NRCS−Montana−Technical Note−Plant Materials−MT-112 1 

United States Department of Agriculture

NATURAL RESOURCES CONSERVATION SERVICE

Plant Materials Technical Note No. MT-112

February 2016 

PLANT MATERIALS TECHNICAL NOTE

THE SALINITY TOLERANCE OF 18 TREES AND SHRUBS TESTED ON A 

HEAVY-TEXTURED SOIL IN SOUTH-CENTRAL MONTANA

Joseph D. Scianna, USDA-NRCS, Bridger Plant Materials Center, Bridger, Montana

Figure 1. Tree and shrub salinity tolerance study, Bridger, Montana (NRCS photo).

Abstract

Numerous acres of salt-affected soils across Montana and Wyoming are marginally productive, 

have low species diversity, and are prone to erosion. In some cases, vegetative practices such 

as Tree and Shrub Establishment (Code 612), Windbreak/Shelterbelt Establishment (Code 

380), and Riparian Forest Buffer (Code 390) can be used to establish woody vegetation on such 

sites in order to improve site stability, species diversity, and productivity. To determine the 

adaptability of various woody plants to salt-affected soils, 18 species of woody plants were 

planted in a non-replicated study (MT-06-0005) across a salinity gradient at the Bridger Plant 

Materials Center, Bridger, Montana, on a sub-irrigated, salt-affected, silty clay loam site in 2006

(see Figure 1). Plant evaluation data was collected for several years, including survival, height, 

and vigor rating. Soil salinity data was collected using a Geonics® EM-38, as well as lab 

analysis of soil samples. Approximations of soil salinity tolerance of each species were 

determined by examining plant performance across USDA soil salinity categories over time. 

Study details will be reported in the project report for this study, available in October 2016. The 

following salinity tolerances are based on the results of this study alone, and given test site 

conditions.
NRCS−Montana−Technical Note−Plant Materials−MT-112 2 

I. Tolerant to “Moderately Saline” soils (8 to <16 dS/M)

Silver buffaloberry Shepherdia argentea (native)

II. Tolerant to “Slightly Saline” soils (4 to <8 dS/M)

Blueleaf honeysuckle Lonicera korolkowii (non-native)

Silverberry Elaeagnus commutata (native)

Golden currant Ribes aureum (native)

Siberian peashrub Caragana arborescens (non-native)

Snowberry Symphoricarpos species (native)

Skunkbush sumac Rhus trilobata (native)

Plains cottonwood Populus deltoides (native)

III. Tolerant to “Very Slightly Saline soils (2 to <4 dS/M)

Seaberry hippophae rhamnoides (non-native, restricted use)

IV. Not well-adapted to “Non-Saline” (<2 dS/M) on heavy-textured soils

American plum Prunus americana (native)

Ponderosa pine Pinus ponderosa (native)

Common chokecherry Prunus virginiana (native)

Colorado spruce Picea pungens (native to North America, not native to Montana) 

Western sandcherry Prunus besseyi (native)

Nanking cherry Prunus tomentosa (non-native)

Introduction

Sites dominated by salt-affected soils are often sparsely vegetated, or the existing plant

community consists of weedy species and low ecological diversity. These site are prone to air 

and water erosion, and have low agricultural productivity. The establishment of trees and shrubs 

on these sites improves soil stability, reduces soil erosion, increases soil organic matter, and 

improves plant community function by creating vertical strata. Much of the available tree and 

shrub salinity tolerance information is based on observational and/or anecdotal information, or 

extrapolated from greenhouse studies conducted under ideal growing conditions. In many 

cases, site history or changes in management over time are unknown. Additionally, plant salinity 

tolerance is often reported in relative and undefined terms, such as “tolerant”, “very tolerant”, 

etc. This study attempted to demonstrate tree and shrub salinity tolerance under conditions 

similar to those encountered by conservation planners and to qualify tolerance in terms of the 

USDA soil salinity classification system.

