the mature plantation matrix may alter important within-fragment conditions, which are yet to be documented. Small fragments were also characterized as having higher soil moisture and canopy cover, and lower daily maximum temperatures, which is strongly influenced by the structure of the adjacent plantation. Rates of recruitment of the dominant shrub appear to be more pronounced within fragments, irrespective of size, than in areas of continuous forest (although not significant at alpha = 0.05). This finding, in concert with microclimatic changes in small fragments, may have caused an increase in structural complexity within fragments, which may also positively influence plant species density in small fragments. We also show that the affect of vertebrate herbivores on understorey seedlings is species-specific, but that their influence is largely uniform across the fragmented landscape and continuous forest areas. These findings have been generated from a single point in time and therefore, it is expected that due to the nature of the landscape (forest removal and a subsequent cycle of plantation development and harvesting) the long-term biodiversity in forest-plantation systems will be imperiled more so than traditional grass-forest systems because of profound ecological changes that are occurring not just in space, but in time. In addition, many of our results suggest that there is a minimum size of fragment to be maintained in these landscapes below which ecological processes are disrupted and may therefore be of reduced value to native biodiversity.