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Table 1 Time-trend analysis of annual variables in the Chilcotin watershed by period

From: Dramatic increase in water use efficiency with cumulative forest disturbance at the large forested watershed scale

Type of variable

Variable

1971—1999

2000—2016

Tau

P-value

Tau

P-value

Forest disturbance

CECA

1.000

 < 0.001

0.950

 < 0.001

Carbon

AGBIO

0.995

 < 0.001

− 0.750

 < 0.001

TEC

1.000

 < 0.001

− 0.267

0.163

DOM

0.995

 < 0.001

0.783

 < 0.001

NPP

0.974

 < 0.001

− 0.217

0.260

NBP

-0.799

 < 0.001

− 0.133

0.499

Climate

Tmean

0.280

0.038

0.200

0.300

Tmax

0.280

0.038

0.217

0.260

Tmin

0.302

0.026

0.067

0.753

P

0.127

0.353

− 0.083

0.685

PET

0.206

0.128

0.233

0.224

Water

ET

0.164

0.228

− 0.417

0.027

Q

0.185

0.173

0.333

0.079

Runoff ratio

0.037

0.797

0.150

0.444

Carbon and water relationship

WUE

0.032

0.828

0.383

0.043

  1. Where, tau is the z-statistic from the Mann–Kendall test indicating the direction of change of the variable; p-value is the level of significance from the Mann–Kendall test; and bolded italics indicate significant trends at a significance level of 0.05), CECA cumulative clear-cut area, AGBIO  above ground biomass, DOM  dead organic matter, TEC total ecosystem carbon, NPP  net primary production, NBP net biome production, Tmean annual average daily temperature, Tmin annual minimum daily temperature, Tmax  annual maximum daily temperature, P  precipitation, PET  potential evapotranspiration, ET evapotranspiration, Q mean annual streamflow, WUE water use efficiency