My research aims to understand how arid and semi-arid ecosystems function; specifically the relationships between plants, animals and soil processes. This work is necessarily multi-disciplinary, and covers the broad areas of rangeland ecology, ecosystem engineering (the effects of organisms on soil processes), soil biology, ecology of desert soil crusts, rangeland health assessment, woody weed encroachment and soil restoration. The focus of my research is on the semi-arid woodlands of eastern Australia, and I have long-term research interests in west-central Idaho and the Chihuahuan Desert in the western United States.
Animals can influence plants and other animals in a variety of different ways, either directly through predation, competition or facilitation, or indirectly through their activities. These indirect, non-trophic effects include activities such as consuming material or moving sediment around in the landscape. This latter type of effect has recently been termed ecosystem engineering. Ecosystem engineering occurs when animals disturb the soil while foraging or creating bedding sites.
Foraging pits influence a range of soil and ecological processes such as nutrient cycling, infiltration of water, and capture and decomposition of organic material. These effects in turn influence plant germination, productivity and diversity, often with positive feedback effects on the animal creating the pit. The engineering effects of animals is being investigated in a number of studies in Australia and the western United States.
Some of the areas of ecosystem engineering research that the group is currently involved in include:
Ground-dwelling invertebrates such as ants and termites are important components of arid and semi-arid ecosystems. Ants and termites affect ecosystem processes through their effects on soil properties. They modify the soil by creating nest structures, which alter soil hydrology, organic matter and nutrients, and regulate the resource flows in deserts. They therefore help to establish fine-scale patchiness which is important for the functioning of desert systems.
Our research aims to determine the nature of the links between invertebrate activities and soil processes. Current projects include:
Biological soil crusts are made up of non-vascular plants (sometimes called cryptogams) and surface soils. The group includes lichens, bryophytes (mosses and liverworts), algae, cyanobacteria, fungi and bacteria. Crusts play important roles in terrestrial and aquatic ecosystems. They protect the soil against erosion, fix nitrogen, phosphorus and carbon and sequestering it in the soil, moderate soil moisture, influence the germination and establishment of vascular plants, and provide habitat for soil animals.
Our research has centred on the distribution of crusts, their roles in ecological and soil processes in arid Australia. NSW, and their usefulness as monitoring tools. In some ecosystems they are important indicators of landscape health.
Trees and shrubs have major effects on the way that water moves through the soil and the production and retention of nutrients. In the semi-arid woodlands, trees are focal points of soil activity and major drivers of ecosystem processes. As landscapes become degraded, the importance of trees in controlling excess surface water becomes critical.
Our work in eastern Australia concentrates on two main areas of research. In eastern Australia isolated trees are a feature of peri-agricultural areas, and extensive areas of native vegetation have been removed leaving isolated trees. We are examining the important of these isolated trees for moderating key ecosystem processes such as nutrient retention and water flow. The second area of research is in areas of extensive shrub encroachment in Australiaâ€™s semi-arid and arid woodlands. Here we are looking at whether the presence of shrubs is consistent with the desertification paradigm and thus whether shrub-dominated landscapes are ecologically depauperate as claimed in the literature.
James Glasier (PhD candidate)
Gabriella Radnan (PhD candidate)
Stefani Daryanto (PhD)
Samantha Travers (PhD)
James, A.I., Eldridge, D.J. and Moseby, K. (in press). Foraging pits, litter and plant germination in an arid shrubland. Journal of Arid Environments (in press).
Eldridge, D.J. and Lunt, I.D. (in press). Resilience of soil seed banks to site degradation in intermittently-flooded riverine woodlands. Journal of Vegetation Science(in press)
Eldridge, D.J., Whitford, W.G. and Duval, B.D. (2009). Animal disturbances promote shrub maintenance in a desertified grassland Journal of Ecology (in press).
James, A.I., Eldridge, D.J. and Hill, B. (2009) Animal foraging pits as sinks for litter and nutrients in an Australian desert shrubland. Ecography (in press)
Eldridge, D.J. and Whitford, W.G. (2009). Soil disturbance by native animals along grazing gradients in an arid grassland. Journal of Arid Environments 73, 1144-1148.
Eldridge, D.J. and James, A.I. (2009). Soil-disturbance by native animals plays a critical role in maintaining healthy Australian landscapes. Ecological Management and Restoration 10, S27-S34.
Eldridge, D.J. and Whitford, W.G. (2009). Badger (Taxidea taxus) disturbances increase soil heterogeneity in a degraded shrub-steppe ecosystem. Journal of Arid Environments 73, 66-73.
O'Bryen, E., Prober, S.M., Lunt, I.D. and Eldridge, D.J.
