Non Forested Biomes

Non Forested Biomes

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TOPIC: Non Forested Biomes
http://groups.google.com/group/entstrees/browse_thread/thread/53fb48a5b1252569?hl=en
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== 1 of 2 ==
Date: Tues, Feb 19 2008 7:45 pm
From: "Edward Frank"

Ents,

Our focus in this organization is primarily the forests of the eastern United Sates and its trees. Rightly so. The forests of the eastern US are a kaleidoscope of varied ecosystem subsets and tree associations. These are categorized as temperate broadleaf and mixed forests. Structurally more complex than needleleaf forests with considerably higher species diversity, the temperate forests are generally representative of warmer latitudes. Aboveground biomass is lower than that of temperate needleleaf with below ground biomass being intermediate. (http://www.undp.org/biodiversity/biodiversitycd/ecoTypes.htm )

These forest settings however are not the only biomes in which we find trees. There are numerous examples of biomes in which trees may play a role, but are not the dominant feature. Some time back I added a button for Prairies because of some reports from prairie remnants encountered by Bob Leverett and Monica on their westward journey. I also was fascinated by prairies on my trips to the west. Other such environments include examples like swamps, savannahs, marshes, chaparral, and alpine settings. I am thinking of altering the website to devote a section to these non-forested biomes, replacing the Prairie section, and making it a subsection of this larger topic. I know this may seem trivial to many of you, but I feel organization affects how we approach a topic and how we think about it. Looking on the web there are as many different definitions and groupings of biomes as there are people trying to discuss them. I want to outline some of the proposed biome classifications for use on the ENTS website. Wilkipedia (http://en.wikipedia.org/wiki/Biome } defines biome as follows: "A biome is a climatically and geographically defined area of ecologically similar communities of plants, animals, and soil organisms, often referred to as ecosystems. Biomes are defined based on factors such as plant structures (such as trees, shrubs, and grasses), leaf types (such as broadleaf and needleleaf), plant spacing (forest, woodland, savanna), and climate. Unlike ecozones, biomes are not defined by genetic, taxonomic, or historical similarities. Biomes are often identified with particular patterns of ecological succession and climax vegetation."

Grassland Biome (Great Plains, Rocky Mountain Foothills)

"Grassland biomes are large, rolling terrains of grasses, flowers and herbs. Latitude, soil and local climates for the most part determine what kinds of plants grow in a particular grassland. A grassland is a region where the average annual precipitation is great enough to support grasses, and in some areas a few trees. The precipitation is so erratic that drought and fire prevent large forests from growing. Grasses can survive fires because they grow from the bottom instead of the top. Their stems can grow again after being burned off. The soil of most grasslands is also too thin and dry for trees to survive. ..

There are two different types of grasslands; tall-grass, which are humid and very wet, and short-grass, which are dry, with hotter summers and colder winters than the tall-grass prairie. The settlers found both on their journey west. When they crossed the Mississippi River they came into some very tall grass, some as high as 11 feet. Here it rained quite often and it was very humid. As they traveled further west and approached the Rocky Mountains, the grass became shorter. There was less rain in the summer and the winters got colder. These were the short-grass prairies.

The most common types of plant life on the North American prairie are Buffalo Grass, Sunflower, Crazy Weed, Asters, Blazing Stars, Coneflowers, Goldenrods, Clover, and Wild Indigos. Some common animals in the grasslands are Coyotes, Eagles, Bobcats, the Gray Wolf, Wild Turkey, Fly Catcher, Canadian Geese, Crickets, Dung Beetle, Bison, and Prairie Chicken." (http://www.blueplanetbiomes.org/grasslands.htm)

Tropical Savannah (Everglades)

The tropical savanna is a biome characterized by tall grasses and occasional trees. Large regions of tropical savanna extend through the nations of Botswana, Namibia, and Kenya in Africa, southern Brazil, India, and Australia. Surprisingly, the Everglades of southern Florida in North America is also a tropical savanna. (http://www.cotf.edu/ete/modules/msese/earthsysflr/savannah.html )

