Levels Of Human Influence Research Articles

No evidence hunting bait increases American black bear population growth in Maine, USA

AbstractAmerican black bear (Ursus americanus) populations are increasing throughout much of North America. Use of multiple harvest methods, including hunting over bait, is intended to increase harvest success rates to meet harvest and population management objectives. However, black bear population growth can be influenced by food availability, and some speculate the use of bait may inadvertently increase bear abundance through food resource supplementation. We collected hair from black bears captured from 2005–2019 and a selection of potential food items, including those used as bait from 3 study areas in Maine, USA, with different levels of human influence. We used stable isotope analysis of the black bear hair and food item samples to evaluate the contribution of different identified food groups to the diet of individual bears. We found no evidence that greater contribution of human food resources, including bait, increased the number of cubs per litter for reproductive females or that human foods comprised a greater part of the diet in years when natural food resources were less abundant. Approximately 69% of black bear harvest occurred over bait. We found the probability of reproductive‐age females to be harvested increased with average representation of human foods with high carbon enrichment (including bait) in their diet, but the relationship was weak, likely because of sampling constraints. Additionally, the probability of being harvested was greater in years when natural food resources were scarce. We conclude that bait is not available on the landscape in large enough amounts or for a sufficient amount of time in Maine to substantially influence female reproduction. Our results indicate hunting over bait is an effective tool in a state that is attempting to maintain a stable bear population via harvest, and dispels conjecture that hunting over bait may increase cub production and offset the intention of harvest.

Spiders (Araneae) from three human-influenced habitats in the Golsfjellet mountain area, central southern Norway

Three sites at 900 m a.s.l. in the sub-alpine mountain birch forest region and under different levels of human-influence were investigated. Site 1: An open birch forest with some scattered spruces, a rich bush and field layer and a rich moss cover; very little grazed. Site 2: Tree and bush layer removed, a rich field layer invaded by open area species and some ’culture indicators’; there was a rich moss cover. Site 3: Grazed; tree layer, bush layer and moss cover absent. Pitfall trapping (18 May – 18 Aug. 2000) in site 1 - 3 resulted in 48, 48 and 22 spider species (in total 64 species). In site 1 and 2 Pardosa riparia (C.L.Koch, 1833) and Alopecosa pulverulenta (Clerck, 1757) were dominating. P. sphagnicola (Dahl, 1908) was also fairly common in site 1, P. palustris and P. hyperborea (Thorell, 1872) in site 2. Site 3 was almost completely dominated by Pardosa palustris (73.2 %) and Erigone atra Blackwall, 1841 (18.2 %); present (absent elsewhere) were also some specimens of Oedothorax retusus (Westring, 1851) (4.6 %).

New tools and recommendations for a better management of harmful algal blooms under the European Marine Strategy Framework Directive

Marine harmful algal blooms (HABs), caused by various aquatic microalgae, pose significant risks to ecosystems, some socio-economic activities and human health. Traditionally managed as a public health issue through reactive control measures such as beach closures, seafood trade bans or closure of mollusc production areas, the multifaceted linkages of HABs with environmental and socio-economic factors require more comprehensive ecosystem-based management approach tools to support policies. This study promotes a coordinated understanding and implementation of HAB assessment and management under the Marine Strategy Framework Directive (MSFD), targeting the achievement of Good Environmental Status (GES) in European marine waters. We introduce two novel tools: GES4HABs (GES for HABs) decision tree, and MAMBO (environMental mAtrix for the Management of BlOoms), a decision support matrix. These tools aim to streamline HABs reporting and prioritize resource allocation and management interventions. The GES4HABs decision tree defines a sequence of decision steps to identify HAB management strategies according to their state (evaluated against predefined baselines) and causes (anthropic or natural). MAMBO is proposed to address different HABs and their interaction with human and environmental pressures. The matrix utilizes two axes: natural trophic status and level of human influence, capturing major aspects such as nutrient supply. While acknowledging the limitations of this simplified framework, MAMBO categorizes marine regions into quadrants of varying management viability. Regions with high human influence and eutrophic conditions are identified as most suitable for effective management intervention, whereas regions with minimal or mixed human influence are deemed less amenable to active management. In addition, we explore and describe various indicators, monitoring methods and initiatives that may be relevant to support assessments of HAB status and associated pressures and impacts in the MSFD reporting. Finally, we provide some recommendations to promote the consideration of HABs in ecosystem-based management strategies, intensify efforts for harmonizing and defining best practices of analysis, monitoring and assessment methodologies, and foster international and cross-sectoral coordination to optimize resources, efforts and roles.

