Silviculture Systems

Silvicultural Prescriptions


Conifers

White pine now occupies mostly sandy and glacial outwash soils within the forest. Successful regeneration methods all rely upon natural regeneration through the seed tree regeneration method. About 8-10 seed trees are left per acre but in most cases reserves of smaller pine, or other species are left as individuals or groups for increasing age-class structure, wildlife habitat and/or timber value. Where regeneration does not satisfactorily establish enrichment planting is practiced. In almost all circumstances pine is crop tree pruned and release cleaned at about 25 years (30-40 per acre), followed by several crown thinning. On most pine sites rotations vary between 60 and 80 years.

Hemlock is managed in a diverse set of stand development pathways. Most hemlock stands comprise a scattered oak overstory with hemlock represented in all strata from the understory to the canopy. Selection systems that use groups and/or patches of 1/3 acre in size are the normal method to sustain hemlock on moist sites where adelgid is either less prevalent and/or where hemlock is more resistant. The gap size is enough to create a diversity of regeneration including oak, pine and hemlock. In these circumstances the cutting cycle is about 21 years with 3-4 age classes represented within the stand.

On north and northwest facing slopes hemlock is managed through variants of the strip shelterwood method. Strip width to secure advance regeneration is about the height of the existing canopy. Such methods are new for the management of the forest but will be increasingly used under these circumstances and again where cool moist conditions allow for greater resilience of hemlock to adelgid infestation.

On drier sites hemlock stands are converted to oak-hardwood stands through uniform shelterwoods systems but group reserves of hemlock are left primarily as thermal cover and habitat structure for wildlife. These stands are considered adelgid susceptible because they are south facing or on upland sites.

Hardwoods

There are two primary hardwood stand types - upland and midslope oak stands and valley/mesic maple-ash-tulip poplar stands. Oak stands are usually managed through shelterwoods with closer spacing between parent trees on drier sites (30-40 ft) as compared to midslopes (40-60 ft) and valley sites (50-70ft). This is a reflection of the ability to secure oak regeneration relatively easier on drier sites that can persist for long periods of time in understory conditions (50% survival after ten years). Strong masting years throughout the forest are infrequent (once every ten years) making valley sites very susceptible to poor oak regeneration establishment (few oak seedlings survive in understory conditions on such sites after five years). Oak shelterwoods on valley sites therefore need to be opportunistically planned immediately after heavy mast years with wide-open spacing to promote release from more the shade tolerant competition of the sugar maple.

Oak shelterwoods in almost all cases are planned as irregular systems with the use of single-tree and group reserves that serve to diversify species composition, increase wildlife habitat structure, and/or add additional pre-commercial or unrealized timber value. On mesic sites with sugar maple single-tree reserves of sugar maple are often part of oak shelterwood cuts. Also, in circumstances where prolific advanced regeneration is apparent, uniform and group group shelterwood systems are by-passed in favor of one-cut shelterwoods. On drier oak sites with persistent laurel in the understory, advance regeneration of hardwoods is often lacking - under such circumstances uniform shelterwoods are marked in tandem with site scarification of laurel (or in certain circumstances with the use of prescribed groundstory fires).

For maple-ash-tulip poplar sites uniform shelterwoods are implemented with a relatively closer spacing of masting maple, ash and poplar (30-40 ft) to encourage more sugar maple over shade intolerant ash and poplar. Where adequate regeneration exists of sugar maple one-cut shelterwoods are conducted with reserves of ash and poplar to supplement the regeneration release of maple.

Fields

In certain areas stands are being maintained as meadows and shrublands for diversification of wildlife habitat. This is being done through the use of prescribed fire and through the enrichment planting of selected shrub species important for wildlife forage and cover.
 

Forest Health & Protected Areas Assessments


Four hundred forest health and understory diversity plots were established in 1986 and are remeasured for floristic diversity, woody debris, forest structure, and tree species regeneration at ten-year intervals. These plots taken together assess current stand level conditions of groundstory herbaceous diversity, regeneration, vertical structure and woody debris in relation to current silvicultural prescriptions and management regimes.

The regeneration measurements have helped guide management in assessing regional differences in deer browse impact across the forest, and susceptibility to regeneration failure related to forest light conditions, seed source, and soil type. Groundstory floristic diversity measures have been used to assess and strategically plan for a sensitive areas network within the School Forests. Forest structure and composition and woody debris measures are used to gauge wildlife (bird, amphibian, mammal) habitat suitability. During the last five years the wetlands of the forest have been assessed on the ground and using remotly sensed information. Each year amphibians have been quantified and related to local conditions including factors such as hydroperiod, wetland area, water chemistry, and forest cover. Change in wetland cover has also been documented as a result of the reinvasion of beaver. The seral sequence set up by beaver activities as well as the subsequent decay of their work results in a highly dynamic mosaic of wetland environment that suit different species at different points in their development and decay. Taken together these measures have been used to quantitatively support landscape-level integration of sensitive and special areas (riparian systems and wetlands; biologically unique areas; older forest components; early seral habitat; and recreational viewsheds) into a working forest landscape.

The Yale Myers Forest has been a privately managed forest for nearly 100 years. This time span is relatively rare in the US and, along with an exceptional archival record of monitoring forest change and timber harvest, it is proof of commitment to sustainable management and to the long term protection of the resource. In addition, cutting edge research on the forest has led to changes in management to cater to better understandings of biodiversity conservation and forest dynamics. In particular the forest has been a pioneer to the nation in developing the forest stand dynamics paradigm used in silviculture and in adjusting regeneration methods to differences in site. Site specific understanding of oak in mixed species stands has allowed for some of the most sophisticated silviculture in the nation. Continuous long-term monitoring protocols allow for adjustments and changes in forest management that relate to maintaining and increasing groundstory floristics and wildlife habitat quality.

Identification & Protection of Rare, Threatened, and Endangered Species


No known endangered, threatened or rare species that are Federally listed have been found on the Yale Myers Forest. The State of Connecticut Natural Heritage Program has surveyed the property, as has The Nature Conservancy. Species that these organizations have defined as endangered have been protected. All are within the existing protected areas reserve system of the forest. In addition the following protocols are followed:

1) Continuous long term biodiversity monitoring programs, terrestrial monitoring started in 1978 and aquatic monitoring started in 1996, evaluate the impact of forest management on biodiversity through out the forest on a ten-year and annual basis respectively.

2) Seven-year interval inspections are made by trained students at the stand scale as pre-treatment inventories.

3) Research continues to advance changes and refinements to silvicultural prescriptions to conserve biodiversity.

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