Dome Island: a reserve for uninterrupted natural processes

Lake George’s Dome Island has a rich history dating back to its formation during the last glacial period over 10,000 years ago. Since then, many peoples have resided in the area, such as the Abenaki and Haudenosaunee, followed by the European settlers. Dome also has a rich research history dating back to around 1956 when John Apperson donated the island to The Nature Conservancy to become a reserve for uninterrupted natural processes. For the past two years, Skidmore students and faculty, partnered with TNC, have been studying these natural processes with a focus on the relationship between the trees and soil of the island. Dome’s unique history of preservation allows for a multitude of research questions that Skidmore students hope to continue to explore! 

Around 650 million years ago, the Lake George basin was formed by the stretching of the continent’s crust. The rifting of the crust caused the basin to be displaced, creating a basin around 1500 feet deep. 1.6 million years ago there were a multitude of glaciers over the region, specifically the Laurentide ice sheet, the last of which receded around 10,000 to 12,000 years ago, leaving behind a buildup of materials that dammed the basin, allowing it to fill with water, thus forming the lake.  

There is  some uncertainty  as to who the first European to visit Lake George was, the possibilities being either Samuel de Champlain in the early 1600s or Father Isaac Jones in the mid 1600s.

There were many wars that took place in the 1700s: King George's war, the French and Indian war, and most importantly, the American Revolution. It is likely that Dome was used for scouting expeditions during these times and musket parts have been recovered on the island

After the Revolutionary War, Dome and other Lake George islands were acquired by the state of New York.

Bolton held its first town meeting.

The county was established and had a main export of lumber, and although there is no evidence that Dome was ever harvested, there is the possibly that some trees were cut down. 

The state granted the island to William Smith, who passed it off to his daughter.

William Smith's daughter passed the island to Stephen S. Wendell.

Sexton, a banker, encouraged Union College students to use the island for recreation, which could have led to increased shoreline erosion from landings. At one point in time there was a huge Union College banner on the island.

There was an increase in Lake George's water level, increasing shoreline erosion on Dome and other islands.

On the west side of the island there was a landslide, and out of fear of further erosion, John Apperson riprapped that side of the island.

Upwards of 130 tons of stone was taken to the island for further shoreline protection.

Lucy A. S. Giese and Horicon Realty Corp. held the island for a short periods of time.

Two Dome Island post cards with a flagpole on the south end of the island.

[image of postcard]

McCaddon acquired the island from Horicon Realty Corp.

Apperson purchased Dome island for $4,500 (or $85,000 today). During his ownership, poison ivy was introduced in the hopes of it helping to prevent shoreline erosion. Chestnuts were also planted on the island.

Apperson donated the island to TNC, where he wanted it to be a place of "uninterrupted natural processes".

There is a long history of research that was completed on Dome Island, ranging from botany to ecosystem science, and history to aquatic systems!

Breisch, one of the main researchers on Dome Island, has studied its vegetation and species composition and its change for nearly 50 years.

The presence of hemlock woolly adelgid (HWA) was detected on Dome. Currently, there are around 1950 hemlocks on Dome, comprising 31.4% of the Islands basal area (BA). BA refers to the area covered by a tree stem, basically the area of the cross-section of the tree.

During the Fall semester of 2019, students Sebastian Gatton and Samuel Sheppard conducted spatial research on Dome Island as part of their Senior capstone project. They georeferenced trees on a small portion of the island and measured their diameter. Other spatial analysis tools such as  Ripley’s K  and  Nearest Neighbor Index , were used to quantify the spatial aggregation patterns of overstory trees with respect to species and size class. Since the study area was not the entire island, research for the remaining area was conducted during the summer of 2020.

What are the spatial relationships between the overstory community and soil biophysical components? How does tree age, distribution, and growth reflect disturbance history and forest dynamics? - Summer 2020 ESS Research Team 

In June of 2020, in the midst of a global pandemic, Sebastian Gatton and Siddharth Nizamuddin traveled to Dome Island to complete the tree dataset. Following all New York State COVID-19 protocols, the two students worked on dome for three weeks straight. They geolocated all 4000+ trees above 10cm on the island, measuring their diameter at breast height (DBH) to judge size, and collecting 250 tree cores.

After all the data had been collected, the tree cores were sent to Eliana and Emme for analysis. The two students analyzed the cores to collect the age and growth rates of the cored trees. The age data was used to analyze the disturbance history of the island, illustrating any large patterns of tree growth. The growth rates, along with the DBH were utilized to create a linear regression model to predict age from the tree’s radius.  

On Dome Island, there are a variety of different conditions, like soil depth and slope aspect, that affect the distribution of trees, particularly by type. With these conditions in mind, Dome has a stark distribution pattern of coniferous trees being located on the western side of the island and along the edges, while deciduous trees tend to be located primarily in center of the island. Below is a web map application that allows you to turn the deciduous and coniferous tree layers on and off to visual this distribution pattern. 

Coniferous tree species are trees that typically produce cones as a method of seed dispersal and whose leaves are small and compact or needle-like. On Dome, coniferous tree species include the Eastern Hemlock, Eastern Red Cedar, and White Pine. Typically, coniferous species have shallow rooting depths in comparison to other tree types, able to grow in shallow and rocky soils. In the case of Dome, the western side of the island, along with island edges, have more shallow soil, providing the conifers with an environmental condition that makes them more competitive than deciduous species.  