Larval fish assemblages in selected Brazilian estuaries: Species-environment relationships under different anthropogenic influences

We investigate the effects of spatial changes in environmental conditions and anthropogenic influences on larval fish communities in two tropical estuaries with varying levels of human impact. Our findings revealed a distinct structure of larval fish assemblages between the two estuaries located in northeastern Brazil, and we observed that eutrophication, characterized by high concentrations of nutrients, had adverse effects on the abundance and richness of larval fish assemblages. Additionally, we observed that a decrease in rainfall had an impact on larval fish assemblages, particularly during the dry season, when intermittent upstream rivers lead to changes in salinity and species composition within the estuaries. This study contributed to evaluating the community descriptors of two tropical estuaries under different levels of human influence, providing insights into the vulnerability of larval fish assemblages to climate change, specifically in relation to human influences and hypersalinity and the effects of marinization in shallow tropical estuaries in this region.

Large carnivore encounters through the lens of mobile videos on social media

AbstractUnderstanding local encounters with large carnivores is important for promoting sustainable coexistence. The use of smartphones and social media in geographically remote areas offers a novel avenue to study human–wildlife encounters from a local perspective. We conducted a content analysis of mobile videos on social media (n = 207) to characterize human encounters with snow leopards, gray wolves, and brown bears on the Tibetan Plateau in China. We also used ethnographic interviews to understand the backgrounds and motivations of videographers. Results show large carnivore encounters are not necessarily conflictual. Over half of encounters are neutral without observable interference between people and predators. The likelihood of a “negative encounter” is significantly associated with the target species, the distance between the videographer and the animal, the level of human influence in the surroundings, and the presence of other animals (i.e., dogs and livestock). Local Tibetan herders document unusual encounters with carnivores using videos for various reasons, but what is deemed unusual is context‐dependent and fluid. Our study demonstrates that social media videos can provide valuable insights into the diversity and complexity of human–wildlife interactions. We encourage conservationists to develop visual participatory programs to better engage local people in conservation knowledge production.

Hematology and biochemistry reference intervals for American crocodiles (Crocodylus acutus) in South Florida.

The American crocodile (Crocodylus acutus) is considered a vulnerable species by the International Union for Conservation of Nature (IUCN) Red List across its range and classified as locally threatened in several countries. There is a lack of knowledge involving hematological and physiological parameters in American crocodile populations, limiting our understanding of what are considered "normal" blood analyte results for the species and how to link them with health assessments. In this study, we analyzed 40 hematological and biochemical parameters and estimated reference intervals (RIs) for 35 of them based on 436 clinically healthy wild American crocodiles caught in South Florida between 2015 and 2021. Crocodiles were captured across three areas with different levels of human influence [low = Everglades National Park (ENP), medium = Biscayne Bay Estuary (BBE), and high = Turkey Point Nuclear Power Plant (TP)]. There was very strong-to-strong evidence for an effect of where animals were caught on five analytes: basophils %, phosphorus, proportion of (pr) alpha-2 globulins, absolute count (abs) of gamma globulins, and corticosterone, so no reference values were estimated but general statistics are presented and discussed. From the remaining analytes, we found no evidence that sex or size class had an effect on red blood cell (RBC), azurophils and monocytes abs, triglycerides, and albumin abs. However, we did find moderate-to-strong evidence that sex influenced azurophils % and size class influenced white blood cell (WBC), heterophils %, monocytes %, basophils abs, creatine phosphokinase (CPK), potassium, glucose, bile acids, alpha-1 globulin abs, and alpha-2 globulin pr and abs. Finally, there was strong evidence that both sex and size class influenced PCV, lymphocytes % and abs, eosinophils % and abs, aspartate aminotransferase (AST), calcium, sodium, chloride, total protein, albumin/globulin (A/G) ratio, albumin pr, alpha-1 globulin, and beta globulin abs. Intraspecific analysis showed that size is the variable that most influenced analytes explaining up to 29% of the variation, which relates to our findings based on intraindividual analysis. We compared our results with blood parameters reported for conspecifics as well as closely related species and discussed implication of those results for clinical diagnosis and American crocodile conservation.

