Monitoring

The Yale School Forests Program monitors the flora and fauna of its lands as part of its management and research activities.

Terrestrial : Continuous Forest Inventory | Vegetation | Birds | Deer

Aquatic: Amphibians | Fish

Invasive Species

Terrestrial

The floristic species diversity of our forest groundstory has increased nearly two-fold over the past 25 years of monitoring. Three hundred and sixty-five angiospermous plant species have been recorded in the groundstory plots.

In the 1980's, regeneration was patchy due mainly to high deer populations in the central and southwestern parts of the forest. Browsing preference was for hemlock, black birch and red oak; white pine was avoided, creating noticeable shifts in regeneration composition. Red oak, though a principle forest canopy tree, was almost absent as advanced regeneration. Since a formal hunting program started, the deer population has dropped from approximately 35 to 20 per square mile. Currently, no obvious browsing preference can be detected and regeneration is abundant for all major tree species. Where stand conditions merit the use of shelterwood systems, red oak regeneration establishment is vigorous and abundant.

Lastly, standing snags and fallen coarse woody debris structures have increased in size class and distribution with the use of regeneration methods and with the development of older age classes of stands.

Continuous Forest Inventory

The Yale Forests collects continuous forest inventory to track long-term changes in forest-wide standing tree volumes. The 2004 CFI for the Yale Myers Forest shows a decrease in merchantable timber volume for the first time since the data has been collected. This is due in part to the redistribution of age classes resulting from the current emphasis on regeneration harvests, and possibly to reduced eastern hemlock increment growth as the result of infestation by the hemlock woolly adelgid.

  Standing Volume, 1993 Standing Volume, 2004 Harvested, 1994-2004 Net Change
Oak 14.7 12.9 1.3 -1.8
Pine 9.3 12.0 1.4 +2.7
Hemlock 13.3 12.1 1.0 -1.2
Other Hardwoods 9.3 6.2 0.4 -3.1
Total 46.6 43.2 4.1 -3.4

Measured in million board feet of merchantable sawtimber. Totals are for 5,808 acres of production forest.

Vegetation

Woody and non-woody vegetation at Yale Myers Forest is currently monitored through a series of 400 permanent plots located throughout the forest. These plots were developed in 1986 as part of a long-term research effort to track floristic changes in relation to forest management practices, and are re-sampled on an approximately 10 year cycle. When identified during these periodic vegetation inventories, in consultation with Yale School Forests staff as well as state and regional biodiversity experts, areas that contain rare, threatened and endangered plant species are incorporated into our reserve system.

Data from these plots identify 31 tree species currently present at the forest. Dominant species include red oak, red maple, eastern hemlock, black birch, white pine and sugar maple. Importance values for all tree species from the 1996 survey are shown in the table below.

A total of 181 herbaceous understory species were identified during the 1996 survey. The number increased by approximately 20% during the 2004 survey. This increase was due in part to a more refined protocol for identifying graminoid species, and a greater abundance of early-successional species resulting from regeneration treatments over the last decade.

The density of snags and volume of coarse woody debris has also increased, with snag density being above the 12 snags per hectare average required by the forest’s Best Management Practices.

The above trends can be related to three primary factors:

  1. The continued succession of the forest from the stem exclusion to understory reinitiation stage of stand development.
  2. Reduced impact of deer herbivory.
  3. Fifteen years of seed tree, shelterwood and selection-based silvicultural prescriptions that have created more heterogeneous stand structures, compositions and age classes.
Tree Species at the Yale Myers Forest and Their Relative Importance
Common Name Scientific Name Importance Value Common Name Scientific Name Importance Value
           
Red Oak Quercus rubra 35.0 Musclewood Carpinus caroliniana 0.8
Red Maple Acer rubrum 29.6 Mockernut Hickory Carya tomentosa 0.6
Eastern Hemlock Tsuga canadensis 26.9 American Beech Fagus grandifolia 0.5
Black Birch Betula lenta 20.5 Black Gum Nyssa sylvatica 0.5
White Pine Pinus strobus 18.1 Swamp White Oak Quercus bicolor 0.3
Sugar Maple Acer saccharum 17.0 Red Pine Pinus resinosa 0.3
Snags Necrodendron erectus 15.5 Hophornbeam Ostrya virginiana 0.3
White Oak Quercus alba 13.3 Flowering Dogwood Cornus florida 0.2
American Ash Fraxinus americana 10.4 American Chestnut Castanea dentata 0.2
Black Oak Quercus velutina 7.8 Striped Maple Acer pennsylvanicum 0.2
Paper Birch Betula papyrifera 5.8 Slippery Elm Ulmus rubra 0.2
Pignut Hickory Carya glabra 4.3 Big-Tooted Aspen Populus grandifolia 0.2
Shagbark Hickory Carya ovata 4.2 Norway Spruce Picea abies 0.2
Yellow Birch Betula alleghaniensis 4.1 American Basswood Tilia americana 0.2
Black Cherry Prunus serotina 2.9 Bitternut Hickory Carya cordiformis 0.2
Tulip Poplar Liriodendron tulipfera 0.8      

 

Birds

A study of the birds of the Yale Myers Forest is currently underway.

