How big should Reserves be?

Patch reserves will typically be relatively small (tens or hundreds of acres) and will be defined by the extent of the unique resources (rare species, steep slopes, etc.) intended for conservation. The goal and objectives established above for matrix reserves infer that reserve size should be based on the expected extent of natural disturbance events. Natural disturbances are common in southern New England forests, and range from frequent, small disturbances (e.g., annual wind events that disrupt <1 acre of forest canopy) to occasional, catastrophic disturbances (e.g. major windstorms that disrupt as much as 5,000 contiguous acres of forest canopy once every few centuries) (Table 2). Major wind events like tornadoes and hurricanes often disrupt more than 5,000 total acres across the landscape (hurricanes in particular can impact millions of acres), but disturbance is typically not continuous, and historically the largest individual disturbance patches do not appear to exceed about 5,000 acres in this area. EEA supports having a limited number of large reserves of 5,000± acres that represent the diversity of forest ecosystems that occur in Massachusetts.

Table 2.

Comparison of characteristics among infrequent catastrophic disturbances in the Northern Appalachian Ecoregion (adapted from Foster et al. (1998) by Anderson and Bernstein (2003)).

	Tornado	Hurricane	Down- Bursts	Large Fires	Insect Outbreak	Ice Storms	Flood
Maximum Size of Severe Damage Patch (acres	5,000	803	3,400	57-150	?	<5	?
Return Interval (years)	100-300	60-200	?	400-6,000	10	2	20-100

Where should reserves be located, and how many reserves
should there be?

During 2004, forest managers from the EEA agencies worked to identify potential matrix reserve sites that would represent the diversity of forest ecosystems occurring within the relatively un-fragmented forest landscapes remaining in Massachusetts. The EEA effort is based on a fundamental assumption that matrix reserves should occur in relatively un-fragmented forest landscapes where they can be buffered from impacts of human development by working forestlands outside the reserve.

The EEA agencies worked with The Nature Conservancy (TNC) to evaluate relatively un-fragmented forest blocks that had previously been identified in Massachusetts by TNC. A geographical information systems (GIS) analysis was conducted to identify the portion of each matrix block that contained the largest patches of interior forest habitat and that contained the lowest density of roads and transmission lines. This analysis identified 23 sites representing eight different types of forest ecosystems. Each of the 23 sites was ranked according to 11 ecological criteria that were weighted by an expert panel established by EEA (Figs. 1 and 2). Eight of the highest ranked sites were selected to represent ecoregions and ecological land units (ELUs) occurring in Massachusetts (ELUs capture diversity of elevation, geology, and landform).

Figure 1.

Biodiversity Value: Forest Reserve Evaluation Criteria

Figure 2.

Large Reserve Expert Choice Rankings

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This information is provided by the Executive Office of Energy and Environmental Affairs, Office of Policy, Land and Forest