Human-Machine Integration in Processes within Industry 4.0 Management.

The aim of this work is to use IIoT technology and advanced data processing to promote integration strategies between these elements to achieve a better understanding of the processing of information and thus increase the integrability of the human–machine binomial, enabling appropriate management strategies. Therefore, the major objective of this paper is to evaluate how human–machine integration helps to explain the variability associated with value creation processes. It will be carried out through an action research methodology in two different case studies covering different sectors and having different complexity levels. By covering cases from different sectors and involving different value stream architectures, with different levels of human influence and organisational requirements, it will be possible to assess the transparency increases reached as well as the benefits of analysing processes with higher level of integration between them.

Phylogenetic structure of alien plant species pools from European donor habitats

AbstractAimMany plant species native to Europe have naturalized worldwide. We tested whether the phylogenetic structure of the species pools of European habitats is related to the proportion of species from each habitat that has naturalized outside Europe (habitat’s donor role) and whether the donated species are more phylogenetically related to each other than expected by chance.LocationEurope (native range), the rest of the world (invaded range).Time periodLastc. 100 years.Major taxa studiedAngiospermae.MethodsWe selected 33 habitats in Europe and analysed their species pools, including 9,636 plant species, of which 2,293 have naturalized outside Europe. We assessed the phylogenetic structure of each habitat as the difference between the observed and expected mean pairwise phylogenetic distance (MPD) for (a) the whole species pool and (b) subgroups of species that have naturalized outside Europe and those that have not. We used generalized linear models to test for the effects of the phylogenetic structure and the level of human influence on the habitat’s donor role.ResultsHabitats strongly to moderately influenced by humans often showed phylogenetically clustered species pools. Within the clustered species pools, those species that have naturalized outside Europe showed a random phylogenetic structure. Species pools of less human‐influenced natural habitats varied from phylogenetically clustered to overdispersed, with donated naturalized species also often showing random patterns within the species pools. Donor roles in both habitat groups increased with increasing MPD within habitats.Main conclusionsEuropean human‐influenced habitats donate closely related species that often naturalize in disturbed habitats outside their native range. Natural habitats donate species from different lineages with various ecological strategies that allow them to succeed in different habitats in the invaded range. However, the naturalized species donated by most European habitats are phylogenetically random subsets of their species pools.

Guiding principles for rewilding.

There has been much recent interest in the concept of rewilding as a tool for nature conservation, but also confusion over the idea, which has limited its utility. We developed a unifying definition and 10 guiding principles for rewilding through a survey of 59 rewilding experts, a summary of key organizations' rewilding visions, and workshops involving over 100 participants from around the world. The guiding principles convey that rewilding exits on a continuum of scale, connectivity, and level of human influence and aims to restore ecosystem structure and functions to achieve a self-sustaining autonomous nature. These principles clarify the concept of rewilding and improve its effectiveness as a tool to achieve global conservation targets, including those of the UN Decade on Ecosystem Restoration and post-2020 Global Biodiversity Framework. Finally, we suggest differences in rewilding perspectives lie largely in the extent to which it is seen as achievable and in specific interventions. An understanding of the context of rewilding projects is the key to success, and careful site-specific interpretations will help achieve the aims of rewilding.

Seeing the wood despite the trees: Exploring human disturbance impact on plant diversity, community structure, and standing biomass in fragmented high Andean forests.

