Abstract
The average annual rainfall was close to the average for the Jornada Experimental Range basin (225 mm∙y−1). Decomposition of leaf litter bags on the soil surface was a function of the rainfall at the site and of soil texture. Sites with the highest splash erosion and infiltration (highest sand content) had the highest decomposition rates. There was no evidence that run-off, run-on processes had an effect on the decomposition of surface litter. Root decomposition was only different at one of the tarbush sites (p > 0.001) and that difference was primarily due to soil texture and spatial distribution of rainfall. High concentration of the clay-silt fraction resulted in differences in mass loss of surface litter at grassland, dry-lakes, and tarbush sites. One site at each of these was different from the other two sites because they are between 8 and 20 km from the other two sites.
Highlights
In mesic environments, decomposition rates can be predicted by a regression model based on actual evapotranspiration (AET) and lignin content of the dead plant material [1]
The grassland sites were primarily affected by annual rainfall: mountain grassland mass loss 78% with precipitation of 265.7 mm, basin grassland mass loss 43% with precipitation of 93.7 mm, and distant grassland 64%
Two of the dry lake sites that flooded had high decomposition rates of more than 80% with precipitation of 200.8 mm and the litter mass remaining at the tobosa grass dry lake was 46%
Summary
Decomposition rates can be predicted by a regression model based on actual evapotranspiration (AET) and lignin content of the dead plant material [1]. The AET model greatly underestimates mass losses in deserts [2]. In a study of five species (one shrub, one tree, and three grass species) there were no consistent results relating mass losses to litter chemistry or antecedent precipitation [3]. Experiments using sprinkler irrigation to simulate rainfall found that litter placed in the field during an extended dry period lost mass faster than non-irrigated litter [4]. In the winter rainfall Negev Desert, irrigation increased mass losses during the rainless summer [5]. Imposition of drought had no effect on decomposition rates of creosote bush leaf litter on the soil surface
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