Disturbance, decomposition and patchiness in thatch

Abstract

SynopsisSome roofs that are thatched with combed wheat reed develop patches of more rapid decay within an otherwise uniform matrix of less rapid decay. Changes in the length and weight of reed from patches and matrix were estimated for one roof by comparison with samples of unused, undecayed reed. The fungal communities associated with patches and matrix were analysed using a particle plating method and the distribution of patches between and within roofs was analysed for departures from randomness. Reed from a patch was shorter than from the surrounding matrix due to more rapid loss of length. Weight loss was greatest at the thatch surface but only extended into the thatch for 8.5 cm in both cases. It is therefore probable that the decomposer communities of patches and matrix respond similarly to an environmental variable, probably water potential, that varies with depth. Fungal community analysis indicated that distinct functional units, or associations, of four and two taxa were present in the matrix and patches respectively. An analysis of patch distribution on a sample of roofs indicated that certain roofs are predisposed to develop patches. However, on individual roofs patches are distributed randomly. Predisposition may be due to relatively high levels of endogenous nitrogen in the thatching reed.