Some Plants Develop A Tolerance To Deer

Browsing by overabundant white-tailed deer (Odocoileus virginianus) has altered ecological relationships in forest communities across eastern North America.  Recent work suggests that deer browsing also selects for particular plant defensive traits.  The increased tolerance of historically browsed populations suggests that these populations developed increased tolerance or that historically protected populations lost tolerance over time.  Variation in tolerance traits in native plant species may allow them to persist in the face of rapid ecological change.

An experiment with 26 populations of jewelweed (Impatiens capensis), a common wetland native plant, found that historically browsed populations tolerated being eaten by deer far better than historically protected plant populations.




Related –  Youngest Trees In The Forest Tell The Biggest Story

The largest trees in a forest may command the most attention, but the smallest seedlings and youngest saplings are the ones that are most critical to the composition and diversity of the forest overall.

The patterns of composition and diversity among a forest’s mature trees are largely set by processes that occur in trees’ earliest life stages.  “What we found was that the seedlings are more diverse than the statistical expectations predicted them to be, but the larger trees’ levels of diversity were about the same as the predictions.”

These results are the first quantitative evidence that the earliest life cycle stages of individual trees are more critical than later stages to the overall relative abundances of mature trees in a forest. The findings of this study will be published online in the Proceedings of the National Academy of Sciences this week.

The stronger influence of ecological sorting processes operating at the earliest life cycle stages compared to later life stages, which they quantified, also likely occurs in other highly diverse ecosystems including grasslands and herbaceous plant communities.  The results underscore the importance of support for long-term research as well as the need to investigate the early life stages — for example, the smallest, newly germinated seedlings — where the most critical processes are occurring.  “I think it helps us understand where to focus in order to really understand the biased sorting processes that create the composition and diversity patterns in the forest overall.”