‘Ecologically complex carbon’– linking biodiversity values,carbon storage and habitat structure in some austral temperate forests

Aim We assessed how avian biodiversity and above‐ground carbon storage were related in different forest age‐classes, including mature stands (> 100 years), in a managed, mixed‐species eucalypt forest. Location Gippsland, south‐eastern Australia. Methods In 50 2‐ha stands ranging in age from ≤ 5 years to mature stands > 100 years, we undertook repeated avian surveys, performed detailed habitat measurements and estimated amounts of above‐ground carbon. Extensive wildfire reduced the number of sites to 28 (seven in each of four age classes) upon which analyses and inferences were made. We also analysed data on carbon storage and some bird responses from previously published studies. Results Mature vegetation (> 100 years) had the greatest richness, abundance and biomass of birds. Key ecological resources, such as tree‐hollows for nesting, generally occurred mostly in stands > 60 years. Avian richness per unit of above‐ground carbon storage was relatively low for stands of 20–60 years. While above‐ground carbon storage appeared to increase in a monotonic fashion as stands age and mature, there were quantum increases in all measures of avian biodiversity in mature stands (> 100 years). Main conclusions Our results suggest that carbon is organized in a different way, with substantially greater biodiversity benefits, in very old stands. Mature vegetation simultaneously maximizes both avian biodiversity and above‐ground carbon storage. These results bolster arguments for allocating highest priorities to the preservation of old‐growth forest stands rather than alternative investments (e.g. reafforestation for carbon sequestration).     

Rehabilitation of Swamp Paperbark (<Emphasis Type="Italic">Melaleuca ericifolia</Emphasis>) wetlands in south-eastern Australia: effects of hydrology,microtopography, plant age and planting technique on the success of community-based revegetation trials

Wetlands dominated by Swamp Paperbarks (Melaleuca spp., Myrtaceae) are common in coastal regions across Australia. Many of these wetlands have been filled in for coastal development or otherwise degraded as a consequence of altered water regimes and increased salinity. Substantial resources, often involving community groups, are now being allocated to revegetating the remaining wetland sites, yet only rarely is the effectiveness of the rehabilitation strategies or on-ground procedures robustly assessed. As part of a larger project investigating the condition and rehabilitation of brackish-water wetlands of the Gippsland Lakes, we overlaid a scientifically informed experimental design on a set of community-based planting trials to test the effects of water depth, microtopography, plant age and planting method on the survival and growth of seedlings of Melaleuca ericifolia Sm. in Dowd Morass, a degraded, Ramsar-listed wetland in south-eastern Australia. Although previous laboratory and greenhouse studies have shown M. ericifolia seedlings to be salt tolerant, the strongly interactive effects of waterlogging and salinity resulted in high seedling mortality (>90%) in the field-based revegetation trials. Seedlings survived best if planted on naturally raised hummocks vegetated with Paspalum distichum L. (Gramineae), but their height was reduced compared with seedlings planted in shallowly flooded environments. Age of plants and depth of water were important factors in the survival and growth of M. ericifolia seedlings, whereas planting method seemed to have little effect on survival. Improved testing of revegetation methods and reporting of success or otherwise of revegetation trials will improve the effectiveness and accountability of projects aiming to rehabilitate degraded coastal wetlands.     

Substantial genetic substructuring in southeastern and alpine Australia revealed by molecular phylogeography of the Egernia whitii (Lacertilia: Scincidae) species group

Palaeoclimatic events and biogeographical processes since the mid-Tertiary are believed to have strongly influenced the evolution and distribution of the terrestrial vertebrate fauna of southeastern Australia. We examined the phylogeography of the temperate-adapted members of the Egernia whitii species group, a group of skinks that comprise both widespread low- to mid-elevation (E. whitii) and montane-restricted species (Egernia guthega, Egernia montana), in order to obtain important insights into the influence of past biogeographical processes on the herpetofauna of southeastern Australia. Sequence data were obtained from all six temperate-adapted species within the E. whitii species group, and specifically from across the distributional ranges of E. whitii, E. guthega and E. montana. We targeted a fragment of the ND4 mitochondrial gene (696 bp) and analysed the data using maximum likelihood and Bayesian methods. Our data reveal a deep phylogeographical break in the east Gippsland region of Victoria between 'northern' (Queensland, New South Wales, Australian Capital Territory) and 'southern' (Victoria, Tasmania, South Australia) populations of E. whitii. This divergence appears to have occurred during the late Miocene-Pliocene, with the Gippsland basin possibly forming a geographical barrier to dispersal. Substantial structuring within both the 'northern' and the 'southern' clades is consistent with the effects of Plio-Pleistocene glacial-interglacial cycles. Pleistocene glacial cycles also appear to have shaped the phylogeographical patterns observed in the alpine species, E. guthega and E. montana. We used our results to examine the biogeographical process that led to the origin and subsequent diversification of the lowland and alpine herpetofauna of southeastern Australia.