PARENT SESSION
Contributed Oral Session 152: Biodiversity: Soils; Seeds
Friday, August 12, 8:00 AM - 11:30 AM, Meeting Room 513 E, Level 5, Palais des congrès de Montréal
Longterm effect of pasture biodiversity on soil food web structure and ecosystem productivity.
Adl, Sina*,1, Maharning, Ardhini1, Mills, Aaron1, McElroy, Michel1, 1 Dalhousie University, Halifax, Nova Scotia, Canada
ABSTRACT- With succession, community structure changes, and the diversity of species in the food web change. This has consequences on the functioning and productivity of the ecosystem. The species diversity of soil protists and micro-invertebrates is affected by above-ground management as well as the vegetation, and in agro-ecosystems, by the cropping system. In previous studies, we showed that the soil community in some agro-ecosystems require 4-8 years to recover from previous management practise. We also showed that the dynamics of the food web structure was scale dependent and varies over several days, through seasons, and over several years with succession. To complement these results, we have turned to a series of new field studies on commercial and experimental agroecosystems. To study the linkages between above-ground diversity and management, with below-ground food web structure on the long-term, we have initiated a series of comparative field studies on commercial farming operations. We have also initiated a 5 year study on replicated experimental grazed pastures to manipulate plant diversity and management intensity, to monitor changes in the below-ground food web structure and species diversity. Supplementary subplots (2x2 m) are used to isolate the effects of pasture plant species on soil protist, fungi and invertebrate species. The overall system productivity is assayed through the quality and quantity of milk production in dairy cows on the pastures. This set of experiments aim to answer three questions: 1) What is the effect of changing above ground biodiversity (plants, insects, other micro-invertebrates) on below ground diversity (protists, fungi, micro-invertebrates)? 2) What is the effect of above ground management intensity (extensive, control, intensive) on below ground diversity? 3) Do changes in above-ground diversity and management affect below-ground diversity and food web structure immediately, or over several years? Here we present results and statistical patterns from the first three years into this six year project. We show that above ground biodiversity does not necessarily correlate with below ground biodiversity. We also show that community structure changes below ground and above ground may be occurring at different time scales.
Key words: Biodiversity, Foodweb, Community, Soil