Tropical savannas or grasslands are associated with the tropical wet and dry climate type (Koeppen's Aw), but they are not generally considered to be a climatic climax. Instead, savannas develop in regions where the climax community should be some form of seasonal forest or woodland, but edaphic conditions or disturbances prevent the establishment of those species of trees associated with the climax community. Seasonal forests of the tropics are also widespread and vary along a latitudinal/moisture gradient between the tropical broadleaf evergreen forest of the equatorial zone and the deserts of the subtropics. The word savanna stems from an Amerind term for plains which became Hispanicized after the Spanish Conquest. The vegetation. Savannas are characterized by a continuous cover of perennial grasses, often 3 to 6 feet tall at maturity. They may or may not also have an open canopy of drought-resistant, fire-resistant, or browse-resistant trees, or they may have an open shrub layer. Distinction is made between tree or woodland savanna, park savanna, shrub savanna and grass savanna. Furthermore, savannas may be distinguished according to the dominant taxon in the tree layer: for example, palm savannas, pine savannas, and acacia savannas. (http://www.runet.edu/~swoodwar/CLASSES/GEOG235/biomes/savanna/savanna.html )

Temperate Savannah / Semi-Savannah (Cross-Timbers Area - TX, OK, KA)

( http://www.uark.edu/misc/xtimber/introduction.html ) The Cross Timbers and Post Oak Savanna form the frontier between the eastern deciduous forest and the grasslands of the southern Great Plains. This great ecotone preserves some of the largest tracts of relatively undisturbed ancient forest and woodland left in the eastern United States, and offers an exceptional opportunity for environmental research, education, and conservation. These rugged old-growth woodlands were not commercially important, but have high ecological integrity and preserve vital components of our eroding biodiversity. They form a key link in the oak archipelago that extends from Central America into southeastern Canada, and provide essential habitat for many species, including neotropical migratory birds.

(http://en.wikipedia.org/wiki/Cross_Timbers ) The Cross Timbers is a semi-savanna on the southern Great Plains running from southeastern Kansas, across central Oklahoma, into central Texas. It lies at the eastern edge of the great prairies and the western edge of the deciduous forest. The Cross Timbers is mainly post oak (Quercus stellata) and blackjack oak (Quercus marilandica) forests interspersed with patches of open prairie (both tall and mixed grass). One of the three sub-regions of the North Central Plains of Texas. The thick growth formed an almost impenetrable barrier for early American explorers and travelers. Washington Irving, in 1835, described it as "like struggling through forests of cast iron."[1] Josiah Gregg described the Cross Timbers in 1845 as varying in width from five to thirty miles and attributed their denseness to the continual burning of the prairies.[2]

Gregg, Commerce of the Prairies, V. II, Ch. 10, p. 200: "The Cross Timbers vary in width from five to thirty miles, and entirely cut off the communication betwixt the interior prairies and those of the great plains. They may be considered as the 'fringe' of the great prairies, being a continuous brushy strip, composed of various kinds of undergrowth; such as black-jack, post-oaks, and in some places hickory, elm, etc., intermixed with a very diminutive dwarf oak, called by the hunters, 'shin-oak.' Most of the timber appears to be kept small by the continual inroads of the 'burning prairies;' for, being killed almost annually, it is constantly replaced by scions of undergrowth; so that it becomes more and more dense every reproduction. In some places, however, the oaks are of considerable size, and able to withstand the conflagrations. The Underwood is so matted in many places with grapevines, green-briars, etc., as to form almost impenetrable 'roughs,' which serve as hiding-places for wild beasts, as well as wild Indians; and would, in savage warfare, prove almost as formidable as the hammocks of Florida".

Chaparral Biome (http://en.wikipedia.org/wiki/Chaparral )

Chaparral is a shrubland or heathland plant community found primarily in California, USA, that is shaped by a Mediterranean climate (mild, wet winters and hot dry summers) and wildfire. Similar plant communities are found in the five other Mediterranean climate regions around the world, including the Mediterranean Basin (where it is known as maquis), central Chile (where it is called matorral), South African Cape Region (known there as fynbos), and in Western and Southern Australia.