(2009). Frequent fire promotes diversity and cover of biological soil crusts in a derived temperate grassland. Oecologia
159, 827-838. download PDF file
(2009) Badger (Taxidea taxus
) mounds affect soil hydrological properties in a degraded shrub-steppe. American Midland Naturalist
161, 350-358. download PDF file
and Koen, T.B. (2008). Formation of nutrient-poor soil patches in a semi-arid woodland by the European rabbit (Oryctolagus cuniculus
L.). Austral Ecology
. 33, 88-98. download PDF file
and Kwok, A.B.C. (2008). Soil disturbance by animals at varying spatial scales in a semi-arid Australian woodland. The Rangeland Journal
30, 327-337. download PDF file
James, A.I., Eldridge,
D.J., Koen, T.B. and Whitford, W.G. (2008). Landscape position moderates how ant nests affect hydrology and soil chemistry across a Chihuahuan Desert watershed. Landscape Ecology
23, 961-975. download PDF file
Williams, W.J., Eldridge, D.J.
and Alchin, B.M. (2008). Grazing and drought reduce cyanobacterial soil crusts in an Australian Acacia woodland. Journal of Arid Environments
72, 1062-1071. download PDF file
Deines, L., Rosentreter, R., Eldridge, D.J.
and Serpe, M.D. (2007). Germination and seedling establishment of two annual grasses on lichen-dominated biological soil crusts. Plant and Soil
295, 23-35. download PDF file
and Mensinga, A. (2007). Foraging pits of the Short-Beaked Echidna (Tachyglossus aculeatus
) as small-scale patches in a semi-arid Australian box woodland. Soil Biology and Biochemistry
39, 1055-1065. download PDF file
James, A.I. and Eldridge, D.J.
(2007). Reintroduction of fossorial native mammals and potential impacts on ecosystem processes in an Australian desert landscape.Biological Conservation
138, 351-359. download PDF file
Lunt, I.D., Eldridge, D.J.,
Morgan, J.W. and Will, G.B. (2007). A framework to predict the effects of livestock grazing and grazing exclusion on conservation values in natural ecosystems in Australia. Australian Journal of Botany
55, 401-415. download PDF file
Semple, W.S., Koen, T.B., Eldridge, D.J.
, Düttmer, K.M. and Parker, B. (2006). Variation in soil properties on two partially revegetated saline scalds. Australian Journal of Experimental Agriculture
46, 1279-1289. download PDF file
Eldridge, D.J., Freudenberger, D. and Koen, T.B. 2006. Diversity and abundance of biological soil crust taxa in relation to fine and coarse-scale disturbances in a grassy eucalypt woodland in eastern Australia. Plant and Soil 281, 55-68. download PDF file
Thompson, W.A., Eldridge, D.J. and Bonser, S.R. 2006. Structure of biological soil crust communities in Callitris glaucophylla woodlands of New South Wales, Australia.Journal of Vegetation Science 17, 271-280. download PDF file
Eldridge, D.J., Constantinides, C. and Vine, A. 2006. Short-term vegetation and soil responses to mechanical destruction of rabbit (Oryctolagus cuniculus L.) warrens in an Australian box woodland. Restoration Ecology 14, 50-59. download PDF file
Thompson, W.A. and Eldridge, D.J. 2005. Plant cover and composition in relation to density of Callitris glaucophylla (white cypress pine) along a rainfall gradient in eastern Australia. Australian Journal of Botany 53, 545-554. download PDF file
Thompson, W.A. and Eldridge, D.J. 2005. White cypress pine (Callitris glaucophylla): a review of its roles in landscape and ecological processes in eastern Australia.Australian Journal of Botany 53, 555-570. download PDF file
Eldridge, D.J. and Wong, V.N.L. 2004. Clumped and isolated trees influence soil nutrient levels in an Australian temperate box woodland. Plant and Soil 270, 331-342.download PDF file
Eldridge, D.J. and Freudenberger, D. 2005. Ecosystem wicks: woodland trees enhance water flow in a fragmented agricultural landscape in eastern Australia. Austral Ecology30, 336-347. download PDF file
Eldridge, D.J. 2004. Mounds of the American badger (Taxidea taxus): significant geomorphic features of North American shrub-steppe ecosystems. Journal of Mammalogy 85, 1060-1067. download PDF file
Eldridge, D.J. and Rosentreter, R.R. 2004. Shrub mounds enhance water flow in a shrub-steppe community in southwestern Idaho, USA. In: Hild, A.L., Shaw, N.L., Meyer, S., Booth, D.T., McArthur, E.D. (Compilers). Seed and soil dynamics in shrubland ecosystems. USDA Forest Service Proceedings RMRS-P-31, Ogden Utah. download PDF file
Hilty, J., Eldridge, D.J., Rosentreter, R., Wicklow-Howard, M. and Pellant, M. 2004. Recovery of biological soil crusts following wildfire on the western Snake River Plain, Idaho. Journal of Range Management 57, 89-96. download PDF file
Eldridge, D.J., Harrison, L., Parker, L. and Milligan, A. 2003. Condition and biodiversity of vegetation remnants: MIA. Natural Resource Management June 2003, 63-66.
Hilty, J., Eldridge, D.J., Rosentreter, R. and Wicklow-Howard, M. 2003. Burning and seeding influence soil surface morphology in an Artemisia shrubland in southern Idaho. Arid Land Research and Management 17, 1-11.
