Ecological Site Description Ecological Site Characteristics Site Identification



Yüklə 0.97 Mb.
səhifə2/6
tarix21.08.2017
ölçüsü0.97 Mb.
1   2   3   4   5   6

Plant Communities


Ecological Dynamics of the Site

This ecological site occurs on a variety of substrates in seasonally dry, hot, regions of the southeast-facing coast of Puna district of the Island of Hawai`i. Plant communities evolved without the presence of large mammals or the regular occurrence of fires. Volcanic activity with catastrophic lava flows has been frequent both historically and within the past few thousand years. This has created a mosaic of bare lava, older lava flows with native and introduced vegetation in various stages of regeneration, and small kipukas with older soils that, in most cases, have been cultivated by humans. Native plant communities probably did not carry lava-ignited fires easily due to the nature of the vegetation. However, alien understory vegetation is very susceptible to fire. The original forest plant community is now disturbed and fragmented due to fires, timber cutting, domestic and feral ungulate foraging, clearing for agriculture and housing, and alien species invasion. Fountaingrass is beginning to invade this ecological site and has formed limited but dense stands in places.


State and transition diagram

State 1 – Native Dry Forest

Plant Community 1

This state represents the Historic Climax Plant Community. The general aspect is a forest with an open or closed upper canopy of lama and pandanus 20 to 30 feet tall, a secondary canopy of alahe`e 8 to 15 feet tall, and a sparse understory of shrubs, herbs, and vines. These forests have standing live timber of 150 to 800 cubic feet per acre, with a representative value of about 250 cubic feet per acre. Intact examples of this forest probably do not exist today, so this plant community description is partly conjectural.


Pathways from this state/plant community

To State 2, Mixed Alien/Native Forest, via “A&J”:

A = gradual weed invasion; J = feral ungulate foraging.

Alien weeds are able to invade stands of Native Dry Forest. These weeds include grasses, shrubs, ferns, vines, and trees. The conversion to Mixed Alien/Native Forest is accelerated by feral ungulate foraging, which generally has much greater impact on native plants than on alien plants.
To State 4, Alien Weedy Meadow, via “E”:

E = fire.

Fire can obliterate Native Dry Forest. In most cases the forest is replaced by alien shrubs and grasses that dominate surrounding areas. In a few cases the native shrub `a`ali`i is a major component of the new plant community.
To State 5, Pasture, via “G&H”:

G = land clearing; H = pasture establishment.



Native Dry Forest can be converted to Pasture by clearing the forest with heavy machinery and planting desirable pasture species. On lava substrates, underlying lava rock is ripped and crushed by heavy machinery. Ripping and crushing produces some fine mineral particles and small, abundant gaps between the rock fragments. When this is done on organic soils about 50% of the soil organic matter may be lost in the process due to exposure to air and higher temperatures.
Plant species listed in the following tables have been observed in the course of field work or are derived from reliable records.

Abbreviations:

Origin: n = native (endemic or indigenous); a = alien (introduced by humans).

Type: t = tree; tf = tree fern; s = shrub; h = herb (forb); v = vine; f = fern; g = grasslike (grasses, sedges, rushes).
Composite representation of State 1, Plant Community 1, Native Dry Forest.

Scientific name

%Canopy cover by height class (ft)













0.1 -

2

2.1 -

4.5

4.6 -

13

13.1 -

40

40.1 -

80

80.1 -

120

Total cover

Local

common name

NRCS

common name

Origin

Type

NRCS

Code

Metrosideros polymorpha

tr

tr

5

20







20

'ohi'a lehua

'ohi'a lehua

n

t

MEPO5

Pandanus tectorius

tr

1

1

20







20

pandanus

Tahitian screwpine

n

t

PATE2

Diospyros sandwicensis

1

1

5

5







10

lama

lama

n

t

DISA10

Erythrina sandwicensis

tr

tr

tr

tr







tr

wili wili

wili wili

n

t

ERSA11

Psydrax odoratum

1

1

10

1







10

alahe`e

alahe`e

n

t

CAOD2

Pleomele hawaiiensis

?

?

?

?







?

hala pepe

Hawai'i hala pepe

n

t

PLHA4

Bobea timonioides

?

?

?

?







?

`ahakea

`ahakea

n

t

BOTI

Pritchardia affinis

?

?

?

?







?

loulu

Hawai`i pritchardia

n

t

PRAF

Osteomeles anthyllidifolia

1

1













1

`ulei

Hawai'i hawthorn

n

s

OSAN

Wikstroemia sp.

tr

1

5










5

`akia

false ohelo

n

s

WIKST

Styphelia tameiameiae

1

1













1

pukiawe

pukiawe

n

s

STTA

Dodonaea viscosa

1

1













1

`a`ali`i

Florida hopbush

n

s

DOVI

Scaevola sericea

1

1













1

naupaka kahakai

beach naupaka

n

s

SCSE6

Waltheria indica

1
















1

uhaloa

uhaloa

n

s

WAIN

Peperomia sp.

1
















1

`ala`ala wai nui

peperomia

n

h

PEPER

Cocculus orbiculatus

1
















1

huehue

queen coralbead

n

v

COOR11

Cassytha filiformis

1
















1

dodder laurel

devil's gut

n

v

CAFI4

Mucuna gigantea

1
















1

sea bean

sea bean

n

v

MUGI

Psilotum nudum

1
















1

moa

whisk fern

n

f

PSNU

Grasslike





































Native Forbs

1
















1
















Exotic Forbs





































Native Vines/Epiphytes

1
















1
















Exotic Vines





































Small ferns

1
















1
















Native Shrubs

1

1

5










5
















Exotic Shrubs





































Native Trees

1

1

20

40







50
















Tree ferns (native)





































Exotic Trees & tree ferns





































Lichen

1
















1
















Moss (on ground & logs)

1
















1
















Moss (on trees)

1
















1
















Logs on ground (>4" dia.)

1
















1
















Litter (not logs)

60
















60
















Surface rocks (>3" dia.)

5
















5
















Surface rocks (<3" dia.)

5
















5
















Bare Soil

1
















1















1   2   3   4   5   6


Verilənlər bazası müəlliflik hüququ ilə müdafiə olunur ©azkurs.org 2016
rəhbərliyinə müraciət

    Ana səhifə