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Resource partitioning between ungulate populations in arid environments

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ABSTRACT

Herbivores are major drivers of ecosystem structure, diversity, and function. Resilient ecosystems therefore require viable herbivore populations in a sustainable balance with environmental resource availability. This balance is becoming harder to achieve, with increasingly threatened species reliant on small protected areas in increasingly harsh and unpredictable environments. Arid environments in North Africa exemplify this situation, featuring a biologically distinct species assemblage exposed to extreme and volatile conditions, including habitat loss and climate change‐associated threats. Here, we implement an integrated likelihood approach to relate scimitar‐horned oryx (Oryx dammah) and dorcas gazelle (Gazella dorcas) density, via dung distance sampling, to habitat, predator, and geographic correlates in Dghoumes National Park, Tunisia. We show how two threatened sympatric ungulates partition resources on the habitat axis, exhibiting nonuniform responses to the same vegetation gradient. Scimitar‐horned oryx were positively associated with plant species richness, selecting for vegetated ephemeral watercourses (wadis) dominated by herbaceous cover. Conversely, dorcas gazelle were negatively associated with vegetation density (herbaceous height, litter cover, and herbaceous cover), selecting instead for rocky plains with sparse vegetation. We suggest that adequate plant species richness should be a prerequisite for areas proposed for future ungulate reintroductions in arid and semi‐arid environments. This evidence will inform adaptive management of reintroduced ungulates in protected environments, helping managers and planners design sustainable ecosystems and effective conservation programs.

No MeSH data available.


Indirect density estimates and 95% confidence intervals produced in DISTANCE, stratified by a priori habitat.
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ece32218-fig-0002: Indirect density estimates and 95% confidence intervals produced in DISTANCE, stratified by a priori habitat.

Mentions: All habitat characteristics were higher in the wadi habitat (Wilcoxon rank‐sum test, P < 0.01), except for rock cover, which was lower (W = 78.5, P < 0.01; Appendix S5). Oryx density was higher for the wadi habitat (Fig. 2; Appendix S6) with a selection ratio of 0.74, implying that oryx were three times more likely to select the wadis than the plain. The reverse was true for gazelle, with a selection ratio of 0.29 for the wadi and 0.71 for the plain.


Resource partitioning between ungulate populations in arid environments
Indirect density estimates and 95% confidence intervals produced in DISTANCE, stratified by a priori habitat.
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5016655&req=5

ece32218-fig-0002: Indirect density estimates and 95% confidence intervals produced in DISTANCE, stratified by a priori habitat.
Mentions: All habitat characteristics were higher in the wadi habitat (Wilcoxon rank‐sum test, P < 0.01), except for rock cover, which was lower (W = 78.5, P < 0.01; Appendix S5). Oryx density was higher for the wadi habitat (Fig. 2; Appendix S6) with a selection ratio of 0.74, implying that oryx were three times more likely to select the wadis than the plain. The reverse was true for gazelle, with a selection ratio of 0.29 for the wadi and 0.71 for the plain.

View Article: PubMed Central - PubMed

ABSTRACT

Herbivores are major drivers of ecosystem structure, diversity, and function. Resilient ecosystems therefore require viable herbivore populations in a sustainable balance with environmental resource availability. This balance is becoming harder to achieve, with increasingly threatened species reliant on small protected areas in increasingly harsh and unpredictable environments. Arid environments in North Africa exemplify this situation, featuring a biologically distinct species assemblage exposed to extreme and volatile conditions, including habitat loss and climate change&#8208;associated threats. Here, we implement an integrated likelihood approach to relate scimitar&#8208;horned oryx (Oryx dammah) and dorcas gazelle (Gazella dorcas) density, via dung distance sampling, to habitat, predator, and geographic correlates in Dghoumes National Park, Tunisia. We show how two threatened sympatric ungulates partition resources on the habitat axis, exhibiting nonuniform responses to the same vegetation gradient. Scimitar&#8208;horned oryx were positively associated with plant species richness, selecting for vegetated ephemeral watercourses (wadis) dominated by herbaceous cover. Conversely, dorcas gazelle were negatively associated with vegetation density (herbaceous height, litter cover, and herbaceous cover), selecting instead for rocky plains with sparse vegetation. We suggest that adequate plant species richness should be a prerequisite for areas proposed for future ungulate reintroductions in arid and semi&#8208;arid environments. This evidence will inform adaptive management of reintroduced ungulates in protected environments, helping managers and planners design sustainable ecosystems and effective conservation programs.

No MeSH data available.