Seasonal and spatial variation in living and dead plant material in a grazed grassland as related to plant species diversity.
Abstract
In field studies at Westerholt, Netherlands, (a) an Agrostis capillaris stand lightly grazed by sheep, (b) a moderately grazed Holcus lanatus stand and (c) a heavily grazed Leontodon autumnalis stand were sampled 8 times from Apr. 1986 to Apr. 1988. Av. aboveground biomass was 479.1, 430.8 and 155.3 g/m2 in (a), (b) and (c), resp., of which 140.0, 151.6 and 78.7 g was living plant material. The seasonal pattern of living and dead plant material showed a rapid transition from living material into fresh dead material in summer and autumn, a change from fresh to old dead material in winter and rapid old dead material decomposition in summer and autumn. The previous year's old dead material had completely disappeared when a new generation of dead material started to accumulate; there was no net litter accumulation. Cellulose strip decay rate and the decay rate of dead material were greater in (c) than in (a) or (b). The C:N ratio of fresh dead material increased in the order (c) < (b) < (a). The number of species present increased in the order (a) < (b) < (c).