patrickbdevaney/mia9 · Datasets at Hugging Face

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would have resulted in much natural mortality, limiting
tree densities.
Because of fire suppression, some pine rockland
fragments now have a canopy of hardwoods. The most
common canopy hardwood is wild-tamarind. Exotic
hardwoods may also be common canopy trees in firesuppressed sites, including Australian umbrella tree and
woman’s tongue .
3.4.2 Subcanopy
Subcanopy densities are now much denser and taller than they were under historical conditions.
Conditions are site specific and vary according to geographic location, fire frequency, and
distance to seed sources (especially rockland hammocks). Sites that have received frequent fires,
such as Ludlam Pineland, are probably close to historic conditions, with short palm and
Table 1: Seedling pine plantings
on Miami-Dade County preserves
Preserve Owner
A.D. Barnes Park Parks
Andrew Dodge Pineland DERM
Black Creek Forest EEL
Boystown Pineland EEL
Deering Estate at Cutler Parks
Eachus Pineland EEL
Goulds Pineland EEL
Larry & Penny Thompson Park Parks
Ludlum Pineland EEL
Martinez Pineland Parks
Miami Metrozoo Parks
Navy Wells Pineland Parks
Ned Glenn Nature Preserve EEL
Nixon Smiley Addition EEL
Nixon Smiley Pineland Parks
Palm Drive Pineland EEL
Rockdale Pineland EEL
Ron Ehman Park Parks
Seminole Wayside Park Parks
Trinity Pineland EEL
Tropical Park Parks
West Biscayne Pineland EEL
EEL Program, Management Plan, Part II – Pine Rockland (DRAFT) _____________________________________________________________________________________________________________________
Page 16
hardwoods at low stem densities. Other sites, such as Navy Wells #23, are probably very
different than they were historically. This site now has a tall understory of hardwoods with a
very high stem density.
3.4.3 Herb Layer
The herb layer naturally has the highest diversity of plant species and a diverse array of rare
plant species. Like the subcanopy layer, the herb layer varies greatly between forest fragments.
Some sites that burned frequently and have sparse subcanopy layers have diverse herb layers.
Other sites with dense subcanopies that result in low light penetration and thick duff
accumulations have lost almost all herbaceous species. The overall herb layer in pine rockland
fragments has been degraded, with a loss in density and diversity.
3.4.4 Edges
Historically, edges in the pine rockland ecosystem were limited to ecotones with other habitat
types, especially rockland hammocks and marl prairies (see Sections 2.5 above and 3.5 below).
Because of forest fragmentation, all pine rockland fragments now have edges with artificial
communities, including lawns, agricultural fields, roads, and other vacant land. Edges create a
unique ecotone that can have impacts to the interior of natural sites (See Part I). Edges of pine
rockland fragments vary greatly in vegetation structure and composition, depending upon fire
history, soil disturbance, and management history. These edges typically have dense growths of
exotic and ruderal plant species. Abundant exotic plants include Brazilian pepper and Burma
reed. Initial establishment of these exotic plants on edges allows their population sizes to build in
disturbed soils, and then intact pine rocklands in the interior of the sites are subsequently invaded
due to a heavy seed rain.
3.5 Association with Other Habitat Types
As discussed in Section 2.5, pine rockland was historically associated with other habitat types,
especially rockland hammock and marl prairie. Today, most preserves have only a single habitat
type and have no natural ecotones with other habitats. Exceptions on EEL sites include Silver
Palm Groves, which has a small rockland hammock, and Nixon Smiley Pineland Addition,
which has several small marl prairies. The loss of ecotone habitat has resulted in the loss of many
populations of plant species restricted to the habitat, and has probably reduced the value of pine
rockland for some wildlife species.
3.6 Successional Processes Under Current Conditions
Because of forest fragmentation, human intervention, and a mosaic of urban lands between pine
rockland fragments, successional processes now differ than those discussed in Section 2.6. These
changes are discussed below.
3.6.1 Fire
Since pine rocklands are fire climax communities, natural fire frequency is of great importance.
However, fire periodicity, behavior, and intensity have all been changed on pine rockland
fragments. Under historical conditions, pine rockland fragments burned every three (3) to seven
(7) years, often in large landscape-scale, wind-driven fires. These fires were usually in the spring
EEL Program, Management Plan, Part II – Pine Rockland (DRAFT) _____________________________________________________________________________________________________________________
Page 17
or summer. Following fragmentation, fire periodicity has lengthened considerably at most sites.
Fire has been completely eliminated at some sites. This change can be attributed to two causes:
intentional fire suppression by people and the elimination of large scale landscape-level fires
because of the destruction of natural areas.
In addition to periodicity, fire behavior has changed. Natural fires were usually wind-driven head
fires that were ignited by lightning. Fires now start for a variety of reasons, including lightning,
arson, accident, and by prescription. Many fires, especially prescribed fires, are backing fires
burning into the wind. These are slow moving fires and can damage feeder roots of many plants.
They are typically used because they are easier to control.
Fire intensity has changed with the reduction in fire periodicity. Heavier fuel buildups between
fires result in hotter temperatures and higher flames. Intense fires can have long-lasting impacts
when they occur. Fires that are too intense can result in massive mortality of pines, saw
palmettos, understory hardwoods, and herbs. Following the fires, sites can be invaded more
readily by exotic pest plant species, especially natal grass, and ruderal species. Long term
vegetation recovery following intense fires has not been studied.
3.6.2 Tropical Cyclones
There has been much recent discussion about global warming and hurricane activity. Some argue
that global warming is resulting in stronger, more intense tropical cyclones (Webster et al. 2005).
Some, however, argue against this (Hoyos et al. 2006). Regardless of this debate, the widespread
changes in the overall landscape of Miami-Dade County and the changes to pine rockland

would have resulted in much natural mortality, limiting

tree densities.

