Intensive surveys of structure and change in urban natural areas

59

Landscape and Urban Planning, 15 ( 1988) 59-78 Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands

Intensive Surveys of Structure and Change in Urban Natural Areas

GARRY

F. ROGERS’,*

and ROWAN A. ROWNTREE*

‘Department of Geography, Columbia Umversity, New York, NY 10027(U.S.A.) ‘Northeastern Forest Experiment Station, U.S.D.A. Forest Service, State University of New York, College on Environmental Science and Fdrestry, Syracuse, NY 13210 (U.S.A.) (Accepted for publication 28 September

1987 )

ABSTRACT

Rogers, G.F. and Rowntree, R.A., 1988. Intensive surveys of structure and change in urban natural areas. Landscape Urban Plann., 15. 59-78.

We introduce a methodology developed for surveying high value biotic resources typical of urban parks and natural areas. Procedures include (I) mapping vegetation using a technique

for recognizing separate vegetation units or entities referred to as “entitation “, (2) establishing permanent camera stations for studying change, and (3) classifying the vegetation using a system derived from the life-forms of the plants. We emphasize cost-efficient techniques based on vegetation structure or physiognomy, and we discuss uses of vegetation maps and photographs for public presentations, planning quantitative sampling, and studying habitat change.

INTRODUCTION Patches of plants form a beneficial part of the human habitat (e.g. Ulrich, 1986). Plants found in urban parks and natural areas are especially important because of their accessibility to large numbers of people, and because they illustrate the alteration of natural processes that occurs in human-dominated landscapes. Nat*Present address: 2997 S. Connor St., Salt Lake City, UT 84109, U.S.A.

0169-2046/88/$03.50

0 1988 Elsevier Science Publishers B.V.

ural processes within cities operate under an unusual suite of constraints (Gill and Bonnett, 1973; Laurie, 1979; Sukopp et al., 1979; Poore, 1984). Urban park habitats are comparatively small and isolated, they are subjected to frequent acute disturbance, and they experience chronic impacts from polluted air and toxic wastes. In addition, land-use changes often produce high spatial variability of both the physical habitat and the biotic composition. Most parks are relatively small, plant and animal populations are also small, and plant spe-

ties turnover and physiognomic change can be expected. The procedures we describe are appropriate for the initial phases of intensive surveys and assessments of urban parks or natural areas. IIlustrations and examples of the methods are drawn from work performed in a U.S. Park Service National Recreation Area located in Brooklyn, New York, and a large New York City park located in the Bronx, New York. We restrict consideration to vegetation. More general reviews of surveying, ecological change. and impact assessment can be found in Garton (1984), Westman (1985) and Moore and Chapman (1986). The principal purpose of the initial descriptive phase covered here is to construct a map that gives a spatial representation of variations in the botanical habitat. and to obtain a visual (photographic) record of conditions at the time the map is made. Because of the rapid changes that can occur within an urban ecosystem. the map and photographs should be repeated every 5- 10 years. We propose the following plan for describing and analyzing the terrestrial vegetation: I. Perform reconnaissance survey. A. Map vegetation. animal sightings, disturbance evidence. B. Establish permanent camera stations. C. Conduct taxonomic surveys. II. Classify and summarize the reconnaissance results. III. Publicize results. IV. Use the classification and summaries to: A. Provide substance for public education programs. B. Formulate interim management plans. C. Establish additional camera stations and begin to establish representative permanent quadrats for monitoring demographic and ecosystem processes within entities. D. Perform landscape analysis to identify unique or crucial habitat units, patches. corridors etc.

E. Plan for quantitative data acquisition and analysis. F. Provide a basis for generalizing quantitative data from biotic and environmental studies. G. Provide a matrix connecting individual research projects. V. Obtain and use quantitative data to: A. Refine classifications and interim management plans. B. Predict future trends in plant and animal populations. VI. Regularly repeat permanent observations (maps. photographs, permanent quadrats, and taxonomic surveys). VII. Refine classifications, predictions. and management plans. VIII. Repeat steps III-VII. The initial phases ( I and II) described in this paper are designed to set the stage for the remaining steps. A manual covering portions of phases I and II has been prepared for use in the New York City biological survey (Natural Resources Group. 1987 ). Methods for recognizing and mapping units of vegetation are described by Kiichler ( 1967 ), Mueller-Dombois and Ellenberg ( 1974) and Gilbertson et al. ( 1985 ). In these references, emphasis is placed on projects encompassing larger areas of land than those for which our study is intended. Because we believe the high value of urban parks justifies intensive study. and because of the heterogeneous nature of urban park vegetation. we recommend mapping scales of I:2400 or larger. A combination of Kiichler’s extensive and intensive methods (Kiichler. 1967. pp. I57- 172 ) most closely resembles the methods described here. We differ from Kiichler and others by combining large map scale with non-quantitative structural characteristics of the vegetation and life-forms of individual species (cf. Kiichler, 1967; Mueller-Dombois and Ellenberg. 1974 ). In devising a biological survey scheme for valuable parks and other natural habitats in urban areas, we chose to omit measurements

