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Enzyme Activities and Carbon Dioxide Flux in a Sonoran Desert Urban Ecosystem
Author(s) -
Green Douglas M.,
Oleksyszyn Michelle
Publication year - 2002
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2002.2002
Subject(s) - soil water , ecosystem , cycling , lawn , environmental science , nutrient cycle , vegetation (pathology) , nutrient , invertase , flux (metallurgy) , agronomy , hydrology (agriculture) , ecology , chemistry , biology , geography , soil science , geology , forestry , medicine , biochemistry , geotechnical engineering , organic chemistry , pathology , sucrose
Urban expansion into wildlands significantly changes soil processes such as nutrient cycling and organic matter processing. Knowledge of these changes is important so that the impact of urbanization on ecosystems may be assessed. We measured the activities of invertase, cellulase, and CO 2 flux in mesiscape, xeriscape, and in remnant desert patches in a rapidly urbanizing south central Arizona Sonoran desert ecosystem. In this system, mesiscapes are irrigated watered lawns, xeriscapes include low water‐use vegetation, and desert remnants include undeveloped areas within the urban matrix. Invertase activity ranged from 2.4 to15 mg glucose equivalents (GE) g −1 24 h −1 Invertase activities in mesiscapes during January exceeded desert remnant sites by a factor of six and xeriscape sites by a factor of two. Cellulase activity ranged from 48 to 406 μg GE g −1 24 h −1 Cellulase activity in mesiscapes during January significantly exceeded desert remnant and xeriscape sites by a factor of two. Mesiscape soils were up to 18.4°C cooler than xeriscape soils and had the lowest average temperatures (20.7°C). The average temperature of desert remnant soils was 27.4°C. Over the study period, CO 2 flux rates ranged from 0.212 to 1.760 g m −2 h −1 Maximum rates of CO 2 flux rates occurred in the spring and summer, and flux rates were lowest during the winter months. Winter peaks of enzyme activity are attributed to the onset of dormancy in C‐4 grasses in the fall and establishment of winter lawns by homeowners.