Stability of phytomass dynamics in protected low mountain-steppe landscapes and pastures in the Southern Urals

Abstract

In the steppe zone, the high sensitivity of plant cover to humidity contrasts raises the question of what landscape conditions provide a stable predictable phytoproductivity. Authors of the article tested the hypothesis about the inequality of the spatial factors of variability of functioning under the conditions of the reserved regime and anthropogenic impact on the example of the Aytuarskaya steppe. Based on the deviations of the intra-seasonal increments of the normalized difference vegetation index (NDVI) for 33 pairs of terms from the mean values, the measure of instability of the types of dynamics of green phytomass (Shannon's index) was calculated. To identify the clusters of high and low phytoproductivity, the Hot Spot Analysis was applied based on Getis–Ord statistics. On grazed areas, the background type of dynamics of green phytomass is not dominant in area in contrast to protected areas. The reserve regime stabilizes the dynamics of phytomass due to a higher subordination to landscape-scale processes. Summer loss of phytomass outside the reserve occurs over a larger relative area than in the reserve. Zones of the most unstable phyto-production functioning with high variability of the shape of spots of increased phytomass are characteristic of catchment depressions, lower parts of slopes, and narrowed sectors of gullies.