Wetland trends in the Greater Buffalo Area, New York: 1980-2002

              U.S. Fish & Wildlife Service
Wetland Trends in the
Greater Buffalo Area,
New York: 1980-2002
September 2008 U.S. Fish & Wildlife Service
Wetland Trends in the
Greater Buffalo Area,
New York: 1980-2002
September 2008
by
R. W. Tiner, J.Q. Swords, and H.C. Bergquist
U.S. Fish and Wildlife Service
National Wetlands Inventory Program
Northeast Region
300 Westgate Center Drive Hadley, MA 01035 This report should be cited as: Tiner, R.W., J.Q. Swords, and H.C. Bergquist. 2008. Wetland Trends of the Greater Buffalo Area, New York: 1980-2002. U.S. Fish and Wildlife Service, National Wetlands Inventory Program, Northeast Region, Hadley, MA. 17 pp.
The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the
U.S. Fish and Wildlife Service.
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Wetland Trends in the Greater Buffalo Area, New York: 1980 - 2002
TABLE OF CONTENTS
Introduction……………………………………………………………………………………………………… 1
Study Area………………………………………………………………………………………………………… 1
Methods……………………………………………………………��……………………………………………3
Data Sources……………………………………………………………………………………………………………3 Interpretation of Trends ………………………………………………………………………………………………3 Data Analysis and Tabulation…………………………………………………………………………………………3
Results…………………………………………………………………………………………………………… 4
Wetland and Deepwater Habitat Status 2002……………………………………………………………………… 4
Wetland Trends……………………………………………………………………………………………………… 4
Vegetated Wetlands…………………………………………………………………………………………………… 4
Nonvegetated Wetlands……………………………………………………………………………………………… 5
Study Limitations………………………………………………………………………………………………… 15
Summary………………………………………………………………………………………………………… 16
Acknowledgments……………………………………………………………………………………………… 17
References……………………………………………………………………………………………………… 18
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Wetland Trends in the Greater Buffalo Area, New York: 1980 - 2002 1 INTRODUCTION STUDY AREA The U.S. Fish and Wildlife Service’s National Wetlands Inventory Program (NWI) is responsible for mapping the nation’s wetlands and for conducting assessments of wetland trends. The Greater Buffalo area was identified by the Service’s New York Field Office (Cortland) as an area where wetlands may have been significantly impacted by urban development and where information on the current status and recent trends are needed. This locale likely represents western New York’s top area for wetlands alteration by urban development. Consequently, the NWI initiated a local wetland trends study to evaluate the extent of these impacts and to address the status of wetlands in terms of wetland acreage. This report summarizes the study findings and makes government agencies and the public aware of the general status of and recent changes in wetlands of the Greater Buffalo area. Some changes are natural such as vegetation succession, beaver influences, and plant colonization of shallow water, while other changes are human-induced including creation of wetlands and conversion of wetlands to dry land for a variety of purposes. In addition to increasing public awareness of the status of wetlands, the findings may be used by public agencies and private nonprofit organizations to develop wetland conservation strategies that aid regional and local natural resource planning efforts. The study area is located in the Buffalo metropolitan area in western New York. It is represented by a 1,000 square-mile area of land encompassing parts of Erie and Niagara Counties. The study area includes a broad flat area representing part of the former lakebed of Glacial Lake Tonawanda that existed some 10,000 years ago. A series of escarpments cut across the region marking the borders of former lake shores. Lake Erie, the Niagara River, and Niagara Falls mark the western edge of the study area, while other major watercourses in the area include several creeks: Tonawanda, Ellicott, Mud, Buffalo, Cazenovia, and Cayuga. Buffalo, Tonawanda, Lockport, and Niagara Falls are the major cities within the study area. The study area includes 21-1:24,000 NWI maps: Lewiston, Ransomville, Cambria, Lockport, Gasport, Niagara Falls, Tonawanda West, Tonawanda