How do invasive plants impact African wild mammals?

背景：肯尼亚大面积的土地已经被引进的植物物种入侵。这些入侵往往对人们的生计产生负面影响，降低了牧场对畜牧业的饲料价值。然而，这些入侵对野生哺乳动物的影响尚未完全了解，但这些可能对人类与野生动物的冲突产生重要影响。牧场的入侵可能会影响野生动物物种的栖息地质量，从而影响它们在景观中的移动，分布和栖息地使用，我们需要这些信息，以充分了解植物入侵对生态和人类的影响，以及植物入侵是否加剧了人类与野生动物的冲突。为了实现人类与野生动物在景观中的共存，我们需要更好地了解两者如何与植物入侵相互作用，以及入侵者的清除将产生什么样的影响，以便有效地减轻入侵者的影响和人类与野生动物的冲突。该项目将评估莱基皮亚县（肯尼亚）景观中野生哺乳动物的分布和栖息地利用情况，与仙人掌入侵有关，仙人掌已知会形成阻碍野生动物和牲畜移动的单种林分。其中一些入侵已经受到生物控制，这提供了一个机会，了解哺乳动物的分布如何随着时间的推移，入侵者清除后可能会发生变化。目的：在这个项目中，博士候选人将解决以下四个问题：1）入侵如何影响野生哺乳动物在景观中的分布和运动？2)人类与野生动物冲突在景观中的分布情况如何？3)目前的入侵是否创造了一种“回避景观”，增加了人类与野生动物相遇和冲突的可能性？4)植物入侵的生物控制对野生哺乳动物的移动和分布有什么影响？研究方法：Q1将使用相机捕获和占用分析方法2来估计和模拟景观中野生动物的密度和运动。这些方法已被用于监测入侵哺乳动物在景观中的分布，但尚未被用于评估入侵植物与本地哺乳动物分布的关系。第二个问题将通过对当地家庭的调查和文化测绘技术3来解决，以绘制和分类景观中的冲突。将利用生境调查、遥感和地理信息系统来获取关于地貌状况（被入侵、未被入侵;农民使用或未使用）和其他地貌特征（集水区、定居点、海拔）的信息。然后，这些数据将被用于建立景观模型，这将使我们能够使用动物密度和运动的数据来测试植物入侵是否会造成“回避景观”，导致人类与野生动物冲突的风险增加（Q3）。Q4将在调查区域使用相机捕获和栖息地选择模型来解决，该调查区域包括已经进行仙人掌生物控制的区域，以评估，野生哺乳动物的移动和分布是如何受到仙人掌移除的影响。Shackleton et al.（2017）African Journal of Range and Forage Science doi：10.2989/10220119.2017.1301551; 2. Davis et al.（2018）Biological Invasions 20：877-890; 3. Constant et al.（2015）Biodiversity and Conservation 24（12）：2967-2989.

Background: Large areas of land in Kenya have been invaded by introduced plant species. These invasions often have negative impacts on peoples' livelihoods, by reducing the forage value of rangelands for pastoral livestock1. However, the impacts of these invasions on wild mammals are not fully understood, yet these might have important implications for human-wildlife conflicts. Invasions of rangelands may affect habitat quality for wildlife species, and thus their movement, distribution and habitat use within a landscape, and we need this information in order to fully understand the ecological and human impacts that plant invasions have, and whether plant invasions exacerbate human-wildlife conflicts. To achieve coexistence of humans and wildlife within landscape, we need to better understand how both interact with plant invasions, and what the effect of invader removal will be, so that invader impacts and human-wildlife conflicts can be mitigated effectively. This project will assess the distribution and habitat use of wild mammals in landscapes of Laikipia county (Kenya) in relation to invasions by prickly pear cacti (Opuntia), which are known to form monospecific stands that impede wild and livestock animal movements. Some of these invasions have been subjected to biological control, which offers an opportunity to understand how mammal distributions may change over time after invader removal. Aims: In this project, the PhD candidate will address the following four questions:1) How do invasions affect the distribution and movement of wild mammals in the landscape?2) What is the distribution of human-wildlife conflicts within the landscape?3) Do current invasions create a 'landscape of avoidance', that increases the likelihood of human-wildlife encounters and conflicts?4) What are the impacts of biological control of plant invasions, on wild mammal movement and distribution?Methods: Q1 will be addressed using camera-trapping and occupancy analysis methods2 to estimate and model the density and movement of wildlife in the landscape. These methods have been used to monitor the distribution of invasive mammals in landscapes, but have not yet been used to assess how invasive plants related to native mammal distributions. Q2 will be addressed with surveys of local households and cultural mapping techniques3 to map and categorise conflicts in the landscape. Habitat surveys, remote sensing and GIS will be used to capture information on landscape status (invaded, not invaded; used or not used by farmers), and other landscape features (catchments, settlements, elevation). These data will then be used to build landscape models, which will allow us to test, using data on animal densities and movements, whether plant invasions create a 'landscape of avoidance' leading to increased risk of human-wildlife conflicts (Q3).Q4 will be addressed using camera-trapping and habitat selection models in a survey area that includes areas where Opuntia biological control has been undertaken, to assess, how wild mammal movement and distribution are impacted by Opuntia removal.References: 1. Shackleton et al. (2017) African Journal of Range and Forage Science doi: 10.2989/10220119.2017.1301551; 2. Davis et al. (2018) Biological Invasions 20: 877-890; 3. Constant et al. (2015) Biodiversity and Conservation 24(12): 2967-2989.