Abstract: Taking the litter of Tamarix in Tarim Basin as the research objects, litter-bag methods were applied to reveal the decomposition differences and main driving factors in halophytic habitats (H₁) and arid habitats (H₂). The results showed that:(1) Decomposed in H₁ and H₂ by 720 d, the litter residual rates of Tamarix were 83.50% and 53.73% respectively. The difference of residue decomposition was extremely significant (P < 0.01) during the decomposing periods of day 0-720. (2) The decomposition coefficient were 0.082 and 0.320, the t_0.5 values were 9.398 yrs and 2.166 yrs, and t_0.95 values were 40.618 yrs and 9.362 yrs in H₁, H₂. (3) C elements were enriching-releasing alternately in H₁, and a single enriching-releasing model in H₂. N elements showed accumulating-releasing alternation pattern in H₁, but opposite change trend in H₂. P elements were gradually released during day 0-360 decomposition, while in day 360-720 the rule of P elements changed, H₁ was gradually accumulating, and H₂ was cumulating-releasing. Lignin showed gradually releasing pattern, and cellulose releasing pattern was enriched and released alternately. During the decomposing periods of the 720 d, C, N, P, lignin and cellulose residual rates were significant differences in different habitats (P < 0.01). (4) Comprehensive analysis showed that the changes of microhabitat had different restriction factors on the decomposition of litter. Na⁺ content of the soil in saline habitat was the critical factor for restricting the decomposition of litter, while residual amount, Mg²⁺ content of the soil and total phosphorus content of litter in arid habitats had a combining role to litter decomposition.

Key words: litter, Tamarix, decomposition, arid habitat, saline habitat