East, Clarence Center, Wolcottsville, Buffalo NW, Buffalo NE, Lancaster, Clarence, Buffalo SE, Orchard Park, East Aurora, Angola, Eden, Hamburg and Colden (Figure 1). Wetland Trends in the Greater Buffalo Area, New York: 1980 - 2002 2 Figure 1. Location of study area in western New York. Note: Holland is not in the study area. Wetland Trends in the Greater Buffalo Area, New York: 1980 - 2002 3 METHODS Wetland trends can be analyzed a number of ways. Two common approaches to determining wetland trends are: 1) statistically based plot sampling and 2) inventory of change. The former requires evaluation of sample plots (e.g., four-square mile plots) randomly selected within a particular geographic area. This method is used for very large geographic areas like major ecoregions, entire states, or the whole country. The latter approach involves conducting an area-wide inventory of wetlands covering multiple time periods. This approach is generally used for small geographic areas where more detailed investigations can be carried out. For this study, we chose the inventory of change approach to evaluate wetland trends. Change detection was done through conventional photointerpretation. We examined aerial imagery to determine wetland trends for two time periods: 1978/81-1994 and 1994-2002. Data Sources The 2002 NWI data were available for this study and served as the foundation for the project. These data were derived by a combination of aerial image analysis and interpreting collateral data sources. Aerial image interpretation was done via computer onscreen techniques. For time one (1980-era), 1978 and 1981 black and white 1:80,000 aerial photos were used; this was the imagery used to produce the original NWI maps for this part of New York state. For time two, 1994 color-infrared one-meter digital imagery was acquired from the New York Cyber Security & Critical Infrastructure Coordination Unit (NYS&C). For the contemporary period (time three - 2002), one-foot resolution true color digital imagery was obtained from NYS&C. These sources allowed an assessment of wetland changes from 1980 to 1994 to 2002. Digital soils data available from the USDA Natural Resources Conservation Service were consulted to help delineate drier-end wetlands (e.g., seasonally saturated flatwoods) that typically are hard to detect through conventional photointerpretation. Interpretation of Trends Changes in wetlands due to both natural and human-induced actions were detected on the imagery by directly comparing the status of wetlands on each set of imagery. An on-screen, “heads up” process was used for detection and delineation. This method required working back in time comparing the 2002 NWI wetlands to the 1994 imagery and the 1994 wetlands to the 1980-era photos. The most current NWI data and the 2002 imagery (from which it was derived) were used as the foundation for the trends assessment.1 The 1980-era imagery was scanned and geo­rectified for computer applications. Wetlands were added, deleted, or their boundaries were reconfigured to more accurately represent their status at the applicable time period. Wetlands and deepwater habitats were classified according to the Service’s official wetland classification system (Cowardin et al. 1979) which is the U.S. national standard for wetland classification (Federal Geographic Data Committee 1996). Wetland changes between 2002 and 1994 were identified by overlaying the 2002 NWI data on the 1994 imagery. The causes of the changes were determined by consulting the 2002 images. The same procedure was used, but with different imagery to assess wetland changes from 1980 to 1994. Each change was digitized, with the cause recorded, creating a trends data layer for each time interval (i.e., 2002-1994 and 1994-1980). Conversions of wetlands to nonwetlands were labeled by their respective land use or land cover classification following Anderson et al. (1976). The minimum area of change detected was approximately 0.5 acre. Data Analysis and Tabulation Geospatial data were analyzed through geographic information system technology, using ArcGIS 9.1 (Environmental Systems Research Institute, Inc., ESRI). Statistics addressing wetland status and trends for the study were generated using this program. 