Increasing harvest and overexploitation of wild plants for non‐timber forest products can significantly affect population dynamics of harvested populations. While the most common approach to assess the effect of harvest and perturbation of vital rates is focused on the long‐term population growth rate, most management strategies are planned and implemented over the short‐term. We developed an integral projection model to investigate the effects of harvest on the demography and the short‐ and long‐term population dynamics of Harvest had no significant effect on the size‐dependent growth of lianas, but survival rates increased with size. Harvest had a significant negative effect on size‐dependent survival where larger lianas experienced greater mortality rates under high harvest pressure than smaller lianas. In the populations under high harvest pressure, survival of smaller lianas was greater than that of populations with low harvest pressure. Harvest had no significant effect on clonal or sexual reproduction, but fertility was size‐dependent. The long‐term population growth rates of Elasticity patterns were dominated by survival of larger lianas irrespective of harvest treatments. Life table response experiment analyses indicated that high harvest caused the 6% reduction in population growth rates by significantly reducing the survival of large lianas and increasing the survival‐growth of smaller lianas including vegetative reproductive individuals.
It has been proposed that in slow‐growing vertebrate populations survival generally has a greater influence on population growth than reproduction. Despite many studies cautioning against such generalizations for conservation, wildlife management for slow‐growing populations still often focuses on perturbing survival without careful evaluation as to whether those changes are likely or feasible. Here, we evaluate the relative importance of reproduction and survival for the conservation of two bottlenose dolphin (
in the stable population reproductive output is higher, and adult survival is lower; the difference in viability between the two populations is due to the difference in reproduction; reproductive rates are variable, whereas survival rates are relatively constant over time; perturbations on the basis of observed, temporal variation indicate that population dynamics are much more influenced by reproduction than by adult survival; for the apparently declining population, raising reproductive rates would be an effective and feasible tool to reverse the forecast population decline; increasing survival would be ineffective.
Our findings highlight the importance of reproduction – even in slow‐growing populations – and the need to assess the effect of natural variation in vital rates on population viability. We echo others in cautioning against generalizations based on life‐history traits and recommend that population modeling for conservation should also take into account the magnitude of vital rate changes that could be attained under alternative management scenarios.
more » « less- NSF-PAR ID:
- 10016148
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Ecology and Evolution
- Volume:
- 6
- Issue:
- 11
- ISSN:
- 2045-7758
- Format(s):
- Medium: X Size: p. 3496-3512
- Size(s):
- ["p. 3496-3512"]
- Sponsoring Org:
- National Science Foundation
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