Plant community patterns in a gypsum area of NE Spain. II. Effects of ion washing on topographic distribution of vegetation

Properties of soil pockets on arid Nama Karoo inselbergs–the effect of geology and derived landforms

“…Phosphorus distribution in this study, however, showed an opposite trend. The downwashing of nutrient and salts, particularly sodium and nitrogen, has also been reported from other hilly semi-arid areas (Guerrero-Campo et al, 1999) and a Nigerian inselberg was found to contribute significant quantities of potassium and nitrogen to the surrounding landscape (Isichei et al, 1990).…”

The crystallization water of gypsum rocks is a relevant water source for plants

“…The dominant substratum in this area is gypsum, with a few thin inserted outcrops of marls and clays 34 . Almost-pure flour-like gypsum soils (with gypsum contents typically 460-70%), such as the ones included in this study, are particularly stressful areas due to their low water retention and fertility 12 . Climate is semi-arid and highly seasonal, with a mean annual temperature of 14.6°C, and an average annual rainfall of 326 mm, which falls mainly during spring and autumn 35 ( Supplementary Fig.…”

“…All of them are small woody sub-shrubs with a similar architecture to H. squamatum and shallow root systems 11 . Due to their shallow roots and their preferred distribution on the slope of gypsum hills, these species do not have access to the water table 12 . Consequently, rain or dew water stored as free water in the soil and the crystallization water of gypsum are the only potential sources of water for them.…”

“…This species has shallow roots 11 that do not reach the water table 12 , and remains phenologically active during summer 13 . Consequently, the main sources of water available to this and other shallow-rooted plants growing on gypsum hills are free soil water and potentially also gypsum crystallization water.…”

Determinants of Land Degradation and Fragmentation in Semiarid Vegetation at Landscape Scale

“…This degradation process affects both vegetation and soil, but vegetation is normally destroyed first, causing soil exposure and loss (Papanastasis 1999). In arid environments, several authors report negative relationships between plant cover and accelerated soil erosion and loss (Ruiz-Flano et al 1992;Cerda1 997;Navas and Machı´n 1997;Sole´-Benet et al 1997;Guerrero-Campo et al 1999;Lasanta et al 2000), while recuperation of soil and vegetation after land abandonment is difficult and appears to take decades (Ruecker et al 1998;Alados et al 2004). Thus vegetation cover is a good indicator of ecosystem conservation in dry areas (Rubio and Bochet 1998).…”