Carbon/Nitrogen Status Including Protease Activities of Arctic Soils Associated with Shrubs of Varying Height around Toolik Field Station, Alaska 2009.

Organic and mineral soil cores were collected from 18 transects differentiated by shrub height into three replica groups: high (average 64 cm ± SE 1.01); medium (39 ± SE 1); and low (18 ± SE 0.4); and percent plant functional group cover. Replica sample cores were taken from each transect, and after homogenization and K2SO4 extraction, if required, samples were analyzed for % C (carbon) and N (nitrogen); non-purgeable organic C (NPOC); total N (TN); dissolved inorganic and organic N (DIN, DON); microbial biomass C (MB-C) and N (MB-N). As a measure of N status, protease activity (native and potential) was determined together with total free amino acids and total soluble protein. Bulk density and pH values were also measured. K2SO4 extracted samples from a three-month incubation were analyzed as above and net mineralization was assessed.本研究从18条野外样带中采集有机与矿质土壤芯样，基于灌木高度将样带划分为3个重复组：高灌木组（平均高度64 cm ± 标准误（Standard Error, SE）1.01）、中灌木组（39 ± SE 1）、低灌木组（18 ± SE 0.4），并同步采集各条样带的植物功能群盖度百分比数据。从每条样带中采集重复土壤芯样，经均质化处理与硫酸钾（K₂SO₄）浸提（依实验需求执行）后，对样品开展以下指标分析：碳（C）、氮（N）百分含量；非挥发性有机碳（Non-purgeable Organic C, NPOC）；总氮（Total N, TN）；溶解性无机氮（Dissolved Inorganic N, DIN）与溶解性有机氮（Dissolved Organic N, DON）；微生物生物量碳（Microbial Biomass C, MB-C）与微生物生物量氮（Microbial Biomass N, MB-N）。作为氮素营养状况的表征指标，本研究测定了蛋白酶活性（固有活性与潜在活性），同时测定了总游离氨基酸与总可溶性蛋白含量。此外还测定了土壤容重与pH值。对经3个月恒温培养后的硫酸钾浸提样品，按照上述方法开展分析，并评估了净矿化（Net Mineralization）速率。