Globally, high-density populations of feral deer have been associated with a range of negative ecological consequences. Within Australia, limited quantitative research has assessed the impacts of deer, particularly in threatened ecological communities (TECs). Our study aimed to quantify the impact of feral deer on the herbivory of a range of woody plant species, non-woody growth forms and TECs; and assess whether feral deer increase herbivory in TECs above background rates caused by native herbivores. We surveyed 356 transects across 89 sites representing eight TECs and collected herbivory data for woody and non-woody plants. At each site, we recorded the presence or absence of deer sign and abundance of macropod pellets to account for variations in herbivory between groups of sympatric species. Generalised linear mixed models were developed to predict: (i) proportion of individual plants browsed (or grazed); and (ii) average browsing (or grazing) intensity for woody plant species and non-woody plants. Controlling for macropod abundance, we found the average grazing intensity and proportion of non-woody plants grazed was higher when deer were present compared to absent. Specifically, grazing pressure on rushes, cycads, sedges and grasses was significantly higher where deer were present. In contrast, we did not observe a significant impact of deer on woody plant species. The presence of deer resulted in higher grazing intensity in coastal saltmarsh, freshwater wetland, littoral rainforest and bangalay sand forest TECs. Although the deer population across our study region generally appears to be at low density compared to neighbouring regions, their presence is resulting in grazing pressure above that caused by native herbivores for a range of non-woody plants. Our results contribute to a growing body of research about the ecological impacts of feral deer in Australia and can be used as a baseline for ongoing regional monitoring of deer impacts in TECs.

中文翻译：

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量化野鹿对一系列受威胁生态群落和植物生长形式造成的浏览压力变化

在全球范围内，高密度的野鹿种群与一系列负面生态后果有关。在澳大利亚，有限的定量研究评估了鹿的影响，特别是在受威胁的生态社区 (TEC) 中。我们的研究旨在量化野鹿对一系列木本植物物种、非木本生长形式和 TEC 的食草性的影响；并评估野鹿是否使 TEC 中的食草动物增加，高于由本地食草动物引起的背景比率。我们调查了代表 8 个 TEC 的 89 个地点的 356 个样带，并收集了木本和非木本植物的食草数据。在每个地点，我们记录了鹿标志的存在与否以及巨足动物颗粒的丰度，以解释同域物种之间食草性的变化。开发了广义线性混合模型来预测：(i) 被浏览（或放牧）的单个植物的比例；(ii) 木本植物物种和非木本植物的平均浏览（或放牧）强度。控制巨足类动物的丰度，我们发现与没有鹿相比，鹿存在时的平均放牧强度和非木本植物的放牧比例更高。具体而言，在有鹿的地方，对灯心草、苏铁、莎草和草的放牧压力明显更高。相比之下，我们没有观察到鹿对木本植物物种的显着影响。鹿的存在导致沿海盐沼、淡水湿地、沿海热带雨林和孟加拉沙林 TEC 的放牧强度更高。尽管与邻近地区相比，我们研究区域内的鹿种群通常似乎密度较低，但它们的存在导致放牧压力高于本地食草动物对一系列非木本植物造成的压力。我们的结果有助于越来越多的关于澳大利亚野鹿生态影响的研究，并可用作持续区域监测 TEC 中鹿影响的基线。