Impacts of culling and exclusion of browsers on vegetation recovery across New Zealand forests

David Wright, Andrew Tanentzap, Olivier Flores, Sean Husheer, Richard Duncan, Susan Wiser, David Coomes

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

Introduced browsing animals negatively impact New Zealand’s indigenous ecosystems. Eradicating introduced browsers is currently unfeasible at large scales, but culling since the 1960s has successfully reduced populations to a fraction of their earlier sizes. Here we ask whether culling of ungulates has allowed populations of woody plant species to recover across New Zealand forests. Using 73 pairs of permanent fenced exclosure and unfenced control plots, we found rapid increases in sapling densities within exclosures located in disturbed forests, particularly if a seedling bank was already present. Recovery was slower in thinning stands and hampered by dense fern cover. We inferred ungulate diet preference from species recovery rates inside exclosures to test whether culling increased abundance of preferred species across a national network of 574 unfenced permanent forest plots. Across this network, saplings were observed irrespective of their preference to ungulates in the 1970s, but preferred species were rarer within disturbed sites in the 1990s after long-term culling and despite nationwide increases in sapling densities. This indicates that preferred species are relatively heavily affected by browsing after culling, presumably because remaining animals will increase consumption of preferred species as competition is reduced. Our results clearly suggest that culling will not return preferred plants to the landscape immediately, even given suitable conditions for regeneration. Complete removal of ungulates rather than simply reducing their densities may be required for recovery in heavily browsed temperate forests, but since this is only feasible at small spatial scales, management efforts must target sites of high conservation value.
Original languageEnglish
Pages (from-to)64-71
Number of pages8
JournalBiological Conservation
Volume153
DOIs
Publication statusPublished - 2012
Externally publishedYes

Fingerprint

culling (plants)
culling
ungulate
ungulates
vegetation
sapling
saplings
browsing
animal
woody plant
fern
temperate forests
temperate forest
rare species
woody plants
ferns and fern allies
food choices
thinning (plants)
thinning
animals

Cite this

Wright, David ; Tanentzap, Andrew ; Flores, Olivier ; Husheer, Sean ; Duncan, Richard ; Wiser, Susan ; Coomes, David. / Impacts of culling and exclusion of browsers on vegetation recovery across New Zealand forests. In: Biological Conservation. 2012 ; Vol. 153. pp. 64-71.
@article{26c007d69ff24d9892d33b7814d3f300,
title = "Impacts of culling and exclusion of browsers on vegetation recovery across New Zealand forests",
abstract = "Introduced browsing animals negatively impact New Zealand’s indigenous ecosystems. Eradicating introduced browsers is currently unfeasible at large scales, but culling since the 1960s has successfully reduced populations to a fraction of their earlier sizes. Here we ask whether culling of ungulates has allowed populations of woody plant species to recover across New Zealand forests. Using 73 pairs of permanent fenced exclosure and unfenced control plots, we found rapid increases in sapling densities within exclosures located in disturbed forests, particularly if a seedling bank was already present. Recovery was slower in thinning stands and hampered by dense fern cover. We inferred ungulate diet preference from species recovery rates inside exclosures to test whether culling increased abundance of preferred species across a national network of 574 unfenced permanent forest plots. Across this network, saplings were observed irrespective of their preference to ungulates in the 1970s, but preferred species were rarer within disturbed sites in the 1990s after long-term culling and despite nationwide increases in sapling densities. This indicates that preferred species are relatively heavily affected by browsing after culling, presumably because remaining animals will increase consumption of preferred species as competition is reduced. Our results clearly suggest that culling will not return preferred plants to the landscape immediately, even given suitable conditions for regeneration. Complete removal of ungulates rather than simply reducing their densities may be required for recovery in heavily browsed temperate forests, but since this is only feasible at small spatial scales, management efforts must target sites of high conservation value.",
keywords = "Diet-switching, Fern layers, Forest recovery, Herbivory, Plant–herbivore interactions, Ungulate.",
author = "David Wright and Andrew Tanentzap and Olivier Flores and Sean Husheer and Richard Duncan and Susan Wiser and David Coomes",
year = "2012",
doi = "10.1016/j.biocon.2012.04.033",
language = "English",
volume = "153",
pages = "64--71",
journal = "Biological Conservation",
issn = "0006-3207",
publisher = "Elsevier BV",

}

Impacts of culling and exclusion of browsers on vegetation recovery across New Zealand forests. / Wright, David; Tanentzap, Andrew; Flores, Olivier; Husheer, Sean; Duncan, Richard; Wiser, Susan; Coomes, David.

