The resilience of an ecosystem determines recovery time after pressures as well as ecosystem resistance. Short recovery time and high erodibility can be used for distinguishing sustainable and unsustainable ecosystems. A transitions zone can be considered as a critical threshold in non-equilibrium state, where is emersion of heterogeneous patterns of vegetation, soil and bare rock. To distinguish desert ecosystem base on transition zones, the approach was applied in Khorasan Razavi province in north-east of Iran. To determine ecogeomorphic threshold in transition zones of semi-arid ecosystems, the spectral and morphological algorithms were implemented in remote sensing images of MODIS surface reflectance. The spectral angle mapper analysis was applied for surface conditions (vegetation, bare soil and rock) and the mathematical morphology algorithm of dilation was used for identifying potentials erodibility and recovery in heterogeneous patterns. Detailed assessment of this mappingwas achieved by implementation an iterative self-organized clustering technique (ISODATA) and calculation of separability of formed typologies classes using application of transformed divergence algorithm. Several desert threshold were detected in susceptible ecosystems to desertification in KR under the influence of natural and anthropogenic factors. Some of intrinsic thresholds were crossed due to influences of ecogeomorphic factors, such as formation, lithology, soil, land cover and geomorphology. Some of them are crossing under the anthropogenic disturbances, because of the high rate of disturbances over the ecosystem resilience. Meanwhile, in prone areas which have the high potential to desertification like KR, ecosystem reach to the tipping points and will cross over into the desert state.

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