Prescribed burning is an important management tool in jarrah (Eucalyptus marginata Sm.) forests of southwest Western Australia to reduce the risk of damaging bushfires. In 1986 to 1987, we established long-term study sites in dry (mean annual rainfall ~700 mm) and moist (mean annual rainfall ~1000 mm) jarrah forests to assess the effects of prescribed burning, as well as other fire treatments including fire exclusion, on the composition, richness, and relative abundance of forest understory vegetation. Over almost 30 years, species assemblages within all fire treatments changed significantly through time, but the changes were independent of treatment. The pattern of change in composition of fire response types over elapsed time was different between sites. At the dry site, changes in species assemblages were initially relatively large in the first decade or so of the study, but slowed thereafter. At the moist site, compositional change driven by obligate seeding shrubs occurred faster and more uniformly with time across all treatments. Species richness was also independent of fire treatment at both sites. Species richness decreased with elapsed time on the moist site but increased with elapsed time on the dry site. The stronger elapsed-time effect rendered the time since fire effect on loss of species richness on the moist site to be insignificant, but there was an inverse relationship with time since fire at the dry site. Within each site, there were clear patterns of changing abundance based on life form and fire response groups, but this was not consistent between sites. At the scale of the current study, jarrah forest plant communities displayed resilience to imposed experimental fire regimes. Over time, either elapsed time or time since fire, species assemblages across all treatments changed regardless of fire treatment, but changes were mostly associated with specific plant life forms and fire response traits, suggesting that the process is both deterministic and stochastic. While many species changed in abundance over time, no species were lost as a result of the fire treatments. Within the fire frequency and intensity ranges investigated in this study, there was flexibility in the application of prescribed fire to achieve management objectives without loss of plant diversity.

中文翻译：

---

rah柳林林下植被组合的精细时空转换与火势无关

在澳大利亚西部西南部的jarrah（Eucalyptus marginata Sm。）森林中，规定的燃烧是一种重要的管理工具，可减少破坏性森林大火的风险。在1986年至1987年，我们在干旱（平均年降水量约700毫米）和潮湿（平均年降水量约1000毫米）的jarrah森林中建立了长期研究地点，以评估规定的燃烧以及包括火在内的其他火灾处理的影响排除林下植被的组成，丰富度和相对丰度。在将近30年的时间里，所有火灾处理过程中的物种组合随时间发生了显着变化，但这些变化与处理无关。不同地点的火灾响应类型组成随时间的变化模式是不同的。在干燥的地方 在研究的头十年左右，物种组成的变化最初相对较大，但此后变慢了。在潮湿处，在所有处理中，随着时间的推移，专性灌木丛驱动的成分变化发生得更快，更均匀。物种丰富度也与两个地点的火处理无关。物种丰富度在潮湿的地方随着时间的流逝而减少，但在干燥的地方随着时间的流逝而增加。较强的消逝时间效应使自火灾起因于潮湿场所丧失物种丰富性的时间微不足道，但自干燥场所起因于火灾起时间与时间呈反比关系。在每个场所内，都有根据生命形式和火灾响应组而变化的丰富度的明确模式，但这在场所之间并不一致。以目前的研究规模 Jarrah森林植物群落表现出对施加的实验性火势的抵抗力。随着时间的推移，无论是经过的时间还是火灾发生后的时间，所有处理的物种组合都发生变化，而与火灾处理无关，但这些变化主要与特定的植物生命形式和火灾响应特征有关，这表明该过程既是确定性的也是随机的。尽管许多物种会随着时间的流逝而发生变化，但没有任何物种因火灾而损失。在本研究调查的火灾频率和强度范围内，在使用规定的火灾以实现管理目标而不会损失植物多样性的情况下具有灵活性。在所有处理中，物种组合都发生了变化，无论是否进行火种处理，但这些变化主要与特定的植物生命形式和火种响应特征有关，这表明该过程既是确定性的也是随机的。尽管许多物种会随着时间的流逝而发生变化，但没有任何物种因火灾而损失。在本研究调查的火灾频率和强度范围内，在使用规定的火灾以实现管理目标而不会损失植物多样性的情况下具有灵活性。在所有处理中，物种组合都发生了变化，无论是否进行火种处理，但这些变化主要与特定的植物生命形式和火种响应特征有关，这表明该过程既是确定性的也是随机的。尽管许多物种会随着时间的流逝而发生变化，但没有任何物种因火灾而损失。在本研究调查的火灾频率和强度范围内，在使用规定的火灾以实现管理目标而不会损失植物多样性的情况下具有灵活性。