patrickbdevaney/mia9 · Datasets at Hugging Face

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hammocks develop into dense shrublands. Height and coverage of understory palms, especially
saw palmetto and cabbage palm, increases as do understory hardwoods such as wax myrtle,
myrsine, and marlberry. Most fire suppressed sites also have dense coverage of exotic pest
plants, especially Brazilian pepper and Burma reed. As a general rule, pine rocklands do not
succeed to rockland hammocks without the proper seed sources, and even then the time to reach
complete succession to a climax rockland hammock is unknown.
Marl prairies dissected the Miami Rock Ridge, dividing the pine rocklands into a series of
isolated islands. Marl prairies are short hydroperiod wetlands with a marl soil substrate that is
derived from the precipitation of calcium carbonate from periphyton. The marl prairies that were
adjacent to pine rocklands were mainly treeless, dominated by forbs, grasses, and sedges. Water
stood or flowed through these prairies for up to several months during the summer wet season.
Where pine rockland and marl prairie intersected there was a mix of plant species common to
both communities. It is likely that wildlife use was heavy, especially for terrestrial animals that
visited the edges of the marl prairies for drinking water. The marl prairie ecosystem is discussed
as an independent chapter in this management plan.
2.6 Historical Successional Processes
The pine rockland ecosystem is subject to a number of natural stressors, which influence
community structure and composition. In some circumstances the pine rockland community can
succeed into other ecosystems. Natural processes that determine the ecological characteristics of
pine rocklands include fires, the regular occurrence of tropical cyclones, and the rather sporadic
incidence of frosts.
EEL Program, Management Plan, Part II – Pine Rockland (DRAFT) _____________________________________________________________________________________________________________________
Page 10
2.6.1 Fire
Fire frequency for pine rocklands in
Miami-Dade County is generally accepted
as about once every three (3) to seven (7)
years (Hofstetter 1973, Snyder 1990,
USFWS 2000), although Olmsted and
Loope (1984) suggest that 3-7 years may
be too frequent for young pines to attain a
large enough size to survive a fire. It has
been suggested that these fires are usually
ignited by lightning in the summer rainy
season between June and October (Doren
et al. 1993), or between April and June
(Beckage et al. 2003). Given that lightning
strikes occur year-round, and begin to
increase in the transition from the dry season to the wet season between March and May
(Hodanish et al. 1997), ignition probably occurred most frequently in the spring when vegetation
was at its driest (Beckage et al. 2003). Since lightning strikes can occur year-round (Hodanish et
al. 1997), fires probably occurred throughout the year, but more frequently in the spring and/or
summer when lightning is much more frequent.
Long-term temporal patterns of fire occurrence were probably influenced by El Niño induced
climate oscillations, resulting in very short times between fires during some decades, and very
long intervals in other decades (Beckage et al. 2003). Periods of short intervals may have been
important in reducing shrub biomass. Longer intervals may have allowed for pine seedlings to
grow and reach canopy height, which 3-7 year fire intervals may have prevented (Olmsted and
Loope 1984).
Fires set by indigenous people may have also influenced pine rocklands and may have differed
from theoretical natural fire regimes (Pyne et al. 1982). Fires may have been set by Tequesta
Indians to assist hunting efforts and maintain coontie, an important food source (Van Essen
2006). The amount, type, and seasonality of aboriginal burning are unknown.
2.6.2 Tropical Cyclones
June 1 through November 30 marks the annual hurricane season. During this period Miami-Dade
County may be crossed by one or more tropical cyclones, including tropical depressions, tropical
storms, and hurricanes. The main impact of these storms is the strong winds. Hurricanes have
winds in excess of 74 miles per hour. These storms can also bring large amounts of rainfall in
very short time periods and cause regional flooding.
Tropical cyclones can have significant impacts on pine rocklands. Strong winds can topple pine
trees. On Long Pine Key in ENP, Hurricane Andrew caused the deaths of 20 to 32% of pine trees
in the two (2) years after the storm, with local mortality ranging from only 3 to 4% up to 50 to
60% (Platt et al. 2000). Larger pine trees were more likely to be killed than smaller trees (Platt et
al. 2000). Hurricane Donna in 1960 is reported to have snapped or toppled one (1) to two (2)
Fire in pine rocklands
Photo by Keith Bradley, IRC
EEL Program, Management Plan, Part II – Pine Rockland (DRAFT) _____________________________________________________________________________________________________________________
Page 11
pine trees per acre on Long Pine Key (Craighead 1971). Hurricane Andrew also toppled,
defoliated, or top killed understory hardwoods, reducing subcanopy densities.
Hurricanes can also cause high storm surges, which can temporarily flood coastal pine rocklands.
Salt damage can kill vegetation, including trees, palms, hardwoods, and herbs. In 1992,
Hurricane Andrew’s storm surge reached almost 17 feet at the Deering Estate South Addition
and EEL site, covering pine rocklands. In addition to the pine rockland being flooded, a five (5)
to ten (10) foot tall and 15 to 30 foot wide rack line of dead vegetation and debris was deposited
in the pine rockland. The area covered by the rack line has now succeeded from pine rockland to
a dense shrubland covered by hardwoods, which invaded the rich organic soils left by the
decomposing debris.
2.6.3 Freezes
Freezes and cold weather kill or top-kill many plant species in pine rocklands, especially tropical
hardwoods (Olmsted et al. 1993). Because some pine rocklands can have a large component of
tropical species, freezes can have a major impact, at least temporarily. Freezes can be very
beneficial in removing living hardwood biomass (FNAI and FDNR 1990), but will leave a large
amount of dead woody matter. This dead material is later removed by fires.
2.7 Rare Organisms
Plant and animal species in any ecosystem range from abundant to extremely rare, even under
completely natural conditions. Prior to non-indigenous settlement, some plant and animal species
in pine rocklands were undoubtedly rare even before major human influences. Because botanical
exploration did not start in Miami-Dade County with any significance until the late 1800s, and
poor data was collected even then, we will never fully know the historical abundance of most
plant species. It is also likely that some plant species were never recorded by any botanist and
were lost due to habitat destruction or disturbance without the knowledge of the botanical
community. Examples of plant species that may have been historically rare include Bahama
manjack and Carter’s orchid.
EEL Program, Management Plan, Part II – Pine Rockland (DRAFT) _____________________________________________________________________________________________________________________
Page 12
3.0 Current Conditions, Threats, and Trends
This section discusses the current state of the pine rockland ecosystem in Miami-Dade County
including not only the properties owned and/or managed by EEL, but those owned by other
public entities and private landowners.

