Effects Of Moss-dominated Biological Soil Crusts On Soil Enzyme Activities And Their Correlations With Soil Physicochemical Properties On The Loess Plateau Of China

Biological soil crusts are able to increase soil nutrients and improve soil fertility through promoting soil enzyme activities on the Loess Plateau,but their mechanisms have not yet been fully investigated.To provide more insight into this issue,we sampled the representative moss-dominated biological soil crusts(hereafter moss crusts;about 30-year-old)and corresponding uncrust on loess and aeolian soil,respectively,at 0–12 cm depth on the Loess Plateau,Northern Shaanxi Province of China.Afterwards,the hydrolase activities of the samples were measured,and their correlations with soil physicochemical properties were also analyzed.The results showed that:(1)Compared with uncrust,the activities of urease,alkaline phosphatase,invertase,and protease of the moss crusts significantly increased by 92.4%,110.4%,119.9%,and 83.0% on loess soil,respectively;while they were significantly increased by 11.2%,50.5%,199.6%,and 21.4%on aeolian,respectilvey.The moss crusts significantly increased the activity of catalase,peroxidase,polyphenol oxidase by 2.27,15.13 and 5.32 times on loess soil;while they were significantly increased by 2.04,18.58 and 8.68 times on aeolian soil.(2)Compared with uncrust,the soil moisture was decreased by 6.5%and 0.8% on loess and aeolian soil,respectively;whereas the soil temperature was decrease by 2.1 and 3.3 °C on loess and aeolian soil,respectively.It is means that the moss crusts have significantly effect on redistribute of soil moisture and soil temperature.(3)The result indicated that the soil carbon of the moss crusts significantly increased.The moss crusts significantly increased the content of organic matter,readily oxidized organic carbon and microbial biomass carbon by 1.59,5.79 and 4.96 times on loess soil;while they were significantly increased by 1.29,3.16 and 4.69 times on aeolian soil.The development of moss crusts plays an important role in accelerating soilcarbon cycle.(4)The result indicated that the soil nitrogen of the moss crusts significantly increased.The moss crusts significantly increased the content of total nitrogen,available nitrogen and microbial biomass nitrogen by 2.502.08 and 3.04 times on loess soil;while they were significantly increased by3.29,2.15 and 2.29 times on aeolian soil.The development of moss crusts was beneficial to the accumulation of soil nitrogen.(5)The soil nitrogen of the moss crusts significantly increased.The moss crusts significantly increased the content of total phosphorus and available phosphorus by 2.31 and 2.87 times on loess soil;while they were significantly increased by 1.78 and 5.28 times on aeolian soil.The development of moss crusts can promote the availability of phosphorus in soil.(6)The result indicated that moss crust strengthens the relationship between soil enzyme activity and soil nutrient,and soil enzyme has positive effect on soil nutrients.In conclusion,the moss crusts could significantly improve soil nutrients and fertility through increasing soil enzyme activities on the Loess Plateau of China;and these effects could be mostly attributed to the more suitable moisture and temperature of the soil enzymatic reaction,which are regulated by the moss crusts.