Deciduous tree species typically produce seeds with a protective coating, either a fruit or nut and lose their leaves seasonally in the fall. On Dome, there are a total of 19 deciduous tree species: 

• American Beech
• American Chestnut
• American Elm
• Basswood
• Big Toothed Aspen
• Black Cherry
• Sweet Birch
• Cottonwood
• Hornbeam
• Ironwood
• Red Maple
• Red Oak
• Shadbush
• Striped Maple
• Sugar Maple
• Swamp White Oak
• White Ash
• White Birch
• White Oak 

These deciduous or hardwood species are clustered on the center portion of the island where the soils tend to be deeper. Due to this prime location, there is also likely a lot of competition between the hardwoods, thus resulting in a “bald-spot” on Dome Island, where the trees are less dense. 

From the Ripley’s K and Nearest Neighbor Index mentioned above, students were able to determine how trees on the island were spatially distributed by size. Smaller trees, ranging from 10cm to 40cm, were clustered on a small scale, meaning that these trees likely established in forest gaps from disturbance. Larger trees, around 40cm to +60cm, were not aggregated on a small scale, meaning that they tend not to be grouped with each other at closed range. However, these large trees are aggregated on a large scale, representing likely a larger disturbance event that occurred in the past. 

As mentioned, 254 tree cores were collected on Dome Island. These cores are a sample about the size of a thin straw that was taken from the bark to the center of each of these trees. By doing so, the tree rings are exposed and can be counted, giving age, and measured, giving growth rate. This information allows us to analyze the history of these trees, and thus begin to interpret the land use and growth history of Dome Island. Pairing the data from each core with the total diameter of each tree determines how much that tree grew in size each year. With both of these measurements, we can begin to uncover the past.

By accumulating the measurements between each ring, we are able to create chronological growth charts for Dome island and predictive regression models for age-diameter relationships. The predictive regression models are based off of radial growth and are for the five most common species on the island. These regression charts utilize the cumulative ring measurements and use those increments to predict age. The chronological growth charts allow us to analyze the possible disturbance histories for parts of the island. These charts show the growth in five main areas of the island because trees in similar geographic areas will have experienced similar disturbances and general growth conditions. Human instinct urges us to look for large scale correlations and trends, such as the prediction that older trees are larger in size. While some trends are found and we can see patterns on large scales, our data highlights the variation of growth between species and even individuals of the same species growing under different conditions. This variation can be explained by the understanding that trees grow differently based on their environmental conditions. These growth conditions include space, competition, water, nutrients, and light availability. In addition to environmental factors, different species have varying ability to grow in different conditions. 

Tree Age Regressions

Variation of tree growth within species is explicitly shown in our regression equations that predict age. By looking at these graphs, we can begin to explore how trees grow. In each of these graphs there are trees that are of similar age but vary in radius (and thus DBH). In the case of the eastern hemlock, the relationship between light availability and size can be observed. Hemlocks are shade tolerant, meaning that it can reside in the shaded understory for a long period of time with little change in size but if the canopy opens, they will release and we will see a rapid increase in growth. More shade intolerant species are unable to survive in the shade and therefore we see less of this slow growth and release pattern present in the shade tolerant species. Shade tolerant species, like the hemlock, have lot of variation due to the different conditions experienced by these trees and whether they have yet to release. Other species on Dome Island can experience this same phenomenon but not as strongly and thus we are able to create a strongly correlated regression model while for the hemlock we are not. The relationship between age and size is not always clear - and rightly so: a perfect correlation would mean we have overlooked the natural variation found in ecosystems. Even so, there is a huge opportunity to use the information we have to refine the growth - age regression model to attempt to accurately predict age for a variety of species on Dome Island. The Dome Island project has, for decades, been an ongoing project building on previous knowledge, and this is one topic that shows potential for future work.

Cumulative Growth

Similar to the regression graphs, growth graphs for specific parts of the Island, or stands, show the growth rate of trees based on the measured distance between rings. Unlike age regression models, the growth graphs show age relative to time, giving us a greater understanding of patterns of growth and not just an individual. When disturbances such as wind, rainstorms, logging, or fire occur they kill trees in the affected area, opening room in the canopy and making growth resources more readily available to the remaining community, allowing for release, expedited growth, and even growth of a new cohort. A section of the island that has experienced one of these large-scale disturbances is the Northern stand. Around 1930 there is large-scale initiation and release in growth of slow growing trees and new growth indicating a disturbance likely occurred in that time period. Although this growth seems to last over multiple years, accounting for error in dendrochronology interpretation, and trees moving from seedlings to DBH (height where we cored) at different rates, there is likely to be variation, and this appears to be a discrete establishment event. On the other hand, the SE and SW stands experienced episodic small-scale disturbance events. This can be things like storms and wind, but it will generally remove a small number of trees. Age related mortality, wind throw, and disease are other examples of small-scale disturbances. In the SE and SW stands, we can see that there is an even spread of establish and growth over the years versus stand 1 where the trees release at one period of time.

In 2019, two student research teams from Skidmore College began studying the island. The first team, composed of students Jacob Adams, Adam Kazas, and Elle Ping, studied nutrient content on the island. Soil cores were collected on a large scale from the island and processed in the lab to identify levels of soil organic matter, root biomass, and other variables. The values gathered were compared to each other, and the students were able to identify which parts of the Dome had high or lower concentrations of these variables. The other team, composed of Zoe Pagliaro and Shay Kolodney, conducted research using the Quick Carbon (QC) app, and drilled holes from 0-15cm and 15-30cm deep to collect soil. This soil was then analyzed with a spectrophotometer in field to identify the carbon content in the soil. The samples were then further analyzed in the lab to get carbon-nitrogen ratios and nitrogen.