61

of species quantities and to emphasize the physical features of the vegetation, its physiognomy and life-forms. A prime benefit of this approach is the speed with which tangible results, maps and photographs, can be produced. Detailed measurements and species identifications are time-consuming operations, and although their value is unquestioned, such a beginning for a survey of urban natural areas does not respond to the need to produce quickly displayable results. Maps and photographs can be produced as adjuncts to a quantitative system, but by making them central rather than incidental their quality and thus their usefulness are likely to be improved. Also, by emphasizing careful reconnaissance methods using a tightly controlled spatial coordinate system for recording information in the field, all facets of the survey can be related to specific field sites. Thus the maps, photographs, and other information acquired during the survey can be repeated at later dates to study change. There are other reasons for beginning a survey with a classification system based on structural features of the vegetation. By not depending on floristic (i.e. species lists) criteria, such a system is useful for preliminary analyses when a complete floristic inventory is not available. Also, plant species of the same life-form have been shown to be closely associated along major environmental gradients (Whittaker, 1975, pp. 6 l-65 ). Consequently, applications of the system can provide important initial indications of spatial variations of habitat conditions. Further, photographs, vegetation maps, and physiognomic profiles derived from the classification can be used to describe the distribution of vertical habitat structure of importance to animals. The distribution and abundance of many animal species has been found to be more closely associated with the structural complexity of the vegetation than with particular plant species. This has been found to be true for insects (e.g. Strong and Levin, 1979), birds (e.g. MacArthur and

MacArthur, 196 1; Erdelen, 1984 ) , mammals (e.g. Bond et al., 1980), and fish (e.g. Tonn 1982). Southwood et al. and Magnuson, ( 1979) found that animal species turnover during succession was more closely related to vegetation-physiognomy turnover than to shifts of plant species composition. Thus, we recommend this system because the entity maps, and maps derived after classification show the spatial distribution of habitats defined by ecologically important characteristics that provide data for studies of spatial habitat patterns (see Naveh and Lieberman, 1984; Risser et al., 1984). Finally, we recommend the system described below because of its generality, its familiarity to ecologists and managers throughout the world, and its flexibility that permits use at a variety of scales, including the large scale needed for urban natural areas. ENTITATION An essential component of landscape study is some form of description. Even when quantitative analysis is the primary goal, initial subjective identification of vegetation (or habitat) units is recognized to be the most efficient and generally effective beginning. Entitation is the process of visual discernment of landscape units. The resulting units tend to be defined by the physical characteristics of prominent plant species, and thus they sometimes resemble the “dominance-types” of Whittaker ( 1975, p. 128 ). The physiognomic approach is more detailed than simple dominance systems, because it includes information on plant crown architecture, life-form, abundance, phenology, and size for overstory and understory plants. For entitation, physical habitat features such as slope, drainage, stoniness, and evidence of disturbances such as trampling and fire, are also important. Thus the units are visually distinct and often reflect important environmental controls. Most importantly, however, the entities provide a practical and convenient means of communication about the

62

TABLE I Entitation form used by the New York City Parks and Recreation Natural Resources Group. The form is designed to act primarily as a checklist, with space provided for location information, dominant species’ names. and comments. Terms are defined in Table IV N.4TURAL RESOURCES GROUP NEW YORK CITY PARKS AND RECREATION ENTITATION OF PELHAM BAY PARK LOCATION: Unit No. 6; Easting 47400: Northmg: 14850 FORMATION I Closed forest 2 Woodland 3 Scrub 4 Terrestrial herb. 5 Desert 6 .4quatic plant

TOPOGRAPHY 1 Knoll 2 Undulating 3 Slope 4 Level

Y

DOMIN.4NT WOODY PLANTS I Evergreen 2 Evergreen w/decid. 3 Deciduous 4 Deciduous w/ever. VEGETATION I Phanerophytes 2 Chamaephytes 3 Hemicryptophytes 4 Geophytes 5 Therophytes 6 Lianas 7 Thallophytes

DRAINAGE 1 Excess drained 2 Well drained 3 Moist 4 Wet 5 Surface water Y WILDLIFE INDEX 1 No. sitings 2 lor2 33or4 44or5 5 6 or more

x

PLANT SPECIES (In order of dominance) I Black locust

5m+ --

Sm-

X

2

Goldenrod

-~

x

3

RUtILlS

--

x

4

Chives

x

5

Perrenial herbs

X

6

Black cherry

HISTORICAL INDICATORS I Landfill 2 Road 3 Fence 4 Hedgerow 5 Building 6 Full-crown tree 7 Exotic planting 8 Other

-

-X

-

ENVIRONMENTAL 1 Fire 2 Erosion 3 Soil compaction 4 Dumping 5 Pollution 6 Trash 7 Vandalism 8 Other

DISTURBANCE -

63 TABLE 1 (Continued) CURRENT USE (in order of importance) 1 Picnic 2 Woodgathering 3Auto-access 4 Fireplace 5 sports 6 Foot traffic 7 Other

