patrickbdevaney/mia9 · Datasets at Hugging Face

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periodically (see section 2.2.3). With the lowered water table these sites never flood today and
many plant species’ roots probably no longer reach ground water.
3.2.3 Sea Level Rise
Sea level rise may become a major environmental concern in South Florida if projected trends
continue. The South Florida Regional Planning Council is anticipating a five (5) foot rise in sea
level over the next 200 years. Sea level rise has already been implicated in the reduction of pine
rockland habitat in the lower Florida Keys (Ross et al. 1994), and the complete loss of pine
rocklands on Key Largo (Alexander 1953).
Sea level rise in Miami-Dade County will initially impact only the few coastal pine rocklands,
especially the Deering South Addition, an EEL site on Biscayne Bay. Loss of the pine rockland
ecosystem will be initiated not by inundation, but by saltwater intrusion to the water table, killing
pine rockland plant species. A more detailed Geographic Information Systems (GIS) analysis is
needed, but many pine rocklands may not be impacted directly because of their high elevation
and inland locations.
3.3 Climate
It has been suggested that the climate of Miami-Dade County has changed with the drainage of
wetlands (Marshall and Pielke 2004). Marshall and Pielke have hypothesized that prior to
drainage, a persistent moisture flux from heat-retaining wetlands prevented freezing
temperatures. Post-drainage freezes may have become more common.
In contrast to the findings of Marshall and Pielke (2004), large cities, such as greater-Miami, are
known to act as heat islands because of the heat retention by manmade structures. Urban heat
islands can be as much as two (2) to ten (10) degrees warmer than surrounding areas. Global
warming is also a factor, which may raise temperatures in Miami-Dade County.
Changes in climate may have many effects, although they are hard to predict. Possible impacts
may be changes in flowering and fruiting phenology of plants, fewer (or more) freezes changing
hardwood subcanopy structure and composition, changes in soil moisture and thereby seed
germination, changes in plant respiration rates, and susceptibility to biological invasions by
exotic organisms.
3.4 Vegetation Structure and Composition
Although the same three vegetation layers are still conceptually present in existing fragments of
pine rocklands, in many cases they depart significantly from the original structure and species
EEL Program, Management Plan, Part II – Pine Rockland (DRAFT) _____________________________________________________________________________________________________________________
Page 15
richness. The following paragraphs describe some of the most relevant changes and use the
description made in the previous section for comparison purposes.
3.4.1 Canopy
The historical canopy of pine rocklands, consisting of South Florida slash pine, was significantly
altered following non-indigenous settlement. The first major impact to the pine canopy was
logging. Large scale logging took place in Miami-Dade County from the very early 1900s to the
1950s (Craighead, 1971, Wade et al. 1980, USFWS 2000). Although some small areas of Long
Pine Key in ENP were never logged, it is likely that all or nearly all areas of pine rockland
outside of the national park were logged. Craighead (1971) reports a discussion with a mill
owner in 1952 who stated that during World War II every pine that could be made into a 2x4 was
cut down.
Following the end of logging activities, the pine canopy recovered in most pine rockland
fragments by 1992, resulting in an even-aged stand of mature pines. In August 1992, Hurricane
Andrew hit South Florida, and in the two years following almost the entire canopy of pine in
Miami-Dade County outside of ENP was lost. While hurricane winds killed many trees, the main
source of mortality was a widespread outbreak of a variety of beetles and weevils in the
weakened trees after the storm, including Ips species (I.
calligraphis, I. avulsus, and I. grandicollis), Hylobius
pales, and Pachylobius picivoris (DERM 1995).
In the mid 1990s, efforts were made to reestablish pine
trees on sites where they were lost. Pine seedlings were
planted on 22 preserves, including 12 EEL sites (Table
1). Many of these trees are now 6 to 15 feet tall. A
negative result of the reintroduction of pines has been
the establishment of extreme densities of trees in some
places due to overplanting. Mortality in many plantings
was much lower than anticipated. In addition, few sites
where pines have been planted have burned. Fires
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

periodically (see section 2.2.3). With the lowered water table these sites never flood today and

many plant species’ roots probably no longer reach ground water.

