The effects of litter quantity and quality on soil nutrients and litter invertebrates in two contrasting forests of southwestern China
Lu, J. M. C.. 2013. University of British Columbia
Abstract
Yunnan Province in southwestern China is a highly biodiverse region in the world, yet a
large part of the forests are cut down every year to accommodate plantations of rubber, tea
and eucalyptus. Within the small areas of protected habitats, recent observations indicate that
there is a lack of regeneration of seedlings. One possible explanation for this lack of
regeneration could be due to litter dynamics. We designed and carried out a short term litter
decomposition experiment to test the direct effects of litter manipulations on soil nutrients and
litter invertebrates in a lowland and a montane tropical forest.
Our experimental design involved testing both litter quantity and litter quality. To test
for the effects of litter quantity, we manipulated different depths of mixed litter, with and
without periodic topping up. To test for the effects of litter quality, we compared single species
of litter versus mixed litter control plots. The response of soil nutrients to these manipulations
were monitored using ion exchange membranes. We show a clear difference in the available
soil nutrients between the two sites, and while the litter quantity experiment had an effect on
soil nutrients at the lowland site, it had no effect at the montane site. The litter quality
treatments produced no overall difference in responses at either site.
The response of litter invertebrates to litter manipulations was estimated using pitfall
traps. We show that, litter invertebrate composition between the two forests is different.
Invertebrate abundance does increase with increasing biomass at the montane site, although
there seems to be a threshold of litter volume beyond which there is an effect. In the lowland
site, invertebrate abundance is highest in the litter removal plots, although a general increase
with litter biomass was detected. Litter species does not have an effect on either invertebrate
abundance or richness at either site.
