Biometric Challenges of Hawaii Forest Management

N. Koch

Research Forester

Introduction• Current problem:

– Lack of adequate data and models for proper native forest management

• History– How did this come about?

• Present situation– Why such models are more important today?

• Currently used methods for forest management– Mostly empirical

Focus on koa

• External volume equations for most exotic species are well known– Allows for adequate management, with

reservations• No site indexes

• No stocking guides

• No growth curves (yet)

– However, better than the situation for koa!

Background• Historic lack of dedicated forest industry in

Hawaii– Most forest cleared for other uses

• Grazing• Agriculture

– Sugar– Pineapple

– Remaining forests dedicated to non-timber use• Watershed protection• Parkland

Background (cont.)

• Forest industry relegated to “mining” of timber resources– Clearing land for agriculture– Extraction of pasture timber– Small-scale extraction in watershed forests

Existing models

• Early efforts by the Forest Service– 1960’s and 1970’s:

“Predicting volumes in four Hawaii hardwoods...first multivariate equations developed” Sharpnack, David (1966)

...requires 4 inputs:DBH

HTTDIB (top diam. inside bark)Diam. Inside bark at 1st 16’ log

Existing models (cont.)

Acacia koa volume (cuft)

V = -13.8719 + 1.7332 (DBH) – 1.2125 TDIB +

0.0022 DBH2 (HT) (FC) + 0.0033 TDIB2 (HT) (FC) +

11.7450 (HT)

TDIB – Top inside bark diameter

FC - Form class = Inside bark diameter at 16’ / DBH

...Laborious to collect data and process it!!!

Existing models (cont.)

• Early efforts by the Forest Service– 1960’s and 1970’s:

“Guide to log defect indicators in Koa, Ohia... preliminary rules for volume deductions” Burgan et al. (1971)

... Difficult to apply in field estimations

Present situation• Demand for quality forest products outstrips

supply, particularly in native woods– Increased conversion of pastures to forest– Increased interest in active forest management

• A shift from extractive uses

– Forest management in Hawaii as a worthwhile alternative to agriculture/grazing

• Environmental concerns• Government incentives• Wood prices (koa is worth more than mahogany)

Present situation (cont.)• Forest management for timber based on

rudimentary equations– Eg. Use of Acacia melanoxylon in lieu of A.

koa

• Difficult to establish value of standing trees• Little data on site indexes, growth curves,

stocking guides– Unknown returns on forest investment– Difficult to prepare silvicultural prescriptions

Present situation (cont.)

• Use non-volume basis for native forest management– Basal area

– Stems/acre

– Diameter distribution

• Not able to utilize volume control for allowable harvests

Complicating factors

• Acacia koa– Variable growth form

• Young forest

Young, forest grown Koa

Young, forest grown Koa

Complicating factors

• Acacia koa– Variable growth form

• Young forest

• Pasture & forest relicts

Forest relicts

Forest relicts

Forest relicts

Complicating factors

• Acacia koa– Variable growth form

• Young forest

• Pasture & forest relicts

• Old field

Old field Koa

Old field Koa

Complicating factors

• Acacia koa– Variable phenotype

• Young forest

• Pasture & forest relicts

• Young pasture

– Genetic variability• Heartwood (important – value driver)

• Elevational

• Inter-island

Genetic variability of heartwood

Current work

• Exotics:– Division of forestry and wildlife has prepared

local volume equations for• Eucalyptus grandis

• Eucalyptus saligna

• Flindersia brayleyana

– Forest solutions working on young koa volume equations (DBH & HT based)

• Taper data collected

Current challenges

• Coordination of data collection and synthesis– Preparation of local volume equations, growth

models and stocking guides• Partnerships with land management agencies

• Collaboration with biometry experts

• Invitation– Forest Solutions would like to collaborate with

biometry experts to resolve these issues