High Andean forests harbor a remarkably high biodiversity and play a key role in providing vital ecosystem services for neighboring cities and settlements. However, they are among the most fragmented and threatened ecosystems in the neotropics. To preserve their unique biodiversity, a deeper understanding of the effects of anthropogenic perturbations on them is urgently needed. Here, we characterized the plant communities of high Andean forest remnants in the hinterland of Bogotá in 32 0.04 ha plots. We assessed the woody vegetation and sampled the understory and epiphytic cover. We gathered data on compositional and structural parameters and compiled a broad array of variables related to anthropogenic disturbance, ranging from local to landscape‐wide metrics. We also assessed phylogenetic diversity and functional diversity. We employed nonmetric multidimensional scaling (NMDS) to select meaningful variables in a first step of the analysis. Then, we performed partial redundancy analysis (pRDA) and generalized linear models (GLMs) in order to test how selected environmental and anthropogenic variables are affecting the composition, diversity, and aboveground biomass of these forests. Identified woody vegetation and understory layer communities were characterized by differences in elevation, temperature, and relative humidity, but were also related to different levels of human influence. We found that the increase of human‐related disturbance resulted in less phylogenetic diversity and in the phylogenetic clustering of the woody vegetation and in lower aboveground biomass (AGB) values. As to the understory, disturbance was associated with a higher diversity, jointly with a higher phylogenetic dispersion. The most relevant disturbance predictors identified here were as follows: edge effect, proximity of cattle, minimum fragment age, and median patch size. Interestingly, AGB was efficiently predicted by the proportion of late successional species. We therefore recommend the use of AGB and abundance of late successional species as indicators of human disturbance on high Andean forests.

Human influences on male waving behavior in the fiddler crab Leptuca pugilator

ABSTRACT Fiddler crabs are numerically dominant consumers within salt marshes and understanding how their behavior is influenced by human activities can therefore shed light on the health of disturbed marsh communities. We investigated how various levels of human influence in South Carolina salt marshes alter male waving behavior in the sand fiddler crab Leptuca pugilator across 21 marsh sites. We show that male waving behavior decreases with increasing levels of human influence across these sites (i.e., car and pedestrian traffic, marsh size). Given the central role of male waving in L. pugilator reproduction, territoriality, and other intra- and interspecific interactions, our results show that human influence in salt marsh habitats has the potential to directly alter the success of this widespread marsh consumer. This study highlights the importance of studying the influence of anthropogenic disturbances on behavior of salt marsh species as human presence in coastal areas continues to grow.

Enhancing biodiversity conservation in existing land-use plans with widely available datasets and spatial analysis techniques

SUMMARYIn many developing countries, high rates of deforestation and biodiversity loss make conservation efforts urgent. Improving existing land-use plans can be an option for enhancing biodiversity conservation. We showcase an approach to enhancing an existing forest land-use plan using widely available data and spatial tools, focusing on Argentina's Southern Yungas ecoregion. We mapped the distribution of wilderness areas and species and habitats of conservation concern, assessed their representation in the land-use plan and quantified potential changes in habitat availability and forest connectivity. Wilderness comprised 48% of the study area, and the highest concentrations of elements of conservation concern were in the north. In the current land-use plan, wilderness areas often occur in regions where logging and grazing are allowed, and a large proportion of the forest with the highest conservation value (43%) is under some level of human influence. Furthermore, we found that deforestation being legally allowed in the land-use plan could reduce forest connectivity and habitat availability substantially. We recommend updating the current land-use plan by considering human influence and elements of conservation concern. More broadly, we demonstrate that widely available spatial datasets and straightforward approaches can improve the usefulness of existing land-use plans so that they more fully incorporate conservation goals.

Using Landsat time series for characterizing forest disturbance dynamics in the coupled human and natural systems of Central Europe