MOWING

1 Last year 2 l-5 years 3 Not mowed

_ Y

TREES

1 Pruned 2 Not pruned

-z_

1 Removed 2 Not removed

_ _._x_

TRASH

COMMENTS, DESCRIPTIONS, AND EXPLANATIONS OF CHOICES MARRED: (Continue on back) Woodland dominated by black locust; rare pin oak, scotch pine, elderberry. No tree regeneration; tree mortality along old road and storm drain, at border. Fires regularly burn understory; fire break would encourage regeneration DATE: 1 June 1985

structure of the biological landscape (Whittaker, 1975, p. 127). After an entity is defined, notes are made describing its salient biological and physical features, and any evidence of trends. Whatever the observer feels might help characterize and understand the entity should be recorded. In the New York City biological survey a checklist (Table 1) is used to ensure that the information required for classification is recorded. In the New York survey, additional observations were made of the physical characteristics of the site, the presence of wildlife, site history, signs of disturbance, and current use and maintenance practice (Fig. 1). If too much additional information is collected, however, the efficiency of the entitation approach is lost. Examples of entity descriptions are provided in the following section covering repeat photography. Mapping should be done in the field using a base map made from enlargements of aerial photographs upon which a control grid (e.g. the Universal Transverse Mercator) has been drafted (Figs. 1 and 2 ) . Final maps can be digitized for computer storage and display, or can be traced onto vellum directly from the photographs. An example is shown in Fig. 3. Land survey techniques that are useful, especially if aerial photograph coverage is poor, are described by Gilbertson et al. ( 1985 ).

The finished map serves a variety of purposes: it provides basic information on the amounts and locations of patches of forest, woodland, herbland, and wetland, and it shows the spatial relations of various entities to one another and to other features of the landscape. The map might suggest important problems and questions that require further research, and it will be useful in choosing sites for more intensive sampling and analysis. The map also serves as a record against which future maps can be compared to determine the nature and extent of changes occurring in the landscape. During the process of entitation, the investigators will become intimately familiar with the area under study. In addition to the field descriptions, the investigators’ recall of details that might have been omitted or overlooked at the time an entity was described will often be useful. For these reasons it is important to plan for the continuity of personnel. PHOTOGRAPHY Here we describe a system for making repeatable photographs from permanently marked camera stations. Carefully documented terrestrial photographs taken at the time an entity is being described provide inexpensive, yet highly detailed records of the characteristics of habitat and landscape, and

Fig. 1. Aerial photograph base map for Floyd Bennett Field. an abandoned airport now part of Gateway National Recreation Area. .A 50-m grid based on the Universal Transverse Mercator (UTM) coordinate system was drawn on enlarged aerial photographs. the photographs were then divided into subsections (.4-S). and each was photographed and enlarged to form a page in the field atlas used as the base map for entitation. Scale: Each subsection is 400 x 500 m. and consists of 80 grid cells. 50 m’.

enable study of landscape change using photographs of the same scene made at a later date. Photographs are particularly useful when the physical structure of the vegetation is of concern. The photographs are also useful for public displays illustrating entity features (e.g. Shuttleworth, 1980 ). Sequences of photographs of the same scene can be used to measure changes in many landscape features (Rogers et al., 1984). They have

been used to study geological processes (e.g. Buckler and Winters, 1983), changes at archaeological sites (Lekson, 1983), changes in cities (Watson and Gillon, 1976 ), changes in the cultural landscape (Ganzel, 1978 ), changes at wilderness campsites (Cole, 1983 ). and the causes of wildlife population fluctuations (Gruell, 1986 ). The most frequent use of repeated photographs for studying botanical changes has been to measure the more general

65

Fig. 2. Enlargement of subsection G, Fig. 1. Enlargements of subsections A-S formed the pages of a field atlas used during the entitation of Floyd Bennett Field. The location of entities and camera stations is facilitated by including UTM grid designation with all location information. Scale: each grid cell is 50 m’. The upper right portion of this scene illustrates the invasion of little bluestem (Andropogon scoparius) dominated grassland by the darker appearing patches of bayberty (Myrica pensylvanica) shrubs (Rogers et al., 1985). Reeds (Phrugmites austrulis) dominate the center and left center of the scene. and abandoned airport runways in various stages of colonization by plants (visible as faint linear patterns in the lower left of the scene), extend from the right center to the lower center and lower left of the scene.

aspects of changing composition and physical architecture of vegetation (e.g. Hastings and Turner, 1965; Gruell, 1983), but detailed analyses of establishment, growth, and population fluctuations have also been made (Noble and Crisp, 1980). Matching photographs of the same scene are particularly useful for recording and measuring changes in landscapes

heavily used by people; they provide a wealth of visual information that would be difficult and costly to record by other means (e.g. Magill and Twiss, 1965; Benson, 1983 ). Locating the unmarked point at which an historic photograph was taken is discussed by Malde ( 1973), Harrison ( 1974), and Rogers et al. ( 1984), and the use of stereophotogra-

66

Fig. 3. The entity map for part of Floyd Bennett Field, Gateway National Recreational Area, New York. The entities are classified in Fig. 5.

