Grazing Landscape Research Articles

Boundary detection in an arid grazing landscape: the perspective of plants and small mammals

Boundary detection in an arid grazing landscape: the perspective of plants and small mammals

Managing the grazing landscape: Insights for agricultural adaptation from a mid-drought photo-elicitation study in the Australian sheep-wheat belt

Globally, and under uncertain climate conditions, the agricultural sector will need to feed more people without degrading the ecosystem services on which production depends. Eastern Australia, coming out of a decade of drought, is at the leading edge of this challenge. Measures to adapt agriculture to increasing climate variability are urgently sought. One particularly promising measure is an adaptive grazing decision-making practice called holistic management (HM), typically involving high-intensity, short-duration rotational grazing and the encouragement of pastures with low chemical input needs. Here, we use photo-elicitation to compare the landscape perceptions of HM graziers with those of more conventional graziers, based on their choice of photo targets and the stories those photographs elicited. During that process, HM graziers described their use of adaptive farm management techniques to gain outcomes for production and ecosystems alike, demonstrating a system-based understanding of their farms conducive to farming under increased climate variability. We conclude that HM grazing should be encouraged so as to adapt the industry to climate change. More widespread uptake of HM practices – for public benefit as well as personal – depends on incentives to reduce start-up costs and expand the instruction of HM principles, first targeting those with high adaptive capacity, and removing policies that delay adaptation.

Lessons from visualising the landscape and habitat implications of tree decline—and its remediation through tree planting—in Australia's grazing landscapes

Tree decline has been documented in farming and grazing landscapes around the world, with negative consequences for biodiversity and important ecosystem services. We have used solution-oriented transdisciplinary research to understand the possible consequences of scattered tree decline in Australia's temperate grazing landscapes, and explore appropriate management and policy responses. Here, we document the scenario modelling process that culminated our stakeholder engagement. We simulated tree decline and its consequences for landscape aesthetics and biodiversity, using photo-realistic visualisations based on photographs identified as significant by graziers, and empirically derived habitat relationships for a series of birds and bats. The results foreshadow dramatic visual and ecological impacts for the region. We also modelled the aesthetic and habitat impacts of fully costed remediation scenarios, including widespread scattered tree planting and densely seeding poor paddocks under temporary stock exclusion. The visualisations revealed to the research team that: (1) dense seeding has a more lasting impact for scattered trees than scattered planting; (2) the benefits of any kind of planting is short-lived if accompanied by conventional grazing practices; and (3) grazed woodlands are most at risk. The graziers to whom we presented our scenarios in the last of our stakeholder workshops responded well to both kinds of visualisations, but it was clear that the experience also extracted a cost. We reflect here on our methods and outcomes, and draw out lessons from our work for other studies of this kind.

Litterfall and associated nutrient pools extend beyond the canopy of scattered eucalypt trees in temperate pastures

Scattered paddock trees are a keystone feature of temperate grazing landscapes of Australia. However, our understanding of their influence on their immediate environment, and specifically the spatial distribution and characteristics of litter, is still limited. Here, we quantified the spatial pattern of litter around 4 Eucalyptus species (Eucalyptus melliodora A. Cunn. Ex Schauer, E. viminalis Labill., E. blakelyi Maiden and E. michaeliana Blakely) in grazing landscapes on the Northern Tablelands of NSW, Australia. We examined the effect of species and soil parent material (basalt, granite and meta-sediments) on litter chemistry and chemical pools. Between 54–145 kg of litter was found around individual trees and litter density consistently declined with distance from the tree (330 g.m−2 in the inner canopy to 4 g.m−2 in the open paddock). However, an equivalent quantity of litter was found beneath and beyond the canopy indicating that a large quantity of the litter and nutrients fell beyond the edge of the canopy. Overall, leaf litter accounted for 23 to 34% of litterfall and had larger nutrient concentrations and pools than bark or stick litter. Most litter nutrients concentrations were independent of tree species or parent material but our results suggest that P, K and S were removed in foliage prior to abscission whilst Ca and Fe concentrations increased. The spatial patterns of litter distribution around scattered trees coincide with spatial patterns in soil properties that are frequently observed in these environments, and provide strong evidence of a significant link between these factors. Our results suggest that the removal of scattered trees from pastoral landscapes in this region of Australia will result in the loss of a significant litter input to the soil surface and will diminish this potentially important source of soil nutrients.