A typical chaparral plant community consists of densely-growing evergreen scrub oaks and other drought-resistant shrubs. It often grows so densely that it is all but impenetrable to large animals and humans. This, and its generally arid condition, makes it notoriously prone to wildfires. Although many chaparral plant species require some fire cue (heat, smoke, or charred wood) for germination, chaparral plants are not "adapted" to fire per se. Rather, these species are adapted to particular fire regimes involving season, frequency, intensity and severity of the burn.

Hot and Dry Desert Biomes (Southwestern and Western US)

(http://www.blueplanetbiomes.org/desert.htm ) "A Hot and Dry Desert is, as you can tell from the name, hot and dry. Most Hot and Dry Deserts don't have very many plants. They do have some low down plants though. The only animals they have that can survive have the ability to burrow under ground. This is because they would not be able to live in the hot sun and heat. They only come out in the night when it is a little cooler. .Hot and Dry Deserts temperature ranges from 20 to 25° C. The extreme maximum temperature for Hot Desert ranges from 43.5 to 49° C. Cold Deserts temperature in winter ranges from -2 to 4° C and in the summer 21 to 26° C a year"

"The precipitation in Hot and Dry Deserts and the precipitation in Cold Deserts is different. Hot and Dry Deserts usually have very little rainfall and/or concentrated rainfall in short periods between long rainless periods. This averages out to under 15 cm a year. .. Hot and Dry Deserts are warm throughout the fall and spring seasons and very hot during the summer. the winters usually have very little if any rainfall. Cold Deserts have quite a bit of snow during winter. The summer and the beginning of the spring are barely warm enough for a few lichens, grasses and mosses to grow."

"Hot and Dry Deserts vegetation is very rare. Plants are almost all ground-hugging shrubs and short woody trees. All of the leaves are replete (packed with nutrients). Some examples of these kinds of plant are Turpentine Bush, Prickly Pears, and Brittle Bush. For all of these plants to survive they have to have adaptations. Some of the adaptations in this case are the ability to store water for long periods of time and the ability to stand the hot weather. Hot and Dry Deserts animals include small nocturnal (only active at night) carnivores. There are also insects, arachnids, reptiles, and birds. Some examples of these animals are Borrowers, Mourning Wheatears, and Horned Vipers."

A good example of this category are some of the deserts in the arid and semi-arid southwest. http://www.nativetreesociety.org/fieldtrips/us_west/arizona/sedona/sedona_canyon.htm Don Bertolette forwarded a photo of a tree growing in the red rock are of Sedona Canyon. He ask is this a an old growth ? I would not call it a forest , but certainly it was an old-growth system, with old trees.

Alpine Biomes (Mountain regions - generally above the tree line)

The tree line is not a sharp demarcation. It is a gray line with some trees above and more trees below that is used to demarcate the transition from a generally wooded upper mountain slopes to a tundra like alpine biome. However these twisted and scattered trees are some of our most significant resources. Most of the Bristlecone Pines, the world's oldest living things, in the White Mountains of eastern California are above what would be called a tree line and in an alpine setting. Similar examples exist across the mountain tops of eastern United States as well.

http://www.blueplanetbiomes.org/alpine.htm ) Cold, snowy, windy. When you hear those words they make you think of mountains. The Alpine biome is like winter is to people in New England; snow, high winds, ice, all the typical winter things. In Latin the word for 'high mountain' is 'alpes'. That is where today's word alpine comes from. Alpine biomes are found in the mountain regions all around the world. They are usually at an altitude of about 10,000 feet or more. The Alpine biome lies just below the snow line of a mountain. As you go up a mountain, you will travel through many biomes. In the North American Rocky Mountains you begin in a desert biome. As you climb you go through a deciduous forest biome, grassland biome, steppe biome, and taiga biome before you reach the cold Alpine biome.