hammocks develop into dense shrublands. Height and coverage of understory palms, especially

saw palmetto and cabbage palm, increases as do understory hardwoods such as wax myrtle,

myrsine, and marlberry. Most fire suppressed sites also have dense coverage of exotic pest

plants, especially Brazilian pepper and Burma reed. As a general rule, pine rocklands do not

succeed to rockland hammocks without the proper seed sources, and even then the time to reach

complete succession to a climax rockland hammock is unknown.

Marl prairies dissected the Miami Rock Ridge, dividing the pine rocklands into a series of

isolated islands. Marl prairies are short hydroperiod wetlands with a marl soil substrate that is

derived from the precipitation of calcium carbonate from periphyton. The marl prairies that were

adjacent to pine rocklands were mainly treeless, dominated by forbs, grasses, and sedges. Water

stood or flowed through these prairies for up to several months during the summer wet season.

Where pine rockland and marl prairie intersected there was a mix of plant species common to

both communities. It is likely that wildlife use was heavy, especially for terrestrial animals that

visited the edges of the marl prairies for drinking water. The marl prairie ecosystem is discussed

as an independent chapter in this management plan.

2.6 Historical Successional Processes

The pine rockland ecosystem is subject to a number of natural stressors, which influence

community structure and composition. In some circumstances the pine rockland community can

succeed into other ecosystems. Natural processes that determine the ecological characteristics of

pine rocklands include fires, the regular occurrence of tropical cyclones, and the rather sporadic

incidence of frosts.

