Responses of the soil phosphorus fraction distribution to a chronosequence and soil depth in deserts undergoing revegetation

AbstractElucidating the changes in phosphorus (P) fractions (available P [A‐P], dicalcium phosphate [Ca2‐P], aluminium‐bond phosphate [Al‐P], iron‐bond phosphate [Fe‐P], octacalcium phosphate [Ca8‐P], deca‐calcium phosphate [Ca10‐P], occluded‐P [O‐P] and organic P [Po]) in revegetated deserts is essential for understanding how P responds to environmental changes in arid regions. To investigate this, we selected a chronosequence of desert revegetation sites (12, 32, 41, 58 and 66 years old) and compared them to a moving dune without plant cover and a naturally vegetated desert. We used non‐metric multidimensional scaling to analyse the similarity among the three types of sites and redundancy analysis to explore the contribution of environmental factors on P fractions. The results showed that revegetation for >41 years significantly improved the total P, A‐P, Ca2‐P, Ca10‐P and Po concentrations in contrast to the moving dune (p < .05). Specifically, Ca8‐P and Po concentrations reached their maximum at 66 years, whereas Al‐P and Fe‐P concentrations reached their maximum at 32 years of revegetation. The Po concentration steadily increased as the number of revegetation years increased. Across a profile of 0–200 cm, two patterns of P fractions in revegetated deserts were found (from 0 to 10 cm: Ca10‐P > Ca8‐P > O‐P > Ca2‐P > Po > A‐P; from 10 to 200 cm: Ca10‐P > O‐P > Po > A‐P), with Ca10‐P accounting for 65%–85% of the total P concentration which suggested that the low bioavailable P fractions throughout the soil profile may have constrained the progress of revegetation efforts in deserts. Soil total nitrogen, soil organic matter and soil organic carbon were important in explaining the variation in P fractions, with a relatively high explanation (>20%, p < .01). This study highlights the positive impact of revegetation on P fractions and their distribution patterns in contrast to moving dunes, and also explores the responses of P to environmental variations.