phy for measuring objects and distances in a scene is discussed by Malde ( 1973). Problems associated with improperly matched photographs, and questions of reliability are illustrated and discussed by Rogers et al. ( 1984). The principal requirements for making duplicate photographs of the same scene are that the camera (the center of the lens) must be located in the same position, and must be aimed at the same point. Photographs repeated on the same dates and the same time of day will be easier to compare, because differences in the angle of sunlight, and to some extent the character of the vegetation. arising from seasonal and hourly variations are eliminated. A permanent marker is placed beneath the center of the lens (using a plumb bob), and the height of the center of the lens above the marker and ground is recorded. Markers placed in soil should be driven into the ground until their top is level with, or slightly below, the ground surface so that they remain undisturbed. Markers

can be relocated using a surveyor’s metal detector or magnetic locator. Measurements taken from the photographs are simplified if the camera is levelled using a spirit level and aimed horizontally. The location of camera stations should be carefully documented. This can be done by showing their location on the entity map, and, when practical, recording the direction and distance from the marker to a nearby object expected to remain more or less permanently. A panorama of two or more overlapping photographs will also be of aid in relocating camera stations. When making a panorama, the camera is rotated so that the center of the lens remains directly above the marker (Malde, 1983). Camera locations should also be chosen with future vegetation developments in mind. Rock outcrops, sidewalks, pavement, and structures, particularly when any of these provide an elevated vantage point, serve as ideal camera station locations from which future scenes

67

TABLE 2 Repeat photography data form used at Gateway National Recreation Area, Brooklyn, New York. The information form refers to Fig. 4

given on the

GATEWAY NATIONAL RECREATION AREA Repeat Photography Data Number 03; Photographer(s) G. Rogers, P. Grady Date 1O/29/83; Time 1: 15 EDT; Visibility Very Good Location E. of runway, 14.8 m W. of outer edge of breakwater Easting 94400; Northing 95300 Roll/frame

11916

11917

Pan. segments Stereo separation

7is15cmtotherightof6

Azimuth (deg)

314”

314”

Marker height

6.5 cm

6.5 cm

Lens height

143.5 cm

143.5 cm

Focal length

28 mm

28 mm

View angle

75”

75”

F-stop

11

11

Focus (m )

4.5

4.5

Exposure time

l/60

l/60

Lens filter

None

None

Film type

PanX

PanX

Developer

Kodak

Kodak

Paper type

Kodak Polyfiber

Kodak Polyfiber

Exposure time

35 s

15s

F-stop

8

8

Filter

6

6

Developer

Dektol

Dektol

Comments:

(continue on back) The tripod used as an aiming point is 145 cm high, and is 10 m from the camera station

Fig. 4. The camera station location and photographic information recorded for this scene are given in Table 2. Entity descriptions are as follows: the entity occupying the foreground of this scene is dominated by hemicryptophytic perennial caespitose grasses that are shorter than I m and are not mat forming. Subdominants include geophytic clonal perennial herbs (:lrt~misia vulgaris and Solidago spp.). A few phanerophytic caespitose shrubs (,M~rrcapens?,lvanica) are scattered along the boundary of this entity and the one visible in the right center of the scene dominated by cobblestones and scattered Spurt/m spp. The entity located just beyond the aiming point in the center and left center of the scene is a thicket composed mainly of the phanerophytic eaespitose shrubs Baccharis halimfolia and .lfyx-a pensyh’anica, with scattered Rosa and Rhus copall~nwn. 4 phanerophytic scaposc deciduous tree (Elueugnus spp. ) forms a discontinuous upper layer. and grasses dominate the primarily hemicryptophytic undergrowth.

will less often be obscured by vegetation growth. The timing of photographs is also important for ease of repetition. In woodlands and forests, photographs made in spring will usually provide greater visual coverage. In grasslands, photographs made in autumn when grasses are cured will render most shrubs more visible. Photographs can be accurately repeated with any combination of camera and lens. If a lens with a smaller field of view is used, information on the margins of the scene will be lost, but the geometric properties of the images will be the same (Malde, 1973). Differences in

coverage of the scene and in negative sizes are compensated for in the darkroom by making photographic prints of the same size. Table 2 and Fig. 4 illustrate the use of a form for recording the necessary information for each camera station. THE CLASSIFICATION

SYSTEM

Vegetation classification is performed after entitation, and its purpose is to permit grouping of similar entities to simplify visual display and discussion and to suggest subsets of entities across which common understanding,

69

Fig. 5. Classified entity map (see Fig. 3) showing formation classes at Floyd Bennett Field, Gateway National Recreation Area, New York.

similar problems, standardized quantitative sampling techniques, and related management options apply. Reviews of the approaches to classifying vegetation are provided by Whittaker ( 1962), Kiichler ( 1967), Shimwell ( 197 1) , Mueller-Dombois and Ellenberg (1974), Gauch (1982), Pielou (1984) and Moore and Chapman (1986). Most classifications require quantitative data and are not appropriate for use with the information obtained during entitation. The classification system described here (Table 3 and Fig. 5 ) was developed by Ellenberg ( 1956), and is a product of a long history of intensive study of plant life-forms in relationship to environment (Shimwell, 197 1) . The system is based on a life-form classification incorporating adaptive characteristics important during favorable and unfavorable climatic seasons (Mueller-Dombois and Ellenberg, 1974, pp. 449-465). Thus it expands on the life-form classification by Raunkiaer

( 1934) that is based on adaptations to the unfavorable climatic season. After several revisions, Ellenberg’s system was adopted by UNESCO ( 1973) as the standard for medium-to-small-scale mapping worldwide. In tests performed at Gateway National Recreation Area, New York, the version of the system published by Mueller-Dombois and Ellenberg ( 1974) was found adaptable to the needs of detailed large-scale mapping of small areas (Grady, 1984 ), and further application in the New York City biological survey has confirmed the system’s usefulness at large scales. With the belief that vegetation is determined by environment, some classification systems are based solely on vegetation features (e.g. Fosberg, 1967), so that environmental conditions can be predicted from a knowledge of vegetation without risking errors from circular reasoning. Such systems have been found to be needlessly restrictive since many features of vegetation have no clear relationship to en-

70 TABLE 3 Classification 1.

key for urban vegetation

CLOSED FOREST. Formed by trees at least 5 m tall with interlocking crowns. A. Temperate evergreen forests. Individual trees can shed their leaves, but the canopy is never without green foliage 1. Evergreen conifer forest with rounded crowns (e.g. a.

