PARENT SESSION
Poster Session 2: Forest Ecology
Monday, August 8, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Geostatistical analysis on total and available nitrogen patterns in an evergreen broad-leaf forest of southwestern China.
Huang, Jianhui *,1, Wang, Lixin2, Wang, Jin2, Mou, Paul3, 1 Laboratory of Quantitative Vegetation Ecology, Institute of Botany, the Chinese Academy of Sciences, Beijing, China2 Department of Environmental Sciences, University of Virginia, Charlottesville, VA, USA3 Department of Biology, University of North Carolina at Greensboro, Greensboro, NC, USA
ABSTRACT- Two spatial soil samplings were conducted in an evergreen broadleaf forest in Sichuan Province, southwestern China to evaluate spatial patterns of soil total nitrogen, available nitrogen and their temporal changes. Three random soil samples of top 15 cm soil were collected in June 2000 around the central portion of each of 378 5 x 5 m grids within a 90 x 105 m study area. A PVC pipe of 15 cm long and 5 cm in diameter was inserted near each soil sampling location (1134 in total) after the initial soil samplings. The pipes were covered with clear plastic film on the top to prevent rainwater. The bottom was covered with 1 mm mesh net to prevent soil leaking out, but allow water, gas exchange, and soil micro-fauna entering. The soils in the pipes were collected two months later. All soil samples were analyzed to determine total nitrogen and available nitrogen (NH4, NO3) contents. Spatial variability of total nitrogen and available nitrogen, and their short-term (two months) changes were determined with geostatistical and univariate analysis. Results showed that the degree of spatial dependence of soil total nitrogen is larger than that of available nitrogen in both sampling time, whereas the order of spatial dependence degree of NH4 and NO3 was not consistent over time. The change in degree of spatial dependence is also larger for soil total nitrogen than available nitrogen. In addition, finer scale (<5m) heterogeneity was found much smaller for total nitrogen than any of the available nitrogen forms (NH4, NO3 and NH4 + NO3). These results indicated that different processes governed the heterogeneity pattern of different nitrogen forms and multiple scales were needed when studying heterogeneity of different nitrogen forms.
Key words: evergreen broad-leaf forest, spatial heterogeneity