From venison to beef: seasonal changes in wolf diet composition in a livestock grazing landscape

Wild ungulates are the primary prey for wolves in North America, but livestock predation is a concern in areas where wolves and livestock overlap. Using clusters of global positioning system telemetry relocations and scat analysis, we investigated wolf diets year‐round in southwestern Alberta, where seasonal cattle grazing is the predominant land use and wolf–cattle conflicts have increased in recent years. Both methods indicated a seasonal shift in wolf diets, from wild prey during the non‐grazing season to cattle in the grazing season. Wolves scavenged more frequently during the non‐grazing season than during the grazing season; 85% of all scavenging events occurred at ranchers' boneyards (where livestock carcasses are dumped), where wolves fed on dead livestock. Cattle represent a higher proportion of wolf diets than previously thought; we recommend the sanitary disposal of dead livestock to prevent wolves from becoming accustomed to feeding on livestock, and the development of management plans aimed at reducing predation on cattle if humans and wolves are to coexist on landscapes that are dominated by livestock ranching.

Conservation management of eastern Australian farmland birds in relation to landscape gradients

Summary 1. Birds inhabiting farmland are of conservation concern around the world. In Australia, conservation management has focused primarily on woodland environments. By contrast, semi-natural open areas have received less attention. We argue that long-term conservation strategies should consider broad gradients of environmental conditions. Otherwise, there is a risk that semi-natural open areas will degrade through ‘benign neglect’, and currently common species using these areas will become uncommon. 2. We examined how birds responded to three environmental gradients in an Australian livestock grazing landscape: tree density, grazing intensity and nutrient enrichment. First, we investigated changes in species composition across the environmental gradients in multivariate space. Secondly, we modelled species richness and the response of selected individual species in relation to the gradients. Thirdly, we examined if there were patterns in guild composition and body mass distribution. 3. Tree density was the primary driver of virtually all patterns observed. Species richness peaked at moderately high tree densities. With increasing tree density, species composition changed, foraging guild composition changed and the median body mass of bird species decreased. Small insectivores were more likely to occur in areas with high tree densities, whereas large granivores were more likely to occur in areas with relatively low tree densities. Grazing intensity and nutrient enrichment were less strongly related to bird distribution patterns, although the indirect effects of these gradients may be substantial because they affect tree regeneration. 4. sSynthesis and applications. Relatively dense woodland patches were important for species already of conservation concern, lending support to their active conservation management, for example through livestock exclusion. However, semi-natural open areas also were used by many birds, which represented a different mix of body sizes and foraging guilds. Scattered trees occurring at a range of densities are key habitat elements in semi-natural open areas. However, many scattered trees are dying and are not being replaced by natural regeneration or tree planting. If areas with scattered trees continue to degrade, there is a risk that currently common farmland birds will decline. Management strategies aiming to maintain scattered trees therefore are important, including the planting of individual trees and the adoption of grazing practices that allow for natural tree regeneration.

The disproportionate value of scattered trees

Scattered trees are declining in agricultural landscapes worldwide. They are considered keystone structures because their effect on ecosystem functioning is believed to be disproportionate relative to the small area occupied by any individual tree. We empirically demonstrate the disproportionate value of scattered trees for birds and bats in an Australian livestock grazing landscape. We surveyed birds at 108 sites and bats at 63 sites. Sites spanned the full range of tree densities in the study area, from zero to over 100 trees per hectare. The marginal value of individual trees was highest when trees occurred at low densities. Compared to treeless sites, bird richness doubled with the presence of the first tree; bat richness tripled with the presence of 3–5 trees; and bat activity increased by a factor of 100 with the presence of 3–5 trees. Thereafter, the marginal effect of additional trees on birds and bats diminished rapidly. Although specialist species were restricted to large areas of dense tree cover, scattered trees effectively maintained moderate levels of bird and bat activity throughout largely cleared parts of the landscape. Future management activities should recognize the disproportionate value of scattered trees.

