Data-set for "Prescribed burning consumes key forest structural components: implications for landscape heterogeneity"

Prescribed burning to achieve management objectives is a common practice in fire-prone regions worldwide. Structural components of habitat that are combustible and slow to develop are particularly susceptible to change associated with prescribed burning. We used an experimental, 'whole of landscape' approach to investigate the effect of differing patterns of prescribed burning on key habitat components (logs, stumps, dead trees, litter cover, litter depth and understorey vegetation). Twenty-two landscapes (each ~100 ha) were selected in a dry forest ecosystem in southeast Australia. Experimental burns were conducted in 16 landscapes (stratified by burn extent) while six served as untreated controls. We measured habitat components prior to and after burning. Landscape burn extent ranged from 22-89% across the 16 burn treatments. With the exception of dead standing trees (no change), all measures of habitat components declined as a consequence of burning. The degree of loss increased as the extent to which a landscape was burnt also increased. Prescribed burning had complex effects on the spatial heterogeneity (beta diversity) of structural components within landscapes. Landscapes that were more heterogeneous pre-fire were homogenized by burning, while those that were more homogenous pre-fire tended to display greater differentiation post-burning. Thus, the notion that patch mosaic burning enhances heterogeneity at the landscape-scale depends on prior conditions. These findings have important management implications. Where prescribed burns must be undertaken, effects on important resources can be moderated via control of burn characteristics (e.g. burn extent). Longer-term impacts of prescribed burning will be strongly influenced by the return interval, given the slow rate at which some structural components accumulate (decades to centuries). Management of habitat structural components is important given the critical role they play in: (1) provision of habitat resources for diverse organisms; (2) retention of moisture and nutrients in otherwise dry, low-productivity systems; and (3) carbon storage.

为达成管理目标而开展的计划火烧（prescribed burning），在全球各火灾易发区域均为常用实践。易燃且发育缓慢的栖息地结构组分，尤其易受计划火烧影响而发生变化。我们采用实验性的“全景观（whole of landscape）”研究方法，探究不同计划火烧模式对关键栖息地组分（倒木、伐桩、枯立木、枯落物覆盖度、枯落物厚度及林下植被）的影响。我们在澳大利亚东南部的干旱森林生态系统中选取了22个景观单元（每个面积约100公顷），其中16个按火烧面积分层设置实验火烧处理，剩余6个作为未处理对照样地。我们分别在火烧前后对栖息地组分进行了测定，16个火烧处理样地的景观火烧面积占比介于22%至89%之间。除枯立木未发生显著变化外，其余所有栖息地组分的指标均因火烧出现下降，且损失程度随景观火烧面积占比的提升而加剧。计划火烧对景观内部结构组分的空间异质性（beta diversity）具有复杂影响：火烧前异质性更高的景观单元经火烧后均质化程度提升，而火烧前均质化程度更高的景观单元则在火烧后呈现出更强的分异性。因此，“斑块状火烧可提升景观尺度异质性”这一观点，取决于景观的初始状态。本研究结果具有重要的管理指导意义：在必须开展计划火烧的场景中，可通过调控火烧参数（如火烧面积占比）减轻其对重要资源的负面影响。鉴于部分结构组分的积累速率极为缓慢（需数十年至数百年），计划火烧的回归间隔将对其长期影响产生显著调控作用。栖息地结构组分发挥着多重关键作用，因此对其进行管理至关重要：(1) 为各类生物提供栖息地资源；(2) 在干旱、低生产力的生态系统中留存水分与养分；(3) 参与碳储存。