Recreating Sink Areas on Semiarid Degraded Slopes by Restoration

Abstract

The patchy distribution of semiarid ecosystems determines productivity and controls the retention of resources within the system. Resource fluxes depend on a number of biophysical and soil variables, besides the amount and intensity of particular rainfall events. At two Mediterranean experimental sites with contrasted composition and spatial vegetation arrangement, we evaluated a straightforward way to simplify some of these processes by using different planting techniques that modify the runoff generation threshold and redirect runoff towards the planting hole (M) and enhance the water infiltration and conservation in it (MDW). Traditional planting technique (H) and M were combined with the addition of composted biosolids. Soil moisture was increased with treatments during drought periods in the first 2 years after planting with mean values of 10·1, 8·9 and 6·9% in MDW, M and H, respectively. Lower landscape organization values at the site resulted in sinks being more efficient at retaining resources, with 3·68‐fold more organic matter accumulation on the soil surface of the planting hole, better growth of the Olea europaea‐planted seedlings and a better response to compost application in MDW than in H. At the site with better landscape organization, planting techniques only showed improvement in seedling survival (+20% in MDW than in H). We discuss ecosystem properties, such as plant composition and spatial arrangement, that determine the effectiveness of these techniques as dryland restoration tools and the hierarchy between water and nutrients as essential resources in these semiarid Mediterranean areas. Copyright © 2016 John Wiley & Sons, Ltd.

Carbon balance as affected by biosolid application in reforestations

“…The sink effect of the planting hole increasing the soil surface roughness favouring the organic matter accumulation (Fuentes et al, ), together with the presence of the surviving pines, resulted in significant differences of litter accumulation between holes where the planted pines survived or died. On the contrary, the most recent experiment in Enguera site released a trend to higher litter accumulation and natural vegetation in the planting holes where planted pines died than in holes with living pines.…”

“…This effect could be optimized by forcing the concentration of resources (water, seeds, fine and coarse organic matter, etc.) in the planting hole by redirecting the surface water fluxes (Fuentes et al, ). Carbon accumulated in root fractions showed a trend to be higher in sludge amended planting holes than in control ones.…”

“…In Mediterranean drylands, the beneficial effect of organic matter applications on plant growth, especially by reducing deficiencies of limiting nutrients (Valdecantos et al, 2011), is higher than that provided by other restoration techniques (Barberá et al, 2005;Valdecantos et al, 2014). However, nutritional benefits are surrogated to water availability which, ultimately, determines plant survival in these environments (Fuentes, Smanis, & Valdecantos, 2017;Valdecantos et al, 2014) and, hence, the C storage potential in plant biomass.…”

“…The biochemical effects of relatively small doses can last up to 3 years enhancing the development of both the introduced seedlings and the spontaneous vegetation, taking advantage of the most recalcitrant part of the added organic matter (Pascual, Garciá, & Hernandez, 1999). Our study focused on the surface affected by the planting holes that, together with the low standard planting density (800 seedlings ha −1 ) and the low productivity The sink effect of the planting hole increasing the soil surface roughness favouring the organic matter accumulation (Fuentes et al, 2017), together with the presence of the surviving pines, resulted in significant differences of litter accumulation between holes where the planted pines survived or died. On the contrary, the most recent experiment in Enguera site released a trend to higher litter accumulation and natural vegetation in the planting holes where planted pines died than in holes with living pines.…”

Spatial Variation of Soil Seed Bank under Cushion Plants in a Subalpine Degraded Grassland

“…In fact, the plant patches and their interaction with the sediment, water movement and seeds redistribution is a well‐known issue (Cerdà, ; Akhtar et al, ). Understanding the implications of a plant patches has been useful for restoration of degraded ecosystems (Fuentes et al, ; Wang et al, ). In our study area, intensive grazing with a long history has formed unvegetated‐degraded gaps.…”