Study Design

A total of 30 seedlings of each of 18 species of woody plants were planted across a salinity 

gradient on a sub-irrigated, salt-affected site in 2006. Seedlings were planted on 5-foot, withinrow spacing with 10 feet between rows. Herbaceous competition on 2 feet of either side of the 

seedlings was controlled for the length of the row with herbicide for most of the life of the study.

The study was irrigated annually, 24 to 48 hours before using the soil salinity meter.
NRCS−Montana−Technical Note−Plant Materials−MT-112 3 

Site Conditions

Bridger, Montana is located at an approximate elevation of 3,700 feet above sea level in a 10 to 

11 inch annual precipitation zone. The site falls in USDA Winter Hardiness Zone 4b (-25o to 

-20o F). Average growing season (frost-free days) ranges from approximately 135 to 140 days. 

Soils at the test location are classified as Heldt silty clay loam, 0 to 2 percent and 0 to 6 percent 

slopes. Sodium Adsorption Ratio (SAR) can reach a ratio as high as 30 on the test site, but 

often ranges between 5 and 10.

Results

Percent survival, relative plant vigor rating (1 through 9; 1 the best, 9 the worst), and stem 

height (feet) collected in 2014 were used as the basis for the results presented herein. The 

percentage survival listed in Table 1 represents the percentage of seedlings planted in a given 

soil salinity classification category that survived from 2006 to 2014. It is important to note that 

the number of seedlings planted in each salinity classification category was a function of the 

Table 1. Percentage survival, tree and shrub salinity tolerance study, Bridger, Montana, 2014.

salinity level at their planting location in the row. This resulted in an unequal number of test 

seedlings planted in each salinity range. The soil salinity value at each plant was estimated by 

correlating soil conductivity readings generated by an EM-38 (to a depth of approximately 1.5 

meters) with actual lab analysis of field samples. It is possible that soil salinity may be higher or 

lower in localized areas of the soil profile than reported. Percentage survival values are only 

provided in Table 1 for the highest salinity tolerance category(s) for each species.

Percentage Percentage Percentage Percentage

Percentage Survival Survival Survival Survival

Survival Very Slightly Slightly Moderately Strongly

Non-Saline Saline Saline Saline Saline

<2 dS/M 2 to ≤4 dS/M 4 to <8 dS/M 8 to <16 dS/M ≥16 dS/M

Elaeagnus angustifolia Russian olive 100

Shepherdia argentea silver buffaloberry 60 24

Lonicera korolkowii blueleaf honeysuckle 100 38

Elaeagnus commutata silverberry 100 43

Fraxinus pennsylvanica green ash 88 100*

Ribes aureum golden currant 78 18

Caragana arborescens Siberian peashrub 50 20

Ulmus pumilus Siberian elm 100 20

Symphoricarpos species snowberry 58

Rhus trilobata skunkbush sumac 57 22

Populus deltoides plains cottonwood 100

Hippophae rhamnoides seaberry 67 36 22

Prunus americana American plum 0 17

Pinus ponderosa ponderosa pine 0 7

Prunus virginiana common chokecherry 0

Picea pungens Colorado spruce 0

Prunus besseyi western sandcherry 0

Prunus tomentosa Nanking cherry 0

indicates majority of seedlings should survive in this soil salinity category given test site conditions.

indicates only a relatively small percentage of seedlings should survive in this soil salinity 

category given test site conditions.

* Only 1 green ash seedling planted in this salinity category with extremely low vigor and height

 growth, so no projected tolerance assumed at this salinity level.
NRCS−Montana−Technical Note−Plant Materials−MT-112 4 

The mean vigor rating listed in Table 2 represents the mean vigor of surviving seedlings planted 

in a given soil salinity classification category. The lower the rating number the better the 

seedling vigor. Vigor assessment was based on leaf color and condition, amount of leaf and 

stem necrosis, stem internode length, and other indices of plant condition. The mean vigor 

rating values presented in Table 2 are provided to demonstrate vigor trends across salinity 

gradients. Vigor is an important plant performance variable when selecting species for various 

conservation practices. Surviving, but low vigor plants may not provide the intended 

conservation benefit, such as food for wildlife, pollinator benefits, etc. Low vigor or stressed 

plants often do not reach functional size, produce abundant flowers or fruit, or are predisposed 

to insect and disease pathogens over time.

