Plant Functional Type Classification, Richness and Cover in Eucalyptus salubris Woodlands Across Time Since Fire Chronosequence, Great Western Woodlands SuperSite, 2010-2011

Plant Functional Types (PFTs) are groupings of plants based on traits relevant to processes of vegetation change, allowing generalised predictions of vegetation responses to similar disturbances elsewhere. Recurrent fire is a dominant disturbance in Mediterranean-climate landscapes, yet there have been no studies of how a PFT classification can enhance understanding of vegetation change due to time since fire in ‘fire-sensitive’ Mediterranean-climate woodlands, where the dominant overstorey trees are typically killed by fire. The Great Western Woodlands (GWW) region of south-western Australia supports the world’s largest remaining area of Mediterranean-climate woodland, which in mosaic with mallee, shrublands and salt lakes cover an area of 160 000 km2. Eucalyptus woodlands in this region are typically fire-sensitive, and fire return intervals recorded over recent decades have been much shorter than the long-term average. This has led to considerable conservation concern regarding the loss of mature woodlands, and has highlighted a need to better understand how plant communities change with time since fire. We measured changes in PFT richness and cover in Eucalyptus salubris woodlands with increasing time since fire at 72 50 x 50 m plots using a space-for-time approach. To estimate stand ages for this study we used satellite imagery, growth ring counts and relationships between growth ring counts and plant size, resulting in an estimated time since fire range sampled of 3 to 370 years.

植物功能型（Plant Functional Types，PFTs）是基于与植被变化过程相关的性状对植物进行的类群划分，可用于通用化预测其他区域植被对同类干扰的响应。周期性火灾是地中海气候景观中的主要干扰类型，但目前尚无研究探讨植物功能型分类如何加深对‘火敏感型’地中海气候林地距火时间序列下植被变化的理解，这类林地的优势上层乔木通常会在火灾中死亡。澳大利亚西南部的大西部林地（Great Western Woodlands，GWW）区域拥有全球现存面积最大的地中海气候林地，该区域与矮桉灌丛（mallee）、灌丛及盐湖呈镶嵌分布，总面积达16万平方千米。该区域的桉树林地通常为火敏感型，近数十年记录的火轮回期远低于长期平均水平，这引发了人们对成熟林地丧失的极大保育担忧，同时凸显出深入探究植物群落随距火时间变化规律的必要性。本研究采用以空间代时间法，在72个50 m×50 m的样地中，测定了随距火时间增加的光滑桉（Eucalyptus salubris）林地的植物功能型丰富度与盖度变化。为估算样地的林分火灾后年龄，本研究结合了卫星影像、年轮计数以及年轮计数与植株大小的相关性分析方法，最终获取的采样距火时间范围为3至370年。