Ecology and Management of Larix Forests: A Look Ahead Proceedings of an International Symposium

Whitefish, Montana, U.S.A. October 5-9, 1992

Compilers:

Wyman C. Schmidt Kathy J. McDonald of abnormal meiosis. Around 16 percent of its PMC's were strobili were aborted either by contact with pollination degenerated, and 12.4 percent of cells formed aberrant bags or by frost damage. microspores. We believe that high frequency of meiotic irregularity in Siberian larch was partly due to its earli­ Degeneration of Female Gametophytes ness in meiosis. Abortion of ovules before fertilization, which gave rise Pollen Germination to flat seeds, was observed in 4 to 6.8 percent of ovules depending on the species. Tamarack showed the highest germination rate (78.7 percent) while European larch was the lowest (46.5 per­ Fertilization Frequency cent). The germination tests revealed that there was little correlation between frequency of meiotic abnormality and Frequency of ovules in which fertilization had occurred pollen germination. For example, the pollen germination ranged 75 to 90 percent depending on the cross. The cross rate of Siberian larch was higher than that of Japanese between tamarack and European larch was the lowest, larch, which had the lowest in frequency of meiotic abnor­ while the cross between European larch and Japanese mality. This result indicated that some meiotic irregular­ larch was the highest. It seemed that there might be a cer­ ities could recover to form normal pollen, while pollens that tain degree of incompatibility between some larch species. seemed cytologically normal may have other deficiencies. Embryo Degeneration Pollination Frequency Embryo degeneration during early stages of develop­ Pollination frequencies were more than 90 percent ex­ ment was common in all four species. Embryos degener­ cept in tamarack, whose frequency was 75 percent. Fur­ ated in 20 to 40 percent of the fertilized ovules depending thermore, most of the ovules were pollinated with more on the cross but were most common in the tamarack X than one pollen. This fact indicated that pollen quality European larch cross. The frequency of polyembryony was not the major factor reducing seed yield. at the early stage of embryo development influenced later stage embryo condition. It is possible that competition Abortion of Female Strobili among embryos in a seed contributed to degeneration of embryos. Strobili abortion soon after pollination was high in all four species. In Siberian larch, about 80 percent of

Larix Lyallii and Larix Occidentalis Within USDA Forest Service Research Natural Areas Angela G. Evenden

The Forest Service, U.S. Department of Agriculture, In these cases, prescribed management actions may be participates in a federal program to develop a national required to restore the processes upon which the natural network of Research Natural Areas. The major goal of communities and species depend. this network is to preserve a representative array of all Habitat type and plant association classification sys­ significant natural ecosystems and their inherent pro­ tems are often employed to set targets for ecosystems cesses as ecological baseline areas. The Forest Service to include within the Research Natural Areas network. has established nearly 300 Research Natural Areas na­ Larix lyallii (alpine larch) and L. occidentalis (western tionwide. These areas are important ecological reference larch) are represented in these areas within a variety of sites and are used for scientific studies, education, and classified vegetation types. Larix lyallii is found at high long-term ecological monitoring. The areas are managed elevations, often near treeline, in Abies lasiocarpa forest to maintain natural conditions, with as little human in­ types ofIdaho, Montana, and Washington. Table 1 lists tervention as possible. However, in some ecosystems, the eight areas in the Northwestern United States con­ human activities have interrupted natural processes. taining L. lyallii. Larix occidentalis is a seral component of mid-elevation Pseudotsuga menziesii forest types. Old­ growth and mature stands of L. occidentalis occur within Angela G. Evenden is Natural Areas Program Manager, Intermountain 27 areas in Idaho, Montana, Oregon, and Washington Research Station, Forest Service, U.S. Department of Agriculture, Missoula, (table 2). Common overstory dominants in these RNAs MT 59807, U.s.A.

