Preamble Polynesians introduced food crops and some tree - - PDF document

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Preamble Polynesians introduced food crops and some tree - - PDF document

Oct 17, 2023 436 likes •581 views

Preamble Polynesians introduced food crops and some tree Polynesians introduced food crops and some tree species, and altered lowland areas through burning species, and altered lowland areas through burning Rapid land

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Photo credit: Forest & Kim Starr Photo credit: Forest & Kim Starr

Some Hydrological Impacts of Some Hydrological Impacts of Alien Tree Invasion in Hawai Alien Tree Invasion in Hawai‘ ‘i i

Tom Giambelluca

Geography Department University of Hawai‘i at Mānoa

Preamble

  • Polynesians introduced food crops and some tree

Polynesians introduced food crops and some tree species, and altered lowland areas through burning species, and altered lowland areas through burning

  • Rapid land degradation after European contact:

Rapid land degradation after European contact: sandalwood harvesting, ranching sandalwood harvesting, ranching

  • Extensive planting of introduced tree species during early

Extensive planting of introduced tree species during early 20 20th

th century

century

  • Intentional and accidental introduction of alien plants and

Intentional and accidental introduction of alien plants and animals continues animals continues

  • State of Hawai

State of Hawai‘ ‘i lists 106 highly invasive plant species in i lists 106 highly invasive plant species in the Islands the Islands

  • Many tree species have been found to be invasive

Many tree species have been found to be invasive

Photo credit: Michelle Clapper, USGS-BRD, UH

Perceptions of Perceptions of Hydrological Impacts Hydrological Impacts

Photo credit: Michelle Clapper, USGS-BRD, UH

Once intentionally introduced for soil and water Once intentionally introduced for soil and water conservation, alien trees are now universally conservation, alien trees are now universally perceived as having negative hydrological perceived as having negative hydrological impacts, especially on ground impacts, especially on ground-

  • water recharge.

water recharge. But there has been very little scientific But there has been very little scientific evidence to support this perception. evidence to support this perception. Possible Hydrological Possible Hydrological Impacts of Invasive Trees Impacts of Invasive Trees

Photo credit: Michelle Clapper, USGS-BRD, UH

  • Reduced soil permeability

Reduced soil permeability: : invasive trees invasive trees inhibit ground cover, exposing soil inhibit ground cover, exposing soil

  • Increased runoff and soil erosion

Increased runoff and soil erosion: : exposed exposed soil, effects on soil, effects on throughfall throughfall

  • Reduced above

Reduced above-

  • ground water storage

ground water storage: : in in cloud forests, alien trees support less cloud forests, alien trees support less epiphytic cover, affecting epiphytic cover, affecting stemflow stemflow

  • Increased transpiration

Increased transpiration: : invasive trees are invasive trees are

  • ften fast
  • ften fast-
  • growing, which may correlate with

growing, which may correlate with high water use high water use

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Miconia Miconia calvescens calvescens

Two of the important invasive tree Two of the important invasive tree species in Hawai species in Hawai‘ ‘i i

Psidium Psidium cattleianum cattleianum (strawberry guava) (strawberry guava)

Photo credit: Michelle Clapper, USGS-BRD, UH

Two of the important invasive tree Two of the important invasive tree species in Hawai species in Hawai‘ ‘i i Miconia Miconia Characteristics Characteristics

  • Grows fast

Grows fast

  • Invades quickly

Invades quickly

  • Difficult to eradicate

Difficult to eradicate

  • Dark, opaque leaves

Dark, opaque leaves

  • Large leaves

Large leaves

  • Superficial roots

Superficial roots

  • Prefers steep slopes

Prefers steep slopes

Psidium Psidium Characteristics Characteristics

  • Grows fast

Grows fast

  • Invades quickly

Invades quickly

  • Already widespread in Hawaii

Already widespread in Hawaii

  • Difficult to eradicate

Difficult to eradicate

  • Many stems

Many stems

  • Smooth bark

Smooth bark

Photo credit: Michelle Clapper, USGS-BRD, UH

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Miconia Miconia Pilot Study Pilot Study

  • Under

Under-

  • canopy light levels

canopy light levels

  • Soil characteristics

Soil characteristics

  • Throughfall

Throughfall drop size and velocity drop size and velocity

  • Root exposure as evidence of erosion

Root exposure as evidence of erosion Light Penetration

light fraction 0.01 0.02 0.03 0.04 0.05 1 2 3 4 5 6 7 8 9 10 11 12 10 20 30 40 50 60 70 80 90 100 1 2 3 4 5 6 7 8 9 10 11 12 200 400 600 800 1000 1200 1400 1600 1800 2000 Light under canopy Light in parking lot

Ground Cover

light fraction 0.01 0.02 0.03 0.04 0.05 1 2 3 4 5 6 7 8 9 10 11 12 10 20 30 40 50 60 70 80 90 100 1 2 3 4 5 6 7 8 9 10 11 12 200 400 600 800 1000 1200 1400 1600 1800 2000 Light under canopy Light in parking lot

DROP SIZE MEASUREMENTS

Kazuki Nanko

  • Univ. Tsukuba

Laser disdrometer

Onomea IPIF

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Results

  • f Drop

Size Survey Results

  • f Drop

Size Survey Results

  • f Drop

Size Survey Results

  • f Drop

Size Survey

Natural Rain Artificial Spray

Miconia median drop size = 3.8 mm Very high compared with previous

  • bservations

Median drop size Miconia: 5.5 mm ‘ohia: 3.7 mm

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Miconia Research: Next Steps

  • Use kinetic energy estimates to simulate the

increase in splash detachment, soil erosion potential as a result of Miconia invasion

