Effects of Different Vegetation Patches on Soil Functionality in the Central Iranian Arid Zone

Abstract

This research aimed at evaluating how different vegetation patch types and inter-patch zone affect soil properties/functions and ecological processes. Five main types of patches and one inter-patch zone were identified in an arid rangeland ecosystem in the Ghamishloo National Park and Wildlife refuge, central Iran. Next, twenty-nine soil samples were collected from the patches and the inter-patch to measure soil texture, pH, electrical conductivity (EC), total nitrogen (TN), available phosphorus, bulk density (BD), soil organic matter (SOM), particulate organic matter (POM), basal soil respiration (BSR), hot-water extractable carbohydrates (HWEC), and aggregate stability (as quantified by mean weight diameter, MWD, of water-stable aggregates). At each six patch types and inter-patch zone, eleven soil indicators were measured along three 30-m transects to estimate soil stability, infiltration, and nutrient cycling indices as proposed by the landscape function analysis method. Results indicated that SOM, TN, MWD, HWEC, BSR, POM, and silt content varied significantly between the patch and inter-patch types. Moreover, the difference between shrub patch and inter-patch zone was significant for infiltration and nutrient cycling indices but not for soil stability. Substantial input of organic carbon is required in the soils of inter-patch zone and forb patch type to achieve greater soil functioning. Patches of shrubs, shrub-forbs, and grasses improved soil quality and ecosystem functioning more efficiently than forbs and inter-patch zone; hence, preserving these patches is recommended for conservational solutions in arid fragile ecosystems. The results highlighted the importance of SOM in evaluating functional status of arid rangelands.