Forest Mensuration II Special Lecture Stand Structural Diversity

Forest Mensuration II Special Lecture Stand Structural Diversity

Biological Diversity • • Genetic diversity Stand level diversity ( ) Local landscape diversity ( ) Regional diversity ( ) Structure Species richness Evenness

Objectives • Concepts • Classification of stand structure • Measures of stand structural diversity

Stand structure attributes • • Living trees Snags, CWD Age Composition

Stand structure • Arrangement of trees in space – Vertical – horizontal Stand structural diversity-Variability among trees vertically and horizontally within a stand

Why stand structural diversity? • Ecological – A measure of biodiversity – Wildlife habitat – Ecosystem process (e. g. , productivity) • Social – Visual quality • Management - structure based

Vertical structure Frequency (stems/ha) Single-storied/ normal Multi-storied/ irregular Multi-storied/ inverse J Two-storied/ bimodal Special lecture FORE 3128 Smith et al. 1997

Special lecture FORE 3128

Special lecture FORE 3128

Special lecture FORE 3128

Special lecture FORE 3128

Special lecture FORE 3128

Measures of vertical structural diversity • Shannon-Weiner index (H´) • Variance of tree size (S 2) Special lecture FORE 3128

Shannon-Weiner index (H´) Example Stand A Stand B P 1 0. 9 0. 5 Stand C 0. 33 Special lecture FORE 3128 P 2 P 3 H’ 0. 33 0. 69 0. 34 1. 10 0. 1 0. 5 0. 33

Shannon-Weiner index (H´) Frequency (stems/ha) Proportion (Freq. ) DBH Proportion (BA) Special lecture FORE 3128 DBH

Variance of tree size Frequency Special lecture FORE 3128 DBH Frequency (stems/ha)

Horizontal structure Stand 1 Random Special lecture FORE 3128 Stand 2 Clumped (aggregate) Stand 3 Uniform

Special lecture FORE 3128 Random

Clumped Special lecture FORE 3128

Special lecture FORE 3128 Clumped

Special lecture FORE 3128 Uniform

Measure of horizontal structure Clark and Evans’ test (C) Special lecture FORE 3128

Observed mean distance = (1. 5+1. 8+1. 5+, , , )/15 = 1. 493 m Special lecture FORE 3128

Expected mean distance Random (Poisson) distribution m Standard error m Special lecture FORE 3128

Clark and Evans’ test Clumped -1. 96 Special lecture FORE 3128 Random 0 C Regular 1. 96

Three-dimensional structure Special lecture FORE 3128

Structural complexity index (SCI) z z x x y y

Problem with SCI Stand 1 Stand 2 Stand 3 Tree heights = 5 m Tree heights = 10 m Tree heights = 20 m Special lecture FORE 3128

Summary • Concepts • Classification of stand structure – Vertical – Horizontal • Measures of stand structural diversity – Vertical • Shannon-Weiner index • Variance of tree size – Horizontal: Clark and Evans test – Three-dimensional: SCI Special lecture FORE 3128

Possible research topics • Does increasing structural diversity affect Stand productivity? Silvicultural feasibility? Special lecture FORE 3128

Special lecture FORE 3128

Special lecture FORE 3128

How do we measure landscape structural diversity? Special lecture FORE 3128

Criteria for Sustainable Forest Management • Conserving Biological Diversity • Maintenance and enhancement of Forest Ecosystem Condition and Productivity • Conservation of Soil and Water Resources • Forest Ecosystem Contributions to Globe Ecological Cycles • Multiple Benefits to Society • Accepting Society’s Responsibility for Sustainable Development Special lecture FORE 3128