Recruitment dynamics mediated by ungulate herbivory can affect species coexistence for tree seedling assemblages
Resource
Taiwania, 62(3), 283-293
Journal
Taiwania
Journal Volume
62
Journal Issue
3
Pages
283-293
Date Issued
2017-09
Date
2017-09
Author(s)
Weng, C.Y.
Hsieh, C.H.
Su, M.H.
Abstract
The best-known mechanism that herbivory affects species coexistence of tree seedlings is negative density-dependency driven by specialist natural enemies. However, in a forest with intense herbivory by non-specialists, what causes a diversifying seedling bank if rare species do not benefit from negative density-dependency in dominant species? We hypothesize that generalist herbivores can cause unevenly distributed species-specific mortality, which mediates recruitment dynamics and therefore affects species coexistence. To answer this question, we conducted a fence-control experiment in a montane cloud forest, Taiwan, and found that herbivorous damages were mainly caused by ungulates, which are generalists. We explored ungulate herbivory effects on recruitment dynamics by censusing tree seedling dynamics for three years. We found that herbivorous damages by ungulates significantly cause seedling death, mostly at their early stage of establishment. The percentage of death caused by herbivory varied among species. In particular, nurse plants and seedling initial height help shade-tolerant species to persist under such intense herbivory. Whereas, deaths caused by other factors occurred more often in older seedlings, with a consistent low percentage among species. We then tested species coexistence maintenance by dynamic modelling under different scenarios of ungulate herbivory. Raising percentages of death by herbivory changes relative species abundances by suppressing light-demanding species and increasing shade-tolerant species. Density-dependent mortality immediately after bursts of recruitments can suppress dominance of abundant species. With ungulate herbivory, fluctuating recruitment further prevent rare species from apparent competition induced by abundant species. Such bio-processes can interact with ungulate herbivory so that long-term coexistence can be facilitated.
Subjects
Dynamic modelling
montane cloud forest
recruitment dynamics
seedling
species coexistence
ungulate herbivory
Type
journal article
File(s)![Thumbnail Image]()
Loading...
Name
index.html
Size
23.24 KB
Format
HTML
Checksum
(MD5):60a15f3482b447e8680ffdb12146518a