Ecological Archives A018-041-A1

Jacob P. Verschuyl, Andrew J. Hansen, David B. McWethy, Rex Sallabanks, and Richard L. Hutto. 2008. Is the effect of forest structure on bird diversity modified by forest productivity? Ecological Applications 18:1155–1170.

Appendix A. Predictor code definitions.


Predictor

Definition

canopy.clos

Percent canopy cover

cwd.m3.100m

Coarse Woody Debris (m3/100 m transect)

frosuman

Number of frosty days annually

frosummj

Number of frosty days in May and June

gsi05

Growing Season Index (May)

ndvi129

Normalized Difference Vegetation Index (16 day period starting 8 May)

ndvi145

Normalized Difference Vegetation Index (16 day period starting 24 May)

ndviavg

Normalized Difference Vegetation Index (average from May 8 – July 11)

ndviavgan

Normalized Difference Vegetation Index (annual average)

nppmodis

Modis derived Net Primary Productivity (annual average)

num.mtree

Density of trees > 20 cm dbh

num.sap

Density of saplings < 2 cm dbh

per.con

Percent of the overstory that is conifer

preavgan

Annual Precipitation

preavgas

Average precipitation from April through September

qmd

Quadratic mean diameter of trees > 2 cm dbh

radavgas

Solar radiation from April through September

shade.sap

Density of shade tolerant saplings

shpp

Shrub density

shrdiv

Shrub size diversity

st.complex

Index of horizontal and vertical variation in tree size and density. 

stdev.trdiv

Horizontal variation in tree size diversity

stdev.treecov

Horizontal variation in canopy cover

tempavgas

Average temperature from April through September

tempavgmj

Average temperature in May and June

tpp

Tree density

trdiv

Tree size diversity

underdecid

Percent shrub cover

underherb

Percent herbaceous cover

undertot

Percent understory cover

vpdavgann

Vapor pressure deficit (annual average)

vpdavgjja

Vapor pressure deficit (June, July, and August)


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