Limitations to plant establishment on eroded slopes in southeastern Spain

Abstract

Abstract. The possible causes for the lack of vegetation in five badland sites from southeast Spain were experimentally tested. The main factors affecting seed germination and seedling survival considered were seed availability, regolith water dynamics in relation to rain events, regolith salinity, seedling predation by herbivores and seedling removal by erosion. Four issues are addressed: 1. Both rainfall and the temporal and spatial dynamics of regolith water during the seedling emergence period were monitored in five different zones at one site (Petrer, Alicante). 2. Effects of salinity and water potential on the rate and speed of germination of local seeds were determined. 3. Seed reserve and seedling emergence and mortality were followed throughout one season. 4. Regolith characteristics of all five sites were compared and the consequences for plant colonization discussed. The main factor limiting plant colonization in these sites was the very short duration of available water in the soil, due to the physical and chemical characteristics of the regolith. In addition, high regolith salinity and its effects on seed germination, the aspect of the site and the pattern of rain events, played a very important role reducing germination and survival. Herbivory and erosion were seldom responsible for seedling mortality. However, there were no highly erosive rain events during the study period, although several have been measured during the past few years.

Climate‐driven decrease in erosion in extant Mediterranean badlands

“…In southern Italy however the downwards trend in annual precipitation is largely accounted for by the trend in (decreasing) winter precipitation (see Figure 4) with the result that rainfall during the vegetation growing season is effectively unchanged (Piccarreta et al, 2004). The dominant peripheral vegetation on these Italian badland slopes is Lygeum spartum (Baratella, 2006) which has also been shown to be relatively resistant to both drought and the high salinity characteristic of badland regoliths (García-Fayos et al, 2000). Ironically, a recent assessment of landcover changes for the areas around Pisticci, Aliano and Craco, within the southern Italy study area, shows a decrease in degraded areas since 1955 but much of this change is in fact the result of remodelling badland areas for cereal cultivation (Piccarreta et al, 2006).…”

Ecology of seed germination of Pinus sylvestris L. at its southern, Mediterranean distribution range

“…In addition, the temporal pattern of rainfall also affects the germination pattern. For example, in Mediterranean environments germination is often restricted to short periods in the wetter spring or autumn, but is unlikely to occur during the dry summer (García-Fayos et al, 2000;Quilichini and Debussche, 2000). This may be especially critical for species whose seeds do not undergo dormancy and thus do not form a persistent seed bank.…”

Hydroseeding Application on Degraded Slopes in the Southern Mediterranean Area (Sicily)

“…Despite the success of test 2, the achievement of some of our tests was low (tests 3 and 4 throughout the period of observation and test 1 in October-December) and they would certainly be improved using irrigation as many authors suggest (García-Fayos et al, 2000;Tormo et al, 2006).…”

“…In fact, on equal terms, the mixture including earthworm humus and mulch provided the best results in terms of vegetation cover. Regarding the mixtures that have not provided satisfactory vegetation cover, irrigation is essential as stated by other authors (García-Fayos et al, 2000;Tormo et al, 2006). The next step in determining the effectiveness of the four hydroseeding methods we applied in our region would be irrigation in the summer in order to maintain the vegetation cover reached in the spring period.…”