Pinus)

Understory

( < 5 m) dominated

by phanerophytes

b. Understory

( < 5 m) dominated

by chamaephytes

c.

Understory

( < 5 m) dominated

by hemicryptophytes.

d. Understory

( < 5 m) dominated

by geophytes.

e.

( < 5 m ) dominated by lianas (vines)

Understory

2. Evergreen conifer forest with conical crowns (e.g. a.

Formations

Picea. .4&s).

as in LA. I

B. Temperate deciduous forests. Most trees shed their foliage with the onset of the unfavorable season 1. Cold-deciduous forest with evergreen trees (or shrubs). Deciduous trees dominate, but evergreen species are present as part of the main canopy or in the understory. a.

Cold-deciduous forest with evergreen broad-leaved ( 1). Subformations as in I.A. 1.

b. Cold-deciduous forest with evergreen needle-leaved ( 1 ), Subformations as in I.A. 1.

trees (e.g. 1le.u)

trees (e.g. Jurnperus).

2. Cold-deciduous forest with evergreen needle-leaved trees. Deciduous trees dominate, but some evergreen chamaephytes and phanerophytes under 2 m can be present. a.

Temperate lowland and submontane ( 1 ). Subformations as in I.A. 1.

cold-deciduous

forest. Tree height to 50 m.

b. Cold-deciduous riparian forest (flooded, therefore moister and richer in nutrients than in I.B.2.a). Trees and shrubs with high growth rates and herbaceous undergrowth (Salix nigra. Populus deltoides. Fraxinus pmn.~ylvanica etc. ). ( 1). Temporarily flooded. Between high and average water. (a). Subdivisions as in I.A. I. (2). Seasonally flooded. Between low water and average water. (a). Subdivisions as in I.A.1. c.

Cold-deciduous swamp or peat forest (flooded until late spring or early summer, surface soil organic ). Relatively poor in tree species, ground cover mostly continuous.

71 TABLE 3 (Continued)

( 1). Mainly broad leaved. (a). Subdivisions as in I.A. 1. (2 ). Mixed broad-leaved and deciduous conifers (e.g. Larix luricina). (a). Subdivisions as in LA. 1.

II.

WOODLANDS (open stands of trees). Trees at least 5 m tall with crowns usually not touching, but with coverage of at least 40%. The 40% limit is used because it can be estimated easily in the field since cover equals 40% when the distance between two tree crowns equals mean crown radius (UNESCO, 1973 ). A herbaceous understory can be present. See V.A. I. if tree cover < 40%.

A. Evergreen woodland (i.e. evergreen as defined in LA.) 1. Evergreen sclerophyllous broad-leaved a.

Formations

woodland (e.g. Ilex, Quercus).

as defined in LA. 1.

2. Evergreen needle- or scale-leaved woodland. Crowns of many trees extending to the base of the stem or at least highly branched. a.

Evergreen coniferous woodland with rounded crowns (e.g. Juniperus, Pinus). ( 1 ). Subformations as in LA. 1.

b.

Evergreen coniferous woodland with conical crowns prevailing (mostly subalpine, e.g. A&es). ( 1 ). Subformations as in LA. 1.

B. Deciduous woodland (see LB. ).

1, Cold-deciduous a.

Formations

2. Cold-deciduous a.

woodland with evergreen trees (see LB. 1. ). as in LA. 1. woodland without evergreen trees (see I.B.2.).

Broad-leaved deciduous woodland (e.g. Quercus, Car.va, Prunus). ( 1 ). Subformations as in I.A.1.

b. Needle-leaved deciduous woodland (e.g. Lariw, Tuxodium). ( 1). Subformations as in LA. 1. C.

Mixed deciduous woodland (broad leaved and needle leaved). ( 1). Subformations as in I.A. 1.

d. Cold-deciduous riparian woodland (see I.B.2.b.). ( 1). Subformations as in LA. 1. e.

III.

Cold-deciduous swamp or peat woodland (see I.B.2.c. ). ( 1 ). Subformations as in LA. 1.

SCRUB (shrubland or thicket). Mainly composed of woody chamaephytes and caespitose phanerophytes (e.g. Rosa spp., Myrica spp. in temperate areas. Cercidium and Carnegia in Sonora, Mexico) 0.5-5 m tall (occasionally taller).

72 TABLE

)

3 (Continued A.

B.

Thickets.

Poor in herbaceous

undergrowth.

I.

Mainly

deciduous

(see I.B. ).

2.

Mainly

evergreen

(see I.A.)

a.

Evergreen

broad-leaved

thicket.

b.

Evergreen

needle-leaved

thicket

Shrubland.

Rich in herbaceous

I

deciduous

Mainly

undergrowth.

Temperate

b.

Deciduous alluvial shrubland. island that are often vigorously

c.

