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Published May 23, 2019 | Version v1
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Data from: Recovery of decomposition rates and decomposer invertebrates during rainforest restoration on disused pasture

Authors/Creators

  • 1. Griffith University
  • 2. University of Queensland

Description

Converting forest to pasture can alter the roles of biota in ecosystem functioning, while vegetation restoration should arguably assist functional recovery. Since tests of this are scarce, this study quantifies both litter decomposition rates and their association with decomposer invertebrates, across 25 sites representing different phases of deforestation and subsequent reforestation of rainforest. Open and closed (to exclude macro-invertebrates) mesh bags containing forest leaves were exposed in the field for up to eight months, and invertebrates were extracted from separate collections of ground surface litter. Sites spanned five vegetation categories (five sites in each): reference states of both old-growth forest and grazed-pasture; unassisted woody regrowth aged 20-50 years on former pasture; and assisted regeneration aged 1-3 and 5-10 years after interventions were applied to similar regrowth. Decomposition rates in open-bags were about 50 % slower in pasture than old-growth forest, and abundances of macro- and meso-decomposer invertebrates were 95 % and 77 % lower respectively. However, in all restoration site-types, decomposition rates had recovered to 83 % of old-growth values, and abundances of invertebrate decomposers were similar in old-growth forest. Decomposer community composition at a broad taxonomic level differed strongly between pasture and all other vegetation types. Exclusion of macro-invertebrates decreased decomposition rates by only about 3.1 %, but decomposition rates in open-bags were significantly correlated (across sites) with abundances of both macro- and meso-decomposers, most strongly so for meso-decomposers. Drawing useful generalisations across studies is impeded by differing methodologies and because few include both agricultural and forest reference sites.

Notes

Stone.etal.2019.LitterMassLoss
Macro-invertebrate leaf litter mass loss data from 157 individual 25 x 25 cm, nylon mesh litter bags (mesh size 1 mm). 200 bags were deployed across 25 sites in pasture, mature rainforest and regrowth in sub-tropical Australia for five and eight months. However, some bags developed holes or went missing in the field and were excluded from analyses. Each bag contained leaves of five local tree species common in the study area, but collected from trees outside it in a mature, undamaged condition, one month prior to the experiment. The selected species represented a mix of soft and firm leaves and the pioneer, mid and late successional stages of regeneration: Toona ciliata, Ficus macrophylla, Macaranga tanarius, Castanospermum austral, and Acacia disparrima. Leaves of all species except A. disparrima were cut into 2 x 3 cm pieces to standardise leaf weight and size, and then oven-dried at 50 °C until constant weight, thereby obtaining dry weights of about 0.02 g per leaf-piece. About 4 g of each species was then placed into each bag, totalling about 20 g per bag. We also perforated half of the bags (100 of 200) by making 12, 1-2 cm cuts, six into each side. For each site, this gave four open bags (which allowed access by all sizes of invertebrate) and four closed bags (which excluded macro-invertebrates due to the 1 mm mesh size).
Stone.etal.2019.DecomposerComposition
Macro- and meso-decomposer litter invertebrate composition data- Ambient litter invertebrates were sampled around the mesh leaf litter bags (see litter mass loss data), where we hand-collected a single 1 L litter sample from across the ground surface at each site (25 sites), five months after litter bag deployment. These were transferred to the laboratory within a few hours of collection, and invertebrates were extracted over 72 hours using Tullgren funnels and collected in ethanol-filled jars. Using a light microscope, we first grouped all invertebrates into two body size categories: macro (>1 mm long and wide) and meso (<1 mm long or wide) corresponding to the bag mesh size threshold. We also identified all to a level sufficiently fine to enable a dominant feeding guild (Stork 1987) to be assigned (for example, to Family for most beetles, to Infraorder for termites, to Class for centipedes); these guilds were decomposers (detritivores), predators, herbivores and fungivores. In some cases we chose the feeding guild known to be most common for a broader taxon. These data were then expressed as counts of individuals per site in each body size-feeding guild combination, at the Class or Order level.

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Additional details

Related works

Is cited by
10.1111/btp.12682 (DOI)