Howland Brett, Stojanovic Dejan, Gordon Iain J, Manning Adrian D, Fletcher Don, Lindenmayer David B
Fenner School of Environment and Society, ANU College of Medicine, Biology & Environment Frank Fenner Building, # 141 Australian National University, Canberra, ACT, 0200, Australia.
Fenner School of Environment and Society, ANU College of Medicine, Biology & Environment Frank Fenner Building, # 141 Australian National University, Canberra, ACT, 0200, Australia; James Hutton Institute, Invergowrie, Dundee, DD2 5DA, Scotland, United Kingdom.
PLoS One. 2014 Dec 11;9(12):e105966. doi: 10.1371/journal.pone.0105966. eCollection 2014.
Large mammalian grazers can alter the biotic and abiotic features of their environment through their impacts on vegetation. Grazing at moderate intensity has been recommended for biodiversity conservation. Few studies, however, have empirically tested the benefits of moderate grazing intensity in systems dominated by native grazers. Here we investigated the relationship between (1) density of native eastern grey kangaroos, Macropus giganteus, and grass structure, and (2) grass structure and reptiles (i.e. abundance, richness, diversity and occurrence) across 18 grassland and grassy Eucalyptus woodland properties in south-eastern Australia. There was a strong negative relationship between kangaroo density and grass structure after controlling for tree canopy cover. We therefore used grass structure as a surrogate for grazing intensity. Changes in grazing intensity (i.e. grass structure) significantly affected reptile abundance, reptile species richness, reptile species diversity, and the occurrence of several ground-dwelling reptiles. Reptile abundance, species richness and diversity were highest where grazing intensity was low. Importantly, no species of reptile was more likely to occur at high grazing intensities. Legless lizards (Delma impar, D. inornata) were more likely to be detected in areas subject to moderate grazing intensity, whereas one species (Hemiergis talbingoensis) was less likely to be detected in areas subject to intense grazing and three species (Menetia greyii, Morethia boulengeri, and Lampropholis delicata) did not appear to be affected by grazing intensity. Our data indicate that to maximize reptile abundance, species richness, species diversity, and occurrence of several individual species of reptile, managers will need to subject different areas of the landscape to moderate and low grazing intensities and limit the occurrence and extent of high grazing.
大型哺乳动物食草动物会通过对植被的影响来改变其生存环境的生物和非生物特征。为保护生物多样性，建议进行适度强度的放牧。然而，很少有研究通过实证检验在以本土食草动物为主的系统中适度放牧强度的益处。在此，我们调查了以下两组关系：（1）澳大利亚东南部18处草地和长满草的桉树林地产上，本土东部灰袋鼠（Macropus giganteus）的密度与草结构之间的关系，以及（2）草结构与爬行动物（即数量、丰富度、多样性和出现情况）之间的关系。在控制树冠覆盖后，袋鼠密度与草结构之间存在强烈的负相关关系。因此，我们将草结构用作放牧强度的替代指标。放牧强度的变化（即草结构）显著影响了爬行动物的数量、爬行动物种丰富度、爬行动物种多样性以及几种地栖爬行动物的出现情况。在放牧强度较低的地方，爬行动物的数量、物种丰富度和多样性最高。重要的是，没有哪种爬行动物更可能出现在高放牧强度区域。无腿蜥蜴（Delma impar、D. inornata）在中等放牧强度区域更有可能被发现，而有一种物种（Hemiergis talbingoensis）在高强度放牧区域被发现的可能性较小，还有三种物种（Menetia greyii、Morethia boulengeri和Lampropholis delicata）似乎不受放牧强度的影响。我们的数据表明，为使爬行动物数量、物种丰富度、物种多样性以及几种单个爬行动物种的出现情况最大化，管理者需要对不同区域的景观进行适度和低强度放牧，并限制高强度放牧的出现范围和程度。
