The effect of wind and precipitation on vegetation and biogenic crust covers in the Sde-Hallamish sand dunes

Abstract

Vegetation and biogenic crust covers play an important role in sand dune stabilization, yet there is a lack of high temporal and spatial resolution data on sand dune cover. A field experiment, aimed at measuring the dynamics of biogenic crust and vegetation in sand dunes, was conducted at the Sde‐Hallamish sand dunes in the northwestern Negev Desert, Israel, from July 2008 to August 2010. The climate of the Sde‐Hallamish sand dunes is arid (the mean annual precipitation over the past 13 years is 61 mm), and the dunes are linear and partially stable, mainly due to the presence of biogenic crust and partially due to the presence of vegetation. In July 2008, 10×10 m plots on the four dune habitats (crest, interdune, north slope, and south slope) were treated as follows: (i) removal of vegetation and biogenic crust, (ii) removal of biogenic crust only, (iii) removal of vegetation only, (iv) partial removal of biogenic crust and vegetation, and (v) control plot. The surface coverage of sand, biogenic crust, and vegetation was monitored on a monthly basis, using a remote‐sensing technique especially developed for the Sde‐Hallamish sand dunes. It was found that strong wind events, with durations of several days, accounted for the coverage changes in biogenic crust and vegetation. The response to precipitation was much slower. In addition, no rehabilitation of biogenic crust and vegetation was observed within the experiment time period. The changes in biogenic crust cover were not necessarily related to changes in dune dynamics, since often an increase in biogenic crust cover is a result of wind erosion that exposes old crust that was buried under the sand; wind hardly erodes biogenic crust at all due to its high durability to wind action. The Sde‐Hallamish dunes seem to have become more active as a result of a prolonged drought during the past several years. The field experiment reported here indicates that biogenic crust cover exhibits large seasonal variations that are not necessarily related to the growth of new crust but rather to the exposure of old buried crust.

The effect of sand grain size on the development of cyanobacterial biocrusts

“…By 1989, topsoil biocrusts, covering extensive areas at the inter-dune, were observed (Yair, 2008). In addition to the disturbance being limited to trampling, the DP 2 at the inter-dunes is very low ($60 compared to $320 at the crest upper dune (Amir et al, 2014)), allowing for the deposition of fine particles that favor biocrust development. Thus, there is a feedback between the wind intensity and the biocrust development; the low energy wind environment enhances the deposition of fine particles that favors biocrust growth.…”

Biocrust research: A critical view on eight common hydrological‐related paradigms and dubious theses

“…This is a very common paradigm and is taken as granted by many scholars (Amir et al, ; Coppola et al, ; Danin, ; Danin, Bar‐Or, Dor, & Yisraeli, ; Eldridge & Greene, ; Eldridge & Leys, ; Fearnehough, Fullen, Mitchell, Trueman, & Zhang, ; Fischer, Yair, & Veste, ; Guo, Zhao, Zuo, Drake, & Zhao, ; Herrick, Van Zee, Belnap, Johansen, & Remmenga, ; Knapen, Poesen, Galindo‐Morales, De Baets, & Pals, ; X. R. Li, Wang, Li, & Zhang, ; X. R. Li, Xiao, Zhang, & Wang, ; Liu et al, ; Liu, Song, Gao, Wang, & Li, ; Malam‐Issa et al, ; Malam‐Issa, Défarge, Trichet, Valentin, & Rajot, ; Malam‐Issa, Le Bissonnais, Défarge, & Trichet, ; Rozenstein et al, ; X. P. Wang, Li, Xiao, & Pan, ; Xiao, Zhao, Wang, & Wu, ; Yair, Almog, & Veste, ; Yair & Verrechia, ). The paradigm is based on a seemingly sound rationale.…”

“…The current assay will focus on hydrological and on hydrologicalrelated paradigms and dubious theses (for simplicity, they are mainly referred hereafter as paradigms). Both types of paradigms will be jointly discussed: 2 | COMMON PARADIGMS 2.1 | Biocrusts require physical crusts and or a layer of dust for establishment This is a very common paradigm and is taken as granted by many scholars (Amir et al, 2014;Coppola et al, 2011;Danin, 1978;Danin, Bar-Or, Dor, & Yisraeli, 1989;Eldridge & Greene, 1994;Eldridge & Leys, 2003;Fearnehough, Fullen, Mitchell, Trueman, & Zhang, 1998;Fischer, Yair, & Veste, 2012;Guo, Zhao, Zuo, Drake, & Zhao, 2008; Herrick, Van Zee, Belnap, Johansen, & Remmenga, 2010;Knapen, Poesen, Galindo-Morales, De Baets, & Pals, 2007;X. R. Li, Wang, Li, & Zhang, 2002;X.…”

Landscape Analysis Over 30 Years to Assess the Impact of River Damming On Natural Ecosystem

“…On the other hand, the sand dune area was extended during the period of the study. One of the most important driving forces of sand dunes activity is wind power (Amir et al, 2014) which can increase by decreasing vegetation cover. Another factor of sand dune activity is drought.…”