Forest area characteristics for metropolitan and nonmetropolitan counties of three northeastern states of the United States

Urban Ecology, 8 (1984) 341-346 Elsevier Science Publishers B .V ., Amsterdam - Printed in The Netherlands

341

Short Communication FOREST AREA CHARACTERISTICS FOR METROPOLITAN AND NONMETROPOLITAN COUNTIES OF THREE NORTHEASTERN STATES OF THE UNITED STATES ROBERT T . BROOKS' and ROWAN A . ROWNTREE' USDA Forest Service, Northeastern Forest Experiment Station ' University o f Massachusetts, Amherst, MA 01003 (U.S.A .) ' College of Environmental Science and Forestry, State University NY 13210 (U.S .A .)

of

New York, Syracuse,

(Accepted 1 June 1984)

ABSTRACT Brooks, R.T . and Rowntree, R .A., 1984 . Forest area characteristics for metropolitan and nonmetropolitan counties of three northeastern states of the United States. Urban Ecol., 8 : 341-346 . Analysis of county-level forest area statistics for 208 counties in New York, Pennsylvania, and Ohio, shows : (a) All counties have substantial forest acreage regardless of the degree of urbanization ; even counties with urban centers are more than 30% forested ; and (b) Forest area distribution by stand-size class shows no clear association with the degree of urbanization in the county .

INTRODUCTION

The traditional notion of the city is of an urban core surrounded by a hinterland of agricultural fields and forest . In the eastern United States this picture has been confused by the disaggregation or decentralization of populations and the shift of associated land uses from urban centers to both adjacent and distant counties . Regional shifts in population (e.g. from 'snowbelt' to `sunbelt') have made the picture even more complex . A straightforward analysis of forest area in counties known to have different levels of urbanization can help clarify gross patterns . Measures of variability provide guides to the regularity in these patterns, and to the degree of confidence that can be placed in generalizations . The proximity of both urban and rural populations to forest resources is of interest to those who assign values to forests that have different characteristics . In this paper, we examine county forest statistics of three northeastern states of the United States for the possible effects of urbanization on forest area and structure . For this analysis, we recognized three categories of counties : (a) those with a major urban center (50 000 people or more) are called `central counties' ; (b) those contiguous to a central county, and economically associated with it, are called `peripheral counties' ; and (c) those falling outside the 0304-4009/84/$03 .00

0 1984 Elsevier Science Publishers B .V.

34 2

boundaries of the metropolitan areas formed by central and peripheral counties are termed 'nonmetropolitan counties' .* The working hypothesis was that forest cover, as a percentage of county area, would be smallest in the central counties, largest in the nonmetropolitan counties, and intermediate in the peripheral counties . To evaluate this hypothesis, we compared county forest area statistics for the three urbanization categories . We also examined stand-size, a measure of forest age, for an indication of the effects of urbanization on forest structure . METHODS

We selected three contiguous states in the northeastern United States for analysis : New York, Ohio, and Pennsylvania (Fig . 1) . Although they are not a true sample, these states represent a range of conditions in the eastern deciduous forest region . Current and chronologically equivalent forest resource data are available for New York (Considine and Frieswyk, 1982), Ohio (Dennis and Birch, 1981) and Pennsylvania (Considine and Powell, 1980) . Overall, these states are 61, 27 and 58% forested, respectively, with stands : (a) at least 10% stocked with trees of any size ; (b) greater than 1 acre (0 .4 ha) in area ; and (c) having no competing land uses . These criteria exclude most urban land with tree cover such as street trees or trees on residential lots and in parks . In each state, sawtimber-size acreage is predominant and poletimber and small-size stands are roughly, equally common. Of the 217 counties in these three states, forest area data are unavailable for nine counties of metropolitan New York City, Philadelphia and Cleveland. For each of the remaining 208 counties, we collected data on : (a) total area; (b) total forest area ; (c) area of commercial forest land (forest land producing more than 20 cubic feet per acre (-1 .4 m3 /ha) annually and not reserved from utilization) ; and (d) stand-size distributions (based on dominant size class of tree stems) - sawtimber-size, poletimber-size, or small-size stands - of commercial forest land . Each of the 208 counties was assigned to one of the urbanization categories yielding 37 central counties, 49 peripheral counties, and 122 nonmetropolitan counties (Fig . 1) . Average forest area values were calculated for each urbanization category and by state within each category . To eliminate the effect of different county areas, we standardized all statistics as percentages of either total county area or of county commercial forest area . Variation is presented as the coefficient of variation . `Counties are geopolitical units common to most states in the United States . The U .S . Bureau of the Census divides all counties into those having cities of 50 000 people or more, called `central cities' ; those contiguous to and economically tied to the central city, which with it compose a Standard Metropolitan Statistical Area (SMSA) ; and the remaining counties outside SMSA's . For the three states in this study, there are 36 SMSA's (U .S . Bur. Census, 1980) .

. Fig . 1 . Map of New York, Pennsylvania, and Ohio counties showing their urbanization category and location in the United States

