Main Goals
- Combine Ecological research skills with principles of Expeditionary Studies with a 6 day backpacking research expedition
- Determine how tree species in the Adirondacks are shifting their ranges, and if climate change could be contributing to such shifts
- Characterize Forest Composition on two Adirondack High Peaks with opposing aspects, Gothics and Big Slide
Data ANALYSIS: CHARACTERIZING forest composition
- DBH used to determine relative dominance of mature species by elevation
- Occurrence of species at plot centers used to calculate relative frequency by elevation
- Plot center distances used to determine density by elevation
- Relative frequency, dominance, and density added to determine importance value for each species by elevation on each mountain
- All calculations made in R
ACPE: striped maple, ACSA:sugar maple, BEAL: yellow birch, FAGR: American beech, TSCA:hemlock, ABBA:balsam fir, PIRU: red spruce
Data ANALYSIS: Logistic Regressions
- Logistic regressions were performed for the frequencies of the four most important species on both mountains: American beech, red spruce, balsam fir, and striped maple
- Regression models were used to predict frequency of each species by age and elevation on each mountain
- For species with a humped regression, the elevation of maximum occupancy was used as the threshold (represented by the horizontal lines)
- For species with linear regressions, a value of 0.4 was used as the threshold for the elevation of the upper/lower range margin (represented by the horizontal lines)
Mature species represented by black lines, juveniles represented by red lines. ABBA-balsam fir, PIRU-red spruce, ACPE-sugar maple, FAGR-American beech
Data ANALYSIS: Calculated Offsets
- The elevation offsets between the mature and sapling thresholds were calculated for each species on both mountains
- The offset values were used to determine how the species range is shifting
Take Homes: Range shifts
- American beech and red spruce shifting upward on both mountains
- Complications of beech bark disease likely causing juveniles to outcompete other shade tolerant species
- Balsam fir prefers higher altitudes, and it is likely that red spruce will start to outcompete fir because of its lower rage margin and upward shift
- Striped maple moving down on both mountains, and overall lack of regeneration of sugar maple on both mountains
- Slight downward shift of balsam fir on gothics with a small upward shift on Big Slide: species is already close to its maximum upper range margin
Take homes: forest composition
- Aspect played an important role in differences in species composition. Big Slide: south facing aspect, Gothics: north facing aspect
- Big slide was dominated by red spruce at 800m, while sugar maple was more prevalent at the same elevation on Gothics
- Big Slide had a much higher concentration of balsam fir over red spruce from 800m-1000m
- Gothics had more spruce than fir, with upper elevations also characterized by the presence of yellow birch (800m-1000m)