Table 2. Mean vigor rating, tree and shrub salinity tolerance study, Bridger, Montana, 2014.

The mean plant heights listed in Table 3 represent the mean height in feet of surviving seedlings 

planted in a given soil salinity classification category. Mean height values are provided in Table 

3 for the highest salinity tolerance category(s) for each species, and in limited cases, to 

demonstrate important trends in height. When selecting species for various conservation 

practices, it is important to consider whether height is an important conservation benefit and 

goal of the planting.

Mean Mean Mean Mean

Mean Vigor Rating Vigor Rating Vigor Rating Vigor Rating

Vigor Rating1 Very Slightly Slightly Moderately Strongly

Non-Saline Saline Saline Saline Saline

<2 dS/M 2 to ≤4 dS/M 4 to <8 dS/M 8 to <16 dS/M ≥16 dS/M

Elaeagnus angustifolia Russian olive 2.0 2.0 2.2 4.0

Shepherdia argentea silver buffaloberry 4.0 4.7 5.7

Lonicera korolkowii blueleaf honeysuckle 2.2 3.6 5.0

Elaeagnus commutata silverberry 4.2 3.5 4.4 5.5

Fraxinus pennsylvanica green ash 6.0 7.0 6.9 8.0

Ribes aureum golden currant 5.4 6.0

Caragana arborescens Siberian peashrub 3.3 4.0 4.1 6.0

Ulmus pumilus Siberian elm 5.5 5.2 4.4 5.0

Symphoricarpos species snowberry 5.0

Rhus trilobata skunkbush sumac 5.5 7.0

Populus deltoides plains cottonwood 6.4 5.9

Hippophae rhamnoides seaberry 3.8 5.0 7.5

Prunus americana American plum

Pinus ponderosa ponderosa pine

Prunus virginiana common chokecherry

Picea pungens Colorado spruce

Prunus besseyi western sandcherry

Prunus tomentosa Nanking cherry

1

 Vigor rating 1 through 9; 1 = best; 4 = average; 9 = nearly dead

indicates a majority of seedlings should survive in this soil salinity category given test site conditions.

indicates only a relatively small percentage of seedlings should survive at this soil salinity 

category given test site conditions.
NRCS−Montana−Technical Note−Plant Materials−MT-112 5 

Table 3. Mean plant height, tree and shrub salinity tolerance study, Bridger, Montana, 2014.

Table 4 lists the maximum soil salinity classification category recommended for each species 

tested. Russian olive is an invasive weed in riparian areas and is listed as a regulated plant in 

Montana and a noxious weed in Wyoming. It is therefore not recommended or allowed and was 

only included in this study as a standard of comparison. The other species are listed as “not 

recommended” for a given soil salinity classification category if survival was less than 50%, or 

there was only one test seedling planted in that salinity range. It should be noted, however, 

there may be situations where survival of less than 50% meets an intended conservation goal. 

Green ash was listed as “not recommended” because height and vigor were unacceptably low, 

despite adequate plant survival. Seaberry Hippophae rhamnoides is listed as “restricted use” 

and should only be planted under controlled and monitored conditions; since it is non-native and 

has not been extensively field tested in Montana and Wyoming. Species with a “conditional 

recommendation” should be planted in soils with salinity values in the lower end of the category

range.