1 For the 2002 NWI data, the target mapping unit (tmu) was approximately 1 acre, recognizing the inherent limitations of photointerpretation for mapping wetlands (Tiner 1990). Such targets are for general guidance only, and many conspicuous, smaller wetlands are often mapped, with ponds being the most common wetland type mapped below the tmu. Wetland Trends in the Greater Buffalo Area, New York: 1980 - 2002 4 RESULTS Wetland and Deepwater Habitat Status: 2002 Wetlands occupied nearly 114 square miles of the study area. This amounts to 11 percent of the land area. Forested wetlands were the dominant type, representing 70 percent of the area’s wetlands (Table 1). Nearly all of these forested wetlands were dominated by broad-leaved deciduous trees. Sixty-eight percent of the forested wetlands were seasonally saturated flatwoods.2 Scrub-shrub wetlands were next in abundance, accounting for 13 percent of the wetlands, followed by emergent wetlands with nearly 6,600 acres inventoried (9% of the wetlands). Ponds (e.g., palustrine unconsolidated bottoms and shores) totaled nearly 3,500 acres, comprising about 5 percent of the area’s wetlands. The waters of Lake Erie dominated the deepwater portion of the study area, with over 35,000 acres inventoried (Table 1). Riverine waters accounted for nearly 11,000 acres. Wetland Trends The general trends for the region were losses of vegetated wetlands (forested, scrub-shrub, and emergent types) and gains in nonvegetated wetlands (ponds and shallow lakes/impoundments) (Table 2). Vegetated wetland losses were greater during the 14-year period from 1980-1994 than from 1994-2002 and the rate of change was higher as well: net annual losses of 109 acres vs. 67 acres. Vegetated Wetlands Losses and Changes in Wetland Type From 1980-1994, a total of 1,560 acres of vegetated wetlands were converted to nonwetland or nonvegetated wetlands (ponds and unconsolidated shores) (Table 3). Forty-three percent of the losses were attributed to residential development, while nearly 13 percent was due to commercial development, almost 11 percent to pond construction, and over 9 percent to gravel mining operations. The average annual loss of these wetlands during this period was 111 acres. Forested wetlands received the brunt of the impacts, declining by more than 1,200 acres from 1980-1994. This amounts to a two percent loss of forested wetland and comprised over three-quarters of the vegetated wetland losses. Scrub-shrub wetlands absorbed the second heaviest losses during this period with 186 acres lost (13 acres average annual loss), representing nearly two percent of these wetlands. Nearly 90 acres of emergent wetlands were lost which amounts to 1.3% of the 1980 extent of these wetlands. From 1994-2002, 545 acres of vegetated wetlands were destroyed. Residential development remained the major cause of wetland loss, being responsible for nearly 38 percent of the losses. Conversion of vegetated wetland to “transitional land” (land going to some type of development that could not be determined as the work was in progress) was the second leading cause of vegetated wetland loss, accounting for 22 percent of the total losses. Pond construction and commercial development accounted for 26 percent of the losses, with each responsible for about 13 percent of the losses. Almost 390 acres of forested wetlands were lost including 24 acres that were excavated to create emergent wetland. Average annual loss of forested wetland amounted to about 49 acres (less than half of what it was during the 1980-1994 period). Nearly one percent (0.8%) of the forested wetlands that existed in 1994 was destroyed during this eight-year period. About one percent of the other vegetated wetlands were also lost by 2002. Nearly 84 acres of scrub-shrub wetlands and roughly 64 acres of emergent wetlands were lost. Gains Seventy-three acres of vegetated wetlands became established from 1980-1994. Most of this increase (51 acres) came from abandonment of agriculture in a farmed wetland that became vegetated with shrub and emergent wetland species. Most of the remaining gain in vegetated wetlands was created by excavating depressions in upland which were then colonized by aquatic bed vegetation or wetland emergent plants. Nearly seven acres of “dead” forested wetland were the result of beaver activity which converted an upland forest to a shallow water depressional wetland with standing dead trees. 