Soil respiration rate and its sensitivity to temperature in pasture systems of dry-tropics

Kaur, Kamaljit, Jalota, Rajesh K., and Midmore, David J. (2010) Soil respiration rate and its sensitivity to temperature in pasture systems of dry-tropics. Acta Agriculturae Scandinavica, Section B - Soil and Plant Science, 6 (5). pp. 407-419.

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Abstract

Tree clearing is a topical issue the world over. In Queensland, the high rates of clearing in the past were mainly to increase pasture production. The present research evaluates the impact of clearing on some soil biological properties, i.e. total soil respiration, root respiration, microbial respiration, and microbial biomass (C and N), and the response of soil respiration to change in temperature.

In-field and laboratory (polyhouse) experiments were undertaken. For in-field studies, paired cleared and uncleared pasture plots were selected to represent three major tree communities of the region, i.e. Eucalyptus populnea, E. melanophloia, and Acacia harpophylla. The cleared sites were chosen to represent three different time-since-clearing durations (5, 11-13, and 33 years; n=18 for cleared and uncleared plots) to determine the temporal impact of clearing on soil biological properties. Experiments were conducted in the polyhouse to study in detail the response of soil respiration to changes in soil temperature and soil moisture, and to complement in-field studies for estimating root respiration.

The average rate of CO2 emission was 964 g CO2/m2/yr, with no significant difference (P<0.05) among cleared and uncleared sites. Microbial respiration and microbial biomass were greater at uncleared compared with those at cleared sites. The Q 10-value of 1.42 (measured for different seasons in a year) for in-field measurements suggested a small response of soil respiration to soil temperature, possibly due to the limited availability of soil moisture and/or organic matter. However, results from the polyhouse experiment suggested greater sensitivity of root respiration to temperature change than for total soil respiration. Since root biomass (herbaceous roots) was greater at the cleared than at uncleared sites, and root respiration increased with an increase in temperature, we speculate that with rising ambient temperature and consequently soil temperature, total soil respiration in cleared pastures will increase at a faster rate than that in uncleared pastures.

Item ID: 10797
Item Type: Article (Refereed Research - C1)
Keywords: tropical biology; microbial biomass; microbial respiration; root respiration; tree clearing
ISSN: 1651-1913
Date Deposited: 30 Apr 2010 06:07
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0501 Ecological Applications > 050102 Ecosystem Function @ 75%
05 ENVIRONMENTAL SCIENCES > 0503 Soil Sciences > 050303 Soil Biology @ 25%
SEO Codes: 83 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 8304 Pasture, Browse and Fodder Crops > 830403 Native and Residual Pastures @ 50%
83 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 8304 Pasture, Browse and Fodder Crops > 830406 Sown Pastures (excl. Lucerne) @ 50%
Citation Count from Web of Science Web of Science 3
Downloads: Total: 6
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