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Georgia Growing-Stock Mortality by Disturbance Type and Species

Overview

This query calculates average annual mortality of growing-stock trees (at least 5 inches d.b.h.) on timberland in Georgia, grouped by disturbance type and species. Unlike the damage agent query which uses tree-level AGENTCD, this uses condition-level DSTRBCD1 to identify disturbances affecting the forest condition.

Key Components

Tables Used

  • POP_STRATUM - Statistical strata and expansion factors
  • POP_PLOT_STRATUM_ASSGN - Links plots to strata
  • PLOT - Plot locations with previous plot linkages
  • PLOTGEOM - Plot geometry (required for join)
  • COND - Condition data with disturbance codes
  • TREE - Tree measurements
  • TREE_GRM_BEGIN, TREE_GRM_MIDPT - Growth period tree data
  • TREE_GRM_COMPONENT - Mortality components with growing stock focus
  • REF_SPECIES - Species reference data

Key Fields

  • DSTRBCD1 - Primary disturbance code at condition level (0-95)
  • SUBP_TPAMORT_UNADJ_GS_TIMBER - Unadjusted mortality for growing stock timber
  • SUBP_SUBPTYP_GRM_GS_TIMBER - Subplot type for growing stock
  • SUBP_COMPONENT_GS_TIMBER - Component type (filtered for MORTALITY%)

Disturbance Categories

The query includes 32 specific disturbance types: - 0: No visible disturbance - 10-12: Insect damage (general, understory, trees) - 20-22: Disease damage (general, understory, trees) - 30-32: Fire damage (general, ground, crown) - 40-46: Animal damage (general, beaver, porcupine, deer, bear, rabbit, livestock) - 50-54: Weather damage (general, ice, wind, flooding, drought) - 60: Vegetation competition - 70: Unknown/other - 80: Human-caused damage - 90-95: Geologic disturbances

Filters

  • Growing stock timber components only (_GS_TIMBER columns)
  • Mortality components only (COMPONENT LIKE 'MORTALITY%')
  • Georgia state (rscd = 33)
  • 2023 GRM evaluation (evalid = 132303)

Results Summary

Total Annual Growing Stock Mortality by Disturbance Type

Disturbance Type Trees per Year Species Count % of Total
No visible disturbance 22,520,652 62 61.9%
Insect damage to trees 2,675,919 26 7.3%
Wind damage 2,637,548 29 7.2%
Ground fire damage 2,454,826 31 6.7%
Disease damage to trees 1,237,966 22 3.4%
Insect damage (general) 1,183,199 14 3.2%
Fire (general) 995,907 4 2.7%
Human-caused damage 944,404 6 2.6%
Beaver damage 504,575 10 1.4%

Total: ~36.3 million growing stock trees per year (same as damage agent total)

Key Differences from Damage Agent Analysis

  • No visible disturbance dominates (61.9%) - many trees die without condition-level disturbance
  • Wind damage appears significant at condition level (7.2%)
  • Fire damage is more prominent (ground fire 6.7%, general fire 2.7%)
  • Insect and disease show lower percentages than tree-level analysis

Notes

  • Condition-level disturbances (DSTRBCD1) capture area-wide impacts
  • Tree-level damage agents (AGENTCD) capture individual tree mortality causes
  • The difference explains why "No visible disturbance" is so high - individual trees can die from specific agents in undisturbed conditions
  • Wind, fire, and beaver create visible condition-level changes
  • Total mortality matches the damage agent query (36.3M trees/year)

Query Translation Notes

Oracle to DuckDB changes:

  • LPAD(SPCD, 4, '0') → printf('%04d', SPCD)
  • Extensive CASE statement for 32 disturbance types maintained
  • Complex nested joins maintained for GRM table relationships
  • Schema prefix FS_FIADB. removed for DuckDB