Modeling stem volume growth of Qinghai spruce (Picea crassifolia Kom.) in Qilian Mountains of Northwest China

Abstract

Qinghai spruce (Picea crassifolia Kom.), the dominant species in Qilian Mountains of Northwest China, has an important role in ecological service function, especially in carbon sequestration. The current work simulated stem volume growth of Qinghai spruce at individual and stand levels using a widespread bio-geochemical cycle (BIOME-BGC) model and considering the crown projection area (CPA). CPA was introduced because photosynthesis was only carried out on the vegetation canopy. The results showed that: (1) the CPA-simulated stem volume of individual Qinghai spruce in the three sites fitted well with the observed stem volume; (2) the introduction of CPA corrected the over-predicted stem volume for relatively younger stands and the under-predicted stem volume for relatively older stands in BIOME-BGC; and (3) meteorological factors may be crucial parameters that influence the model accuracy, aside from CPA. Therefore, CPA should be considered in correcting the carbon simulated by BIOME-BGC, and the meteorological data should be improved to obtain high-accuracy BIOME-BGC outputs.