In the summer average temperatures range from 10 to 15° C . In the winter the temperatures are below freezing. The winter season can last from October to May. The summer season may last from June to September. The temperatures in the Alpine biome can also change from warm to freezing in one day. Because the severe climate of the Alpine biome, plants and animals have developed adaptations to those conditions. There are only about 200 species of Alpine plants. At high altitudes there is very little CO2, which plants need to carry on photosynthesis. Because of the cold and wind, most plants are small perennial groundcover plants which grow and reproduce slowly. They protect themselves from the cold and wind by hugging the ground. Taller plants or trees would soon get blown over and freeze. When plants die they don't decompose very quickly because of the cold. This makes for poor soil conditions. Most Alpine plants can grow in sandy and rocky soil. Plants have also adapted to the dry conditions of the Alpine biome. Plant books and catalogs warn you about over watering Alpine plants.

Wetland Types

The EPA has a good classification of wetland types that we encounter in the United States. http://www.epa.gov/owow/wetlands/types/ "Wetlands are areas where water covers the soil, or is present either at or near the surface of the soil all year or for varying periods of time during the year, including during the growing season. Water saturation largely determines how the soil develops and the types of plant and animal communities living in and on the soil. Wetlands may support both aquatic and terrestrial species. The prolonged presence of water creates conditions that favor the growth of specially adapted plants and promote the development of characteristic wetlands soils."

-- EPA, America's Wetlands: Our Vital Link Between Land and Water

1) Marshes :

a) Tidal

b) Nontidal

i) Wet Meadows

ii) Prairie Potholes

iii) Vernal Pools

iv) Playa Lakes

2) Swamps

a) Forested Swamps

i) Bottomland Hardwoods

b) Shrub Swamps

i) Mangrove Swamps

3) Bogs

a) Northern bogs

b) Pocosins

4) Fens

Marshes:

http://www.epa.gov/owow/wetlands/types/marsh.html Marshes are defined as wetlands frequently or continually inundated with water, characterized by emergent soft-stemmed vegetation adapted to saturated soil conditions. There are many different kinds of marshes, ranging from the prairie potholes to the Everglades, coastal to inland, freshwater to saltwater. All types receive most of their water from surface water, and many marshes are also fed by groundwater. Nutrients are plentiful and the pH is usually neutral leading to an abundance of plant and animal life. For the purposes of this publication, we have divided marshes into two primary categories: tidal and non-tidal.

Non-tidal marshes are the most prevalent and widely distributed wetlands in North America. They are mostly freshwater marshes, although some are brackish or alkaline. They frequently occur along streams in poorly drained depressions, and in the shallow water along the boundaries of lakes, ponds, and rivers. Water levels in these wetlands generally vary from a few inches to two or three feet, and some marshes, like prairie potholes, may periodically dry out completely.

It is easy to recognize a non-tidal marsh by its characteristic soils, vegetation, and wildlife. Highly organic, mineral rich soils of sand, silt, and clay underlie these wetlands, while lily pads, cattails (see photo), reeds, and bulrushes provide excellent habitat for waterfowl and other small mammals, such as red-winged blackbirds, great blue herons, otters, and muskrats. prairie potholes, playa lakes, vernal pools, and wet meadows are all examples of non-tidal marshes.

Tidal marshes can be found along protected coastlines in middle and high latitudes worldwide. They are most prevalent in the United States on the eastern coast from Maine to Florida and continuing on to Louisiana and Texas along the Gulf of Mexico. Some are freshwater marshes, others are brackish (somewhat salty), and still others are saline (salty), but they are all influenced by the motion of ocean tides. Tidal marshes are normally categorized into two distinct zones, the lower or intertidal marsh and the upper or high marsh.

In saline tidal marshes, the lower marsh is normally covered and exposed daily by the tide. It is predominantly covered by the tall form of smooth cordgrass (Spartina alterniflora). The saline marsh is covered by water only sporadically, and is characterized by short smooth cordgrass, spike grass,and black grass (Juncus gerardii). Saline marshes support a highly specialized set of life adapted for saline conditions. Brackish and fresh tidal marshes are also associated with specific plants and animals, but they tend to have a greater variety of plant life than saline marshes.