3.2.3 Sea Level Rise

Sea level rise may become a major environmental concern in South Florida if projected trends

continue. The South Florida Regional Planning Council is anticipating a five (5) foot rise in sea

level over the next 200 years. Sea level rise has already been implicated in the reduction of pine

rockland habitat in the lower Florida Keys (Ross et al. 1994), and the complete loss of pine

rocklands on Key Largo (Alexander 1953).

Sea level rise in Miami-Dade County will initially impact only the few coastal pine rocklands,

especially the Deering South Addition, an EEL site on Biscayne Bay. Loss of the pine rockland

ecosystem will be initiated not by inundation, but by saltwater intrusion to the water table, killing

pine rockland plant species. A more detailed Geographic Information Systems (GIS) analysis is

needed, but many pine rocklands may not be impacted directly because of their high elevation

and inland locations.

3.3 Climate

It has been suggested that the climate of Miami-Dade County has changed with the drainage of

wetlands (Marshall and Pielke 2004). Marshall and Pielke have hypothesized that prior to

drainage, a persistent moisture flux from heat-retaining wetlands prevented freezing

temperatures. Post-drainage freezes may have become more common.

In contrast to the findings of Marshall and Pielke (2004), large cities, such as greater-Miami, are

known to act as heat islands because of the heat retention by manmade structures. Urban heat

islands can be as much as two (2) to ten (10) degrees warmer than surrounding areas. Global

warming is also a factor, which may raise temperatures in Miami-Dade County.

Changes in climate may have many effects, although they are hard to predict. Possible impacts

may be changes in flowering and fruiting phenology of plants, fewer (or more) freezes changing

hardwood subcanopy structure and composition, changes in soil moisture and thereby seed

germination, changes in plant respiration rates, and susceptibility to biological invasions by

exotic organisms.

3.4 Vegetation Structure and Composition

Although the same three vegetation layers are still conceptually present in existing fragments of

pine rocklands, in many cases they depart significantly from the original structure and species

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

Page 15

richness. The following paragraphs describe some of the most relevant changes and use the

description made in the previous section for comparison purposes.

3.4.1 Canopy

The historical canopy of pine rocklands, consisting of South Florida slash pine, was significantly

altered following non-indigenous settlement. The first major impact to the pine canopy was

logging. Large scale logging took place in Miami-Dade County from the very early 1900s to the

1950s (Craighead, 1971, Wade et al. 1980, USFWS 2000). Although some small areas of Long

Pine Key in ENP were never logged, it is likely that all or nearly all areas of pine rockland

outside of the national park were logged. Craighead (1971) reports a discussion with a mill

owner in 1952 who stated that during World War II every pine that could be made into a 2x4 was

cut down.

Following the end of logging activities, the pine canopy recovered in most pine rockland

fragments by 1992, resulting in an even-aged stand of mature pines. In August 1992, Hurricane

Andrew hit South Florida, and in the two years following almost the entire canopy of pine in

Miami-Dade County outside of ENP was lost. While hurricane winds killed many trees, the main

source of mortality was a widespread outbreak of a variety of beetles and weevils in the

weakened trees after the storm, including Ips species (I.

calligraphis, I. avulsus, and I. grandicollis), Hylobius

pales, and Pachylobius picivoris (DERM 1995).

In the mid 1990s, efforts were made to reestablish pine

trees on sites where they were lost. Pine seedlings were

planted on 22 preserves, including 12 EEL sites (Table

1). Many of these trees are now 6 to 15 feet tall. A

negative result of the reintroduction of pines has been

the establishment of extreme densities of trees in some

places due to overplanting. Mortality in many plantings

was much lower than anticipated. In addition, few sites

where pines have been planted have burned. Fires

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