Effects of Soil Acidification on Forest Health and Biodiversity
in the Adirondack Mountains
Michael Whalen
SUNY College of Environmental Science and Forestry
Final Report to the Edna Bailey Sussman Foundation, 2016
Introduction
Acid rain is a byproduct of industrial pollution and has acidified the vulnerable mountain soils of the Adirondacks, leaching their beneficial nutrients and adversely affecting trees like sugar maple, (Acer saccharum), an economically important species. Meanwhile, American beech (Fagus grandifolia) has been impaired by Beech Bark Disease (BBD) throughout the region. BBD causes dense root suckering as trees compensate for canopy mortality. These thickets change forest structure, threatening biodiversity. No research to date has investigated soil acidification’s influence on tree susceptibility to disease and the cascading ecological effects on forest health and biodiversity.
In a 2015 study I investigated soil acidification’s effect on understory plant diversity and A. saccharum recruitment. I collected data on the abundance of herbaceous plants and seedlings at 50 Adirondack sites. This data complements soil chemistry data available from USGS for each site. Sites are arranged along an acidification gradient and all contain A. saccharum and F. grandifolia with varying BBD severity.
In the summer of 2016, I conducted new research as an intern under the supervision of Dr. Gregory Lawrence of the USGS New York Water Science Center. My objective was to pursue new research. Expanding on the work done in 2015, I leveraged our existing datasets to determine the combined impacts of soil acidification and disease on forest health. To accomplish this we characterized BBD severity, stand structure, and bird assemblages on 60 plots within the 20 watersheds surveyed in 2015 and on an additional 10 watersheds identified from pervious studies conducted by Dr. Blair Page, Dr. Collin Beier, and Jennifer Yantachka Corman. I hypothesize that acidification increased the susceptibility of F. grandifolia to BBD. Highly acidified F. grandifolia stands will be more infected, denser, and shorter than less acidified stands. Thus, higher acidification will correspond with lower understory herbaceous biodiversity, A. saccharum recruitment, and songbird diversity due to changes in habitat suitability.
Work Completed
Watersheds were selected to represent a gradient of soil chemistry. We were particularly focused on representing a range in calcium availability, which is closely tied to the history of acid rain-mediated acidification. The resultant 30 watersheds represent the range of acidification and calcium availability that exists in Adirondacks.
Plots were selected through a stratified, random process. In each watershed a plot previously sampled for soil chemistry was retained. An additional plot was then selected from a random list of coordinates based on the presence of 30% or more beech trees in the overstory or 16 or more beech per square meter in the understory (definition of a “beech thicket”). This resulted in 1-3 plots per watershed, for a total of 60 plots in 30 watersheds.
Avian point counts were conducted in 3 rounds from late May until early July at each of these plots. Each individual was counted by sight or sound, the time of its detection was recorded, as was the estimated distance to the bird.
Vegetation sampling was time-intensive and so was conducted on only 1 plot per watershed. Plots were selected at random from locations with discrete soil data, unless a “beech thicket” had been identified, in which case this plot was surveyed. Each survey consisted of 16 subplots radiating from the origin of the main plot at the 4 cardinal directions (Figure 1). Each subplot was separated by 20 meters along its respective transect. At each subplot, the point-centered quarter method was conducted in two rounds on trees between 1 and 10 cm in dbh and on trees > 10 cm dbh. For all trees, percent cover of various BBD symptoms was estimated 6 ft up the trunk. For all trees > 10 cm dbh, height class, crown dieback and any specific crown defects were recorded. At the majority of these subplots we also recorded leaf litter depth in 4 locations around the origin. We also used the robel pole method to estimate the vertical density of understory vegetation at the subplot origin.
Figure 1. Vegetation survey design.
Data Collected
Vegetation data collection yielded measures on 3,840 trees, while vertical vegetation structure data was collected on 480 plots. We conducted 180 avian point counts in three rounds at 60 plots with 1,879 birds detected. There were 48 bird species detected (listed in Appendix A).