Eldridge, D.J. and Koen, T.B. 2003. Detecting environmental change in eastern Australia: rangeland health in the semi-arid woodlands. Science of the Total Environment 310, 211-219. download PDF file
Eldridge, D.J. and Leys, J.F. 2003. Exploring some relationship between biological soil crusts, soil aggregation and wind erosion. Journal of Arid Environments 53, 457-466.download PDF file
Eldridge, D.J. and Wilson, B.R. 2003. Storage of carbon in soil and vegetation in paired roadside sites in the box woodlands of eastern Australia. Australian Forestry 65, 268-272.
Eldridge, D.J., Zaady, E. and Shachak, M. 2002. The impact of disturbance on runoff and sediment production and its implications for the management of desert ecosystems. Landscape Ecology 17, 587-597. download PDF file
Eldridge, D.J. and Squires, V.R. 2002. Estimating pastoral productivity of semi-arid rangeland in northern Shaanxi Province, China using an Environmental Resource Assessment System. Land Degradation and Management 16, 37-45.
Eldridge, D.J. and Rath, D. 2002. Hip holes: kangaroo resting sites enhance the physical and chemical environment of woodland soils. Austral Ecology 27, 527-536.download PDF file
Eldridge, D.J. and Simpson, R. 2002. Rabbit (Oryctolagus cuniculus L.) impacts on vegetation and soils, and implications for management of wooded rangelands. Basic and Applied Ecology 3, 19-29. download PDF file
Eldridge, D.J. and Myers, C.A. 2001. The impact of warrens of the European rabbit (Oryctolagus cuniculus L.) on soil and ecological processes in a semi-arid Australian woodland. Journal of Arid Environments 47, 325-337. download PDF file
Eldridge, D.J., Semple, W.S. and Koen, T.B. 2000. Dynamics of cryptogamic soil crusts in a derived grassland in south-eastern Australia. Austral Ecology 25, 232-240.download PDF file
Eldridge, D.J., Zaady, E., Shachak, M. 2000. Infiltration through three contrasting biological soil crusts in patterned landscapes in the Negev, Israel. Catena 40, 323-336.download PDF file
Stafford, M.J. and Eldridge, D.J. 2000. Vegetation, soils and management of 'Zara': a sandhill remnant on the Riverine Plain. Cunninghamia 6, 717-746.
Eldridge, D.J. 2000. Ecology and management of biological soil crusts: recent developments and future challenges. Bryologist 103, 742-747.
Eldridge, D.J. 2003. Biological soil crusts: nature's natual soil healers. In: Brown, C.L., Hall, F. and Mill, J. (eds). Plant Conservation: Approaches and Techniques from an Australian Perspective. Australian Network for Plant Conservation, Canberra.
Eldridge, D.J. 2002. Assessing catchment health. In: K. Kent, G. Earl., B. Mullins, I. Lunt and R. Webster (eds.) Native Vegetation Guide for the Riverina: Notes for Land Managers on its Management and Restoration. pp. 20-24. Charles Sturt University, Albury.
Rosentreter, R. and Eldridge, D.J. 2002. Monitoring biodiversity and ecosystem function: grasslands, deserts and steppe. In: P.L. Nimis, C. Scheidegger and P.A. Wolseley (eds.) Monitoring with Lichens; Monitoring Lichens. pp. 223-237. Kluwer, Netherlands. download PDF file
Eldridge, D.J. 2001. Biological soil crusts of Australia. In: J. Belnap and O. Lange (eds.) Biological Soil Crusts: Structure, Management and Function. Ecological Studies 150,pp. 119-132. Springer-Verlag, Berlin.
Eldridge, D.J. 2001. Biological soil crusts and water relations in of Australian deserts. In: J. Belnap and O. Lange (eds.) Biological Soil Crusts: Structure, Management and Function. Ecological Studies 150, pp. 315-326. Springer-Verlag, Berlin.
Belnap, J. and Eldridge, D.J. 2001. Disturbance and recovery of biological soil crusts. In: J. Belnap and O. Lange (eds.) Biological Soil Crusts: Structure, Management and Function. Ecological Studies 150, pp. 363-384. Springer-Verlag, Berlin.
Warren, S.D. and Eldridge, D.J. 2001. Biological soil crusts and livestock in arid regions: are they compatible? In: J. Belnap and O. Lange (eds.) Biological Soil Crusts: Structure, Management and Function. Ecological Studies 150, pp. 401-416. Springer-Verlag, Berlin.
Rosentreter, R., Eldridge, D.J. and Kaltenecker, J.H. 2001. Monitoring and manageent of biological soil crusts. In: J. Belnap and O. Lange (eds.) Biological Soil Crusts:Ecology and Function. Ecological Studies 150, pp. 457-470, Springer-Verlag, Berlin.
Eldridge, D.J., Lepage, M., Bryannah, M.A. and Ouedraogo, P. 2001. Soil Biota. In: Valentin, C., Tongway, D.J., d'Herb, J.M. and Sergieri, J. (eds.) Banded Vegetation Patterning in Arid and Semi-Arid Environments: Ecological Processes and Consequences for Management. Ecological Studies 149, pp. 105-131. Springer-Verlag, Amsterdam.