TY - JOUR

T1 - The disproportionate value of scattered trees

AU - Fischer, Jörn

AU - Stott, Jenny

AU - Law, Bradley S.

N1 - Times Cited: 0

PY - 2010/6

Y1 - 2010/6

N2 - 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.

AB - 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.

KW - Biology

KW - Bats

KW - Birds

KW - Isolated trees

KW - Keystone structures

KW - Paddock trees

KW - Tree regeneration

KW - Scattered trees

KW - Tree decline

KW - Environmental planning

UR - http://www.scopus.com/inward/record.url?scp=77954815470&partnerID=8YFLogxK

U2 - 10.1016/j.biocon.2010.03.030

DO - 10.1016/j.biocon.2010.03.030

M3 - Journal articles

VL - 143

SP - 1564

EP - 1567

JO - Biological Conservation

JF - Biological Conservation

SN - 0006-3207

IS - 6

ER -