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Foliar resorption is a principal nutrient conservation mechanism in terrestrial vegetation that could be sensitive to ongoing changes in climate and atmospheric nitrogen (N) deposition. We quantified N resorption in northern hardwood forests along an elevation gradient of decreasing temperature and increasing soil N availability to evaluate how this critical nutrient cycling process can be expected to respond to global and regional environmental changes. Foliar N resorption proficiency (NRP) increased significantly at lower elevations for both sugar maple and American beech, the dominant species in these forests. Foliar N resorption efficiency (NRE) also decreased with increasing elevation, but only in one year. Both species exhibited strong negative relationships between NRP and soil N availability. Thus, we anticipate that with climate warming and decreasing N inputs, northern hardwood forests can be expected to exhibit stronger N conservation via foliar resorption. Both species also exhibited strong correlations between resorption efficiency of N and C, but resorption of both elements was much greater for beech than sugar maple, suggesting contrasting mechanisms of nutrient conservation between these two widespread species.
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This content will become publicly available on October 1, 2026
Patterns of Herbivory and Resource Utilization of Tree Seedlings Along an Altitudinal Gradient
In montane areas, climate change can shift tree species distributions upslope over time which can affect forest ecosystem structure and functioning. Seedlings of low-elevation temperate broadleaf trees establishing beyond their ranges at high elevations need to overcome both herbivore pressure and soil nutrient limitations. To assess the influence of these two stressors, we quantified leaf and stem herbivory, soil and foliar nutrient status, and two-year survival of experimentally grown seedlings of two hardwood species, sugar maple (Acer saccharum) and American beech (Fagus grandifolia) along elevation gradients in the Green Mountains of Vermont, USA. While insect foliar herbivory was reduced on maple seedlings growing beyond range boundaries, suggesting enemy escape, the opposite pattern was observed for beech. Mammalian browsing increased with elevation for both species. In general, foliar nutrient concentrations and resource utilization (that is, the relationship between soil nutrient availability and foliar nutrient status) declined with elevation for both species (although more so for maple, especially calcium), while toxic foliar aluminum concentrations increased for maple. Survival decreased with elevation for both species, but especially for sugar maple, linked more to declining foliar nutrient status than herbivory at higher elevations. Thus, the effects of herbivory and nutrient utilization on seedling survival can be critical for shaping tree species range shifts and, ultimately, species composition and forest ecosystem functioning.
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- Award ID(s):
- 1759724
- PAR ID:
- 10628312
- Publisher / Repository:
- Springer Nature
- Date Published:
- Journal Name:
- Ecosystems
- Volume:
- 28
- Issue:
- 5
- ISSN:
- 1432-9840
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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