Excluded

County Classification

0

W

3 44 RESULTS AND DISCUSSION

Forest statistics for New York, Pennsylvania, and Ohio counties show that these highly urbanized states are extensively forested, and that even the most urban counties have considerable forest area, averaging 35% forest cover (Table I) . Counties peripheral to urban centers that include the agricultural hinterland are, on the average, only slightly less forested (33%) . As there is no major difference in county forest area between central and peripheral counties, that portion of our hypothesis stating that forest area increases from central to peripheral counties is not supported . One explanation may be that peripheral counties may contain as much urbanized land as do central counties though the pattern of urbanization may be more dispersed and less obvious in peripheral counties . Variation in county forest cover is greatest (coefficient of variation of 68%) in peripheral counties . This statistic is indicative of the dynamic land development situation commonly associated with lands at the urban fringe . Forest land adjacent to the urban core is easily converted to residential or commercial use . Additionally, agricultural land is often vacated because of financial constraints to continued agricultural use and may revert to forest cover . These patterns of land cover change are not uniform about the urban center but are associated with established transportation routes and development . Consequently, resulting patterns of forest cover are more variable peripheral to the urban center than within the urban core itself where changes in land cover are more uniform . Nonmetropolitan counties are the most forested of the three urbanization categories, with an average of 51% of county area in forest cover . This supports that part of our hypothesis predicting greater forest area in rural areas than in urban areas . Forest area is least variable (coefficient of variation of 51%) in rural counties, indicative of a consistent and relatively stable land cover pattern. Forest stand-size distributions show little difference among the three urbanization categories . Generally, forests of New York, Pennsylvania, and Ohio are second-growth stands resulting from natural reforestation of abandoned farmland or from regeneration following heavy logging of historically forested lands . Sawtimber-size stands dominate the forests of all three urbanization categories with more than 44% of commercial forest area in such stands in each category . The range in proportional area of sawtimber-size stands between the three urbanization categories is only 3 .2% . These stands are only now reaching silvicultural and economic maturity . Poletimber-size and small-size stands share the balance of forest area more or less equally . Poletimber-size stands are slightly more common in nonmetropolitan counties (28%) than in either peripheral (23%) or central counties (24%) . Many of the poletimber-size stands, intermediate in age and diameter, originated when cropland was abandoned during the 1930's .

208

All counties

(29 .3) (28 .5) (72 .7) (50 .6)

(39 .2) (41 .4) (92 .2) (67 .7)

(34 .0)' (47 .1) (75 .7) (59 .5)

43 .7 (57 .8)

61 .8 64.3 32 .1 50.5

44.9 47 .0 17 .3 33 .1

45 .6 44.1 21 .5 35 .3

Percentage of forested county area

area by

(25 .7) (26 .7) (31 .8) (28 .9)

(27 .4) (36 .2) (26 .1) (31 .0)

(30 .7) (35 .1) (28 .3) (34 .5)

45 .0 (30 .5)

40 .9 46 .7 44 .8 44 .4

41 .8 53 .5 47 .0 47 .3

34 .6 51 .2 44 .8 44 .1

Sawtimber

(26 .7) (31 .4) (55 .9) (41 .6)

(29 .0) (50 .4) (54 .3) (46 .2)

(43 .4) (61 .4) (40 .7) (48 .7)

26 .3 (44 .4)

28 .4 33 .0 24 .5 28 .3

27 .8 23 .2 20 .4 23 .2

29 .1 20 .9 22 .7 23 .8

Poletimber

(42 .7) (57 .5) (51 .5) (53 .5)

(44 .0) (50 .6) (47 .8) (48 .5)

28 .6 (50 .7)

30 .6 20 .3 30 .7 27 .3

30 .4 23 .3 32 .6 29 .5

36 .3 27 .9 32 .6 32 .0

Small

(36 .7) (60 .5) (39 .0) (44 .6)

size class, for 208 coun-

Percentage of county commercial forest area by size class

'Coefficient of variation = standard deviation/mean (Freese, 1967, p . 5) .

32 40 50 122

14 13 22 49

Peripheral New York Pennsylvania Ohio Total peripheral

Nonmetropolitan New York Pennsylvania Ohio Total nonmetropolitan

10 12 15 37

Number of counties

Central New York Pennsylvania Ohio Total central

Urbanization category and state

Mean percentage of county area that is forested and distribution of commercial forest ties in three northeastern United States (coefficients of variation in parenthesis)

TABLE I

346

The areal extent of poletimber-size stands will probably remain relatively static, balanced by losses through maturity to sawtimber and gains from smaller diameter stands . Small-size stands are most common in central counties (32%), least common in nonmetropolitan counties (27%), and intermediate in peripheral counties (30%) . These stands originated from more recent land use decisions . They will continue to be common where land development and speculation force abandonment of agricultural cropland . Small-size stands may become more common in rural counties as the increasing value of maturing forest trees induces increased harvesting and regeneration of stands . ACKNOWLEDGEMENTS

We thank Thomas Considine, Clyde Hunt, and Ralph Nyland, and two anonymous reviewers for their constructive reviews of this manuscript . REFERENCES Considine, T .J ., Jr . and Frieswyk, T.S ., 1982 . Forest statistics for New York, 1980 . USDA For . Serv . Resour . Bull . NE-71, 118 pp . Considine, T .J ., Jr . and Powell, D .S ., 1980 . Forest statistics for Pennsylvania, 1978 . USDA For . Serv . Resour . Bull . NE-65, 88 pp . Dennis, D .F . and Birch, T .W ., 1981 . Forest statistics for Ohio, 1979 . USDA For. Se". Resour . Bull . NE-68, 79 pp . Freese, F ., 1967 . Elementary Statistical Methods for Foresters . Agricultural Handbook 317, U .S . Department of Agriculture, Washington, DC, 87 pp . U .S . Bur . Census,. 1980 . State and Metropolitan Area Data Book, 1979 . U .S . Department of Commerce, Washington, DC, 562 pp . U .S . Bur . Census, 1981a. Census of Agriculture 1979 . Vol . I, State and County Data . Part 32, New York . U .S . Department of Commerce, Washington DC, 484 pp . U.S . Bur : Census, 1981b . Census of Agriculture 1979 . Vol . I, State and County Data . Part 35, Ohio U .S. Department of Commerce, Washington, DC, 643 pp . U .S . Bur . Census, 1981c . Census of Agriculture 1979 . Vol . I, State and County Data . Part 38, Pennsylvania. U.S . Department of Commerce, Washington, DC, 523 pp .