|Question On Notice No. 1901 asked in the Legislative Council on 12 March 2019 by Hon Diane Evers |
Question Directed to the: Minister for Environment
Minister responding: Hon S.N. Dawson
Parliament: 40 Session: 1
(1) How is the growth rate of marri estimated (please list all relevant documents used to make the estimate).?
(2) Over what dates has the estimate been made?
Answered on 10 April 2019
(1) and (2) In south-west forests marri generally occurs mixed with mostly jarrah and/or karri. Growth rates for each tree species vary greatly with tree age, climate, site conditions and relative density (or structure) of the stand. The pattern of growth over time also varies depending on the variable measured (such as diameter, height or volume).
Growth rates for marri can be estimated directly from measurement of trees of known age over extended periods of time, or indirectly using dendrochronological techniques such as tree ring counts. Both approaches have been used at various times and for specific purposes by the Department of Biodiversity, Conservation and Attractions (DBCA) and predecessor agencies. In forests available for timber production, DBCA maintains a strategic forest inventory system which includes plots containing marri from which growth can be estimated, as well as various silvicultural research experiment plots. A series of Sustained Yield information sheets is available on the DBCA website that explains the process and basis of calculations of growth and yield used in preparing the Draft Forest Management Plan 2014-2023.