Understorey Forest Management as a Potential Tool to Promote Taxonomic and Functional Diversity in Eucalyptus Plantations

Abstract

Intensive forest management simplifies habitat structure, reducing capacity to support a diverse range of species. Eucalyptus plantations can be managed by two approaches; ‘regrowth’, where stems are cut to stumps to allow regeneration which maintains understory vegetation, or by ‘seedling’ establishment following clearfell and suppression of understory vegetation. We proposed that regrowth stands, which have enhanced structural complexity in understorey layers, positively influence taxon and functional diversity. We predicted functional redundancy in seedling stands as they will be composed of a few tolerant species sharing a limited number of functional traits, whereas regrowth stands will also demonstrate functional redundancy by supporting multiple functional trait combinations and multiple species. Taxonomic diversity was measured by counts of birds and spider webs and collection of ground-dwelling spiders and ants using pitfall traps. Functional diversity was measured using trait data for each species. Understorey forest management was an important driver of diversity and functional redundancy, but responses were not consistent across taxonomic groups. Species-trait relationships, representing the specific requirements of the various organisms, were driving each response. Therefore, management that promotes vegetation complexity has the potential to improve the capacity of homogenous forest environments to support resilient communities and ultimately to ensure sustainability of the economically important global forest resource.