Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 406401
Title Large herbivores may alter vegetation structure of semi-arid savannas through soil nutrient mediation
Author(s) Waal, C. van der; Kool, A.; Meijer, S.S.; Kohi, E.; Heitkonig, I.M.A.; Boer, W.F. de; Langevelde, F. van; Grant, R.C.; Peel, M.J.S.; Slotow, R.; Knegt, H.J. de; Prins, H.H.T.; Kroon, H. de
Source Oecologia 165 (2011)4. - ISSN 0029-8549 - p. 1095 - 1107.
DOI https://doi.org/10.1007/s00442-010-1899-3
Department(s) Resource Ecology
PE&RC
Publication type Refereed Article in a scientific journal
Publication year 2011
Keyword(s) south-african savanna - kruger-national-park - tree recruitment - woody cover - bottom-up - fire - plant - nitrogen - grass - ecosystems
Abstract In savannas, the tree-grass balance is governed by water, nutrients, fire and herbivory, and their interactions. We studied the hypothesis that herbivores indirectly affect vegetation structure by changing the availability of soil nutrients, which, in turn, alters the competition between trees and grasses. Nine abandoned livestock holding-pen areas (kraals), enriched by dung and urine, were contrasted with nearby control sites in a semi-arid savanna. About 40 years after abandonment, kraal sites still showed high soil concentrations of inorganic N, extractable P, K, Ca and Mg compared to controls. Kraals also had a high plant production potential and offered high quality forage. The intense grazing and high herbivore dung and urine deposition rates in kraals fit the accelerated nutrient cycling model described for fertile systems elsewhere. Data of a concurrent experiment also showed that bush-cleared patches resulted in an increase in impala dung deposition, probably because impala preferred open sites to avoid predation. Kraal sites had very low tree densities compared to control sites, thus the high impala dung deposition rates here may be in part driven by the open structure of kraal sites, which may explain the persistence of nutrients in kraals. Experiments indicated that tree seedlings were increasingly constrained when competing with grasses under fertile conditions, which might explain the low tree recruitment observed in kraals. In conclusion, large herbivores may indirectly keep existing nutrient hotspots such as abandoned kraals structurally open by maintaining a high local soil fertility, which, in turn, constrains woody recruitment in a negative feedback loop. The maintenance of nutrient hotspots such as abandoned kraals by herbivores contributes to the structural heterogeneity of nutrient-poor savanna vegetation.
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