Deciduous

peat shrubland

d.

Palustrine

deciduous

e.

Lacustrine

2. Evergreen

upland

deciduous

not touching.

shrubland Composed of fast growing shrubs occurring as pioneers flooded. therefore undergrowth is very sparse.

with Sphagnum

or other

on banks

of channels

or

peat mosses.

shrubland.

Periodically

flooded,

shrubland.

Fast-growing

shrubs

or having

groundwater-saturated

soils (e.g. C‘&u/u?r-

occurring

as pioneers

at edges of permanent

open water.

(e.g. Tavus)

IV.

DWARF-SHRUB

V

HERBACEOUS VEGETATION (Graminoids: grass and grasslike plants such as sedges ((‘ares) and rushes(Juncus). and forbs: broad-leaved herbs such as clover ( Trifolium) and ferns.) Woody plants can bc present. but their cover should not exceed 40%. We agree with the authors of the UNESCO ( 1973: pp. 28-29) classification that the term grassland can bc used to refer to graminoid vegetation, and that terms such as Savannah and steppe might be misunderstood and should therefore not be used, or should be added parenthetically. However, we have used the special terms, meadow and lawn to refer to cool season short grasslands with the understanding that lawns are maintained shrub free by people. Here we have modified the UNESCO classification to separate terrestrial and aquatic vegetation at the Formation Subclass level. and reduced “grassland” to Formation Group level, thereby reducing tall, medium, and short grasslands to the Formation level rather than Formation Groups as they were in the original classification (UNESCO, 1973 ). A.

Terrestrial I,

(heaths,

Most shrubs

interlocked.

1.

deciduous

shrubland

shrubs

(see LB. ).

a.

thus occidentalis

Individual

herbaceous

cryptograms,

deserts).

To 0.5 m tall

vegetation

Grassland (e.g. “prairies”. “steppes”. etc.: temperate, with late summer drought and winter frost). Woody plant cover is less than 40%. This Formation Group is usually more resistant to woody plant invasion than the meadow Formation Group dominated by cold season grasses and forbs. Warm season grasses dominate. a.

arc fully Tall grassland. Grasses and other graminoid growth forms are over 2 m tall when the inflorescences developed (e.g. Phragrnites). Some grass species that usually exceed 2 m will mature at lesser heights. In these circumstances these grasses are rarely dominant. and classification proceeds under another Formation, or Formation Class. Forbs can be present. but their cover is less than 50% of the total herb cover.

73 TABLE 3 (Continued)

( 1). Tall grassland with trees. Trees cover less than 40%, and shrubs might not be present. For categories with tree cover exceeding 40% go to Formation Class II. Tall grassland with shrubs (shrub Savannah; e.g. Phrugmitex with Myricu. Shrubs cover less than 40%, else go to Formation Class III. (3). Tall grassland without woody plants. In New York Phrugmites in moist sites that are often seasonally flooded. Medium tall grassland. Medium-sized herbs 0.5-2 m tall when inflorescences are fully developed (e.g. P&cum virgatum). Forb cover is less than 50%. ( 1 ). Subformations as in V.A. 1.a. above. (2).

b.

c.

Short grassland. Composed of plants less than 0.5 m tall when mature (e.g. Andropugon is less than 50%. ( 1). Subformations as in V.A. 1.a. above.

scopurius).

Forb cover

2. Meadows and lawns. Hemicryptophytic cool season grasses usually dominate, but lawns are variable and can be composed of warm season grasses such as C.ynodon. More forbs are usually present than in grasslands, but they are often scarce in heavily tended lawns. a.

Meadows. Dominated by hemicryptophytic sod-forming grasses, often rich in forbs. Many plants can remain at least partly green during the winter, even below the snow at higher latitudes. ( 1 )-( 3). Subformations as in V.A. I .a. above. (4). Sedge-rush meadow. Graminoid herbs dominating sites with periodically water-logged soil.

b.

Lawns (defined as maintained turf grasses). Lawns are consistently dominated but the phenology of the grasses and the abundance of forbs is highly variable. ( I ). Subformations as in V.A. 1.a. above.

by short sod-forming

grasses,

3. Forb vegetation (e.g. Ptendwm aquilmium). Forb cover exceeds 50%. graminoids can be present, but cover less than 50%. Woody life-forms only exceptionally present. a.

Perennial forb communities dominanted by nongraminoid hemicryptophytes and geophytes. Annuals of little importance. ( 1 ). Forest-border forb vegetation. Occurs as a narrow transitional band consisting of hemicryptophytes, geophytes, and therophytes, and growing more vigorously than the adjacent meadow or lawn. (2). Tall-forb vegetation. Dense stands of broad-leaved herbs. Mostly dicotyledons taller than 0.5 m. (3). Fern thicket (e.g. Pteridium uquilinium). (4). Perennial forb vegetation on organic deposits at flood lines. Consists ofbroad-leaved herbs growing abundantly on partially decomposed organic depositions which are often renewed by floods. (5 ). Perennial ruderal (weed) herb vegetation on debris, ruins, and other habitats highly modified by human activities. Broad-leaved herbs usually dominate. (6). Perennial ruderal (weed) forb vegetation on cultivated land. Mostly hemicryptophytic or geophytic forbs growing in the shade of cultivated perennial plant stands (e.g. nurseries and gardens).

b. Ephemeral or annual (i.e. plants usually live less than one year) forb vegetation. Therophytes dominate. ( 1 ). Ephemeral halophytic vegetation. (2). Ephemeral ruderal herb vegetation growing on debris, ruins, and other habitats highly modified by human activities. (3). Ephemeral ruderal vegetation on cultivated land. B. Semi-aquatic herbaceous vegetation. Includes freshwater and intertidal saltwater wetlands.

