English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The distribution of giant Andean rosettes and soil moisture content during the dry season were studied in blocky and sandy talus slopes of the high Venezuelan paramo between 4335 and 4400 m. Rosette plants were virtually restricted to blocky talus and to areas downslope from isolated boulders embedded in sandy talus. Plant roots always grew upslope and beneath stones. Water content at the soil surface was 10 to 20 times greater under blocky talus and beneath boulders than in contiguous, bare sandy talus. The soil surface in the latter was very dry (< 1 '"O water) when sampled both in 1987 and 1989. Soil moisture increased sharply with depth in all locations sampled, but always remained substantially higher below stones even at 20 cm depth. The amount of water available for plant growth above the permanent wilting point [PWP -1500 kPa) was also significantly greater under stones and boulders. Soil texture was similar (sand to loamy sand) in both talus types. Organic matter content was slightly higher in blocky talus, but its effects on water retention at PWP were minor, and could not be used to explain the observed differences in field moisture. Soil profiles in sandy talus were of a Typic Cryorthent, while the blocky talus was underlain by a fragmental Entic Cryumbrept. Several dry-season records of soil temperature show that both the maxima and minima were sorne\vbat lower under stones, but the differences with sandy talus were minor, and probably did not affect soil moisture. The higher water content found under stones and blocks could result from 3 processes. During precipitation, water readily flows over the inlpervious stone surfaces, and becomes concentrated in the sandy soil matrix found between and beneath stones. Afterwards, reduced water losses by evaporation occur due to the insulation provided by the superficial openwork layer of stones, which prevents capillary rise to the talus surface. In addition, falling temperatures at sunset could result in condensation in the hollow spaces between stones. Andean rosettes colonize blocky talus areas, and their roots grow under the stones, because soil there remains moist during the dry season, allowing plants to survive it more readily than in the desiccated bare sandy talus areas.

Soil moisture and the distribution of giant Andean rosettes on talus slopes of a desert paramo