Sabine Kasel

Measuring and managing ecosystem goods and services in changing landscapes: a south-east Australian perspective

This paper reviews approaches to measuring and managing the multiple ecosystem goods and services (ESS) provided by production landscapes. A synthesis of these approaches was used to analyse changes in supply of ESS in heavily cleared and fragmented production landscapes in south-east Australia. This included analysis of spatial and temporal trade-offs and synergies among multiple ESS. Spatially explicit, up-to-date and reliable information can be used to assess ESS supplied from different types of land uses and land cover and from different parts of a landscape. This can support effective management and payment systems for ESS in production landscapes.

Waterbird use of artificial wetlands in an Australian urban landscape

With the loss of natural wetlands, artificial wetlands are becoming increasingly important as habitat for waterbirds. We investigated the relationships between waterbirds and various biophysical parameters on artificial wetlands in an Australian urban valley. The densities (birds per hectare) of several species were correlated (mostly positively) with wetland area, and correlations were observed between certain species and other physical and water chemistry variables. Waterbird community structure, based on both abundance (birds per wetland) and density data, was most consistently positively correlated with the relative amount of wetland perimeter that was vegetated, surface area, distance to nearest wetland, public accessibility and shoreline irregularity. We also compared the relative use of the two types of urban wetlands, namely urban lakes and stormwater treatment wetlands, and found for both abundance and density that the number of individuals and species did not vary significantly between wetland types but that significant differences were observed for particular species and feeding guilds, with no species or guild being more abundant or found in greater density on an urban lake than a stormwater treatment wetland. Designing wetlands to provide a diversity of habitat will benefit most species.

Role of plant functional traits in determining vegetation composition of abandoned grazing land in north-eastern Victoria, Australia

Abstract Question: In the Northern Hemisphere, species with dispersal limitations are typically absent from secondary forests. In Australia, little is known about dispersal mechanisms and other traits that drive species composition within post-agricultural, secondary forest. We asked whether mode of seed dispersal, nutrient uptake strategy, fire response, and life form in extant vegetation differ according to land-use history. We also asked whether functional traits of Australian species that confer tolerance to grazing and re-colonisation potential differ from those in the Northern Hemisphere. Location: Delatite Peninsula, NE Victoria, Australia. Methods: The vegetation of primary and secondary forests was surveyed using a paired-plot design. Eight traits were measured for all species recorded. ANOSIM tests and Non-metric Multi-dimensional Scaling were used to test differences in the abundance of plant attributes between land-use types. Results: Land-use history had a significant effect on vegetation composition. Specific leaf area (SLA) proved to be the best predictor of response to land-use change. Primary forest species were typically myrmecochorous phanerophytes with low SLA. In the secondary forest, species were typically therophytes with epizoochorous dispersal and high SLA. Conclusions: The attributes of species in secondary forests provide tolerance to grazing suggesting that disturbance caused by past grazing activity determined the composition of these forests. Myrmecochores were rare in secondary forests, suggesting that species had failed to re-colonise due to dispersal limitations. Functional traits that resulted in species loss through disturbance and prevented re-colonisation were different to those in the Northern Hemisphere and were attributable to the sclerophyllous nature of the primary forest. Nomenclature: Ross & Walsh (2003).

Do generalisations of global trade-offs in plant design apply to an Australian sclerophyllous flora?

Functional-trait analysis at a global scale has found evidence for evolutionary specialisation of species into those designed to acquire resources rapidly and those designed to conserve resources. The present study aimed to determine whether such a trade-off exists in sclerophyllous vegetation in Australia. We measured 10 traits for 167 plant species. The first axis of a principal components analysis represented a trade-off between resource acquisition and resource conservation, consistent with global trends. Common traits shared by resource-conservative species included low specific leaf area (SLA), resprouting, ant-dispersal, and ericoid mycorrhizal and ectomycorrhizal associations. These attributes were typical of 3 of 13 functional groups produced by cluster analysis (eucalypts, ant-dispersed shrubs, ericoid heaths) that had the lowest SLA, and were almost exclusively native shrubs and trees. Resource-acquisitive species had high SLA, a small stature, annual life cycle, arbuscular mycorrhizal or non-mycorrhizal associations, and small, wind-dispersed seeds. These attributes are similar to those identified for species with a ruderal strategy and were typical of the functional groups representing wind-dispersed composites, AM annuals and non-mycorrhizal annuals that had the highest SLA and were dominated by introduced species. Comparable trait associations have been found in other studies, suggesting that similar processes drive plant design at a global scale. However, there were some patterns specific to the flora studied that were attributable to adaptations to suit the nutrient-poor soils and arid conditions typical of the Australian environment.