2 These wetlands were largely identified by the presence of hydric soil areas map units in undeveloped areas; hydric soil locations were derived from digital soil data of USDA county soil surveys, while aerial imagery was consulted to determine the current status of the land as either developed or undeveloped hydric soil. Wetland Trends in the Greater Buffalo Area, New York: 1980 - 2002 5 From 1994-2002, only nine acres of vegetated wetland were created from upland. In addition, 24 acres of forested wetlands were excavated to create emergent wetland habitat. Nonvegetated Wetlands Losses Nonvegetated wetlands are mostly ponds. Only 25 acres of these habitats were altered from 1980-1994, and only 14 from 1994-2002 (Table 4). Most of them were filled in for upland development or destroyed during sand and gravel pit mining operations. Gains Increases in nonvegetated wetlands mainly through pond construction occurred throughout the study period (1980­2002). Palustrine unconsolidated bottom acreage rose by 38 percent from 1980-1994 and by nearly 10 percent from 1994 to 2002. Overall, pond acreage (palustrine unconsolidated shore and bottom) increased by nearly 1,220 acres during the 22-year period (Table 4). From 1980 to 1994, 81 percent (715 acres) of the gain came from upland (45% from cropland), with the remainder (164 acres) coming from wetland (mostly forested wetland: 64%). From 1994 to 2002, a slightly greater percentage of the gain came from wetlands: 22 percent vs. 19 percent from 1980 to 1994. Most of the increase in pond acreage still came from agricultural lands, yet 126 acres of shallow water lacustrine habitat were created by excavating upland fields/thickets along the Erie Canal at the boat ramp near Carlisle Gardens and in building a large impoundment next to the New York Thruway toll plaza at Bowmansville Wetland Trends in the Greater Buffalo Area, New York: 1980 - 2002
Table 1. Extent of wetlands and deepwater habitats in the Greater Buffalo area, 2002
NWI Classification Acreage
Habitat System Class
Wetland Lacustrine Unconsolidated Bottom 1, 479.9
Unconsolidated Shore 197.9
Aquatic Bed 5.8
-----------------------------------------------­--------------
­Total
Lacustrine Wetlands 1,683.6
Palustrine Aquatic Bed 25.4
Emergent 6,558.4
Farmed 219.6
Forested 51,186.9
Scrub-Shrub 9,589.0
Unconsolidated Bottom 3,318.9
Unconsolidated Shore 160.2
-----------------------------------------------­---------------
­Total
Palustrine Wetlands 71,058.4
Riverine Unconsolidated Shore 90.2
GRAND TOTAL - WETLAND 72,832.2
Deepwater
Habitat
Lacustrine Unconsolidated Bottom 35,078.8
Riverine Rock Bottom 266.2
Unconsolidated Bottom 10,447.0
----------------------------------------------­-----------------
­Total
Riverine DW Habitat 10,713.2
GRAND TOTAL - DEEPWATER HABITAT 45,792.0
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Table 2. General wetland trends in the Greater Buffalo Metro area 1980 to 2002.
Wetland Type 1980 Acreage 1994 Acreage Change 1980 - 1994 2002 Acreage Change 1994 - 2002
Lacustrine 1,610.6 1,610.6 0 1,683.6 +73.0
Palustrine
Aquatic Bed 18.3 22.9 +4.6 acres 25.4 +2.5 acres
Farmed 270.0 219.6 -50.4 acres 219.6 0
Scrub-Shrub 9,859.3 9,672.9 -186.4 acres 9,589.0 -83.9 acres
Emergent 6,709.5 6,621.9 -87.6 acres 6,558.4 -63.5 acres
Forested 52,782.7 51,575.5 -1,207.7 acres 51,186.9 -388.6 acres
Unconsolidated
Bottom
2,197.3 3,022.3 +825.0 acres 3,318.9 +296.6 acres
Unconsolidated 63.0 90.5 +27.5 acres 160.2 +69.7 acres
Shore
Total Palustrine 71,900.1 71,225.6 -674.5 acres 71,058.4 -167.2 acres
Riverine
Unconsolidated
Shore
90.2 90.2 0 90.2 0
Wetland Trends in the Greater Buffalo Area, New York: 1980 - 2002
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Wetland Trends in the Greater Buffalo Area, New York: 1980 - 2002
Table 3. Causes of vegetated wetland trends. Wetland codes: EM – Emergent, SS – Scrub-Shrub, FO – Forested, PUB
