Evolution of soil respiration depends on biological soil crusts across a 50-year chronosequence of desert revegetation

摘要

Despite intensive study in recent decades, soil respiration rate (Rs) and its evolution accompanying vegetation succession remain perplexing. Using a 50-year chronosequence of sand-fixing revegetation in the Tengger Desert of China, we took intact soil columns of 20cm in depth, incubated them at 12 levels of soil water content (0-0.4m(3)m(-3)) and at nine temperatures (5-45 degrees C) in a growth chamber, and measured Rs. The results showed that Rs increased rapidly 15 to 20years following revegetation but stabilized after 25years. Rs for soils covered with moss crusts were markedly higher than those covered with algal crusts. Further, Rs correlated significantly with sand content (negatively) and fine particle contents (positively), and increased exponentially with increased soil organic matter (SOM) and total nitrogen (TN) contents. Soil texture had a stronger influence on Rs than did SOM and TN. Also, Rs increased linearly with increased coverage and depth of biological soil crusts, which had a more pronounced influence on Rs than did soil physicochemical properties. Our results suggest that the capacity of carbon sequestration likely increases during the 50-year period after revegetation because the linear increase in SOM outweighs the limited sigmoidal increase in Rs.