The effect of plant litter on ecosystem properties in a Mediterranean semi‐arid shrubland

Abstract

Abstract. We studied the distribution of litter in a shrubland of the Negev with a semi‐arid Mediterranean climate of less than 200 mm of rainfall per year. Our focus was on the effects of litter on properties of landscape patches relevant to ecosystem processes (water runoff and soil erosion), annual plant community responses (seedling density, biomass production and species richness), and animal activity (soil disturbance by termites). Three 60‐m transects, extending across a pair of opposing north‐ and south‐facing slopes and their drainage channel, showed that litter accumulates not only under shrubs, but to a lesser extent also on the crusted inter‐shrub open areas. We used 35 experimental units (‘cells’, 0.5m × 1 m), each containing a crust and a shrub patch. Because runoff flows from crusted patches and is intercepted by shrub patches, the latter were in the lower third of the cells. Leaf litter was added in single and double amounts providing ca. 0.5 and 1.0 cm litter depth, to either, both, or none of the patches. Litter addition significantly decreased the amount of runoff, regardless of the location and amount of litter applied. Litter on the crust increased species number and seedling density of species with low abundance. Adding a double litter layer increased annual plant biomass production, while a single amount had no effect. Litter addition to the shrub patch affected neither biomass nor species richness. Litter addition to both patches at both quantities caused a large increase in termite activity. Termites caused disturbance by disrupting the crust, which may contribute to the reduction in runoff amounts. In the open, flat crust patches, annual plant communities are limited in their productivity and species richness, as there are few structures stopping the outflow of water, soil and seeds. Litter adds such structures, but affects the plant communities only when added to litter‐free crust. Litter accumulation and its patchy distribution have large impacts on landscape patch properties affecting resource distribution, plant productivity and diversity, and animal activity. Therefore, understanding litter distribution in relation to the patchy structure of the landscape of semi‐arid shrubland should be viewed as an important component of shrubland management.

Do biotic interactions modulate ecosystem functioning along stress gradients? Insights from semi-arid plant and biological soil crust communities

“…Direct effects of biotic interactions on these variables are likely to work primarily at the scale of plant patches (Cortina & Maestre 2005), and may not be translated to the inter-patch areas, which are the dominant land cover in arid and semi-arid ecosystems. However, soil attributes in these areas may be largely affected by plant patches (Maestre et al 2009c), as these can modify the microclimate in their surroundings through shading, and can provide carbon, water and nutrients through processes such as hydraulic lift, lateral root growth and litter inputs (Breshears et al 1998;Caldwell et al 1998;Boeken & Orenstein 2001). The influence of plant patches on the functioning of the inter-patch areas is going to be increasingly important with changes in cover, irrespective of whether such changes are driven by facilitation or not.…”

Identifying and prioritising services in European terrestrial and freshwater ecosystems

“…Mudelsee et al 2003). Well managed grassland and heathland/shrubland ecosystems were ranked as providing some contribution to erosion (Boeken and Orenstein 2001;Rodriguez et al 2006) and natural hazard regulation (Scott et al 1998) under particular conditions like steep slopes (Quétier et al 2007). …”

Structural Changes of Desertified and Managed Shrubland Landscapes in Response to Drought: Spectral, Spatial and Temporal Analyses

“…On the one hand, a decrease in precipitation and higher temperatures are drivers of woody vegetation mortality [19][20][21][22], and on the other hand, stronger rainfall intensities increase the susceptibility of soil to erosion and flash floods [23]. These changes disturb the function of the present ecosystem source-sink relationship by reducing the shrub cover, which decreases the sink function, resulting in a reduction in resource conservation and an expansion of the biocrust areas that increase the source function of that system, resulting in the leakage of resources [24][25][26]. In addition to climatic changes, the shrublands in arid and semi-arid areas have been exposed to human activities for thousands of years.…”