Visualizing Soil Temperature Regime

Background

The estimateSTR() function from the soilDB package applies a soil temperature regime (STR) classification using rules from Soil Taxonomy (12th edition). Accurate classification of STR depends on the following properties:

• MAST: mean annual soil temperature (degrees C, at 50cm)
• MSST: mean summer soil temperature (degrees C, at 50cm)
• MWST: mean winter soil temperature (degrees C, at 50cm)
• O horizon presence / absence
• permafrost presence / absence

The function will generate reasonable, but possibly wrong, results if missing O horizon, saturation, and permafrost values. This is only an issue for the gelic / cryic / frigid STR, e.g. in very cold climates.

STR include:

• gelic (suggests permafrost argument)
• cryic (suggests permafrost, O.hz, and saturated arguments)
• frigid (suggests O.hz, and saturated arguments)
• mesic
• thermic
• hyperthermic
• isofrigid
• isomesic
• isothermic
• isohyperthermic

Setup

You will need the latest version of soilDB:

# install.packages('devtools', dep=TRUE)
devtools::install_github("ncss-tech/soilDB", dependencies=FALSE, upgrade_dependencies=FALSE)

Basic Usage

Note that this function is vectorized and works as expected, as long as each argument is the same length.

library(soilDB)

estimateSTR(mast = 12, mean.summer = 15, mean.winter = 8)

## [1] mesic
## 10 Levels: gelic cryic frigid isofrigid mesic isomesic thermic isothermic ... isohyperthermic

estimateSTR(mast = 4, mean.summer = 8, mean.winter = 1, O.hz = TRUE, saturated = FALSE, permafrost = FALSE)

## [1] frigid
## 10 Levels: gelic cryic frigid isofrigid mesic isomesic thermic isothermic ... isohyperthermic

Graphical Summaries

These are quite dense. Some notes:

• The “O horizon / Saturation” flags come into play at the cryic / frigid break. “X” means “no”, “O” means O horizon present, and “S” means “saturation” as specified in the keys.
• Rows with a “?” describe situations in which STR is estimated by splitting the difference in temperature thresholds when O horizon and / or Saturation values are missing.

par(mar=c(4,1,0,1))
STRplot(mast = 0:25, msst = 10, mwst = 1)

STRplot(mast = 0:25, msst = 9, mwst = 1)

STRplot(mast = 0:25, msst = 7, mwst = 1)

STRplot(mast = 0:25, msst = 6, mwst = 1)

STRplot(mast = 0:25, msst = 5, mwst = 1)

par(mar=c(4,1,0,1))
STRplot(mast = 5, msst = 1:18, mwst = 0)

STRplot(mast = 5, msst = 1:18, mwst = 1)

STRplot(mast = 5, msst = 1:18, mwst = 2)

STRplot(mast = 5, msst = 1:18, mwst = 3)

STRplot(mast = 5, msst = 1:18, mwst = 5)

par(mar=c(4,1,0,1))
STRplot(mast = 10, msst = 1:18, mwst = 5)

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This document is based on aqp version 1.41 and soilDB version 2.6.13.