Remote sensing is a key information source for improving the spatiotemporal understanding of forest ecosystem dynamics. Yet, the mapping and attribution of forest change remains challenging, particularly in areas where a number of interacting disturbance agents simultaneously affect forest development. The forest ecosystems of Central Europe are coupled human and natural systems, with natural and human disturbances affecting forests both individually and in combination. To better understand the complex forest disturbance dynamics in such systems, we utilize 32-year Landsat time series to map forest disturbances in five sites across Austria, the Czech Republic, Germany, Poland, and Slovakia. All sites consisted of a National Park and the surrounding forests, reflecting three management zones of different levels of human influence (managed, protected, strictly protected). This allowed for a comparison of spectral, temporal, and spatial disturbance patterns across a gradient from natural to coupled human and natural disturbances. Disturbance maps achieved overall accuracies ranging from 81% to 93%. Disturbance patches were generally small, with 95% of the disturbances being smaller than 10ha. Disturbance rates ranged from 0.29% yr−1 to 0.95% yr−1, and differed substantially among management zones and study sites. Natural disturbances in strictly protected areas were longer in duration (median of 8years) and slightly less variable in magnitude compared to human-dominated disturbances in managed forests (median duration of 1year). However, temporal dynamics between natural and human-dominated disturbances showed strong synchrony, suggesting that disturbance peaks are driven by natural events affecting managed and unmanaged areas simultaneously. Our study demonstrates the potential of remote sensing for mapping forest disturbances in coupled human and natural systems, such as the forests of Central Europe. Yet, we also highlight the complexity of such systems in terms of agent attribution, as many natural disturbances are modified by management responding to them outside protected areas.

Determinants of Paracentrotus lividus sea urchin recruitment under oligotrophic conditions: Implications for conservation management

Sea urchins may deeply shape the structure of macrophyte-dominated communities and require the implementation of sustainable management strategies. In the Mediterranean, the identification of the major recruitment determinants of the keystone sea urchin species Paracentrotus lividus is required, so that source areas of the populations can be identified and exploitation or programmed harvesting can be spatially managed. In this study a collection of eight possible determinants, these encompassing both the biotic (larvae, adult sea urchins, fish, encrusting coralline algae, habitat type and spatial arrangement of habitats) and abiotic (substrate complexity and nutritional status) realms was considered at different spatial scales (site, area, transect and quadrat). Data from a survey including sites subject to different levels of human influence (i.e. from urbanized to protected areas), but all corresponding to an oligotrophic and low-populated region were fitted by means of a generalized linear mixed model. Despite the extensive sampling effort of benthic quadrats, an overall paucity of recruits was found, recruits being aggregated in a very small number of quadrats and in few areas. The analysis of data detected substrate complexity, and adult sea urchin and predatory fish abundances as the momentous determinants of Paracentrotus lividus recruitment. Possible mechanisms of influence are discussed beyond the implications of conservation management.

Distribución espacial de Ocypode quadrata (Decapoda: Ocypodidae) en ocho playas de la zona norte oriental de Cuba

Studies on the ecology of Ocypode quadrata have been mostly carried out in the Northern and Southern part of its distribution range. In despite that this species is common in Cuban beaches, there are no quantitative studies regarding its abundance and spatial distribution. The aim of this study was to report some aspects about the spatial variation of O. quadrata density in sandy beaches, with different levels of human influence, in the North coast of Eastern Cuba. For this, on May 2010, eight beaches with different levels of human influence were surveyed. On each beach, the number of crabs burrows were counted in 45 quadrats of 4m2 located in three different strata (P1, P2 and P3). According to burrow opening diameter, crabs were separated into young and adults forms. To determine the existence of statistical differences in the density of crab burrows among beaches and strata, a two-way ANOVA was developed with a Scheffé-procedure post hoc test. A total of 355 burrows were counted in 360 sample units. The composition by size classes was 237 burrows for young and 118 for adults. From the total of burrows, 74% were located in P1, 20% in P2 and 6% in P3. The higher concentration of burrows was found at Jiguaní beach (0.52 +/- 0.08 burrows/m2) while the lesser concentration was found at Estero Ciego beach (0.06 +/- 0.01 burrows/m2). Most of the beaches did not present significant differences in the burrows density (Scheffé, p>0.05), according to ANOVA results, in despite their different human influence level. Density of individuals was significantly higher in the upper intertidal (P1) areas (Scheffé, p<0.05) with predominance of young crabs. Total density diminished in P2 and P3 strata where a predominance of adult individuals was observed. The interaction term of beach and strata evidenced that the pattern of variation among strata was not the same for all beaches. The general pattern of adults and young specimen spatial distribution in the beaches was very similar to those reported in the literature. In the present study, the first conducted in Cuban beaches, we did not find evidence of direct relationship between the level of human impact and the density of ghost crab burrows.