Swamps

http://www.epa.gov/owow/wetlands/types/swamp.html A swamp is any wetland dominated by woody plants. There are many different kinds of swamps, ranging from the forested red maple, (Acer rubrum), swamps of the Northeast, to the extensive bottomland hardwood forests found along the sluggish rivers of the Southeast. Swamps are characterized by saturated soils during the growing season, and standing water during certain times of the year. The highly organic soils of swamps form a thick, black, nutrient-rich environment for the growth of water-tolerant trees such as cypress (Taxodium spp.), Atlantic white cedar (Chamaecyparis thyoides), and tupelo (Nyssa aquatica). Some swamps are dominated by shrubs, such as buttonbush or smooth alder. Plants, birds, fish, and invertebrates such as freshwater shrimp, crayfish, and clams require the habitats provided by swamps. Many rare species, such as the endangered American crocodile depend on these ecosystems as well. Swamps may be divided into two major classes, depending on the type of vegetation present: shrub swamps, and forested swamps.

Forested swamps are found throughout the United States. They are often inundated with floodwater from nearby rivers and streams. Sometimes, they are covered by many feet of very slowly moving or standing water. In very dry years they may represent the only shallow water for miles and their presence is critical to the survival of wetland-dependent species like wood ducks (Aix sponsa), river otters (Lutra canadensis), and cottonmouth snakes (Agkistrodon piscivorus). Some of the common species of trees found in these wetlands are red maple and pin oak (Quercus palustris) in the Northern United States, overcup oak (Quercus lyrata) and cypress in the South, and willows (Salix spp.) and western hemlock (Tsuga sp.) in the Northwest. Bottomland hardwood swamp is a name commonly given to forested swamps in the south central United States.

Shrub swamps, are similar to forested swamps, except that shrubby vegetation such as buttonbush, willow, dogwood (Cornus sp.) , and swamp rose (Rosa palustris) predominates. In fact, forested and shrub swamps are often found adjacent to one another. The soil is often water logged for much of the year, and covered at times by as much as a few feet of water because this type of swamp is found along slow moving streams and in floodplains. Mangrove swamps are a type of shrub swamp dominated by mangroves that covers vast expanses of southern Florida

Bogs

http://www.epa.gov/owow/wetlands/types/bog.html Bogs are one of North America's most distinctive kinds of wetlands. They are characterized by spongy peat deposits, acidic waters, and a floor covered by a thick carpet of sphagnum moss. Bogs receive all or most of their water from precipitation rather than from runoff, groundwater or streams. As a result, bogs are low in the nutrients needed for plant growth, a condition that is enhanced by acid forming peat mosses. There are two primary ways that a bog can develop: bogs can form as sphagnum moss grows over a lake or pond and slowly fills it (terrestrialization), or bogs can form as sphagnum moss blankets dry land and prevents water from leaving the surface (paludification). Over time, many feet of acidic peat deposits build up in bogs of either origin. The unique and demanding physical and chemical characteristics of bogs result in the presence of plant and animal communities that demonstrate many special adaptations to low nutrient levels, waterlogged conditions, and acidic waters, such as carnivorous plants.

Northern bogs are generally associated with low temperatures and short growing seasons where ample precipitation and high humidity cause excessive moisture to accumulate. Therefore, most bogs in the United States are found in the northern states. Northern bogs often form in old glacial lakes. They may have either considerable amounts of open water surrounded by floating vegetation or vegetation may have completely filled the lake (terrestrialization).

The sphagnum peats of northern bogs cause especially acidic waters. The result is a wetland ecosystem with a very specialized and unique flora and fauna that can grow in these conditions called acidophiles. Nevertheless, bogs support a number of species of plants in addition to the characteristic sphagnum moss, including cotton grass, cranberry, blueberry, pine, Labrador tea, and tamarack. Moose, deer, and lynx are a few of the animals that can be found in northern bogs. The greater sandhill crane, the sora rail, and the great gray owl depend on bogs for survival.

Pocosins are densely vegetated with trees and shrubs. They are subjected to fire about every 10 to 30 years. The word pocosin comes from the Algonquin Native American word for "swamp on a hill". These evergreen shrub and tree dominated landscapes are found on the Atlantic Coastal Plain from Virginia to northern Florida, though most are found in North Carolina. Usually, there is no standing water present in pocosins, but a shallow water table leaves the soil saturated for much of the year.They range in size from less than an acre to several thousand acres located between and isolated from old or existing stream systems in most instances.