– palustrine unconsolidated bottom (= pond), and PUS (palustrine unconsolidated shore = typically, a dry pond or
seasonally wet depression).
Nature of Change Cause of Change Wetland Type Affected Acres Changed Acres Changed
1980-1994 1994-2002
LOSS to Agriculture Emergent 29.5 0.0
Forested 25.1 2.0
Scrub-Shrun 8.3 0.0
(Subtotal) (62.9) (2.0)
Excavation Forested 4.8 0.0
(to River) Scrub-Shrub 3.5 0.0
(Subtotal) (8.3) (0.0)
Excavation Forested 36.1 0.0
(to Lake) Scrub-Shrub 14.4 0.0
(Subtotal) (50.5) (0.0)
Commercial
Development
Emergent
EM/Scrub-Shrub
Forested
FO/SS
Scrub-Shrub
SS/EM
(Subtotal)
3.8
1.7
134.3
0.0
56.4
0.0
(196.2)
7.0
3.2
39.6
10.9
4.6
2.8
(68.1)
Industrial Emergent 3.1 5.0
Development Forested 19.6 18.7
Scrub-Shrun 1.4 7.1
(Subtotal) (24.1) (30.8)
Recreational Emergent 0.0 8.7
Development Forested 8.7 0.0
(Subtotal) (8.7) (8.7)
Residential
Development
Emergent
EM/Scrub-Shrub
Forested
FO/SS
Scrub-Shrub
SS/EM
SS/FO
(Subtotal)
19.7
3.7
555.3
29.3
56.0
7.8
4.3
(676.1)
5.7
5.7
112.0
18.8
6.2
41.6
15.4
(205.4)
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Wetland Trends in the Greater Buffalo Area, New York: 1980 - 2002
Table 3. Causes of vegetated wetland trends. Wetland codes: EM – Emergent, SS – Scrub-Shrub, FO – Forested, PUB
– palustrine unconsolidated bottom (= pond), and PUS (palustrine unconsolidated shore = typically, a dry pond or
seasonally wet depression). Continued
Nature of Change Cause of Change Wetland Type Affected Acres Changed Acres Changed
1980-1994 1994-2002
Transitional Land Emergent
EM/Scrub-Shrub
Forested
FO/SS
FO/EM
Scrub-Shrub
SS/EM
SS/FO
(Subtotal)
2.5
0.0
36.6
6.2
15.4
22.0
0.0
30.6
(113.3)
14.2
0.6
76.6
0.0
25.2
2.4
2.3
0.0
(121.3)
Transportation Emergent 5.7 0.0
EM/Scrub-Shrub 0.0 1.7
Forested 64.6 3.0
FO/SS 1.2 0.0
SS/FO 8.3 0.0
(Subtotal) (79.8) (4.7)
Golf Course Forested 1.7 0.0
(Subtotal) (1.7) (0.0)
Gravel Pit Forested 143.2 0.0
Scrub-Shrub 4.9 0.0
(Subtotal) (148.1) (0.0)
Pond Creation Emergent Wetland
EM/SS
Forested
FO/SS
Scrub-Shrun
SS/EM
(Subtotal)
37.0
3.0
100.3
4.0
17.9
1.3
(163.5)
40.8
3.5
22.1
3.3
0.7
0.0
(70.4)
Unconsolidated Emergent 0.0 1.5
Shore Forested 0.0 32.4
(Subtotal) (0.0) (33.9)
Upland Forested 1.0 0.0
Field/Thicket (Subtotal) (1.0) (0.0)
Rangeland Forested 25.1 0.0
Scrub-Shrub 0.7 0.0
(Subtotal) (25.8) (0.0)
TOTAL LOSSES 1,560.0 545.3
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Wetland Trends in the Greater Buffalo Area, New York: 1980 - 2002
Table 3. Causes of vegetated wetland trends. Wetland codes: EM – Emergent, SS – Scrub-Shrub, FO – Forested, PUB
– palustrine unconsolidated bottom (= pond), and PUS (palustrine unconsolidated shore = typically, a dry pond or
seasonally wet depression). Continued
Nature of Change Cause of Change Wetland Type Affected Acres Changed Acres Changed
1980-1994 1994-2002
GAIN from Upland Aquatic Bed 2.3 0.7
Field/Thicket Emergent 3.3 0.0
EM/Pond 3.1 0.0
(Subtotal) (8.7) (0.7)
Shrub Thicket Aquatic Bed 0.0 1.8
Emergent 1.9 0.0
(Subtotal) (1.9) (1.8)
Agriculture Emergent 0.7 1.8
Scrub-Shrub 0.2 0.0
(Subtotal) (0.9) (1.8)
Rangeland Emergent 0.6 0.0
EM/Pond 1.1 0.0
(Subtotal) (1.7) (0.0)
Beaver-conversion Forested (dead) 6.5 0.0
of Upland Forest (Subtotal) (6.5) (0.0)
Pond Creation Scrub-Shrub 2.7 0.0
Emergent 0.0 4.5
(Subtotal) (2.7) (4.5)
Palustrine Farmed SS/EM 50.5 0.0
(Subtotal) (50.5) (0.0)
TOTAL GAINS 72.9 8.8
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Wetland Trends in the Greater Buffalo Area, New York: 1980 - 2002
Table 3. Causes of vegetated wetland trends. Wetland codes: EM – Emergent, SS – Scrub-Shrub, FO – Forested, PUB
– palustrine unconsolidated bottom (= pond), and PUS (palustrine unconsolidated shore = typically, a dry pond or
seasonally wet depression). Continued
Nature of Change Cause of Change Wetland Type Affected Acres Changed Acres Changed
1980-1994 1994-2002
CHANGE
IN TYPE
Emergent
Forested
Forested/Emergent
Scrub-Shrub
Aquatic Bed 0.5 0.0
Emergent 12.6 23.9 (23.1 =
excavated)
Emergent 2.2 0.0
Aquatic Bed 1.8 0.0
Emergent 0.4 0.0
TOTAL CHANGES IN TYPE* 17.5 23.9
*Conservative figure since emphasis was on detecting losses and gains in wetlands.