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

Page 10

2.6.1 Fire

Fire frequency for pine rocklands in

Miami-Dade County is generally accepted

as about once every three (3) to seven (7)

years (Hofstetter 1973, Snyder 1990,

USFWS 2000), although Olmsted and

Loope (1984) suggest that 3-7 years may

be too frequent for young pines to attain a

large enough size to survive a fire. It has

been suggested that these fires are usually

ignited by lightning in the summer rainy

season between June and October (Doren

et al. 1993), or between April and June

(Beckage et al. 2003). Given that lightning

strikes occur year-round, and begin to

increase in the transition from the dry season to the wet season between March and May

(Hodanish et al. 1997), ignition probably occurred most frequently in the spring when vegetation

was at its driest (Beckage et al. 2003). Since lightning strikes can occur year-round (Hodanish et

al. 1997), fires probably occurred throughout the year, but more frequently in the spring and/or

summer when lightning is much more frequent.

Long-term temporal patterns of fire occurrence were probably influenced by El Niño induced

climate oscillations, resulting in very short times between fires during some decades, and very

long intervals in other decades (Beckage et al. 2003). Periods of short intervals may have been

important in reducing shrub biomass. Longer intervals may have allowed for pine seedlings to

grow and reach canopy height, which 3-7 year fire intervals may have prevented (Olmsted and

Loope 1984).

Fires set by indigenous people may have also influenced pine rocklands and may have differed

from theoretical natural fire regimes (Pyne et al. 1982). Fires may have been set by Tequesta

Indians to assist hunting efforts and maintain coontie, an important food source (Van Essen

2006). The amount, type, and seasonality of aboriginal burning are unknown.

2.6.2 Tropical Cyclones

June 1 through November 30 marks the annual hurricane season. During this period Miami-Dade

County may be crossed by one or more tropical cyclones, including tropical depressions, tropical

storms, and hurricanes. The main impact of these storms is the strong winds. Hurricanes have

winds in excess of 74 miles per hour. These storms can also bring large amounts of rainfall in

very short time periods and cause regional flooding.

Tropical cyclones can have significant impacts on pine rocklands. Strong winds can topple pine

trees. On Long Pine Key in ENP, Hurricane Andrew caused the deaths of 20 to 32% of pine trees

in the two (2) years after the storm, with local mortality ranging from only 3 to 4% up to 50 to

60% (Platt et al. 2000). Larger pine trees were more likely to be killed than smaller trees (Platt et

al. 2000). Hurricane Donna in 1960 is reported to have snapped or toppled one (1) to two (2)

Fire in pine rocklands

Photo by Keith Bradley, IRC

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

Page 11

pine trees per acre on Long Pine Key (Craighead 1971). Hurricane Andrew also toppled,

defoliated, or top killed understory hardwoods, reducing subcanopy densities.

Hurricanes can also cause high storm surges, which can temporarily flood coastal pine rocklands.

Salt damage can kill vegetation, including trees, palms, hardwoods, and herbs. In 1992,

Hurricane Andrew’s storm surge reached almost 17 feet at the Deering Estate South Addition

and EEL site, covering pine rocklands. In addition to the pine rockland being flooded, a five (5)

to ten (10) foot tall and 15 to 30 foot wide rack line of dead vegetation and debris was deposited

in the pine rockland. The area covered by the rack line has now succeeded from pine rockland to

a dense shrubland covered by hardwoods, which invaded the rich organic soils left by the

decomposing debris.

2.6.3 Freezes

Freezes and cold weather kill or top-kill many plant species in pine rocklands, especially tropical

hardwoods (Olmsted et al. 1993). Because some pine rocklands can have a large component of

tropical species, freezes can have a major impact, at least temporarily. Freezes can be very

beneficial in removing living hardwood biomass (FNAI and FDNR 1990), but will leave a large

amount of dead woody matter. This dead material is later removed by fires.

2.7 Rare Organisms

Plant and animal species in any ecosystem range from abundant to extremely rare, even under

completely natural conditions. Prior to non-indigenous settlement, some plant and animal species

in pine rocklands were undoubtedly rare even before major human influences. Because botanical

exploration did not start in Miami-Dade County with any significance until the late 1800s, and

poor data was collected even then, we will never fully know the historical abundance of most

plant species. It is also likely that some plant species were never recorded by any botanist and

were lost due to habitat destruction or disturbance without the knowledge of the botanical

community. Examples of plant species that may have been historically rare include Bahama

manjack and Carter’s orchid.

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

Page 12

3.0 Current Conditions, Threats, and Trends

This section discusses the current state of the pine rockland ecosystem in Miami-Dade County

including not only the properties owned and/or managed by EEL, but those owned by other

public entities and private landowners.