Winterhardiness, Forage Production, and
Persistence of Introduced and Native Grasses and Legumes in Southcentral Alaska

Leslie J. Klebesadel, Emeritus Professor of Agronomy
Agricultural and Forestry Experiment Station; Palmer, Alaska

Bulletin 101; August 1994 (37 pages)

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SUMMARY

This study consisted of four separate field experiments, each of six years duration, conducted at the University of Alaska's Matanuska Research Farm (61.6oN) near Palmer in southcentral Alaska. Objectives were to compare winterhardiness, forage productivity, and general persistence of introduced grass and legume species, strains, and cultivars from various world sources with Alaska-developed cultivars and native Alaskan species.

Twenty-one species of grasses compared (Tables 1 through 4) included eight native to Alaska, four Alaska cultivars, and numerous introduced cultivars and regional strains (one to seven per species) from North America and northern Europe. Legumes included two species of biennial sweetclover and nine species of perennials, six introduced and three native. Each experiment was harvested once near the end of the seeding year and twice annually for five years thereafter.

· All strains evaluated within the following species were inadequately winterhardy for dependable use in this area: orchardgrass (scientific names of species appear in Table 5), tall fescue, meadow fescue, big bluegrass, meadow bromegrass, and reed canarygrass.

· All of the above non-hardy species except reed canarygrass are bunchgrasses, with overwintering tissues relatively exposed to winter stresses. (Information more recent than these experiments has revealed that certain strains of big bluegrass and reed canarygrass from more northern origins than those included in this study are markedly more winterhardy in this area.)

· Grass species marginally winterhardy, or within which individual strains differed widely in hardiness, included timothy, meadow foxtail, creeping foxtail, Russian wildrye, and slender wheatgrass.

· The most winterhardy, productive, and persistent introduced grass cultivars were the northernmost-adapted strains of smooth bromegrass, creeping foxtail,

red fescue, and Kentucky bluegrass.

· All of those most winterhardy introductions were rhizomatous, suggesting that this growth characteristic, with the protection afforded by subterranean positioning of overwintering tissues, is advantageous for winter survival of introductions here.

· Alaska cultivars Nugget Kentucky bluegrass, Arctared red fescue, and Polar bromegrass were among the most winterhardy, productive, and persistent cultivars. The relatively cool growing seasons of this area promote continuous, active, season-long growth, circumventing the unproductive mid-season dormancy typical of these species, especially Kentucky bluegrass, when they are grown at more southern latitudes where summer temperatures are considerably higher.

· Native Alaska strains of bluejoint, arctic wheatgrass, violet wheatgrass, and pumpelly bromegrass were extremely winterhardy and were surpassed in forage production only by the three Alaska cultivars (Nugget, Arctared, Polar) and introduced Garrison creeping foxtail.

· Native Alaska strains of Siberian wildrye, polargrass, salt bluegrass, and slender wheatgrass also were extremely winterhardy but were somewhat lower in total 6-year forage yield than the other native species because (a) native Siberian wildrye and slender wheatgrass were relatively short-lived; they would have rated higher in 2- to 4-year tests but produced little forage in the last years of these 6-year experiments as their stands gradually deteriorated, and (b) polargrass and salt bluegrass, species favored by abundant soil moisture, produced forage at less than full potential due to below-normal precipitation during five of the nine years during these experiments.

· The proportion of total annual forage yield in the first and second harvests each year was influenced by four major factors: (a) date of cuttings, especially the first, which determines the relative length of the growth

period prior to each cutting, (b) occurrence of winter injury which reduced first-cutting yields because plants produced less herbage while they were recovering from injury, (c) early-season moisture deficits that sometimes markedly reduced first cuttings, and (d) the inherent growth characteristics of the several grass species.

· Concerning factor (d) above, approximate proportions of total annual yield in first and second cuttings, respectively, of the very winterhardy strains were: Kentucky bluegrass 1/2:1/2; Polar bromegrass, Arctared red fescue, and Garrison creeping foxtail 2/3:1/3; and seven native Alaskan grasses (pumpelly brome, bluejoint, polargrass, Siberian wildrye, and slender, arctic, and violet wheatgrasses) 3/4:1/4.

· Legumes included in the four experiments (a total of 25 plantings) generally compared unfavorably in winter survival and/or as forage producers with the most winterhardy and productive grasses. All seedings of the perennials alsike clover (2), sainfoin (3), red clover (1), and cicer milkvetch (1) invariably winterkilled totally the first winter.

· The introduced legume cultivars Vernal alfalfa and Erector and Arctic sweetclover winterkilled totally the first winter except for Arctic surviving with 29% stand in one experiment.

· Of three alfalfa strains, an Alaska line of the yellow-flowered Siberian type was the most winterhardy, surviving in all three experiments where included, until stands were terminated with an herbicide; however, forage yields were generally mediocre.

· Native Alaskan legumes (alpine sweetvetch, Williams and Harrington milkvetch) survived winters well but produced little forage. This deficiency suggests that their good winterhardiness and N-fixing attributes suit them better for revegetation purposes than as forages.

· The dominant factor contributing to generally poor winter survival of most perennial grasses and legumes

introduced from more southern latitudes is believed to be their poor adaptation to subarctic winter-hardening conditions during late summer and early autumn, and therefore failure to develop timely freeze tolerance to their full genetic capacity. Those introduced grasses and legumes ordinarily survive winters well in their more southern areas of adaptation but are deficiently winterhardy at the high latitude of Alaska's Matanuska Valley where winter temperatures generally are no more severe, and sometimes less so, than occur at their lower-latitude origins.

· Future potentially useful plant introductions to Alaska from other north-latitude areas should travel directly from origin to Alaska to maintain intact the genetic constitution that confers optimal adaptation to northern climatic effects and patterns. To first culture such introductions for a time at lower latitudes selects away from and discards genetic/physiologic elements critical to north-latitude adaptation.

· Several plant introductions possessing optimal adaptation for the variable and transitional coastal/continental climate of southcentral Alaska have derived from other circumpolar sources such as Iceland and northern Norway that experience relatively analogous winter climates (and reciprocal transfers have been equally successful). Extension of this logic suggests that, for ideal winterhardiness and adaptation to the quite different continental-type winter climate of interior Alaska, introduced plant strains ideally should be sought in other large, north-latitude land masses where similar continental climatic patterns prevail.

· These results summarizing winterhardiness, adaptation, and persistence of numerous grass and legume ecotypes, regional strains, and cultivars, grown for forage in Alaska, should be helpful not only to farmers and ranchers but also to individuals selecting plant materials for various non-farm uses wherein adapted perennial plant cover is required.