Environmental effects on germination phenology of co-occurring eucalypts: implications for regeneration under climate change

Germination is considered one of the important phenological stages that are influenced by environmental factors, with timing and abundance determining plant establishment and recruitment. This study investigates the influence of temperature, soil moisture and light on the germination phenology of six Eucalyptus species from two co-occurring groups of three species representing warm-dry and cool-moist sclerophyll forests. Data from germination experiments were used to calibrate the germination module of the mechanistic model TACA-GEM, to evaluate germination phenology under a range of climate change scenarios. With the exception of E. polyanthemos, the optimal niche for all species was characterised by cool-moist stratification, low light, cool temperatures and high soil moisture. Model results indicated that of the warm-dry species, Eucalyptus microcarpa exhibited greater germination and establishment under projected changes of warmer drier conditions than its co-occurring species Eucalyptus polyanthemos and Eucalyptus tricarpa which suggests that E. microcarpa could maintain its current distribution under a warmer and drier climate in southeastern Australia. Among the cool-moist species, Eucalyptus radiata was the only species that established under projected climate change of the 2080s but at such a low probability that its persistence compared to Eucalyptus obliqua and Eucalyptus sieberi cannot be posited. For all cool-moist species, germination did not benefit from the phenological shifts they displayed. This study successfully demonstrated environmental effects on germination phenology and how a shift in climate can influence the timing and success of recruitment.

Edge type affects leaf-level water relations and estimated transpiration of Eucalyptus arenacea.

While edge effects on tree water relations are well described for closed forests, they remain under-examined in more open forest types. Similarly, there has been minimal evaluation of the effects of contrasting land uses on the water relations of open forest types in highly fragmented landscapes. We examined edge effects on the water relations and gas exchange of a dominant tree (Eucalyptus arenacea Marginson & Ladiges) in an open forest type (temperate woodland) of south-eastern Australia. Edge effects in replicate woodlands adjoined by cleared agricultural land (pasture edges) were compared with those adjoined by 7- to 9-year-old eucalypt plantation with a 25m fire break (plantation edges). Consistent with studies in closed forest types, edge effects were pronounced at pasture edges where photosynthesis, transpiration and stomatal conductance were greater for edge trees than interior trees (75m into woodlands), and were related to greater light availability and significantly higher branch water potentials at woodland edges than interiors. Nonetheless, gas exchange values were only ∼50% greater for edge than interior trees, compared with ∼200% previously found in closed forest types. In contrast to woodlands adjoined by pasture, gas exchange in winter was significantly lower for edge than interior trees in woodlands adjoined by plantations, consistent with shading and buffering effects of plantations on edge microclimate. Plantation edge effects were less pronounced in summer, although higher water use efficiency of edge than interior woodland trees indicated possible competition for water between plantation trees and woodland edge trees in the drier months (an effect that might have been more pronounced were there no firebreak between the two land uses). Scaling up of leaf-level water relations to stand transpiration using a Jarvis-type phenomenological model indicated similar differences between edge types. That is, transpiration was greater at pasture than plantation edges in summer months (most likely due to greater water availability at pasture edges), resulting in significantly greater estimates of annual transpiration at pasture than plantation edges (430 vs. 343lm(-2)year(-1), respectively). Our study highlights the need for landscape-level water flux models to account for edge effects on stand transpiration, particularly in highly fragmented landscapes.

What can a database compiled over 22 years tell us about the use of different types of wetlands by waterfowl in south-eastern Australian summers?

Abstract Understanding the roles of different types of natural and artificial wetlands in providing habitat for waterbirds is crucial to active interventions to conserve wetland biodiversity. This study made use of a large database compiled over 22 years from the ‘Summer Waterfowl Count’ to determine the relative use of five wetland types by 18 species of waterfowl in Victoria, south-eastern Australia. The abundance of 14 species and density of 15 differed significantly (P<0.05) according to wetland type. Waste stabilisation ponds supported significantly higher abundances and densities of many species, a greater number of species and a community structure that was markedly different from the other wetland types. Based on the findings of this study, we believe that the unique characteristics of each wetland type warrant the conservation of each. Moreover, waste stabilisation ponds are significant refugia for waterfowl in Victoria and the trend to modernise sewage treatment plants, to the detriment of waterfowl, should be approached with caution. It is suggested that these findings are probably applicable in other parts of the world, although further research is needed to confirm their universal application.

