Atmospheric Deposition to a Desert Ecosystem and Its Implications for Management

Abstract

The Negev Desert in Israel is a mosaic of macrophytic patches, consisting of shrubs and annual plants growing in a soil mound, and microphytic patches, consisting of algae, cyanobacteria, bacteria, mosses, and lichens growing on a soil crust. Accumulation of soil is often a limiting resource in this ecosystem, so the loose soil mound in the macrophytic patch permits relatively high production of annual plants. To determine whether atmospheric deposition was responsible for soil mound formation, we measured particle deposition in macrophytic and microphytic patches. Our results show that fine particles, consisting mostly of mineral dust, are deposited at similar rates in macrophytic and microphytic patches. However, coarse particles, which are primarily composed of organic material from plant detritus, are deposited at greater rates in macrophytic compared to microphytic patches. The coarse particles have higher concentrations of carbon and nitrogen than the fine particles. Further experimentation showed that much of the runoff water generated from microphytic patches is captured by macrophytic patches downslope. Calculations based on the measured deposition rates suggest that a typical soil mound would require at least 180-290 yr to develop. Since the presence of the soil mound is crucial for annual plant germination and growth, and since annual plants are the major source of productivity in the system, these results imply that the system will be slow to recover from disturbances that reduce the abundance of macrophytic patches, such as livestock grazing and firewood cutting.

Aeolian dust in Colorado Plateau soils: Nutrient inputs and recent change in source

“…K and Mg may strongly influence plant-community composition in semiarid areas (44). Even small increases in the proportion of fine particles, or in some nutrients, may increase invasibility by exotic annual plants (16,45). Our results show that aeolian inputs have increased most plant-essential nutrients in surficial sediments relative to bedrock values.…”

“…M any studies have addressed the presence of aeolian dust in soils and surficial deposits in deserts to provide important geologic and ecologic information bearing on landscape dynamics (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16). From this body of work, we have improved understanding about: (i) current and past sources and flux of dust, hence changing conditions of dust emission; (ii) the genesis of desert soils; (iii) the influences of aeolian silt and clay on water-infiltration rates in soil; (iv) the evolution of desert surfaces (such as desert pavement) relevant to surface stability, as well as the distribution of surface and subsurface water; and (v) interrelations among aeolian dust, distribution of plants and soil crust, rain-water runoff, and productivity.…”

Characteristics of surface runoff in a sandy area in southern Mu Us sandy land

“…During rainfall events, dust that has fallen on the crust seals the matrix porosity of the BSCs, reduces the hydraulic conductivity of the soil surface, prolongs the time for which water remains in the surface of BSCs, and decreases the water infiltration, thereby generating a large amount of runoff [22,23]. Electron microscopy analysis revealed that the upper 1-2 mm layer of the BSCs is typically nonporous when compared with the soil below.…”

Structural Changes of Desertified and Managed Shrubland Landscapes in Response to Drought: Spectral, Spatial and Temporal Analyses

“…However, on a loess substrate, as in our case, biocrusts increase resource and nutrient loss with runoff [28,44,85] and reduce the ability of plants to germinate [86]. The decreased production resulting from crust patch expansion indicates desertification processes in our study area as a result of high frequency drought events [87]. Therefore, we suggest that CI could be an effective indicator for detecting large-scale desertification processes due to climate change and as a tool for studying biocrust dynamics [84].…”