Future Analysis
Using distance data recorded with each tree we will calculate the density and basal area of each species of tree on each watershed. We will also calculate mean disease severity and type, crown dieback, average mortality, and canopy position for all American beech trees. This data will be analyzed using non-metric multidimensional scaling to detect differences in disease severity between plots. We will also conduct regression analysis to see if various abiotic variables, particularly soil chemistry and acid rain history, affect BBD severity, tree mortality, and crown condition and canopy position.
We will conduct a Bayesian analysis of avian data to determine the probability of detecting each species based on environmental, observer, and survey-specific covariates. With a probability of detection we can then address questions about how BBD, vertical understory structure, canopy composition, and soil chemistry affect differences in avian community composition, abundance, and species richness across the northern hardwood forests of the Adirondacks. These questions will be evaluated using canonical correspondence analysis and generalized linear models.
Future Data Collection
If it is determined that we do not have enough data to accurately determine the probability of detection for our most important avian species, I will, pending funding, conduct a second field season to acquire 3 more rounds of avian data.
Acknowledgements
I would like to thank the Edna Bailey Sussman Foundation for their support and Dr. Gregory Lawrence of USGS for supervising my internship. I would also like to thank my advisors, Dr. Martin Dovciak and Dr. Shannon Farrell for their help in planning my research design. I would like to additionally thank Dr. Blair Page, Dr. Collin Beier, and Jennifer Yantachka Corman for suggesting new plot locations and providing me with previous vegetation, avian, and soil-chemical data with which to evaluate these locations and plan my field season. Thank you to the ESF Adirondack Ecological Center for housing and for lending my team gear. Thank you to the Department of Forestry and Natural Resource Management for gear rentals and to the NYDEC for allowing us to conduct research on state land.
Appendix A.
Table 1. Avian Species Detected in 2016 Adirondack Bird Surveys
Common Name / Latin NameAmerican Crow / Corvus brachyrhynchos
American Goldfinch / Spinus tristis
American Redstart / Setophaga ruticilla
American Robin / Turdus migratorius
Baltimore Oriole / Icterus galbula
Black-and-White Warbler / Mniotilta varia
Black-capped Chickadee / Poecile atricapillus
Black-throated Blue Warbler / Setophaga caerulescens
Black-throated Green Warbler / Setophaga virens
Blackburnian Warbler / Setophaga fusca
Blue Jay / Cyanocitta cristata
Blue-headed Vireo / Vireo solitarius
Broad-winged Hawk / Buteo platypterus
Brown Creeper / Certhia americana
Canada Goose / Branta canadensis
Cedar Waxwing / Bombycilla cedrorum
Chestnut-sided Warbler / Setophaga pensylvanica
Common Loon / Gavia immer
Common Raven / Corvus corax
Dark-eyed Junco / Junco hyemalis
Downy Woodpecker / Picoides pubescens
Eastern Wood Pewee / Contopus virens
Golden-crowned Kinglet / Regulus satrapa
Great Crested Flycatcher / Myiarchus crinitus
Hairy Woodpecker / Leuconotopicus villosus
Hermit Thrush / Catharus guttatus
Magnolia Warbler / Setophaga magnolia
Northern Flicker / Colaptes auratus
Northern Parula / Setophaga americana
Ovenbird / Seiurus aurocapilla
Pileated Woodpecker / Hylatomus pileatus
Red-breasted Nuthatch / Sitta canadensis
Red-eyed Vireo / Vireo olivaceus
Red-headed Woodpecker / Melanerpes erythrocephalus
Red-shouldered Hawk / Buteo lineatus
Rose-breasted Grosbeak / Pheucticus ludovicianus
Ruffed Grouse / Bonasa umbellus
Scarlet Tanager / Piranga olivacea
Swainson's Thrush / Catharus ustulatus
Veery / Catharus fuscescens
White-breasted Nuthatch / Sitta carolinensis
White-throated Sparrow / Zonotrichia albicollis
Winter Wren / Troglodytes hiemalis
Wood Thrush / Hylocichla mustelina
Yellow-bellied Sapsucker / Sphyrapicus varius
Yellow-billed Cuckoo / Coccyzus americanus
Yellow-rumped Warbler / Setophaga coronata