  • Use root exposure to estimate rates of soil

erosion

  • Develop proposal to study Miconia in Tahiti

Guava Study Guava Study

  • Compare Native (Thurston) and Invaded

Compare Native (Thurston) and Invaded (Ola (Ola‘ ‘a) Sites a) Sites

  • Water and Carbon Dynamics at Stand Level

Water and Carbon Dynamics at Stand Level

  • Transpiration of Different Species

Transpiration of Different Species

  • Fog Interception

Fog Interception

  • Rainfall and Fog Water Partitioning

Rainfall and Fog Water Partitioning

Photo credit: Michelle Clapper, USGS-BRD, UH

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Field Sites

  • Invaded Forest Site

– ‘ohia forest invaded by Psidium cattleianum (strawberry guava)

  • Native Forest Site

– Metrosideros polymorpha (‘ohia) – Cibotium spp. (hapu‘u; tree fern)

Observations Observations

  • Water vapor and CO2 exchange

Water vapor and CO2 exchange

– – eddy covariance eddy covariance – – sapflow sapflow measurement measurement – – regular live biomass inventory and leaf litter collection regular live biomass inventory and leaf litter collection – – soil respiration measurement soil respiration measurement

  • Micrometeorology

Micrometeorology

– – energy balance energy balance – – leaf wetness leaf wetness – – wind profile wind profile – – fog monitoring fog monitoring – – soil moisture profile soil moisture profile

  • Wet canopy water balance

Wet canopy water balance

– – recording recording throughfall throughfall and and stemflow stemflow measurements measurements – – survey of above survey of above-

  • ground water storage capacity

ground water storage capacity – – gravimetric measurement of epiphytes evaporation gravimetric measurement of epiphytes evaporation

Epiphyte Study Epiphyte Study

Ryan Mudd Ryan Mudd

  • How much water is stored above ground

in epiphytic layer?

  • How does strawberry guava invasion

affect aboveground water storage?

  • How much does epiphyte-stored water

contribute to stand-level ET?

Epiphyte Study Epiphyte Study

0.59 1.48

Water Storage Capacity (mm)

15.5 26.5

Surface Area per Ground Area (%)

0.89 2.57

Biomass (t ha-1) Ola‘a Thurston

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Epiphyte Study Epiphyte Study Epiphyte Study Epiphyte Study

Epiphyte Evaporation at Thurston: About 1/10 of stand level ET

Stemflow Stemflow Study Study

88% 97% (TF+SF):RF 24% 6% Stemflow:RF 64% 91% Througfall:RF Ola‘a (Invaded Forest) Thurston (Native Forest) Stand-Level Evapotranspiration Results

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Energy Partitioning at Native Site

Fraction of energy for ET:

  • Decreases as Rnet

increases

  • Higher for wet-

canopy periods

Energy Partitioning at Native Site

Fraction of energy for ET:

  • Exhibits apparent annual

cycle

  • Cycle roughly corresponds

to LAI cycle MAX: Oct MIN: Apr

Next, look at departures from the annual cycle

Departures of LE Fraction from Annual Cycle

LE fraction anomaly variation:

  • Generally similar to soil

moisture variation

  • But, LE minima precedes SM

minima by about 2 weeks

  • LE maxima and minima match

rainfall match rainfall maxima and minima

RAINFALL SOIL MOISTURE

Wet-canopy evaporation controls departures in LE fraction from the LAI- related annual cycle

Departures of LE Fraction from Annual Cycle Comparing ET of Native and Invaded Stands

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LEinvaded 27% higher

Difference is

  • here. LEnative

has lower minimum

Wet Periods vs Dry Periods

Native: LEwet canopy 65% higher Invaded: LEwet canopy 16% higher Wet Canopy: LEinvaded 8% higher Dry Canopy: LEinvaded 53% higher

Wet Periods vs Dry Periods

Transpiration enhanced at invaded site.

During dry canopy periods, when physiological control over gas exchange is important, ET is much higher in the invaded stand. Why?

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Flux = Velocity x Sapwood Area Transpiration = Flux/Crown Area

Sapflow Study

John DeLay Sample period mean sapflow velocities: ‘Ohia 3.3 Ilex 3.6 Olapa 3.3 Guava 2.7

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Sapflow Study

0.79 0.18 Sapwood/Basal 8675 3800 11046 20955 Total 859 859 Cheirodendron 5392 5392 Guava 800 1760 Ilex 2424 3000 4795 19195 ‘ohia Ola‘a Thurston Ola‘a Thurston Sapwood Area (cm2) Basal Area (cm2)

Based on 400-m2 survey areas

Conclusions

  • Effects of invasive trees in Hawaiian forests

include: Miconia

– Greater light extinction – Reduced ground cover – Large throughfall drop size—greater KE – Higher rates of soil erosion

Conclusions

Effects of invasive trees in Hawaiian forests include: Guava

  • Supports reduced epiphytic cover
  • Less above groundwater storage
  • 27% higher stand-level ET compared with native

site

  • 53% higher ET on dry days compared with native

site

  • Higher transpiration due to much greater sapwood

area in invaded forest

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Implications

For Regional Water Resources:

  • Miconia invasion may enhance storm runoff,

promote soil erosion, and degrade streamwater quality

  • Guava invasion has significant negative

impact on ground-water recharge For Dynamics of Tree Invasion:

  • High transpiration a characteristic of invasive

trees??

Further Work

Impacts of Invasion on Hydrological Proceses:

  • Refine sapflow observations to better understand

plant water dynamics of guava vs ‘ohia

  • Determine impacts of reduced above-ground water

storage

  • Study effects of invasion on cloud water interception

Impacts of Invasion on Carbon Dynamics:

  • Determine how invasion affects carbon exchange

and rates of carbon storage

Thank You