Preamble Polynesians introduced food crops and some tree - PDF document

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: Some Hydrological Impacts of Some Hydrological Impacts of sandalwood harvesting, ranching sandalwood harvesting, ranching Alien Tree Invasion in Hawai‘ ‘i i Alien Tree Invasion in Hawai • Extensive planting of introduced tree species during early • Extensive planting of introduced tree species during early th century 20 20 th century Tom Giambelluca • Intentional and accidental introduction of alien plants and • Intentional and accidental introduction of alien plants and Geography Department animals continues animals continues University of Hawai‘i at M ā noa • State of Hawai‘ ‘i lists 106 highly invasive plant species in i lists 106 highly invasive plant species in • State of Hawai 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 Photo credit: Forest & Kim Starr Photo credit: Forest & Kim Starr Perceptions of Perceptions of Possible Hydrological Possible Hydrological Hydrological Impacts Impacts of Invasive Trees Impacts of Invasive Trees Hydrological Impacts • Reduced soil permeability • Reduced soil permeability: : invasive trees invasive trees Once intentionally introduced for soil and water Once intentionally introduced for soil and water inhibit ground cover, exposing soil inhibit ground cover, exposing soil conservation, alien trees are now universally conservation, alien trees are now universally • Increased runoff and soil erosion • Increased runoff and soil erosion: : exposed exposed perceived as having negative hydrological perceived as having negative hydrological soil, effects on soil, effects on throughfall throughfall impacts, especially on ground- impacts, especially on ground -water recharge. water recharge. • Reduced above • Reduced above- -ground water storage ground water storage: : in in But there has been very little scientific But there has been very little scientific cloud forests, alien trees support less cloud forests, alien trees support less evidence to support this perception. evidence to support this perception. epiphytic cover, affecting stemflow stemflow epiphytic cover, affecting • • Increased transpiration Increased transpiration: : invasive trees are invasive trees are often fast- -growing, which may correlate with growing, which may correlate with often fast high water use high water use Photo credit: Michelle Clapper, USGS-BRD, UH Photo credit: Michelle Clapper, USGS-BRD, UH 1

Two of the important invasive tree Two of the important invasive tree Two of the important invasive tree Two of the important invasive tree species in Hawai‘ ‘i i species in Hawai‘ ‘i i species in Hawai species in Hawai Miconia calvescens calvescens Psidium cattleianum cattleianum (strawberry guava) (strawberry guava) Miconia Psidium Photo credit: Michelle Clapper, USGS-BRD, UH Miconia Characteristics Characteristics Psidium Characteristics Characteristics Miconia Psidium • Grows fast • Grows fast • Grows fast • Grows fast • Invades quickly • Invades quickly • Invades quickly • Invades quickly • Difficult to eradicate • Difficult to eradicate • Already widespread in Hawaii • Already widespread in Hawaii • • Dark, opaque leaves Dark, opaque leaves • • Difficult to eradicate Difficult to eradicate • Large leaves • Large leaves • • Many stems Many stems • Superficial roots • Superficial roots • • Smooth bark Smooth bark • Prefers steep slopes • Prefers steep slopes Photo credit: Michelle Clapper, USGS-BRD, UH 2

100 2000 Light under canopy 90 1800 Light in parking lot Light Penetration Miconia Miconia Pilot Study Pilot Study 80 1600 70 1400 60 1200 50 1000 40 800 30 600 • • Under Under- -canopy light levels canopy light levels 20 400 10 200 • Soil characteristics • 0 0 Soil characteristics 1 2 3 4 5 6 7 8 9 10 11 12 • • Throughfall Throughfall drop size and velocity drop size and velocity light fraction • • Root exposure as evidence of erosion Root exposure as evidence of erosion 0.05 0.04 0.03 0.02 0.01 0 0 1 2 3 4 5 6 7 8 9 10 11 12 DROP SIZE MEASUREMENTS 100 2000 Light under canopy 90 1800 Onomea Light in parking lot Ground Cover 80 1600 70 1400 60 1200 50 1000 40 800 30 600 20 400 10 200 0 0 1 2 3 4 5 6 7 8 9 10 11 12 Kazuki Nanko Univ. Tsukuba IPIF light fraction 0.05 0.04 0.03 0.02 0.01 0 0 1 2 3 4 5 6 7 8 9 10 11 12 Laser disdrometer 3

