Department of Biosciences, Durham University, South Road, Durham, DH1 3LE, United Kingdom.
School of Mathematics and Statistics, University of Sheffield, Hounsfield Rd, Sheffield, S3 7RH, United Kingdom.
Ecol Appl. 2020 Jun;30(4):e02091. doi: 10.1002/eap.2091. Epub 2020 Mar 26.
Prescribed fire is used throughout fire-prone landscapes to conserve biodiversity. Current best practice in managing savanna systems advocates methods based on the assumption that increased fire-mediated landscape heterogeneity (pyrodiversity) will promote biodiversity. However, considerable knowledge gaps remain in our understanding of how savanna wildlife responds to the composition and configuration of pyrodiverse landscapes. The effects of pyrodiversity on functional diversity have rarely been quantified and assessing this relationship at a landscape scale that is commensurate with fire management is important for understanding mechanisms underlying ecosystem resilience. Here, we assess the impact of spatiotemporal variation in a long-term fire regime on avian diversity in North West Province, South Africa. We examined the relationship between (1) species richness, (2) three indices of functional diversity (i.e., functional richness, functional evenness, and functional dispersion) and four measures of pyrodiversity, the spatial extents of fire age classes, and habitat type at the landscape scale. We then used null models to assess differences between observed and expected functional diversity. We found that the proportion of newly burned (<1-yr post-fire), old, unburned (≥10 yr post-fire), and woodland habitat on the landscape predicted species and functional richness. Species richness also increased with the degree of edge contrast between patches of varying fire age, while functional dispersion increased with the degree of patch shape complexity. Lower than expected levels of functional richness suggest that habitat filtering is occurring, resulting in functional redundancy across our study sites. We demonstrate that evaluating functional diversity and redundancy is an important component of conservation planning as they may contribute to previously reported fire resilience. Our findings suggest that it is the type and configuration, rather than the diversity, of fire patches on the landscape that promote avian diversity and conserve ecological functions. A management approach is needed that includes significant coverage of adjacent newly burned and older, unburned savanna habitat; the latter, in particular, is inadequately represented under current burning practices.
计划火烧被广泛应用于易发生火灾的景观中，以保护生物多样性。目前，管理热带稀树草原系统的最佳实践方法基于这样的假设，即增加火烧引起的景观异质性（火多样性）将促进生物多样性。然而，我们在理解热带稀树草原野生动物对火多样景观的组成和配置的反应方面仍然存在相当大的知识差距。火多样性对功能多样性的影响很少被量化，在与火灾管理相称的景观尺度上评估这种关系对于理解生态系统恢复力的机制非常重要。在这里，我们评估了南非西北省长期火灾制度的时空变化对鸟类多样性的影响。我们研究了（1）物种丰富度、（2）三个功能多样性指数（即功能丰富度、功能均匀度和功能离散度）与四种火多样性措施、火龄类别的空间范围以及景观尺度上的栖息地类型之间的关系。然后，我们使用零模型来评估观测到的和预期的功能多样性之间的差异。我们发现，景观上的新燃烧（<1 年火灾后）、旧燃烧（≥10 年火灾后）、未燃烧（≥10 年火灾后）和林地栖息地的比例预测了物种和功能丰富度。物种丰富度也随着斑块之间不同火龄的边缘对比程度的增加而增加，而功能离散度随着斑块形状复杂性的增加而增加。低于预期的功能丰富度表明，存在栖息地过滤，导致我们研究地点之间存在功能冗余。我们证明，评估功能多样性和冗余度是保护规划的一个重要组成部分，因为它们可能有助于解释先前报道的火灾恢复力。我们的研究结果表明，促进鸟类多样性和保护生态功能的是景观上火斑的类型和配置，而不是火斑的多样性。需要采取一种管理方法，包括大面积覆盖相邻的新燃烧和较旧的未燃烧的热带稀树草原栖息地；特别是后者，在当前的燃烧实践中代表性不足。