Yellowstone Bison Genetics: Let Us Move Forward

White and Wallen (2012) disagree with the conclusions and suggestions made in our recent assessment of population structure among Yellowstone National Park (YNP) bison based on 46 autosomal microsatellite loci in 661 animals (Halbert et al. 2012). First, they suggest that “the existing genetic substructure (that we observed) was artificially created.” Specifically, they suggest that the substructure observed between the northern and central populations is the result of human activities, both historical and recent. In fact, the genetic composition of all known existing bison herds was created by, or has been influenced by, anthropogenic activities, although this obviously does not reduce the value of these herds for genetic conservation (Dratch and Gogan 2010). As perspective, many, if not most, species of conservation concern have been influenced by human actions and as a result currently exist as isolated populations. However, it is quite difficult to distinguish between genetic differences caused by human actions and important ancestral variation contained in separate populations without data from early time periods. Therefore, to not lose genetic variation that may be significant or indicative of important genetic variation, the generally acceptable management approach is to attempt to retain this variation based on the observed population genetic subdivision (Hedrick et al. 1986). Potential support for the opinion of White and Wallen (2012) about the large contribution of human actions to the observed genetic differentiation in YNP bison could come from genetic evaluation of bison samples from just before the relocation efforts of 1935–1936 (Cahalane 1944) or from the end of the period of intensive livestock-like management in the 1950s (Meagher 1973). However, if the observed differences were created by human-influenced events before the 1950s, then one would predict that in the last half century since then, natural exchange between the subpopulations would have greatly reduced or eliminated this genetic signal of differentiation. Regardless of the level of human influence on the observed levels of population differentiation, we must collectively move forward as good stewards of this natural resource with the best available scientific information. As such, it is paramount that we consider the long-term effects of current human interventions (bison “management”) on patterns of genetic diversity. Second, White and Wallen (2012) state that the low level of gene flow (based on FST) we reported is no longer present because of recent higher population numbers. They suggest that radiocollared bison movement data from 2002 to 2011 and a genetics study (nuclear microsatellites) of fecal samples from 99 different animals for 17 of our loci from 2006 and 2008 support a recent higher rate of gene flow between the two subpopulations. However, the details of the movement study and the genetic study are unpublished . We encourage White and Wallen to submit these for peer-review publication so the research can be more fully evaluated and used to inform additional research. Estimates of population structure based on maternally inherited mitochondrial DNA from Gardipee (2007) showed very high differentiation between groups. Further, we examined sex-biased gene flow using her data and found gene flow values that were consistent with estimates from our nuclear data. The unpublished radiocollared bison movement data White and Wallen (2012) report found no movement between the groups for female bison until the years 2006 to 2007. In other words, the lower FST that they report for 2006 surprisingly measures lower differentiation before this documentation of movement between groups. To evaluate the potential effect of recent higher gene flow, let us assume that FST declined from 0.032 (our estimated value) to 0.017 (the average of their two values) in one generation from around 2000 to 2007. Using expression (1) in Halbert et al. (2012), then the rate of gene flow would have had to be 27.1% each way between the two groups. This seems unrealistically high. Furthermore, the substantial evidence of cryptic population structure reported by Halbert et al. (2012) should give pause to observational studies linking YNP bison to particular breeding ranges or subpopulations. That is, while radiocollared bison movement data are immensely useful in understanding patterns of movement (e.g., Olexa and Gogan 2007), empirical genetic data are needed to establish the subpopulation origin of individuals: movement of Journal of Heredity doi:10.1093/jhered/ess051

