1. Restorative pyric herbivory practices in shrub-encroached grasslands enhance nutrient resource availability and spatial heterogeneity.
- Author
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Canals, Rosa M., Múgica, Leire, Durán, María, and Emeterio, Leticia San
- Subjects
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GRASSLANDS , *ION exchange resins , *PRESCRIBED burning , *RESTORATION ecology , *SPECIES pools , *SHRUBS - Abstract
Pyric herbivory (PH), the combination of prescribed burnings and targeted herbivory, is a promising tool for landscape restoration that emulates historical disturbance regimes. Nitrogen (N) and phosphorus (P) are crucial nutrients for plant growth and although several studies have analysed the single effects of fire or grazers in their availability, the combined effect of both disturbances in the soil nutrient budgets have been rarely considered. This research was planned to analyse the 2-year impact of PH restoration practices on the availability of N and P in two Ulex gallii -encroached grasslands in the Pyrenees. We monitored available forms of N and P for two years using periodic replacements of ion exchange resins to test the hypothesis that mid-term effect of targeted grazing was more relevant than short-term effect of burning. Additionally, we investigated the role of temperature and precipitation on nutrients accumulation and compared its significance to management factors. Burning transformed vegetation and litter into a spatially heterogeneous layer of ash and charred material, which resulted in a variable availability of N and P at the rhizosphere level. After two periods of PH, nutrient availability was higher in soils from grazed plots compared to ungrazed, and the impacts of early burns were scarcely discernible. Nitrate was found to be the most rainfall-dependent nutrient, and grazing also affected its spatial distribution. Our results suggest that the heterogeneous nutrient enrichment enhanced by PH is important for promoting the establishment of a diverse pool of plant species, including both N 2 -fixing and non-fixing species. In these rainy areas, the use of burnings alone, without grazing, may perpetuate the dynamics of N 2 -fixing shrub encroachment. [Display omitted] • N-fixing shrub encroachment occurs in many temperate grasslands and is hard to reverse. • Pyric herbivory (PH) combines prescribed burn and targeted herbivory for ecosystem restoration. • We buried IER bags to study soil nutrients, testing if burned soils gain temporary fertility only with grazing. • PH increased nutrient availability and promoted a diverse range of N and P-rich microsites. • Nitrate pools were more sensitive to changes in precipitation and grazing intensity compared to other nutrients. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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