TY - JOUR
T1 - Recruitment of a keystone tree species must concurrently manage flooding and browsing
AU - Horner, Gillis
AU - Cunningham, Shaun
AU - Thomson, James
AU - Baker, Patrick
AU - MAC NALLY, Ralph
AU - Moreno-Mateos, David
N1 - Funding Information:
This research was funded by the Australian Research Council (grants LP0560518, DP120100797), with partial funding by the Department of Sustainability and Environment (DSE) and four Catchment Management Authorities (Goulburn Broken, Mallee, North Central and North East). G.J.H. acknowledges the financial support of the Holsworth Wildlife Research Endowment and in-kind contributions from Parks Victoria and Trust for Nature. G.J.H. is indebted to Charlie and Cheryl Coarser, Rod and Mark Horner for their wonderful encouragement and help with fieldwork. Experimental data (seedling survival, height and sediment salinity) have been registered with figshare doi: 10.6084/m9.figshare.1618656 (Horner et al.).
Publisher Copyright:
© 2015 The Authors. Journal of Applied Ecology © 2015 British Ecological Society
PY - 2016
Y1 - 2016
N2 - Multiple pressures (land-use change, water extraction and climate change) interact to influence biodiversity and ecosystem processes, but direct evidence for interactions among multiple pressures is limited. Floodplain forests are an acute example of how interacting pressures (river regulation, water extraction, decreasing rainfall and mammal browsing) interact to degrade native ecosystems. We conducted a 2-year field experiment to determine how flooding, browsing and sediment salinity interacted to determine in situ seedling survival and growth of the keystone floodplain tree species (Eucalyptus camaldulensis Dehnh.). On semi-arid floodplains of southern Australia, 1-year-old seedlings were planted on the banks of six ephemeral creeks, three of which were flooded with management flows before planting while the others remained dry. Four plots were established at each creek, two open to browsing and two fenced to exclude mammal herbivores. Flooding had a strong positive effect on seedling survival and height, but browsing had strong negative effects. Sediment salinity (a covariate rather than a designed effect) had a weak negative effect on seedling survival and height. The positive effects of flooding were largely offset by the negative interaction with browsing and, to a lesser extent, sediment salinity. Although flooding has been restored to some degraded floodplain forests subjected to river regulation and a drying climate, the long-term success of such actions is likely to be undermined by persistent browsing. Synthesis and applications. Management actions that focus on single pressures (e.g. infrequent flooding) and processes (e.g. mature tree survival) while ignoring other pressures are unlikely to sustain populations of keystone species, suggesting that complementary strategies (managed flooding with herbivore control) are necessary to sustain recruitment and, therefore, ensure the future health of these essential ecosystems.
AB - Multiple pressures (land-use change, water extraction and climate change) interact to influence biodiversity and ecosystem processes, but direct evidence for interactions among multiple pressures is limited. Floodplain forests are an acute example of how interacting pressures (river regulation, water extraction, decreasing rainfall and mammal browsing) interact to degrade native ecosystems. We conducted a 2-year field experiment to determine how flooding, browsing and sediment salinity interacted to determine in situ seedling survival and growth of the keystone floodplain tree species (Eucalyptus camaldulensis Dehnh.). On semi-arid floodplains of southern Australia, 1-year-old seedlings were planted on the banks of six ephemeral creeks, three of which were flooded with management flows before planting while the others remained dry. Four plots were established at each creek, two open to browsing and two fenced to exclude mammal herbivores. Flooding had a strong positive effect on seedling survival and height, but browsing had strong negative effects. Sediment salinity (a covariate rather than a designed effect) had a weak negative effect on seedling survival and height. The positive effects of flooding were largely offset by the negative interaction with browsing and, to a lesser extent, sediment salinity. Although flooding has been restored to some degraded floodplain forests subjected to river regulation and a drying climate, the long-term success of such actions is likely to be undermined by persistent browsing. Synthesis and applications. Management actions that focus on single pressures (e.g. infrequent flooding) and processes (e.g. mature tree survival) while ignoring other pressures are unlikely to sustain populations of keystone species, suggesting that complementary strategies (managed flooding with herbivore control) are necessary to sustain recruitment and, therefore, ensure the future health of these essential ecosystems.
KW - browsing
KW - Eucalyptus camaldulensis
KW - flooding
KW - floodplain forests
KW - herbivory
KW - keystone tree species
KW - multiple pressures
KW - population viability
KW - recruitment
KW - river regulation
UR - http://www.scopus.com/inward/record.url?scp=84995602236&partnerID=8YFLogxK
U2 - 10.1111/1365-2664.12601
DO - 10.1111/1365-2664.12601
M3 - Article
SN - 0021-8901
VL - 53
SP - 944
EP - 952
JO - Journal of Applied Ecology
JF - Journal of Applied Ecology
IS - 3
ER -