TEMPORAL CHANGES IN VERTEBRATES DURING LANDSCAPE TRANSFORMATION: A LARGE‐SCALE “NATURAL EXPERIMENT”

Plantation development is a significant form of landscape change worldwide. We report findings from a large‐scale longitudinal natural experiment that quantified changes in Australian vertebrates as a former grazing landscape was transformed to one dominated by a radiata pine (Pinus radiata) plantation. The study included four main “treatments”: woodland remnants surrounded by emerging radiata pine (52 sites, termed “woodland treatments”), stands of radiata pine (10 sites, “pine controls”), woodland remnants where the surrounding landscape remained unchanged (56 sites, “woodland controls”), and paddocks with scattered woodland trees that surrounded the 56 woodland remnants (10 sites, “paddock controls”). In our study region, woodland is distinguished from forest by differences in tree height, tree spacing, bole length, and canopy development.Between 1998 and 2006, occupancy rates of “woodland treatments” by most mammals and reptiles increased linearly. Similar trends occurred in the “woodland controls,” suggesting that species had increased landscape‐wide, rather than displaying year × treatment interaction effects. We cross‐classified birds according to the statistical significance and nature of time trajectories. Groups included those that: (1) declined in woodland treatments in comparison with woodland controls, (2) decreased within woodland treatments but increased in woodland controls, (3) declined across the entire study area, (4) increased within woodland treatments in comparison with woodland controls, (5) increased within woodland treatments but declined in woodland controls, and (6) increased across the entire study area.Attributes of woodland treatments significantly associated with temporal changes in bird occupancy included: (1) age of surrounding pine stands; (2) number of boundaries with surrounding pines; (3) size of the woodland patches; (4) dominant vegetation type of woodland patches; and (5) temporal changes in vegetation structure in the woodland treatments.Bird species associated with open country and woodland environments were disadvantaged by landscape transformation, whereas those that benefited were forest taxa and/or habitat generalists capable of inhabiting pine stands and adjacent woodland patches. Beyond this generalization, an unanticipated finding was a lack of association between life history attributes and landscape transformation. We suggest that several key processes are likely drivers of change at multiple spatial scales. Recognition of such processes is important for conservation in landscapes transformed by plantation expansion.

Overstorey tree density and understorey regrowth effects on plant composition, stand structure and floristic richness in grazed temperate woodlands in eastern Australia

As natural woodlands decline in both extent and quality worldwide, there is an increasing recognition of the biodiversity conservation value of production landscapes. In low-input, low-productivity grazing systems in Australia, the modification of natural woodlands through overstorey tree and woody regrowth removal are vegetation management options used by landholders to increase native grass production for livestock grazing; however, there is little empirical evidence to indicate at what tree densities biodiversity attributes are compromised. We examined the effects of overstorey tree density and understorey regowth on the floristic composition, stand structure and species richness of eucalypt woodlands in a grazing landscape in the Traprock region of southern Queensland, Australia. We sampled 47 sites stratified according to vegetation type ( Eucalyptus crebra/Eucalyptus dealbata woodland; Eucalyptus melliodora/Eucalyptus microcarpa grassy woodland), density of mature trees (<6 trees/ha; 6–20 trees/ha; >20 trees/ha), and presence/absence of regrowth. Distinct patterns in composition were detected using indicator species analysis and non-metric multidimensional scaling, with low density areas compositionally indistinguishable, although distinct from other land management units. Within vegetation type, medium tree density woodlands were compositionally similar to high density and reference woodlands. Species richness ranged from 18 to 67 species per 500 m 2 across all sites. No differences in total or native species richness were detected across management units; however, some differences in exotic species richness were detected. Differences in grass cover existed between low and high density management units, yet no difference in grass cover was evident between low and medium density management units. Our results suggest that medium tree densities may provide biodiversity benefits concordant with more natural areas, yet not adversely impact on pasture production. Retaining trees in grazing landscapes provides significant landscape heterogeneity and important refuges for species that may be largely excluded from open grassland habitats. Maintaining a medium density of overstorey trees in grazed paddocks can provide both production and biodiversity benefits.

Modeling Historic Rangeland Management and Grazing Pressures in Landscapes of Settlement

Defining historic grazing pressures and rangeland management is vital if early landscape threshold crossing and long–term trajectories of landscape change are to be properly understood. In this paper we use a new environmental simulation model, Bumodel, to assess two contrasting historical grazing landscapes in Mývatnssveit Iceland for two key periods—the colonization period (ca. Landnam, a.d. 872–1000) and the early eighteenth century a.d. Results suggest that there were spatial and temporal variations in productivity and grazing pressure within and between historic grazing areas and indicate that land degradation was not an inevitable consequence of the livestock grazing introduced with settlement. The results also demonstrate the significance of grazing and livestock management strategies in preventing overgrazing, particularly under cooler climatic conditions. The model enables detailed consideration of historic grazing management scenarios and their associated landscape pressures.

