Lecture 12 FORE 3218 Forest Mensuration II Lecture 12 Tree-Growth and Stand-Table Projection Avery and Burkhart, Chapter 16

Lecture 12 FORE 3218 Increase in Tree Diameter  Adding wood just under the bark –In temperate forests, a growing tree adds a yearly layer. What about trees in tropical forests? What about the trees growing under a very stressful environment?  Annual ring width decreases as tree age increases, but basal area and volume may increase  Diameter growth are influenced by spacing (stand density), climate, site characteristics, disturbances

Lecture 12 FORE 3218  How tree height growth is accomplished?  Tree height typically grows in a sigmoid fashion Increase in Tree Height Tree Age (Years) Total Height (m) Cumulative Growth

Lecture 12 FORE 3218 Defining Periodic and Mean Annual Growth  Current annual growth (current annual increment) –The increase in tree size (measured by dbh, height, volume, or biomass) for one year  Periodic annual growth –Average annual growth over a period of 5 or 10 years  Mean or average annual growth –Total tree size at any point in time divided by total age

Lecture 12 FORE 3218 Relationships between Periodic and Mean Annual Growth What if the growth is measured by tree height, volume or biomass?

Lecture 12 FORE 3218 Growth from Stem Analysis  Diameter growth  Height growth  Volume or biomass growth

Lecture 12 FORE 3218 Absolute and Relative Growth Rate  Absolute volume growth rate (m 3 /year)  Relative volume growth rate (growth percent/year)

Lecture 12 FORE 3218 Stand Growth  “The basic elements of stand growth are accretion, mortality, and ingrowth”  Accretion is the growth on all trees that were measured at the beginning of the growth period, including the growth on tree that were cut plus those tree died and were utilized  Mortality is the volume of trees initially measured that died during a growth period and were not utilized  Growth –Gross: change in total stand volume including mortality –Net: change in total stand volume excluding mortality

Lecture 12 FORE 3218 Characteristics of Stand-Table Projection -Procedure 1.Develop a present stand table showing number of tree in each dbh class 2.Determine past periodic growth by dbh classes by increment borings or measurement of PSP 3.Apply past diameter growth rates to the present stand to derive future stand table 4.Apply local volume equation to estimate both present and past stand volume 5.Obtain periodic stand volume growth as the difference during the growth period Best suited to uneven-aged, low-density, and immature timber stands, why?

Lecture 12 FORE 3218 How to determine diameter growth with increment borings  Measure dob  Obtain wood growth in diameter from an increment boring (e.g., 10 years)  Develop a relationship between bark thickness and dib  Calculate dob from dib and the above relationship for any previous years

Lecture 12 FORE 3218 Stand Mortality and Ingrowth  Mortality and ingrowth can be obtained reliably from consecutive reinventories of PSPs. Year 1990 Year 2000

Lecture 12 FORE 3218 Elements of Reliable Stand-Table Projection  Growth-index ratio by dbh classes estimated from surviving trees  Mortality by dbh classes  Ingrowth