PARENT SESSION
Poster Session #5: Soil Ecology.
Monday, August 6, 2001. Presentation from 10:30 AM to 12:00 PM. Exhibition Hall

Do successional changes in aboveground environmental conditions lead to a parallel succession in soil macrofaunal communities?

Negrete-Yankelevich, Simoneta ^1,2, Fragoso, Carlos², Heal, O. William¹, Newton, Adrian¹, ^{1 2}

ABSTRACT- When a forest is cleared, the soil community and its diversity are significantly altered. An important conservation question is whether the composition and diversity of this soil community recover during the process of secondary succession and if associated aboveground environmental changes lead to a parallel succession in the decomposer community. In order to address this question, four successional stages of Cloud Forest in Oaxaca, Mexico were studied (approx. 15, 45, 75 and more than 100 years after clearing). Soil macrofauna (i.e. invertebrates >3mm) was extracted from 49 samples of litter and soil in each successional stage. Soil moisture content, temperature and canopy openness were measured at each sampling point. Soil and litter dry weight were also determined for each sample. Macrofauna was classified into 23 higher taxa. Different successional stages offer significantly different soil physicochemical environments (ANOVAs: soil temperature: F=579.13, p<0.001; soil humidity: F= 61.22, p<0.001; canopy openness: F= 20.60, p<0.001; soil/litter weight: F=16.80, p<0.001). A Canonical Correlation Analysis demonstrated that the composition of macrofaunal communities is correlated with the environmental scenarios offered by the different successional stages and the variation within them (R_total = 0.70756, 4 significant canonical variables). The Shannon Index of Diversity and its variance differ significantly amongst sampling sites (ANOVAs: F=24.26, p<0.001; F=47.05, p<0.001 respectively). Secondary succession appears to favour a more diverse and spatially homogeneous macrofaunal community.

KEY WORDS: Soil macrofauna, secondary succession, Cloud Forest, higher taxon diversity