Phosphorus is essential for plant growth and ecosystem productivity. In many natural forests, plants rely on soil microbes to release bioavailable phosphorus from organic matter. The PhoD gene, which encodes the key enzyme alkaline phosphatase, is a central marker for this microbial process. Its role in fertilized agricultural systems is well-known, but its distribution and drivers in natural forest ecosystems have remained unclear.
In a study published in Functional Ecology on February 03, researchers from the Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences investigated the spatial distribution characteristics of the PhoD gene and its environmental driving factors in tropical and subtropical forests. They revealed that the abundance of PhoD was primarily shaped by elevation, soil pH, and calcium availability.
Researchers investigated the spatial distribution of the PhoD gene abundance across three 20-hectare forest plots in Yunnan Province, China: the lowland tropical forest of Bubeng, the mid-elevation tropical forest of Nabanhe, and the high-elevation subtropical evergreen broad-leaf forest of Ailaoshan. Using molecular techniques, they quantified PhoD gene abundance and examined its relationship with geographical, soil chemical, and biotic factors.
Researchers observed striking differences in PhoD gene abundance among the three forests. They found that the mid-elevation Nabanhe forest had the highest and most widespread abundance, he lowland Bubeng forest had the intermediate, and the high-elevation Ailaoshan forest had the lowest.
At the regional scale, researchers identified elevation, soil pH, and calcium availability as the top three predictors of PhoD gene abundance. Soil pH consistently emerged as a primary driver at both regional and local scales. The effect of elevation was mediated through changes in soil pH and macronutrient levels (total carbon, nitrogen, and phosphorus). Within individual forests, spatial patterns were linked to variations in soil parent material, which influenced local soil pH and calcium content.
"Our findings demonstrate how elevation-driven environmental changes shape the genetic potential for phosphorus mineralization in soil. Soil pH acts as a consistent filter, constraining the microbial community capable of performing this vital function across different landscapes," said YANG Xiaodong from XTBG, one corresponding author of the study. This study lays an important foundation for predicting how the PhoD gene may respond to climate change.