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Wetland Trends in the Greater Buffalo Area, New York: 1980 - 2002
Table 4. Causes of nonvegetated wetland trends. PUB = palustrine unconsolidated bottom = pond; PUS = palustrine
unconsolidated shore = seasonally dry pond (typically).
Nature of Change Cause of Change Nonvegetated
Wetland Type
Acres
Changed
1980-1994
Acres
Changed
1994-2002
LOSS to Commercial Development PUB 0.4 0.2
Residential Development PUB 0.7 0.4
Transitional Land PUS 0.0 1.6
PUB 10.4 3.6
(Subtotal) (10.4) (5.2)
Gravel Pit PUB 7.4 1.2
PUS 3.8 2.5
(Subtotal) (11.2) (3.7)
Rangeland PUB 0.0 4.5
Subtotal Loss to Upland 22.7 9.9
Vegetated Wetland by
Plant Colonization
Emergent PUB 0.0 4.5
Scrub-Shrub Wetland PUB 2.7 0.0
Subtotal Loss to Wetland 2.7 4.5
TOTAL LOSSES 25.4 14.4
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Wetland Trends in the Greater Buffalo Area, New York: 1980 - 2002
Table 4. Causes of nonvegetated wetland trends. PUB = palustrine unconsolidated bottom = pond; PUS = palustrine
unconsolidated shore = seasonally dry pond (typically). Continued
Nature of Change Cause of Change Nonvegetated Acres Acres
Wetland Type Changed Changed
1980-1994 1994-2002
GAIN from Agriculture PUB 315.9 77.1
PUS 5.2 5.3
(Subtotal) (321.1) (82.4)
Upland Forest PUB 89.3 13.6
PUS 1.6 0.0
(Subtotal) (90.9) (13.6)
Golf Course PUB 1.6 0.0
Upland Field/Thicket PUB 110.5 40.2
PUS 6.5 0.9
Lacustrine Shore 0.0 125.9
(Subtotal) (117.0) (167.0)
Gravel Pit PUB 31.2 18.1
PUS 23.8 3.6
(Subtotal) (55.0) (21.7)
Industrial Development PUB 2.5 0.0
Rangeland PUB 45.5 31.7
PUS 0.9 0.0
(Subtotal) (46.4) (31.7)
Upland Shrub Thicket PUB 63.6 5.5
PUS 3.6 0.6
(Subtotal) (67.2) (6.1)
Transitional Upland PUB 12.7 38.4
Transportation PUB 0.5 0.0
Subtotal Gain from Upland 714.9 360.9
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Wetland Trends in the Greater Buffalo Area, New York: 1980 - 2002
Table 4. Causes of nonvegetated wetland trends. PUB = palustrine unconsolidated bottom = pond; PUS = palustrine
unconsolidated shore = seasonally dry pond (typically). Continued
Nature of Change Cause of Change Nonvegetated Acres Acres
Wetland Type Changed Changed
1980-1994 1994-2002
GAIN from Emergent Wetland PUB 37.0 40.8
PUS 0.0 1.5
(Subtotal) (37.0) (42.3)
EM/SS Wetland PUB 3.0 3.5
Forested Wetland PUB 100.3 22.1
FO/SS Wetland PUB 4.0 3.3
Scrub-Shrub Wetland PUB 17.9 0.7
SS/EM Wetland PUB 1.3 0.0
Forested Wetland PUS 0.0 32.4
Subtotal Gain from Wetland 163.5 104.3
TOTAL GAINS 878.4 465.2
CHANGE IN
NONVEGETATED
WETLAND TYPE
PUS PUB 10.1 3.0
PUB PUS 0.0 0.5
TOTAL CHANGES IN TYPE 10.1 3.5
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Wetland Trends in the Greater Buffalo Area, New York: 1980 - 2002 15 STUDY LIMITATIONS Wetlands identified with the wetter water regimes such as permanently flooded, semipermanently flooded, and seasonally flooded are usually the most easily recognized types through photointerpretation and are therefore the most accurately mapped. In contrast, seasonally saturated and temporarily flooded wetlands are quite challenging to detect through remotely sensed techniques. These wetlands typically lack standing water except in few shallow depressions that may contain water (or ice) for extended periods from winter through early spring and for brief periods after heavy summer rains. They have high water tables during these seasons that have supported the establishment of wetland vegetation and formation of hydric soils. The lack of surface wetness makes them particularly difficult to photointerpret as well as to recognize in the field. Both seasonally saturated and temporarily flooded wetlands tend to lack surface water in early spring when most aerial photographs are captured. Examination of soil properties is usually required to verify the existence of these wetlands. Soil surveys conducted by the U.S. Department of Agriculture, Natural Resources Conservation Service provide a useful source of information to aid photointerpreters in mapping these difficult types. This information is now available in digital form to