Abstract.Habitat fragmentation is considered to be one of the greatest threats to biodiversity. Species richness is predicted to decrease with decreasing patch size and increasing isolation, and this has been shown in some ecosystems. However, few studies have specifically investigated the effects of fragmentation on specific vegetation types, or compared different vegetation types within the same region. In this study, we assessed the influence of habitat fragmentation and time since fire on the floristic composition, structure and diversity of three ecosystems with varying fire proneness within the Sunshine Coast region. This study found that the tall-open forest ecosystem (RE 12.9-10.14) had higher overall species richness within fixed sample areas used for this study than did either open forest (RE 12.5.3) or gallery rainforest (RE 12.3.1), because it was composed of species typical of each of these ecosystem types. Open forest species richness was found mostly in the lower stratum, whereas gallery rainforest diversity was found in the upper stratum. Species richness decreased with increasing isolation in the open forest ecosystem where seeds are mostly abiotically dispersed. However, this study did not find strong evidence for reduced species richness within smaller patches in any ecosystem type studied; instead, finding species richness decreased with increasing patch size in the open forest ecosystem. Overall, across ecosystems, time since fire affected vegetation structure, but in fire-prone ecosystems, time since fire was not a determinant of species richness within the sites studied.
Cycads are threatened globally due to land clearing and unsustainable harvesting impacting upon long-living mature plants that are essential for population viability. Cycas megacarpa K.D.Hill is an endangered cycad endemic to central Queensland, Australia. Populations of this species have been impacted by recent infrastructure projects resulting in translocation of individuals to ameliorate losses. Translocations require an understanding of the species demographics and intrapopulation spatial distributions to inform planting design. This project studied the demography and spatial patterns of a population of C. megacarpa (%5600 individuals) within a 96.3 ha area in central Queensland to design a translocation planting that replicates a healthy population. Descriptive statistics were used to analyse the demography of the population. Spatial Point Pattern Analyses (SPPA) were used to determine if the population's spatial arrangement departed from complete spatial randomness across height, gender classes and between female and juvenile cycads. We found this population to possess a 1:1 ratio of male and female cycads. However, male C. megacarpa were on average %0.5 m shorter than female cycads and reached reproductive maturity at shorter heights. SPPA found this population of C. megacarpa to be clustered irrespective of height or gender. A significant spatial relationship was detected between female and juvenile cycads. The results of this study suggest that to replicate a healthy C. megacarpa population, the translocated cycads could be planted in a clustered spatial pattern with known male and female individuals distributed through the clusters at a 1:1 ratio.
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