Author : Andrea Fenner
Publisher :
ISBN 13 :
Total Pages : 31 pages
Book Rating : 4.:/5 (949 download)
Book Synopsis Effects of Long-term Atmospheric Nitrogen Deposition on Extracellular Enzyme Activity in Semi-arid Shrubland Soil by : Andrea Fenner
Download or read book Effects of Long-term Atmospheric Nitrogen Deposition on Extracellular Enzyme Activity in Semi-arid Shrubland Soil written by Andrea Fenner and published by . This book was released on 2015 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt: Anthropogenic nitrogen (N) deposition represents a significant input of N into coastal sage scrub (CSS) and chaparral ecosystems of Southern California. Increased N deposition has the potential to alter the decomposition rate of soil organic matter (SOM) in N limited terrestrial ecosystems through altering the enzymatic activity of soil microorganisms that play a key role in the decomposition process. Since few reports have examined the effects of N deposition on the enzymatic activity of soil microorganisms in semi-arid shrublands, this study aimed to determine how N deposition affects the enzymatic activity of microorganisms that drive the decomposition process. Based on results from other ecosystems, we hypothesized that added N would suppress the enzymatic activity of ligninolytic enzymes (phenol oxidase and peroxidase) and would increase the enzymatic activity of the cellulolytic enzyme, p-Nitrophenyl-ß-D-glucosidase. Enzyme assays were conducted on soil samples collected from eight plots located at two field sites where N addition experiments had been conducted over the last 10 years. Field sites were composed of four unmanipulated control plots and four experimental plots, which received 50 kg N/ha annually. Data collected from the chaparral site indicated that there was a significant difference in peroxidase activity between control and N treatment plots (p-value= 0.016) and a significant difference over time for control and treatment plots in p-Nitrophenyl-ß-D-glucosidase activity (p-value= 0.032) and phenol oxidase activity (p-value= 0.003). Data collected from the CSS site indicated that there was a significant difference in peroxidase activity between control and N treatment plots (p-value= 0.010) and a significant difference over time in peroxidase activity (p-value= 0.001). In addition, there was a significant difference over time for control and treatment plots in p-Nitrophenyl-ß-D-glucosidase activity (p-value= 0.0003) and phenol oxidase activity (p-value= 0.001). The decrease in p-Nitrophenyl-ß-D-glucosidase activity and the lack of suppression of phenol oxidase in some added N plots when compared to control plots differed from our initial hypothesis and was inconsistent with other findings from previous literature. However, much of the findings from previous literature focus on how N deposition affects the activity of enzymes involved in the decomposition of litter not SOM, and because peroxidase may be important in the degradation of older structural C, which is typical of soils, it may not be too surprising that our results indicate that only peroxidase was significantly affected by N addition. Little is known about how N deposition affects the enzymatic activity of enzymes involved in the decomposition of SOM, and whether the activity of these enzymes follow the same patterns of those involved in the decomposition of litter. Findings from this study may provide the insight needed to determine how N deposition affects the activity of enzymes involved in the decomposition of SOM thus, giving us a better understanding of how N deposition affects decomposition rates of SOM in semi-arid shrublands.
