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.

为达成管理目标而实施的规定火烧（prescribed burning）是全球易火区域的常见措施。栖息地中可燃且形成缓慢的结构性组分，尤其易因规定火烧而发生改变。我们采用‘全景观’实验方法，探究不同模式的规定火烧对关键栖息地组分（原木、树桩、枯立木、凋落物覆盖度、凋落物厚度及林下植被）的影响。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（各约100公顷）。对其中16个景观单元（按火烧范围分层）实施了实验性火烧，其余6个作为未处理对照。我们在火烧前后对栖息地组分进行了测量。16个火烧处理单元的景观火烧范围介于22%至89%之间。除枯立木（无变化）外，所有栖息地组分的测量值均因火烧而下降。损失程度随景观单元的火烧范围扩大而加剧。规定火烧对景观内结构性组分的空间异质性（β diversity）具有复杂影响。火烧前异质性较高的景观单元因火烧趋于同质化，而火烧前同质化较高的单元则在火烧后呈现出更显著的分化。因此，斑块镶嵌火烧提升景观尺度异质性的观点，其有效性取决于初始条件。这些发现具有重要的管理启示。在必须实施规定火烧的场景下，可通过调控火烧特征（如火烧范围）来缓解其对关键资源的影响。考虑到部分结构性组分的积累速率缓慢（需数十年至数百年），规定火烧的长期影响将受火烧间隔期的显著影响。栖息地结构性组分的管理至关重要，因其在以下方面发挥核心作用：（1）为多样生物提供栖息资源；（2）在干旱、低生产力系统中保持水分与养分；（3）碳储存。