Modeling impacts of climate change on Joshua trees at their southern boundary: How scale impacts predictions
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- 作者：Cameron W. Barrows ; Michelle L. Murphy-Mariscal
- 关键词：Niche model ; Yucca brevifolia ; Invasive species ; Joshua Tree National Park ; Mahalanobis D2 ; Scale
- 刊名：Biological Conservation
- 出版年：2012
- 出版时间：August, 2012
- 年：2012
- 卷：152
- 期：Complete
- 页码：29-36
- 全文大小：891 K
文摘
Predicting ecological responses to a changing climate is becoming a critical tool to inform natural resource management efforts. Within Joshua Tree National Park (JTNP), Joshua trees (Yucca brevifolia) reach their southern-most distribution. Previous research modeling distributional shifts of Joshua trees in response to climate change have been conducted at large regional scales, predicting widespread extirpation of Joshua trees from their current southern and central distribution. Here we employed the Mahalanobis D2 statistic and constructed a finer-scale model of the Joshua tree¡¯s current distribution within and surrounding JTNP, and then assessed their sensitivity to a gradient of climate change scenarios. Local scale analyses may identify local adaptations and climate-change refugia, a result which may not be possible with larger scale analyses. Under the most severe climate scenario we modeled (a 3 ¡ãC increase in mean July maximum temperature) there was a 90 % reduction in their current distribution, nevertheless a refugium of suitable Joshua tree habitat still remained within JTNP. A niche model for juvenile Joshua trees revealed a near match with the boundary of the +1 ¡ãC shifted adult model providing a level of model validation, consistent with a hypothesis that early levels of climate change may have already had an impact on Joshua tree recruitment. The match of juvenile Joshua trees provides support for the findings of our climate-shifted niche models for the future distribution of this species within JTNP. This analysis represents a more optimistic scenario than previously published models of climate change impacts on Joshua trees.