Vertical Distribution of a Soil Microbial Community as Affected by Plant Ecophysiological Adaptation in a Desert System

Abstract

The spatial and temporal patterns of resource distribution in a desert system have been shown to influence a number of soil biota components and processes. The pattern of possible different resources supplied by two typical halophyte shrubs with different ecophysiological adaptations, Atriplex halimus and Hammada scoparia, was found to be the trigger in the present study on the microbial community temporal and spatial (vertical) scale. The uniqueness of A. halimus, a saltbush plant, is in the creation of 'islands of salinity' in its rhizosphere system and the relatively high percentage of organic matter beneath its canopy, whereas the H. scoparia shrub has a leafless stem with a relatively lower amount of organic matter accumulation beneath its canopy. Soil samples from 0 to 50 cm depths were collected at 10-cm intervals during each of the four seasons. The vertical distribution of the microbial community was measured in the vicinity of the above plant shrubs and in the open spaces between them. The results obtained from the field study demonstrated that plant ecophysiological adaptation played an important role in the temporal and spatial distribution of abiotic conditions and microbial community levels such as microbial biomass, CO 2 evolution, and colony-forming units (CFUs) of both bacteria and fungi. However, we did not find consistency in the positive effect of plant cover on the microbial community. The shrub effect was observed to have a major outcome on microbial variables not only on a temporal but also on a spatial (vertical) basis. This contributed to the understanding of the controversy regarding the difference between the shrubs.

Vertical distribution of soil microbial biomass and its association with shrubs from the Negev Desert

“…During the wet season, the qCO 2 was relatively high in the three deeper layers at each location compared to the top layer as a result of low availability of soil water and organic matter, and the influences of both variables on the microbial community at these soil depths were even greater in the open spaces. These findings are similar to the results reported by Barness et al (2009). Although the amounts of soil water and organic matter were identical at the sampling locations in the three deeper depths during the dry season, the availability of carbon was probably higher in the open spaces since more available carbon was exhausted by proliferation of microorganisms below shrubs during the spring (Sarig and Steinberger, 1994).…”

“…The C mic /C org values beneath both desert shrubs decreased from the upper toward the deeper layer and declined during the dry season as a result of the decrement in carbon source availability. A similar trend was reported by Barness et al (2009). The correlation between C org and C mic /C org below both desert shrubs indicated the effects of vegetation on substrate availability.…”

Arbuscular mycorrhizal fungi in saline soils: vertical distribution at different soil depth

“…In the complex saline environments where soil physical and chemical properties, plant ecophysiological adaptation, and temperature-moisture characteristics are closely related, soil nutrient sources will certainly facilitate soil biota coexistence and activity (Barness et al , 2009). The soils from central Argentina here analyzed were similarly to semi-arid and arid environments, where Chenopodiaceae are common (Aguilera et al , 1998; Aliasgharzadeh et al , 2001; Landwehr et al , 2002; Wilde et al , 2009).…”

Seasonal Patterns of Microbial Community Structure and Enzyme Activities in Coastal Saline Soils of Perennial Halophytes

“…Plant species can influence soil characteristics, enzyme activity and soil microbial community through the excretion or release of root exudates, sloughed off cells, lysates, litter decomposition, exogenous enzymes and oxygen into the rhizosphere (Cao et al , ; Chaudhary et al , ; Dinesh et al , ). Exudates from the roots of halophytic vegetation provide sources of carbon and energy to microbes, considering that plant species, type of metabolism, plant growth stage and season are some of the factors that affect the quantity and quality of exudates released through the roots and microbial community may adapt and develop particular physiological features in response to changes in the nutritional environment (Barness et al , ; Brimecombe et al , ; Mishra et al , ). Owing to the distinct patterns of growth, development, root architecture and resource allocation of different halophytes can lead to differences in the modification in root associated soil compared with those in bulk soil and, thus, result in differential communities and degrees of activity of microbes (Brimecombe et al , ).…”