Environmental heterogeneity promotes floristic turnover in temperate forests of south-eastern Australia more than dispersal limitation and disturbance

ContextAustralia’s temperate forest landscapes encompass broad topographic and edaphic ranges, and are regularly disturbed by fire. Nonetheless, relative contributions of environmental heterogeneity, disturbance regimes, and dispersal limitations to plant species turnover remain poorly understood.ObjectivesTo evaluate the relative influences of deterministic (environmental, disturbance), and stochastic (spatial) processes on plant species turnover [beta-diversity (β diversity)] in natural forest landscapes, and how such influences vary among plant functional types and vegetation strata.MethodsWe assessed the environment and species composition of 81 forest stands, representing a range of structures and fire histories across contiguous landscapes in south-eastern Australia, and examined the potential to explain β diversity using variance partitioning and distance-decay analyses.ResultsExplanatory variables accounted for 34–55% of β diversity of multiple plant functional types, with environmental heterogeneity explaining the greatest proportion (10–25%). Stand structural variables (e.g., leaf area index, height coefficient of variation) accounted for 8–14% of β diversity in understorey life forms and 5% in canopy species, far greater than a single direct descriptor of disturbance history such as time-since-fire which explained just 2% of tree and shrub β diversity. β Diversity increased with increasing geographic distance for all functional types. Dispersal limitation accounted for 5–11% of β diversity, and distance-decay rates varied among plant functional types.ConclusionsLandscape-scale conservation of forest biodiversity will require representation of a broad environmental range as well as metrics that fully capture site disturbance histories, including stand structural complexity as a potential proxy for fire regimes.

Waterbird use of different treatment stages in waste-stabilisation pond systems

Abstract The significance of waste-stabilisation ponds (WSPs) to waterbirds has been well documented, but WSP differ depending on their place and purpose in the sewage-treatment system, and there is little information on how birds use these different types of pond. In mid-winter (July) 2012, waterbirds were counted on WSP at 18 sewage-treatment plants in the Goulburn Valley, Victoria. Winter-storage and maturation ponds supported greater abundance, density (birds ha−1) and richness of waterbirds than aerated and anaerobic ponds. There were no significance differences in the number of species per hectare among types of pond. The abundance and density of diving waterfowl on maturation and winter-storage ponds was greater than on anaerobic and aerated ponds. A multivariate analysis revealed that waterbird community composition (based on both abundance and density) differed significantly between maturation ponds and anaerobic ponds (P <0.001) and also between winter-storage and anaerobic ponds (P <0.01). Comparing among types of WSPs, the waterbird communities of anaerobic ponds were the most distinct and winter-storage and maturation ponds the least different. Although the primary objective of a treatment plant is to treat sewage there is some design flexibility and, where possible, increasing the size or number of maturation and winter-storage ponds, or both, would generally benefit waterfowl.

Leaf traits of Eucalyptus arenacea (Myrtaceae) as indicators of edge effects in temperate woodlands of south-eastern Australia

Despite recent trends in using plant functional traits to describe ecosystem responses to environmental change, few studies have examined the capacity of traits to represent environmental variation for individual species at small spatial scales, such as across forest edges. We examined the utility of 12 easy-to-measure leaf traits (fresh weight to dry weight ratio, specific leaf area (SLA), osmolality, δ13C, δ15N, and concentrations of key nutrients) to detect edge effects on the function of a dominant woodland tree, Eucalyptus arenacea Marginson & Ladiges. The study included replicate E. arenacea trees at the woodland edge (0 m) and interior (75 m from edge) of three woodlands adjoined by pasture and three woodlands adjoined by plantation established on pasture. Leaf traits proved useful in identifying potentially degrading processes at woodland edges. Notably, greater leaf P concentrations and δ15N in edge than interior trees irrespective of edge type (pasture versus plantation) indicated persistent effects of nutrient enrichment from agricultural practices; and leaf osmolality and Na concentrations indicated greatest exposure of woodland trees to salinity at pasture edges. Nonetheless, leaf traits proved less useful in detecting edge effects on tree physiology, with most traits being non-responsive to a pronounced interactive effect of edge type and distance from edge on physiological measures. In addition, negative correlations between SLA and physiological measures of tree productivity were contrary to global relationships. Overall, we found that although particular leaf traits indicated potentially degrading processes of nutrient enrichment and salinisation, they were not reliable indicators of small-scale edge effects on the physiological function of E. arenacea.