A comparison of restoration techniques to accelerate recovery of litter decomposition and microbial activity in an experimental peat bog restoration trial

Abstract

Restoration of mined Restionaceae-dominated peat bogs in northern New Zealand is currently initiated by establishing native vegetation cover to minimise erosion of the remaining peat. The relative effects of various restoration techniques on litter decomposition and microbial activity within experimental litter bags were investigated in a restoration trial established on a mined peat surface. Decomposition and microbial activity of litter were compared between four different restoration treatments: direct transfer of intact habitat ‘islands’; the addition of processed peat with seed; the addition of processed peat with no seed; and recently mined peat surface (a ‘do nothing’ restoration option), with the four treatments replicated at each of five distances from an undisturbed peat bog. Treatments were compared with an undisturbed peat bog (control). Litter decomposition and associated microbial respiration rates were significantly higher in the undisturbed peat bog sites than in any of the restoration treatments, but the technique used to restore mined peatlands did have a significant effect on these ecosystem process rates. Results suggest that ecosystem processes such as decomposition and microbial community activity recover faster with restoration techniques such as direct transfer of intact habitat islands, than with other techniques such as simple seed addition. However, even after 12 months, litter decomposition and microbial activity in restored habitats were still far from reaching the levels recorded in the undisturbed peat bog. In addition, there was a strong relationship between the effort (and cost) applied to plant community restoration treatments and the rate of decomposition and microbial community activity.