1. Freshwater vegetation (riparian, and palustrine wetlands).

TABLE 3 (Continued) a.

Emergent wetlands. Open vegetation on constantly or mostly waterlogged ground, without or with very few woody plants. ( 1 ). Riparian. Emergent marsh associated with channel edges. (2). Lacustrine. Surrounding permanent open water. (3). Palustrine. Associated with semi-permanent water or groundwater-saturated soils.

b. Sedge peat marshes and similar marshes. Dominated by sedges; seasonally flooded. ( 1 ). Tall sedge marsh (frequently flooded and commonly for long periods: as a rule natural). Foliage :aller than 40 cm. Very few other life-forms present. (2). Low sedge marsh (flooded infrequently or only for short periods). Dominated by small sedges less than 40 cm tall (e.g. C’arex Juncus, Scirpus) of low productivity, and mixed with other herbaceous life-forms. c.

Flushes (constantly wet, but rarely flooded). appears at the surface. ( 1). Forb flush. Dominated by small forbs. (2). Moss flush. Dominated by mosses.

Herbaceous vegetation growing in habitats where groundwater

2. Intertidal saltwater vegetation. Substrate is exposed and flooded by tides; includes the associated splash zone a.

Marine. Salinity exceeds 30 parts per thousand with little or no dilution except at the mouths of estuaries. ( I ). Herbaceous. Includes intertidal salt marshes. (a ). Flooded daily (e.g. Spartina alternljlora ), (b). Not flooded daily (e.g. Spartina patens). i). Rich in succulents (e.g. Salicornia). ii). Poor in succulents. (2 ). Algal vegetation. Algae dominant. (a). Rock substrate. i). Blue-green algae dominant. ii). Green algae dominant (e.g. Fuscus, etc). (b). Unconsolidated substrate. including mud flats. i) Subdivisionsas in V.B.2.a.(2).(a).

b. Estuarine. Salinity less than 30 parts per thousand. ( 1 ). Subdivisions as in V.B.2.a. VI.

BEACHES AND OTHER SCARCELY VEGETATED AREAS (desert vegetation is also included in III, IV. and V). Bare mineral soil, sand, or rock dominates, and plants are scattered or absent. Includes vegetation rooted in fissures of rocks. walls. or pavement.

A. Cryptogamic mats. 1. Foliose (i.e. leaf like). Lichens and mosses dominant. 2. Crustose (i.e. crusts). Lichens dominant 3. Blue-green algae. Dark strips on rocks caused by Cyanophyceae

that grow actively when water is trickling down

B. Scarcely vegetated screes. Substrate consists of unstable steeply sloping rock piles beneath weathering cliffs. Dominated by permanent herbs or suffructescent chamaephytes adapted to survive stone movements at the scree surface, sometimes even stopping them.

75 TABLE 3 (Continued) C. Scarcely vegetated sand accumulations 1. Scarcely vegetated sand dunes. a. Tall grass dune. Built up and partially covered by geophytic grasses (e.g. Phamcum vrrgatum) or grass-like plants which are able to adapt their root and shoot systems to sand burial. b. Short grass dune (mostly inland). Low hemicryptophytic c.

or geophytic grasses and sedges.

Forb dunes (e.g. Limonium carolinianurn, Solidago sempervirens).

2. Bare sand dunes. Only exceptionally with some isolated plants. a.

Shifting dunes in forest environments.

b. Shifting dunes in beach environments. 3. Artificial beach. Outside of tidal range.

D. Scarcely vegetated artificial surfaces (i.e. roads, parking lots, airstrips, courtyards, buildings, recreational facilities, etc.). Vegetation in cracks and patches covering less than 40% of the surface. Known as wall vegetation, pavement vegetation, chasmophytic vegetation, etc. E.

VII.

Scarcely vegetated compacted paction and disturbance.

surfaces (i.e. dumps, heavy equipment

yards, etc.) Vegetation restricted by soil com-

FRESHWATER AQUATIC VEGETATION (semi-aquatic freshwater and marine wetlands are included in V.). Lacustrine habitats located in topographic depressions or cutoff river channels. Less than 40% cover of trees, shrubs, emergents, mosses, or lichens. Composed of rooted or floating plants that endure or require water over the soil more or less continuously.

A. Rooted floating leaf vegetation. Includes submergents of Nymphaeceae. B. Free-floating fresh water vegetation (not rooted). 1. Broad-leaved free-floating plants that disappear in winter. 2. Lemna-dominated

free-floating vegetation.

