The Hemlock Forest is a "keystone community" is the Catskill Mountain region. The forested riparian zone in the deep, cool ravines where the rocky headwaters of Catskill streams arise is dominated by Hemlock stands. Vigorous, healthy Hemlock forests are essential to support the complex aquatic biotic assemblage characteristic of these richly-oxygenated waters. Threats to the integrity of the Riparian Hemlock Forest include both an introduced pest (Hemlock Woolly Adelgid) and increased nitrate inputs from precipitation. With the help of both the NYS DEC and the US Forest Service, we have been able to take a closer look at this integral part of our ecosystem.

Hemlock Woolly Adelgid - Hemlock Woolly Adelgid infestations in the Catskills are evident - and the threat to our hemlock forests is real. Because the woolly adelgid is no small threat, ONHS has established an Adelgid Monitoring and Verification Team. Team members are assigned sub-basins of the Esopus Creek to map the presence of hemlocks and monitor the spread of adelgid infestations.

Map of infestations in the Esopus Watershed | Map of infestations in the Sawkill Watershed

Last year, we corroborated with the NYS DEC to test the effectiveness of biocontrol to limit the spread of adelgids in the Catskills. Predatory beetles (2,500 of them) were released in the vicinity of West Shokan. To date, the beetles have survived and are eating the adelgids. This year we will be able to assess whether they over-winter and are able to reproduce.

Food Web of the Hemlock Forest - ONHS has an on-going project to understand the complex dynamics of this community. By gathering baseline data on organisms at all trophic levels, we will ultimately be able to integrate this information into a model of the Riparian Hemlock Community food web. As more data are available, the model will become a powerful predictive tool for management.

When conditions are favorable, herbivores may reach outbreak levels and cause extensive defoliation in these forests. Organisms at many trophic levels participate in the food web of the Hemlock Forest. We have identified lepidopterous herbivores and hymenopterous parasitoids that are important determinants of population control of these herbivores.

Ectomyccorrhizal fungi - Increased nitrogen levels may retard the establishment and maintenance of the ectomycorrhizal symbiosis that is essential to hemlock vitatlity. Many of the ectomycorrhizal fungi belong to the class Basidiomycetes. The fungal growth stage is composed entirely of thread-like elements (hyphae) that branch throughout the substrate. Trees depend on this complex and permanent union between their roots and hyphae (mycorrhizae). This symbiotic relationship results in the fungus facilitating absorption of nutrients (i.e. phosphorous) and water from the soil and translocating these to the tree, while the tree returns the favor by supplying the fungus with simple sugars. Hyphae are beneficial to the tree in a number of ways: Their growth and branching habit extend the root systems of their host, and also help to bind soil together - reducing any erosion.

The objective of this study is to obtain baseline and time series data on the composition, richness, diversity, equitability, and abundance of ectomycorrhizal fungi in stands of hemlock (Tsuga canadensis) growing in the riparian zone of rocky headwater streams in the Catskill Mountains. Primary emphasis is to quantify the productivity and relative dominance of species of macrofungi (fungi that are visible to the naked eye and that fruit with a fruiting body) known or suspected to form ectomycorrhizae. Ectomycorrhizal health is monitored quantitatively by microscopic examination of hemlock roots.

With the help of two summer interns (funded by the NYS DEC), we have prepared a summary list of macrofungi of old growth hemlock forests of the Catskills, prepared a voucher collection of macrofungi of the Catskills, and established a database and photoarchive of these macrofungi.