Making the matrix matter: challenges in Australian grazing landscapes

Many ecological theories are based on the concept of patches. Patches are a useful starting point for conservation efforts, but a focus on patches alone will not always achieve desired conservation outcomes. Conservation strategies in the grazing landscapes of southeastern Australia suggest that large patches of trees are widely regarded as ‘habitat’ while other forms of habitat are largely ignored. We provide data on birds and reptiles from the Nanangroe grazing landscape that illustrate the potential habitat value of areas located between large patches of trees – that is, the matrix. Despite evidence on its potential value, present conservation strategies rarely consider the matrix. Possible reasons for this bias relate to the economics of farming and the history of land use, the current environmental law framework, and also the reluctance of ecologists to study the matrix. More scientific evidence on the role of the matrix will be crucial if conservation strategies are to consider not only patches, but entire landscapes. However, for science to be relevant to land management, there is a need for new research approaches. First, an increased consideration of environmental policy and law will increase the likelihood of scientific findings being adopted by policy makers. Second, at an applied level, more practical on-ground research into farming practices and clearer communication are necessary to achieve more sustainable matrix management in Australian grazing landscapes.

The challenge of managing multiple species at multiple scales: reptiles in an Australian grazing landscape

Summary Understanding the ecological effects of processes operating at multiple spatial scales on multiple species is a key challenge in ecology. It underpins both basic research and the increasing recognition of scale‐dependence in conservation biology. Organisms are affected by ecological processes operating at multiple spatial scales. Hence the study of multiple species and spatial scales is a key challenge in ecology. A spatially nested experimental design was used to investigate the habitat relationships of reptiles in a grazing landscape in southern New South Wales, Australia. Regression modelling was used to relate the presence of species and species richness to habitat variables. Different species were predicted by different habitat variables, and some species reflected habitat structure at one, but not all, spatial scales. The four‐fingered skink Carlia tetradactyla was associated with box woodlands, areas with few rocks and many spiders, and areas with a northerly aspect and high tree cover. Boulenger's skink Morethia boulengeri was more likely to be found in areas with many ants and beetles, and also in areas with a northerly aspect and high tree cover. The striped skink Ctenotus robustus and olive legless lizard Delma inornata were significantly more likely to be detected in areas with a simple microhabitat structure. Species richness was highest in box woodlands (Eucalyptus albens and Eucalyptus melliodora) and at sites characterized by a high variability of habitat structure. Different habitat variables varied over different spatial scales. For example, invertebrate abundance varied mostly over tens of metres, while grass/forb cover varied mostly over hundreds to thousands of metres. Synthesis and applications. The multitude of species’ responses and spatial habitat variability highlighted the potential limitations of the fragmentation paradigm because it may oversimplify ecological complexity. On this basis, conservation in variegated grazing landscapes may need to consider changes to livestock management across entire landscapes, rather than concentrate solely on the preservation of particular patches.