facilitate this process. Limited field checking in the general area by NWI personnel found that there was a good correlation between hydric soils and these drier-end wetlands. Nonetheless, the interpretation of these types should be considered conservative and field verification is recommended to evaluate the potential uses of these types. Habitat fragmentation by roads and residential/commercial development has also played a significant role in adversely affecting wetlands. This type of development has often reduced the connectivity among wetlands, especially for those wetlands not intersected by streams. In addition, such development has most likely adversely impacted the hydrology of wetlands across the region as local drainage patterns have been disrupted. Wetland Trends in the Greater Buffalo Area, New York: 1980 - 2002 16 SUMMARY In 2002, wetlands represented eleven percent of the Greater Buffalo area. Forested wetlands remained the dominant type, occupying nearly 51,200 acres and accounting for 70 percent of the region’s wetlands. Over two-thirds of these forested wetlands were seasonally saturated flatwoods (i.e., low-lying seasonally wet forests with water tables at or near the surface from winter through spring). The region lost nearly three percent of its vegetated wetlands from 1980 to 2002 (69,640 to 67,579 acres), while nonvegetated wetland acreage (e.g., ponds) rose by a third (3,961 to 5,253 acres). Residential development was the main cause of the vegetated wetland loss, being responsible for 43 percent of the losses from 1980 to 1994 and for 38 percent of the losses from 1994 to 2002. During the former period, commercial development and pond construction each accounted for 13 percent of the losses. From 1980 to 2002, pond acreage continued to increase, first by 853 acres (1980-1994) and then by 366 acres (1994-2002). Most of the new ponds were built on upland, primarily on cropland. Wetland Trends in the Greater Buffalo Area, New York: 1980 - 2002 17 ACKNOWLEDGMENTS The 2002 NWI data used as the foundation for this study was compiled by photointerpreters in the Department of Plant, Soil, and Insect Sciences at the University of Massachusetts, mainly Irene Huber and Todd Nuerminger. The trends study was performed by the U.S. Fish and Wildlife Service, Northeast Region, National Wetlands Inventory Program. John Swords analyzed the imagery and recorded wetland changes in a digital database. Herbert Bergquist used GIS technology to compile the results in a format for use in this report. Ralph Tiner was responsible for general project design and for summarizing the findings in this report. Funds for this project were provided by the Service’s National Wetlands Inventory Program (Washington Office). Several individuals reviewed the draft report: Jim Dick, Bill Kirschner, and Bill Wilen. I thank them for their help in finalizing this publication. A special thanks to Christine Sevilla for letting us use her flatwood wetland photograph for the cover. This type of wetland is typical of many of the remaining forested wetlands in the study area. Also thanks to Andrew Cruz for preparing the image for Figure 1. Wetland Trends in the Greater Buffalo Area, New York: 1980 - 2002 18 REFERENCES Anderson, J.R., E.E. Hardy, J.T. Roach, and R.E. Witmer. 1976. A Land Use and Land Cover Classification for Use with Remote Sensor Data. U.S. Geological Survey, Reston, VA. Geol. Survey Prof. Paper 964. Cowardin, L.M, V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of Wetlands and Deepwater Habitats of the United States. U.S. Department of the Interior, Fish and Wildlife Service, Washington, DC. FWS/OBS-79/31. Federal Geographic Data Committee. 1996. Wetland classification standard: FGDC-STD-004. http://www.fgdc.gov/standards/projects/FGDC-standards-projects/wetlands/index_html Tiner, R.W., Jr. 1990. Use of high-altitude aerial photography for inventorying forested wetlands in the United States. Forest Ecology and Management 33/34: 593-604. U.S. Fish & Wildlife Service http://www.fws.gov
September 2008
Cover photograph by Christine Sevilla