WATER QUALITY IMPROVEMENT FROM MANAGEMENT PRACTICES IN AGRICULTURAL WATERSHEDS
Location: Agroecosystems Management Research Unit
Title: Changes in soil respiration across a chronosequence of tallgrass prairie reconstructions
Submitted to: Agriculture, Ecosystems and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 13, 2010
Publication Date: November 6, 2010
Citation: Maher, R.M., Asbjornson, H., Kolka, R., Cambardella, C.A., Raich, J.W. 2010. Changes in soil respiration across a chronosequence of tallgrass prairie reconstructions. Agriculture, Ecosystems and Environment. Available: http://dx.doi.org/10.1016/j.agee.2010.09.009.
Interpretive Summary: Increases in atmospheric carbon dioxide concentrations over the past 100 years have been implicated as the primary cause for global warming. Agricultural activities can contribute to overall increases in atmospheric carbon dioxide. Replanting formerly cropped land to tallgrass prairie has the potential to foster sequestration of atmospheric carbon dioxide because tallgrass prairies store more than 50% of their carbon belowground. We studied carbon cycling in reconstructed tallgrass prairies ranging in age from 4 to 12 years old by evaluating total soil respiration from late April through mid-November. We found that total soil respiration was higher in the older prairies than in the younger prairies, and that all prairies had higher total soil respiration than an adjacent field cropped to soybeans. The results show that total soil respiration is linearly related to root biomass, suggesting that belowground carbon changes are important in these ecosystems. This information will be useful to scientists seeking to understand the dynamics of carbon cycling in restored native tallgrass ecosystems.
Close relationships among climatic factors and soil respiration (Rs) are commonly reported. However, variation in Rs across the landscape is compounded by site-specific differences that impede the development of spatially explicit models and whose causes are not clearly known. Among factors that influence Rs, the effect of ecosystem age is poorly documented. We hypothesized that Rs increases with ecosystem age and tested this hypothesis in a chronosequence of tallgrass prairie reconstructions in central Iowa, U.S.A. We also assessed changes in root biomass, root ingrowth, aboveground net primary productivity (ANPP), and the strength of soil temperature and moisture in predicting Rs across the chronosequence. We found a significant increase in total growing-season Rs with prairie age (R2 = 0.83). Growing-season Rs ranged from 624 g C m-2 in a soybean field (age 0) to 939 g C m-2 in the oldest reconstruction (age 12). Soil temperature was a strong predictor of intra-annual Rs among prairies (R2 = 0.78 to 0.87) but correlated poorly in the soybean field (R2 = 0.38). The increase in Rs with age was positively correlated with root biomass carbon (r = 0.89) and nitrogen (r = 0.94) but not with root ingrowth or ANPP. However, exclusion of the anomalous 8 yr old reconstruction resulted in a strong, positive correlation between root ingrowth carbon and Rs (r = 0.99, n = 5). Our findings suggest that growing-season Rs increases with tallgrass prairie age, the accumulation of root biomass, and with increasing rates of root growth during young grassland development.