Because pocosins are found in broad, flat, upland areas far from large streams, they are ombrotrophic like northern bogs, meaning rain provides most of their water. Also like the bogs of the far north, pocosins are found on waterlogged, nutrient poor, acid soils. The soil itself is a mixture of peat and sand containing large amounts of charcoal from periodic burnings. These natural fires occur because pocosins periodically become very dry in the spring or summer. The fires are ecologically important because they increase the diversity of shrub types in pocosins. The most common plants are evergreen trees (loblolly bay, red bay, and sweet bay), and evergreen shrubs (titi, fetterbush, and zenobia). Pocosins provide important habitat for many animals, including some endangered species like the red-cockaded woodpecker. They are especially important as the last refuge for black bears in coastal Virginia and North Carolina, and the red wolf has recently been reintroduced in North Carolina pocosins.

Fens

http://www.epa.gov/owow/wetlands/types/fen.html Fens, are peat-forming wetlands that receive nutrients from sources other than precipitation: usually from upslope sources through drainage from surrounding mineral soils and from groundwater movement. Fens differ from bogs because they are less acidic and have higher nutrient levels. They are therefore able to support a much more diverse plant and animal community. These systems are often covered by grasses, sedges, rushes, and wildflowers. Some fens are characterized by parallel ridges of vegetation separated by less productive hollows. The ridges of these patterned fens form perpendicular to the downslope direction of water movement. Over time, peat may build up and separate the fen from its groundwater supply. When this happens, the fen receives fewer nutrients and may become a bog.

Like bogs, fens are mostly a northern hemisphere phenomenon -- occurring in the northeastern United States, the Great Lakes region, the Rocky Mountains, and much of Canada -- and are generally associated with low temperatures and short growing seasons, where ample precipitation and high humidity cause excessive moisture to accumulate.

Barrens:

Barrens are ecosystems where there is only a limited species diversity due to the nature of the underlying soil. In the case of Pine Barrens, a forested biome, the soil is dry, acidic, and infertile. In examples such as the serpentine barrens, the chemistry of the soil derived from the underlying serpentine bearing bedrock is essentially poisonous to most vegetation types. These are small ecosystems, but one I wanted to mention.

Pine Barrens

http://en.wikipedia.org/wiki/Pine_Barrens Pine barrens, also known as "pine plains", "sand plains", "pinelands", "pine bush", and "pitch pine-scrub oak barrens", occur throughout the northeastern U.S. from New Jersey to Maine (see Atlantic coastal pine barrens) as well as the Midwest and Canada. Pine barrens are plant communities that occur on dry, acidic, infertile soils dominated by grasses, forbs, low shrubs, and scattered trees; most extensive barrens occur in large areas of sandy glacial deposits, including outwash plains, lakebeds, and outwash terraces along rivers. The most common trees are the Jack Pine, Red Pine, Pitch Pine, Blackjack Oak, and Scrub Oak; a scattering of larger Oaks is not unusual. The understory is composed of grasses, sedges, and forbs, many of them common in dry prairies. Plants of the heath family, such as blueberries and bearberry, and shrubs such as prairie willow and hazelnut are common. These species have adaptations that permit them to survive or regenerate well after fire. Pine barrens support a number of rare species, including Lepidoptera such as the Karner Blue butterfly (Lycaeides melissa samuelis) and the barrens buckmoth (Hemileuca maia), and plants such as the Sand-plain Gerardia (Agalinis acuta).

Serpentine Barrens

http://www.nature.org/wherewework/northamerica/states/pennsylvania/preserves/art1594.html Located along the Maryland-Pennsylvania border, the State-Line Serpentine Barrens contains some of the last major remnants of serpentine grassland in eastern North America. The thin soils covering this light green bedrock contain high levels of nickel, chromium and other metals that prove toxic to most plants and animals. However, while lacking nutrients, this habitat supports numerous species-many rare or endangered-that have adapted to the harsh environment over thousands of years.

