An official website of the United States government
Abstract The complex effects of global environmental changes on ecosystems result from the interaction of multiple stressors, their direct impacts on species and their indirect impacts on species interactions. Air pollution (and resulting depletion of soil base cations) and biotic invasion (e.g. beech bark disease [BBD] complex) are two stressors that are affecting the foundational tree species of northern hardwood forests, sugar maple and American beech, in northeastern North America.At the Hubbard Brook Experimental Forest in New Hampshire, a watershed‐scale calcium (Ca) addition in 1999 restored soil Ca that had been lost as a result of acid deposition in a maple‐beech forest that was severely affected by BBD beginning in the 1970s. We present historic data from the reference watershed for BBD progression, 20 years of comparative forest data from the treated and reference watersheds, and tree demographic rates for the most recent decade. We hypothesized that mitigation of soil acidification on the treated watershed in the presence of BBD would favour improved performance of sugar maple, a species that is particularly sensitive to base cation depletion.We observed significant responses of seed production, seedling bank composition, sapling survival and recruitment, and tree mortality and growth to the restoration of soil Ca, indicating that acid rain depletion of soil base cations has influenced demographic rates of maple and beech. Overall, the reduced performance of sugar maple on acidified soils may indirectly favour the persistence of diseased beech trees and a greater abundance of beech vegetative sprouts, effectively promoting the chronic presence of severe BBD in the population.Synthesis. The shifting conditions created by global change have altered long‐term demographic rates and may thereby impact competitive interactions in the current centre of these species ranges and have more profound implications for species persistence and migration potential than previously anticipated.
more »
« less
Hubbard Brook Experimental Forest: Seedling bank – watershed 1 and watershed 6 (2018)
The understory layer is complex and includes groups of stems with distinctly different chances of survival and recruitment to the sapling size class. We explored how calcium amendment has impacted the trajectory of the seedling bank at Hubbard Brook Experimental Forest. The density of all tree stems in the seedling bank in 2018 (19 years after treatment) was greater in CAL (Watershed 1; calcium treatment) than REF (Waterhsed 6; reference) and beech was more abundant than sugar maple in both watersheds. In terms of relative abundance, the treatment had the opposite effects on the two species: the relative density of sugar maple was significantly greater in CAL than REF while the relative density of beech was significantly less. In terms of beech stem origin, Beech sprouts were more abundant than seedlings on both watersheds; however, beech stems of seed origin were more abundant on CAL (mean±1SE: 4.06±0.49 seedlings m-2) than REF (2.98±0.42), while sprouts were fewer (CAL: 14.4±1.30; REF: 20.5±1.47) resulting in the seedling to sprout ratio on CAL (1:3.5) being half that on REF (1:7). The influence on the seedling bank on future composition of these forests remains to be seen. These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station.
more »
« less
- Award ID(s):
- 1637685
- PAR ID:
- 10316989
- Publisher / Repository:
- Environmental Data Initiative
- Date Published:
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
We quantified nitrogen (N) resorption of the two dominant tree species of northern hardwood forests along an elevation gradient using 14 sites at Hubbard Brook Experimental Forest, NH. For these calculations, we also quantified the leaf mass per area for both species, sugar maple and American beech. The original data before averaging for combining with chemistry data is available in an earlier revision of this dataset. Foliar N of sugar maple increased, and N resorption proficiency (NRP) decreased with increasing elevation. In contrast, foliar N and NRP of American beech did not vary significantly with elevation, suggesting that the mechanisms driving patterns of N resorption were distinct between these co-occurring species. While both species exhibited strong correlations between resorption efficiency of C and N, resorption of both elements was much greater for beech than maple. These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station.more » « less
-
Spring and Fall leaf phenology observations have been made at 9 locations at the Hubbard Brook Experimental Forest since 1989. Timing and progression of spring leaf out and fall senescence are recorded for 3 dominant tree species, sugar maple, yellow birch, and beech, in treated and untreated watersheds and high and low elevations. Weekly measurements are taken during the active period of the fall or spring season. These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station.more » « less
-
Tree seeds sorted and counted from long-term reference area litter traps are presented for 1993 until the present. These data are part of the LTER funded quantification of tree annual productivity. Our focal species for seed counts have been sugar maple, American beech and white ash. This data set allows comparison between seed production in reference sites (BB and TF) and the calcium addition watershed (W1) for these species. These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station.more » « less
-
This data set encompasses leaf area and dry weights for collected freshly shot leaves (early August) and fallen leaves (entire leaf fall period) along the elevation gradient of 14 sites used for the nitrogen oligotrophication study at Hubbard Brook Experimental Forest. This data will be used to calculate nutrient resorption along the elevation gradient for sugar maple (collection years: 2020-2022) and American beech (2021-2022). These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station.more » « less
