Spatial heterogeneity of vegetation in Inner Mongolia, China

To understand the vegetative spatial heterogeneity and ecological characteristics of Inner Mongolia, China, we surveyed and analyzed the vegetation, which was composed of coniferous-broadleaf deciduous forest, shrub, grassland, and desert on an east-west gradient. We established 1,122 large quadrats (L-quadrats), 2x2cm on a map (actual Held dimensions : 30x30 km), across an area of approximately 1,180,000 square km. Each L-quadrat was further divided into four small quadrats (S-quadrats), 1 x 1 cm (15 x 15 km). The frequency of occurrence of each vegetation type was recorded in each small quadrat. In the survey, we based the vegetation analysis on a beta-binomial distribution to describe the frequency of occurrence and spatial heterogeneity of each vegetation type. The weighted average heterogeneity of all vegetation composing the landscape provides a measure of landscape-level heterogeneity, which determines the spatial intricateness of the vegetation. Vegetation was classified into 99 types. The maximum spatial heterogeneity (rho) of the vegetation was recorded In Larix forests (V1), which dominated the cold and moist northeast. The minimum spatial heterogeneity was recorded in meadows of Sphora alopecuroides-Glycyrrhlza uralensis (V90) and Caragana teucophloea (V77), which exhibited low heterogeneity and frequency near zero. These are rare patches that warrant protection : V90 comprised two patches in the east, and V77 was a single "island" in the west. The maximum frequency of vegetation was p98 = 0.1838, measured In unirrigated cropland (V98), which covers 4.77% of the land surface of Inner Mongolia ; this measurement did not include water coverage. Higher occurrences of natural vegetation were recorded in grass lands of Stipa grandis (V25) and salt meadows of Achnatherum splendens (V89), which are distributed in central and southern Inner Mongolia and are characteristic of Inner Mongolian vegetation. The maximum spatial heter ogeneity of grassland vegetation was measured in sandlands with Artemisia ordosica (V49), which is distributed throughout southern Inner Mongolia. Based on the weighted average heterogeneity and Shannon-Wiener's diversity index, the macro-vegetation of Inner Mongolia was characterized as grassland and desert.