Because of fire suppression, some pine rockland

fragments now have a canopy of hardwoods. The most

common canopy hardwood is wild-tamarind. Exotic

hardwoods may also be common canopy trees in firesuppressed sites, including Australian umbrella tree and

woman’s tongue .

3.4.2 Subcanopy

Subcanopy densities are now much denser and taller than they were under historical conditions.

Conditions are site specific and vary according to geographic location, fire frequency, and

distance to seed sources (especially rockland hammocks). Sites that have received frequent fires,

such as Ludlam Pineland, are probably close to historic conditions, with short palm and

Table 1: Seedling pine plantings

on Miami-Dade County preserves

Preserve Owner

A.D. Barnes Park Parks

Andrew Dodge Pineland DERM

Black Creek Forest EEL

Boystown Pineland EEL

Deering Estate at Cutler Parks

Eachus Pineland EEL

Goulds Pineland EEL

Larry & Penny Thompson Park Parks

Ludlum Pineland EEL

Martinez Pineland Parks

Miami Metrozoo Parks

Navy Wells Pineland Parks

Ned Glenn Nature Preserve EEL

Nixon Smiley Addition EEL

Nixon Smiley Pineland Parks

Palm Drive Pineland EEL

Rockdale Pineland EEL

Ron Ehman Park Parks

Seminole Wayside Park Parks

Trinity Pineland EEL

Tropical Park Parks

West Biscayne Pineland EEL

EEL Program, Management Plan, Part II – Pine Rockland (DRAFT) _____________________________________________________________________________________________________________________

Page 16

hardwoods at low stem densities. Other sites, such as Navy Wells #23, are probably very

different than they were historically. This site now has a tall understory of hardwoods with a

very high stem density.

3.4.3 Herb Layer

The herb layer naturally has the highest diversity of plant species and a diverse array of rare

plant species. Like the subcanopy layer, the herb layer varies greatly between forest fragments.

Some sites that burned frequently and have sparse subcanopy layers have diverse herb layers.

Other sites with dense subcanopies that result in low light penetration and thick duff

accumulations have lost almost all herbaceous species. The overall herb layer in pine rockland

fragments has been degraded, with a loss in density and diversity.

3.4.4 Edges

Historically, edges in the pine rockland ecosystem were limited to ecotones with other habitat

types, especially rockland hammocks and marl prairies (see Sections 2.5 above and 3.5 below).

Because of forest fragmentation, all pine rockland fragments now have edges with artificial

communities, including lawns, agricultural fields, roads, and other vacant land. Edges create a

unique ecotone that can have impacts to the interior of natural sites (See Part I). Edges of pine

rockland fragments vary greatly in vegetation structure and composition, depending upon fire

history, soil disturbance, and management history. These edges typically have dense growths of

exotic and ruderal plant species. Abundant exotic plants include Brazilian pepper and Burma

reed. Initial establishment of these exotic plants on edges allows their population sizes to build in

disturbed soils, and then intact pine rocklands in the interior of the sites are subsequently invaded

due to a heavy seed rain.

3.5 Association with Other Habitat Types

As discussed in Section 2.5, pine rockland was historically associated with other habitat types,

especially rockland hammock and marl prairie. Today, most preserves have only a single habitat

type and have no natural ecotones with other habitats. Exceptions on EEL sites include Silver

Palm Groves, which has a small rockland hammock, and Nixon Smiley Pineland Addition,

which has several small marl prairies. The loss of ecotone habitat has resulted in the loss of many

populations of plant species restricted to the habitat, and has probably reduced the value of pine

rockland for some wildlife species.

3.6 Successional Processes Under Current Conditions

Because of forest fragmentation, human intervention, and a mosaic of urban lands between pine

rockland fragments, successional processes now differ than those discussed in Section 2.6. These

changes are discussed below.

3.6.1 Fire

Since pine rocklands are fire climax communities, natural fire frequency is of great importance.

However, fire periodicity, behavior, and intensity have all been changed on pine rockland

fragments. Under historical conditions, pine rockland fragments burned every three (3) to seven

(7) years, often in large landscape-scale, wind-driven fires. These fires were usually in the spring

EEL Program, Management Plan, Part II – Pine Rockland (DRAFT) _____________________________________________________________________________________________________________________

Page 17

or summer. Following fragmentation, fire periodicity has lengthened considerably at most sites.

Fire has been completely eliminated at some sites. This change can be attributed to two causes:

intentional fire suppression by people and the elimination of large scale landscape-level fires

because of the destruction of natural areas.

In addition to periodicity, fire behavior has changed. Natural fires were usually wind-driven head

fires that were ignited by lightning. Fires now start for a variety of reasons, including lightning,

arson, accident, and by prescription. Many fires, especially prescribed fires, are backing fires

burning into the wind. These are slow moving fires and can damage feeder roots of many plants.

They are typically used because they are easier to control.

Fire intensity has changed with the reduction in fire periodicity. Heavier fuel buildups between

fires result in hotter temperatures and higher flames. Intense fires can have long-lasting impacts

when they occur. Fires that are too intense can result in massive mortality of pines, saw

palmettos, understory hardwoods, and herbs. Following the fires, sites can be invaded more

readily by exotic pest plant species, especially natal grass, and ruderal species. Long term

vegetation recovery following intense fires has not been studied.

3.6.2 Tropical Cyclones

There has been much recent discussion about global warming and hurricane activity. Some argue

that global warming is resulting in stronger, more intense tropical cyclones (Webster et al. 2005).

Some, however, argue against this (Hoyos et al. 2006). Regardless of this debate, the widespread

changes in the overall landscape of Miami-Dade County and the changes to pine rockland