Mean Mean Mean Mean

Mean Height (ft) Height (ft) Height (ft) Height (ft)

Height (ft) Very Slightly Slightly Moderately Strongly

Non-Saline Saline Saline Saline Saline

<2 dS/M 2 to ≤4 dS/M 4 to <8 dS/M 8 to <16 dS/M ≥16 dS/M

Elaeagnus angustifolia Russian olive 14.9

Shepherdia argentea silver buffaloberry 2.8 2.7

Lonicera korolkowii blueleaf honeysuckle 8.1 6.0

Elaeagnus commutata silverberry 3.3 2.9

Fraxinus pennsylvanica green ash 2.2 1.3

Ribes aureum golden currant 1.8 1.5

Caragana arborescens Siberian peashrub 4.5 3.8 3.0 1.4

Ulmus pumilus Siberian elm 7.5 7.2

Symphoricarpos species snowberry 1.9

Rhus trilobata skunkbush sumac 3.3 2.1

Populus deltoides plains cottonwood 10.6

Hippophae rhamnoides seaberry 4.4 2.2 1.3

Prunus americana American plum

Pinus ponderosa ponderosa pine

Prunus virginiana common chokecherry

Picea pungens Colorado spruce

Prunus besseyi western sandcherry

Prunus tomentosa Nanking cherry

indicates a majority of seedlings should survive in this soil salinity category given test site conditions.

indicates only a relatively small percentage of seedlings should survive in this soil salinity category

given test site conditions.
NRCS−Montana−Technical Note−Plant Materials−MT-112 6 

Table 4. Soil salinity tolerance recommendations for Montana and Wyoming by USDA soil 

salinity classification category, tree and shrub salinity tolerance study, Bridger, Montana, 2014.

Conclusion/Discussion

In general, the soil salinity tolerance of the test plants was lower than frequently reported in 

popular, web-based, and non-referenced sources. It is anticipated that most of the tested 

species will perform better on light-textured and well-drained soils under similar environmental 

and site conditions. The results of this study suggest many “salt-tolerant” woody plants may not 

provide the intended conservation benefits on saline soils. It is important to note the salinity 

tolerance recommendations in this report do not apply to all soil and climatic conditions, but are 

applicable to the site and climatic conditions comparable to Bridger, Montana. Planners should 

consider the goal of the conservation planting and the likelihood that plant performance will 

meet those goals, when selecting woody plant species for salt-affected sites. 

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Percentage Percentage Percentage Percentage

Percentage Survival Survival Survival Survival

Survival Very Slightly Slightly Moderately Strongly

Non-Saline Saline Saline Saline Saline

<2 dS/M 2 to ≤4 dS/M 4 to <8 dS/M 8 to <16 dS/M ≥16 dS/M

Elaeagnus angustifolia Russian olive NA1 NA1 NA1 NA1 NA1

Shepherdia argentea silver buffaloberry √ NR2

Lonicera korolkowii blueleaf honeysuckle √ NR2

Elaeagnus commutata silverberry √ NR2

Fraxinus pennsylvanica green ash NR2 NR2

Ribes aureum golden currant CR3 NR2

Caragana arborescens Siberian peashrub √ NR2

Ulmus pumilus Siberian elm √ NR2

Symphoricarpos species snowberry CR3

Rhus trilobata skunkbush sumac CR3 NR2

Populus deltoides plains cottonwood CR3

Hippophae rhamnoides seaberry RU4 NR2 NR2

Prunus americana American plum NR2

Pinus ponderosa ponderosa pine NR2

Prunus virginiana common chokecherry NR2

Picea pungens Colorado spruce NR2

Prunus besseyi western sandcherry NR2

Prunus tomentosa Nanking cherry NR2

√ indicates recommended for the salinity category given test site conditions.

1

 - NA "not applicable", invasive weed.

2

 - NR "not recommended".

3

 - CR "conditional recommendation", use only at low end of the salinity range for Slightly Saline soils.

4

 - RU "restricted use", untested non-native, use only under controlled conditions.

indicates majority of seedlings should survive this soil salinity category given test site conditions.

indicates only a relatively small percentage of seedlings should survive this soil salinity category

given test site conditions