Abstract:

This study focused on soils in the hilly-mountainous regions and river valley plains of western Hangzhou, China. A total of 95 soil samples representing diverse soil types and land use patterns were collected, and the contents of soil organic carbon, total nitrogen, and total phosphorus were determined, along with their stoichiometric ratios. We explored the effects of natural factors (e.g., altitude, soil moisture) and anthropogenic factors (e.g., land use pattern) on soil ecological stoichiometry. The results indicated that the soil organic carbon to total nitrogen (C/N), organic carbon to total phosphorus (C/P), and total nitrogen to total phosphorus (N/P) ratios in forest land of the hilly-mountainous regions increased with increasing altitude, whereas these ratios in paddy soils of river valley plains increased with increasing soil moisture. Following the conversion of natural soils to agricultural lands (e.g., upland fields including vegetable fields, and perennial crop lands such as tea gardens and orchards), soil organic carbon content decreased whereas total phosphorus content increased, resulting in a consistent decline in soil C/N, C/P, and N/P ratios. Compared with upland soils, paddy soils had higher organic carbon and total nitrogen contents, with a greater increment in organic carbon content, resulting in a higher C/N ratio in paddy soils. In contrast to the substantial spatial variability of C/P and N/P ratios, the soil C/N ratio remained relatively stable with a narrow range of variation, due to the strong coupling between soil organic carbon and total nitrogen contents. Based on the relative magnitudes of the C/N, C/P, and N/P ratios, nitrogen was identified as the primary limiting nutrient for ecosystems in the study area.

Key words: ecological stoichiometry, altitude, land use type, soil property