Rainfall and decomposition in the chihuahuan desert

Abstract

We tested the hypotheses that rates of decomposition in a desert should be higher following single large rain events of 25 mm than evenly spaced 6 mm events and that supplemental rainfall should result in higher populations of soil biota. There were no significant differences in mass losses of creosotebush, Larrea tridentata, leaf litter on plots receiving water supplementation and no added water. On some sampling dates, there were higher mass losses in the 6 mm·week treatment. Weekly rainfall produced higher coefficients of variation in mass losses than the other rainfall regimes. A single event pulse compared with weekly pulses of rainfall during the normal "dry" period resulted in no differences in mass losses. Microarthropods and nematodes exhibited numerical responses to supplemental rainfall but the litter microflora did not. These studies provide direct experimental evidence that the conventional wisdom linking decomposition to rainfall in deserts is wrong. The studies also suggest that the effects of litter fauna on surface litter decomposition are minimal; therefore, future studies should focus on activites of the microflora.

Decomposition of leaf and root litter of Chihuahuan desert shrubs: effects of three years of summer drought

“…There was very little litter mass loss over the next winter-spring period, such that by the third sampling date at 18 months there was still no effect of drought treatment. That there is no impact of drought on decomposition of leaf litter during the first half of this study is consistent with previous studies that report little or no effect of rainfall on decomposition of Larrea litter (Whitford et al, , 1986Santos et al, 1984;Schaefer et al, 1985).…”

“…This contrasts with others studies of these species that found more rapid decay of buried as compared to surface litter Elkins & Whitford, 1982), and with conclusions regarding decay in general (Parton et al, 1987). This difference in rates of surface vs. below-ground decay may be affected by a number of factors, such as climate (Whitford et al, , 1986(Whitford et al, , 1995Santos et al, 1984;Schaefer et al, 1985), seasonal variability (Comanor & Staffeldt, 1978;Moorhead & Reynolds, 1989b), microbial colonization of litter (MacKay et al, 1987a;Moorhead & Reynolds, 1991), and soil texture and moisture (Parton et al, 1987). For example, Comanor & Staffeldt (1978) found that root decay tended to exceed belowground decay during winter-spring periods when soils were wetter and warmer than the surface, whereas decay of surface leaf litter tended to exceed that of roots in late spring through summer.…”

“…Among the uncertain aspects of decomposition and nutrient cycling in arid ecosystems is the role that moisture plays as a controlling factor (Santos et al, 1984;Whitford et al, 1986;Strojan et al, 1987;Moorhead & Reynolds, 1989b). A number of studies have examined the effects of moisture on decomposition under arid conditions by employing moisture augmentation (e.g.…”

“…A number of studies have examined the effects of moisture on decomposition under arid conditions by employing moisture augmentation (e.g. Whitford et al, 1986Whitford et al, , 1988MacKay et al, 1987a). However, Whitford et al (1995) suggest that conclusions regarding the effects of moisture on decomposition in arid systems may depend on whether water is added or removed.…”

Microbial Functional Diversity Associated with Plant Litter Decomposition Along a Climatic Gradient

“…It is also known that its turnover rate is determined by its quality, biotic community, and abiotic factors (e.g., temperature, rainfall, moisture availability) [1, 33, 43-45, 59, 62]. The interaction between the biotic and abiotic factors, along with litter decomposition processes on a temporal and spatial basis, was the subject of many studies conducted in different ecosystems [4,66,67].…”