Identification of de facto protected areas in boreal Canada

Canada is dominated by remote wilderness areas that make important conservation contributions, but are currently only protected de facto by their inaccessibility. Mechanisms for the identification and formal protection of such areas can help ensure that they continue to function naturally and provide essential ecosystem services. However, a lack of spatially explicit, publicly available sources of data on anthropogenic disturbances and natural resource extraction challenges the development of detailed wilderness inventories. We suggest that landscape structure can be used to classify areas of natural landscapes, as trained by the landscape structure of protected areas, and demonstrate this approach by mapping de facto protected areas in Canada’s boreal forest. Overall, between 50%, based on landscape structure, and 80%, based on anthropogenic infrastructure alone, of Canada’s boreal zone exists in large, intact blocks. The true extent of boreal wilderness likely falls within this range, as existing infrastructure datasets may omit disturbance and the protected area network in far northern areas proved inadequate to train effective wilderness classifications. We anticipate that such efforts may be improved by refining the identification of training areas or by classifying along additional landscape metrics. Nevertheless, the areas identified are valuable candidates for protected area expansion, and can contribute to a reserve network that meets national and regional conservation targets and is representative of the range of vegetation productivities, which was used as a biodiversity surrogate. Our general approach need not be limited to the boreal forest, as it has the potential to successfully identify relatively undisturbed (or less disturbed) areas over a range of systems and across levels of human influence.

Ecological condition of central Australian arid-zone rivers

Australian arid-zone rivers are known to be ecologically variable and go through "boom and bust" cycles based on highly variable and unpredictable flow regimes. They are facing increasing pressure from land and water resources development and, whilst they are considered to be still in relatively good condition, no studies have yet been carried out to verify this. Such baseline studies are crucial if we are to assess any ecological changes in response to development and management interventions. The ecological condition of four of these endorheic rivers (Georgina, Diamantina, Cooper-Thomson and Bulloo) flowing into the Lake Eyre and Bulloo Basins in central Australia was assessed using several criteria (level of human influence, habitat condition, water chemistry and aquatic macroinvertebrate composition). Using criteria based on the level of human influence, most of the sites were assessed to be relatively unimpacted (reference) condition. The most discernible and widespread impact was riparian and bank damage by stock access. However, the level of this impact was considered to be only moderate. Most aquatic macroinvertebrates found in the area are considered to be opportunistic and tolerant of a wide range of environmental conditions, but with their life histories known to be linked to flow conditions. Their trophic guild was dominated by collectors and predators. The AusRivAS modelled observed to expected values of macroinvertebrate composition indicated that there were differences in ecological condition between sites (e.g. different waterholes) and between times (e.g. seasons and years). Overall, 75% of sites were assessed to be good condition with the remainder being mildly impaired. Water chemistry of the sites was characterised by high spatial and temporal variability with low conductivity and alkaline pH, relatively high turbidity, total nitrogen and total phosphorus, and wide-ranging dissolved oxygen. Given the high variability in water quality and ecological condition within a catchment, there was little evidence of any overall difference in these factors between the catchments. However, given that the hydrology of each river system is distinctly different, one might expect some differences in ecological structure and function at finer scale. Periods of hydrological isolation (eg. to allow natural dryouts) as well as the maintenance of natural connectivity (eg. instream, overbank and floodplain wetting) are both necessary for the maintenance of ecological integrity of these systems.

Vegetation thickening in an ecological perspective: significance to national greenhouse gas inventories

‘Vegetation thickening’ often refers to an increasing shrub and tree density on many grazed rangelands, woodlands and forests that may or may not have supported such woody plant populations in the past. It is one of several ecosystem changes, including post-clearing re-growth, afforestation and reforestation, which are variants of the same biological phenomenon — the recovery phase of disturbance/recovery cycles that all vegetation undergoes continuously. There are various levels of human influence over both phases. It is important as part of the global carbon cycle and potentially for its implications for implementation of the Kyoto Protocol. Vegetation thickening poses some inventory and carbon accounting challenges in this regard because of difficulties with quantification and attribution. The attribution of carbon sinks to natural, indirect or direct human influence is difficult because of the complex interactions of factors in determining woodland dynamics. The lack of clear scientific distinction of causation requires decisions to be made on how this is calculated in inventories of greenhouse gas emissions. Advantages, disadvantages, workability and dilemmas of five possible accounting approaches to dealing with these human-influenced biological components are discussed. These approaches range from accounting solely for emissions from clearing ignoring complementary re-growth sinks, to full emissions accounting including methane, nitrous oxide and CO2 emissions from the managed animals and land.