3. Free-floating macroscopic algae vegetation (e.g. Spirogyra, Lvngbya contorta, Agmenellum quad ruplicatum)

C. Rooted submergents

(e.g. Elodea, Potamogeton, Ceratophyllum, etc. )

vironment. The revised version of Ellenberg’s system combines environmental factors such as climate and substrate with vegetation physiognomy to form the classification criteria. In one respect, our application of the system is quite different from what was originally in-

tended. Ellenberg’s classification was developed for use with natural vegetation assumed to have been undisturbed while undergoing successional change until reaching equilibrium with prevailing climate and other habitat conditions. This is true of most contemporary sys-

76 TABLE VIII.

3 (Continued) VINELAND. Vegetation dominated by lianas covering where vines sometimes cover trees and shrubs. Species are typical. A.

Lianas

with trees.

B.

Lianas

with shrubs.

C.

Lianas

with trees and shrubs.

D.

Lianas

with herbs.

terns (e.g. Alexander, 1986 ). The equilibrium state is referred to as the potential natural vegetation, or the climax (White, 1979). Our application of the revised Ellenberg system does not require that successional development occurs without disturbance or that climax is reached. We believe that the potential vegetation approach is inappropriate in human-dominated landscapes where environmental conditions - soil, hydrology, etc. - have often been severely modified, where disturbances have accelerated beyond natural ranges, where ecological disasters and catastrophes are frequent, and where successional development cannot be expected to advance beyond early seral phases. Our application is devoted to existing rather than potential vegetation. Applying the Ellenberg system to urban areas requires some terminology changes and the addition of subcategories to the system representing local conditions. Of course, the spatially variable nature of vegetation requires that additional subcategories must be devised in almost any application, regardless of scale and purpose. Below we present a classification key that combines terms and concepts from the keys produced by UNESCO ( 1973 ), MuellerDombois and Ellenberg ( 1974). Grady ( 1984), and the unpublished work of the New York City. Natural Resources Group ( 1987). We have added other extensions and redefinitions necessary to fit the key to urban conditions, but we have maintained the overall

more than 40% of the area. Often found on forest or scrub border: such as Lorziwra japonrcu. To.uicod~,rldron rudicans. and I ‘i/u spp.

structure of the UNESCO ( 1973 ) key. A sideby-side comparison of our key with the UNESCO key should simplify additional urban applications, and use of the key will contribute to standardization of urban surveys. In the classilication (Table 3 ), we provide relatively brief explanations of category distinctions. For a fuller explanation and description of the entities see UNESCO ( 1973). Grady ( 1984) and Natural Resources Group ( 1987). Terms are defined in Table 4. As in other hierarchical classilications, units of unequal rank are distinguished from one another by letters and numbers in outline form. The names of the units are as follows: I, II, etc. = FORMATION CLASS A, B, etc. = Formation subclass 1, 2. etc. = Formation group a, b, etc. = Formation ( 1 ), (2 ), etc. = Subformation (a ) , (b ), etc. = Subdivisions CONCLUSION This paper describes the first steps in a survey and management plan designed to be detailed and yet cost efficient. In designing the plan we kept in mind the probable need for visual results to be produced early in the life of a project. We believe that entity maps and permanent photographs will satisfy this need while supporting and not compromising the necessity to gather objective and repeatable infor-

TABLE 4 Definitions of terms used to describe life-forms. A detailed key is provided by Mueller-Dombois and Ellenberg ( 1974) Self-supporting vascular Phanerophytes

plants

Chamaephytes

Hemicryptophytes Cryptophytes

Plants that grow taller than 50 cm and do not die back below that height. Mature branches or shoots remain less than 50 cm above ground or periodically die back to that height. Buds are produced on aerial branches close to the soil. Shoots die back to ground level. Buds at level of ground. Buds or shoots survive below ground. Includes Geophytes

Helophytes

Hydrophytes

Therophytes

Land plants (rhizomes, bulbs, stem tubers, root tubers). Soil saturated in water or in water rhizomes. Buds at bottom of water.

Thallohemicryptophytes Thallo-theraphytes Thallo-epiphytes Free-moving thallophytes

Mosses, lichens. Cushion-like pulvinate.

or

For example, flat-matted mosses. Annuals. Attached to other plants.

Growing Growing

For their assistance in developing and field testing the ideas contained in this paper we wish to thank Patricia Grady, William Solecki, Mary Vint, John Robertson, Stephen Mader and Richard Pouyat. Financial support was obtained with the assistance of John Tannacredi of Gateway National Recreation Area, and the New York City Department of Parks and Recreation, Natural Resources Group.

Alexander, R.R., 1986. Classification of Wyoming. U.S. Forest Service,

Semi-autotrophic plants Vascular semi-parasites Thallo-semi-parasites Heterotrophic plants Vascular parasites Vascular saprophytes Thallo-parasites Thallo-saprophytes

ACKNOWLEDGEMENTS

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1 year life cycle (annuals). Shoot and root system die after seed production

Vascular plants which need suuuort . Root permanently in ground. Lianas Germinate on other plants, then Hemi-epiphytes root in ground, or germinate on ground, grow up on another plant then disconnect from the soil. Germinate or root on other Epiphytes plants or objects. Errant vasculat Free-moving water plants. hydrophytes Thallophytes (non-vascular) Thallo-chamaephytes

mation of use to managers and planners. The physiognomic-ecologic classification system provides an information-rich summary of field observations in the context of an internationally known system for communicating about the landscape. Successful applications of the system have been made in Gateway Recreation Area, Brooklyn, New York, and several New York City parks.

on living plants. on dead organic matter.

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