Shrubs magnify soil phosphorus depletion in Tibetan meadows: Conclusions from C:N:P stoichiometry and deep soil profiles.
Sci Total Environ
; 785: 147320, 2021 Sep 01.
Article
en En
| MEDLINE
| ID: mdl-33957589
ABSTRACT
Globally, the proliferation of shrubs within grasslands stimulates soil phosphorus (P) cycling and increases topsoil P storage beneath their canopies. However, little is known regarding the impact of shrub encroachment on subsoil P storage, and whether shrubs mediate changes in soil stoichiometry, like increasing P cycling. In grazed meadows on the Tibetan Plateau, soil and roots were sampled to 1 m depth in shrubby Hippophae rhamnoides ssp. sinensis groves and the surrounding grassy areas. Shrubs had higher P content than grasses, but lower CP ratios in their leaves, litter, and roots. Similarly, shrubs had higher microbial P content than grasses, but lower microbial biomass CP and NP ratios in the soil. The larger microbial P stock in the 1 m of soil beneath shrubs responded to the larger root P stock there as well. Thus, both the plants and microbes acquired more P in shrubby areas than in grassy areas by accelerating P mineralization. The greater net production of available P in the topsoil and the synthesis of microbial P throughout the profile under shrubs increased the P solubility. Total P, inorganic P, and organic P stocks were lower under shrubs than under grasses in the top 1 m of soil. This decrease in soil P storage beneath shrubs is most likely attributable to P leaching due to higher P solubility, heavy rainfall, and larger soil gaps. Moreover, shrubs also had larger plant biomass P stock compared to grasses, and thus the depletion of P from the top 1 m of soil was further magnified via plant biomass removal. We concluded that shrubs increase P cycling to overcome the stoichiometric imbalance between their P requirement and the supply in the soil, and the fast P cycling under shrubs magnify P depletion within the rooted soil depth in alpine meadows.
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MEDLINE
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País/Región como asunto:
Asia
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En
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Sci Total Environ
Año:
2021
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Article