The Nature Conservancy has worked to protect globally rare serpentine barrens since 1979, when it joined Chester County's "Concerned Citizens of West Nottingham Township" to oppose the quarrying of serpentine rock near the Goat Hill Barrens. The partnership succeeded in blocking the project, and prevented further damage to surrounding natural areas. Since then, the Conservancy has acquired additional land near the Goat Hill Barrens, transferring some of it to the state for a rare plant preserve. Today, the Conservancy assists with conservation at the Goat Hill Barrens, and also owns and manages the Chrome Barrens located nearby.

http://www.rambles.net/hike_serpbarrens.html Serpentine is a light green-colored rock formed beneath the ocean floor and thrust to the surface during ancient shifts in the Earth's crust. Barrens such as those in Nottingham are found only in three areas of North America: California and southern Oregon, the Gaspe Peninsula and western Newfoundland, and southeastern Pennsylvania and northern Maryland. The Nottingham barrens are among the largest of this region. The thin soil covering the serpentine is low in essential nutrients and high in metals that are toxic to many plants, which is why only very adaptive species have survived there.

Natural Communities - Serpentine Grasslands http://www.dnr.state.md.us/wildlife/serpentine.asp Tens of thousands of acres of grassland dotted with Blackjack and Post Oaks once stretched across northern Maryland and nearby Pennsylvania. Prior to European settlement, most of Baltimore and Harford Counties and adjacent counties in Pennsylvania were covered by this prairie-like grassland. English settlers seeing this virtually treeless expanse referred to it as "The Barrens."

For thousands of years, Native American fire-hunting kept the grasslands relatively free of woody vegetation and created patches of bare ground for herbs to colonize. When European settlement eliminated large-scale frequent fires, the grassland areas were replaced by woodlands. Prairie-like vegetation persisted on serpentine, a dry and nutrient-poor soil. Unfortunately, most of the prairie-like serpentine grasslands have been destroyed in the last century by mining and development, and invading pines and junipers threaten to take what remains.

Four major remnants of the globally rare serpentine grassland still exist in Maryland, occupying less than five percent of the original grassland area but harboring at least 34 rare and endangered plant species. These rare plants at Soldier' Delight, Robert E. Lee, and two privately owned natural areas are increasingly threatened by the encroachment of pines and junipers.

Ed Frank

== 2 of 2 ==
Date: Tues, Feb 19 2008 8:47 pm
From: James Parton

Ed,

This was a very informative post. I found the wetland entry especially
interesting after my visit to Jackson Park over the weekend. What
biome would the longleaf fire forests be?

James P.

== 2 of 3 ==
Date: Wed, Feb 20 2008 6:39 am
From: "Edward Frank"

James,

I guess it would depend on what definition you used. I don't know what to say. Some are more broad sweeps, while others go into excruciating detail. A source to look at for you might be some of the classifications from Maryland:

http://www.dnr.state.md.us/wildlife/nhpnatcomm.asp
This first approximation of Maryland plant communities illustrates the preliminary stages of classification development and provides a framework to continue work. The hierarchy of the classification follows The Nature Conservancy's (TNC) National Classification. The objective of the National Classification is to partition the biophysical landscape into reasonable units for conservation. The basic unit of the classification is the "community element", a vegetation unit of uniform floristic composition, habitat and physiognomy. The alliance level presented here is broader in scale. Developed in part for the National Gap Analysis Program, the community alliances are groups of community elements which share one or more diagnostic species and occur in broadly similar habitat. Whereas the community element is homogenous in composition, the community alliance is typically more variable across its range.

http://www.dnr.state.md.us/wildlife/Md_Veg_Com/toc.asp
Classification of Vegetative Communities of Maryland: First Iteration
A Subset of the International Classification of Ecological Communities:
Terrestrial Vegetation of the United States
Compiled by Jason W. Harrison
Maryland Department of Natural Resources, Maryland Natural Heritage Program

Ed Frank

== 3 of 3 ==
Date: Wed, Feb 20 2008 6:54 am
From: "Edward Frank"

ENTS,

As I was reading about the various biomes or ecotones there were even a number of descriptions of human derived ones including Agricultural Biomes and Urban Biomes. I wonder if there might be, or should be one for heavily timbered forests, or like much of Allegheny National Forest which has been managed to achieve cherry growth at the expense of other species.

Ed

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