In: Biological Conservation, Vol. 153, 2012, p. 64-71.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Impacts of culling and exclusion of browsers on vegetation recovery across New Zealand forests

AU - Wright, David

AU - Tanentzap, Andrew

AU - Flores, Olivier

AU - Husheer, Sean

AU - Duncan, Richard

AU - Wiser, Susan

AU - Coomes, David

PY - 2012

Y1 - 2012

N2 - Introduced browsing animals negatively impact New Zealand’s indigenous ecosystems. Eradicating introduced browsers is currently unfeasible at large scales, but culling since the 1960s has successfully reduced populations to a fraction of their earlier sizes. Here we ask whether culling of ungulates has allowed populations of woody plant species to recover across New Zealand forests. Using 73 pairs of permanent fenced exclosure and unfenced control plots, we found rapid increases in sapling densities within exclosures located in disturbed forests, particularly if a seedling bank was already present. Recovery was slower in thinning stands and hampered by dense fern cover. We inferred ungulate diet preference from species recovery rates inside exclosures to test whether culling increased abundance of preferred species across a national network of 574 unfenced permanent forest plots. Across this network, saplings were observed irrespective of their preference to ungulates in the 1970s, but preferred species were rarer within disturbed sites in the 1990s after long-term culling and despite nationwide increases in sapling densities. This indicates that preferred species are relatively heavily affected by browsing after culling, presumably because remaining animals will increase consumption of preferred species as competition is reduced. Our results clearly suggest that culling will not return preferred plants to the landscape immediately, even given suitable conditions for regeneration. Complete removal of ungulates rather than simply reducing their densities may be required for recovery in heavily browsed temperate forests, but since this is only feasible at small spatial scales, management efforts must target sites of high conservation value.

AB - Introduced browsing animals negatively impact New Zealand’s indigenous ecosystems. Eradicating introduced browsers is currently unfeasible at large scales, but culling since the 1960s has successfully reduced populations to a fraction of their earlier sizes. Here we ask whether culling of ungulates has allowed populations of woody plant species to recover across New Zealand forests. Using 73 pairs of permanent fenced exclosure and unfenced control plots, we found rapid increases in sapling densities within exclosures located in disturbed forests, particularly if a seedling bank was already present. Recovery was slower in thinning stands and hampered by dense fern cover. We inferred ungulate diet preference from species recovery rates inside exclosures to test whether culling increased abundance of preferred species across a national network of 574 unfenced permanent forest plots. Across this network, saplings were observed irrespective of their preference to ungulates in the 1970s, but preferred species were rarer within disturbed sites in the 1990s after long-term culling and despite nationwide increases in sapling densities. This indicates that preferred species are relatively heavily affected by browsing after culling, presumably because remaining animals will increase consumption of preferred species as competition is reduced. Our results clearly suggest that culling will not return preferred plants to the landscape immediately, even given suitable conditions for regeneration. Complete removal of ungulates rather than simply reducing their densities may be required for recovery in heavily browsed temperate forests, but since this is only feasible at small spatial scales, management efforts must target sites of high conservation value.

KW - Diet-switching

KW - Fern layers

KW - Forest recovery

KW - Herbivory

KW - Plant–herbivore interactions

KW - Ungulate.

U2 - 10.1016/j.biocon.2012.04.033

DO - 10.1016/j.biocon.2012.04.033

M3 - Article

VL - 153

SP - 64

EP - 71

JO - Biological Conservation

JF - Biological Conservation

SN - 0006-3207

ER -