Deer

The deer population at the Yale Myers Forest is managed by the Connecticut Department of Environmental Protection.

Aquatic

Since the reintroduction of beaver in the 1960's, the wetland habitat at the Yale Myers Forest has increased from 5% to 15% of the forest area, and presently more than 30 wetlands are occupied by over 100 resident beaver. The alteration of the surface hydrology by the amount and size of flooding from beaver has diversified wetland habitats by promoting open- and closed-canopied swamps.

Today, the wetlands face two major management issues:

  1. Since 1983, phragmites has invaded certain open cattail swamps and poses a problem as an exotic invasive species.
  2. Forest cover around vernal pools and small wetlands has increased, which has changed both light availability and temperature. This, in turn, has shifted the species composition of the aquatic fauna and flora such that wetland systems have moved from being relatively species-rich and autotropic to relatively species-poor and ombrotrophic.

The management regimes in the forest are focused on reversing some of these trends in certain circumstances to diversify wetland habitat.

Amphibians

Since 1996, members of the Skelly Laboratory have been conducting research on the amphibians of Yale Myers Forest. Research activities have included surveys and monitoring that have documented the locations of more than 100 vernal ponds, the presence and absence of amphibian species, and for 2 species, wood frogs (Rana sylvatica) and Spotted Salamanders (Ambystoma maculatum), estimates of population density. The number of ponds visited each year has varied from a minimum of around 10 in the earlier years to around 60 per year in recent years.

Our findings have revealed 10 amphibian species associated with vernal ponds. Some, like spotted salamanders, wood frogs, four toed salamanders (Hemidactylum scutatum), and marbled salamanders (A. opacum) are obligately associated with vernal ponds. Other species such as gray treefrogs (Hyla versicolor), red-spotted newts (Notophthalmus viridescens), and spring peepers (Pseudacris crucifer), have breeding populations in some vernal ponds but are capable of breeding in other varieties of freshwater environments. Still others such as bullfrogs (R. catesbeiana), green frogs (R. clamitans), and pickerel frogs (R. palustris) are seasonal or casual visitors, often acting as predators on species with breeding populations in vernal ponds. Occasionally, green frogs will breed in vernal ponds. If the year is wet enough and the pond retains water through the winter this species can survive to metamorphosis in spite of its 8 to 12 month long larval period.

The species complement at Yale Myers is what would be expected for an undisturbed environment in south central New England. There are no surprising gaps in the species list (missing species include state listed taxa such as blue-spotted salamanders, A. laterale). Yale Myers is near the northern range limit for marbled salamanders. Populations are spottily distributed at Yale Myers. Work by a doctoral student, Mark Urban, has shown that Yale Myers populations are associated with spring fed vernal ponds. Springs may help to elevate wintertime temperatures underneath the ice - critical for this species which hatches out in the fall and survives as free swimming larvae in the winter. Population density studies of wood frogs and spotted salamanders reveal expected variation in numbers from year to year (amphibians are notorious for having variable population densities). However overall patterns in population densities offer no concerns, since population densities show no evidence of downward trends. Overall, our amphibian studies, coupled with studies of nearby areas outside Yale Myers show that the Forest succeeding in acting as a protected area. As an example, the number of species per pond is roughly twice as high at Yale Myers compared to Manchester, Connecticut, just a short drive down the highway.

Fish

Fish populations in the streams at the Yale Myers Forest are currently monitored by the Connecticut Department of Environmental Protection. Surveys are conducted both at the request of the Yale Myers Forest or by Connecticut DEP. he two most recent surveys were conducted in the summers of 1994 and 2005, and employed non-lethal techniques. A total of 15 fish species were sampled between the two surveys. The 1994 survey found 6 species not tallied in 2005, and the 2005 survey found 2 species not tallied in 1994. These numbers should not be interpreted as an increasing or decreasing trend, as the data come from different stream sampling locations. However, the species present are consistent with well-maintained fast and slow moving stream environments, and include 3 species of native and introduced Salmonids.

Invasive Species

The Yale School Forests program is currently remapping the entire forest, which will include the creation of a catalog of invasive species. The species of concern include phragmites, Asian bittersweet, Japanese barberry, multiflora rose, purple loosestrife and, most importantly, hemlock woolly adelgid (HWA). Phragmites and barberry are widespread in the forest and locally dense, while bittersweet is widespread but not dense. Our current management inhibits expansion of these and other invasives by maintaining natural species control of growing space as much as possible.

One of the most dangerous invasive species we have on the forest in Hemlock Woolly Adelgid. Our HWA populations are monitored by Zander Evans. At Yale Myers, HWA does not appear to be as disastrous a pest as it is in other parts of the state, and the forest has experienced only a small decline in standing volume instead of the massive mortality observed elsewhere. A biological control agent for HWA, Sasajisycymnus tsugae, has been released on state land near the forest and may keep HWA for destroying our hemlocks.

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