Fauna conservation in Australian plantation forests – a review

A review of the value for fauna of conifer and eucalypt plantations in Australia is presented. Five key reasons highlight a need for wildlife conservation as part of plantation management. These are: (1) The plantation estate in Australia is set to triple in the coming decades, and where new plantations are located and how they are managed will influence the biota that currently exist in such landscapes. This is particularly critical in many semi-cleared former grazing landscapes where the establishment of new plantations is focused. This is because: (1) (a) native vegetation communities in these areas are poorly represented in the existing reserve system, and, (b) uses such as wood and pulp production need to be balanced with other management values such as wildlife conservation. (2) The maintenance of some elements of the biota within plantations could have benefits for key ecosystem processes like pest control. (3) Although some species cannot be conserved in plantation-dominated landscapes, many species can be through the adoption of (sometimes minor) modifications to forest management. (4) The maintenance (or loss) of biota in plantations is relevant for moves toward ecological standards and the certification of plantations in many parts of the world. And, (5) simple plantation forestry which has a narrow and intensive management focus on producing a forest crop for a limited array of purposes, may not meet societal demands for a range of outputs from plantations in addition to wood and pulp. It also may not be congruent with the principles of ecological sustainability. Our review showed that almost all research undertaken in Australian plantations, both in conifers and eucalypts, highlighted the importance of landscape heterogeneity and stand structural complexity for fauna conservation. At the landscape level, patches of retained native vegetation, strips of riparian vegetation, dams, open and clearing areas can significantly increase the number of native species that occur within plantations. Some species that occur in these areas can also use adjacent planted areas, a result common to conifer and eucalypt plantations. The spatial juxtaposition of stands of varying ages throughout plantation landscapes also can contribute to the maintenance of some populations of native taxa. At the stand level, structural complexity is also important for fauna with many species responding positively to the presence of native understorey plants, the presence of windrowed logs, and logging slash left on the forest floor. The management of plantations to promote landscape heterogeneity and stand structural complexity will, in many cases, involve trade-offs that will influence wood and pulp production. The extent to which this occurs will be dependent on the objectives of plantation management and how far they extend toward the complex plantation forestry model to incorporate social and environmental values in addition to wood and pulp production.

The conservation value of paddock trees for birds in a variegated landscape in southern New South Wales. 2. Paddock trees as stepping stones

The use of paddock trees as stepping stones by birds was assessedin a grazing landscape in southern New South Wales, Australia. A totalof 70 paddock tree sites was surveyed for 20 min each inthe morning, and 36 sites were surveyed again in the afternoon in March2000. During the surveys, the presence, direction of arrival, anddirection of departure to and from sites was recorded for each bird. Astepping stone effect of paddock trees was examined in two ways: (1) byanalysing the arrival and departure direction of birds relative tosurrounding vegetation cover, and (2) by analysing the departuredirection of birds relative to their arrival direction. An arrivaldirection was obtained for 150 independently acting groups of birds, anda departure direction was obtained for 203 independently acting groupsof birds. Both arrival and departure direction were obtained for 87independently acting groups. Foliage-foraging birds tended to followrelatively densely vegetated areas. There was some indication thatgranivores and nectarivores also preferred to move along denselyvegetated areas. This trend was absent for open-country species. Allgroups of birds examined tended to return to their place of origin ormove in the opposite direction of their arrival. This trend was mostpronounced for nectarivores and the foliage-foraging White-plumedHoneyeater (Lichenostomus penicillatus), and lesspronounced for open-country species and parrots. The results arediscussed in relation to the biology and ecology of the various speciesof birds. We conclude that paddock trees have the potential to enhancelandscape connectivity by acting as stepping stones to assist movement.This further highlights their conservation value as demonstrated in thefirst paper of this series.

The Influence of Recent Grazing Pressure and Landscape Position on Grass Recruitment in a Semi-Arid Woodland of Eastern Australia.

This study examined the effects of previous grazing pressure, position in the landscape and apparent seed trapping capability of soil surface micro-sites on recruitment of the perennial grass Monachather paradoxa (mulga oats) in a semi-arid woodland. Seedling emergence was counted on small plots which had been kept moist for one month. The plots were on bare ground, or at grass tussocks, or at log mounds, sited in the run-off, interception and run-on zones of paddocks that had been grazed for six years at 0.3 and 0.8 sheep equivalent/ha. Few naturally occurring perennial grass seedlings emerged on any of the sites. The level of previous grazing pressure influenced the recruitment of grasses from natural sources as well as from seed of M. paradoxa broadcast on the soil surface; significantly more grass seedlings recruited in paddocks stocked at 0.3 than at 0.8 sheep/ha. Emergence of the sown grass did not differ significantly between the three zones in the landscape, but trends in the data suggest the interception zone may have been the most favourable. Recruitment from in situ grass seed was highest in the mulga grove (run-on) zone. Most seedlings of the sown grass emerged around the bases of existing perennial grass tussocks, but recruitment of volunteer perennial and annual grasses was more evenly distributed between the mulga log-mounds and perennial grass tussocks. It is concluded that very low levels of readily germinable seed of perennial grasses remained in the soil at the end of the drought and that areas with a history of high grazing pressure have less probability of grass recruitment when suitable rain occurs.