Results Results of Drop of Drop Size Size Survey Survey Results Results Natural Rain of Drop of Drop Miconia median Size Size drop size = 3.8 mm Survey Very high compared Survey with previous observations Artificial Spray Median drop size Miconia: 5.5 mm ‘ohia: 3.7 mm 4

Miconia Research: Next Steps Guava Study Guava Study • Use kinetic energy estimates to simulate the increase in splash detachment, soil erosion potential as a result of Miconia invasion • • Compare Native (Thurston) and Invaded • Use root exposure to estimate rates of soil Compare Native (Thurston) and Invaded (Ola‘ (Ola ‘a) Sites a) Sites erosion • • 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 • Develop proposal to study Miconia in Tahiti Photo credit: Michelle Clapper, USGS-BRD, UH 5

Field Sites Observations Observations • • Water vapor and CO2 exchange • Water vapor and CO2 exchange Invaded Forest Site – eddy covariance – – ‘ohia forest invaded by Psidium eddy covariance cattleianum (strawberry guava) – 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 • Native Forest Site – energy balance – energy balance – Metrosideros polymorpha (‘ohia) – leaf wetness – leaf wetness – Cibotium spp . (hapu‘u; tree fern) – 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 Epiphyte Study Epiphyte Study • How much water is stored above ground Thurston Ola‘a in epiphytic layer? Biomass (t ha -1 ) 2.57 0.89 • How does strawberry guava invasion affect aboveground water storage? Surface Area per Ground Area (%) 26.5 15.5 • How much does epiphyte-stored water Water Storage Capacity (mm) 1.48 0.59 contribute to stand-level ET? 6

Epiphyte Study Epiphyte Study Epiphyte Study Epiphyte Study Epiphyte Evaporation at Thurston: About 1/10 of stand level ET Stemflow Study Study Stemflow Thurston Ola‘a (Invaded (Native Forest) Forest) Stand-Level Evapotranspiration Results Througfall:RF 91% 64% Stemflow:RF 6% 24% (TF+SF):RF 97% 88% 7

Energy Partitioning at Native Site Energy Partitioning at Native Site Fraction of energy for ET: • Exhibits apparent annual cycle Fraction of energy for ET: • Cycle roughly corresponds to LAI cycle MAX: Oct • Decreases as Rnet Next, look at departures from the annual cycle increases MIN: Apr • Higher for wet- canopy periods Departures of LE Fraction from Annual Cycle Departures of LE Fraction from Annual Cycle SOIL MOISTURE LE fraction anomaly variation: • Generally similar to soil moisture variation • But, LE minima precedes SM Comparing ET of Native and Invaded Stands minima by about 2 weeks • LE maxima and minima match RAINFALL rainfall match rainfall maxima and minima Wet-canopy evaporation controls departures in LE fraction from the LAI- related annual cycle 8

Wet Periods vs Dry Periods LE invaded 27% higher Native: LE wet canopy 65% higher Invaded: LE wet canopy 16% higher Difference is here. LE native has lower minimum Wet Periods vs Dry Periods During dry canopy periods, when Wet Canopy: LE invaded 8% higher Dry Canopy: LE invaded 53% higher physiological control over gas exchange is important, ET is much higher in the invaded stand. Why? Transpiration enhanced at invaded site. 9

Sapflow Study John DeLay Sample period mean sapflow velocities: ‘Ohia 3.3 Ilex 3.6 Flux = Velocity x Sapwood Area Olapa 3.3 Transpiration = Flux/Crown Area Guava 2.7 10