Based on the second law of thermodynamics, an open system shows a stable state where receives minimum energy or maximum entropy. Changes in input of the system leads to the new output, where system shows a new equilibrium point or new landscape, although emerging new landscape are consequence of crossing critical transitions. Intrinsic and extrinsic thresholds can lead to effects that cascade among systems. The nonlinear response of ecosystem to environmental perturbation identifies by bifurcation points in the mathematical curve indicates bistable zone in the ecosystem. In systems subject to gradually changing conditions abrupt and sometimes irreversible shifts between two stable states can take place if a certain threshold (critical point/bifurcation point) is exceeded. Before the critical transition from a vegetated state to a barren state takes place, regular spatial patterns appear. A transition in a system is induced by an external forcing, so changing conditions. Catastrophic transitions can be the result of changing conditions, but may as well be caused by perturbations in system state that force it out of its basin of attraction. Semi arid and arid ecosystems are fragile environments and have low resilience range to respond perturbations and maintain equilibrium. Un-vegetated or vegetated states depend on environmental perturbations (soil degradation, climatic variations, etc.) which cause a critical ecosystem transition. The vulnerability of a system refers to instances where neither its robustness, nor its resilience enables a system to survive without structural changes. In such cases, either the system adapts structurally, or it is driven to chaos (non-equilibrium status). In this article has been discussed formation of vegetation spatial pattern as chaotic responses outgoing pressures in the bistable zone or non-equilibrium status. The results of this article can be useful for ecosystem management in relation to climate changes and human pressures.

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