483 Table 1-List of Research Natural Areas (RNA) on National Forest System lands in Idaho and Montana representing subalpine forests dominated by Larix Iya/lii ParI. (alpine larch). National Forest, RNA size (hectares), elevation range (meters), and associated species are also presented

RNA RNA elevation State and RNA National Forest size range Associated tree species ha m IDAHO Allan Mountain Sawtooth 668 2,912 to 3,707 Abies lasiocarpa Grave Peak Clearwater 146 2,088 to 2,524 Pinus albicaulis, Abies lasiocarpa Salmon Mountain Bitterroot 778 1,939 to 2,682 Pinus albicaulis, Picea engelmannii, Abies lasiocarpa MONTANA Bass Creek Bitterroot 803 1,244 to 2,564 Pinus albicaulis (proposed) Carlton Ridge • Lolo 372 1,700 to 2,500 Pinus albicaulis (overlaps with Larix occidentalis at lower limits in RNA) Dexter Basin Deerlodge 448 2,347 to 3,899 Abies lasiocarpa (proposed) Sapphire Divide Bitterroot 546 2,316 to 2,708 Pinus albicaulis, (proposed) Deerlodge Picea engelmannii, Abies lasiocarpa Tuchuck Flathead 835 1,585 to 2,220 Pinus albicaulis, Abies lasiocarpa

Table 2-List of Research Natural Areas (RNA) on National Forest System lands in Idaho, Montana, Oregon, and Washington representing subalpine forests dominated by Larix occidentalis Nutt. (western larch). National Forest, RNA size (hectares), elevation range (meters), and associated species are also presented

RNA RNA elevation State and RNA National Forest size range Associated tree species ha m IDAHO Aquarius Clearwater 1,579 488 to 1,218 Thuja plicata, Pinus monticola, Abies grandis, Pseudotsuga menziesii Bear Creek Payette 126 2,106 to 2,537 Pseudotsuga menziesii Cuddy Mountain Payette 425 1,474 to 2,754 Pseudotsuga menziesii Hunt Girl Creek Idaho Panhandle 609 1,200 to 1,900 Thuja plicata, Tsuga heterophylla, Pinus monticola, Abies grandis Montford Creek Idaho Panhandle 118 930 to 1,341 Pseudotsuga menziesii, Abies grandis, Pinus monticola Upper Fishhook Idaho Panhandle 130 1,823 Thuja plicata, Abies grandis, Pinus monticola, Pseudotsuga menziesii Upper Shoshone Idaho Panhandle 534 1,090 to 1,954 Pseudotsuga menziesii, Creek Pinus contorta (con.)

484 Table 2 (Con.)

RNA RNA elevation State and RNA National Forest size range Associated tree species ha m MONTANA Bass Creek Bitterroot 803 1,244 to 2,564 Pseudotsuga menziesii, (proposed) Abies grandis Barktable Ridge Lolo 341 1,646 to 1,905 Pinus ponderosa, (proposed) Pinus monticola, Pseudotsuga menziesii Big Creek Kootenai 77 745 to 800 Pinus ponderosa, Pseudotsuga menziesii Carlton Ridge Lolo 372 1,700 to 2,500 Abies lasiocarpa, Picea engelmannii, Pinus contorta (overlaps with Larix Iyallii at upper limits in RNA) Coram Flathead 340 1,060 to 1,440 Pseudotsuga menziesii, Abies lasiocarpa Lower Ross Creek Kootenai 368 866 to 1,402 Thuja plicata, (proposed) Pinus contorta Petty Creek Lolo 125 1,200 to 1,500 Pseudotsuga menziesii, Pinus contorta, Abies grandis Plant Creek Lolo 105 1,500 Pseudotsuga menziesii, Pinus contorta Pyramid Creek Lolo 210 1,600 to 2,460 Pseudotsuga menziesii Swan River Flathead 276 942 to 1,049 Pinus contorta, Pinus monticola, Pseudotsuga menziesii Ulm Peak Kootenai 279 1,273 to 1,953 Pseudotsuga menziesii, Wolf-Weigel Kootenai 101 1,082 to 1,311 Pseudotsuga menziesii

OREGON Canyon Creek Malheur 284 1 ,433 to 1,798 Pseudotsuga menziesii, Abies grandis Indian Creek Wallowa Whitman 396 1,872 to 2,125 Pseudotsuga menziesii, Pinus contorta, Abies lasiocarpa, Tsuga mertensiana Metolius Deschutes 581 850 to 1,460 Pseudotsuga menziesii, Pinus ponderosa, Arctostaphylos patula Mill Creek Mt. Hood 330 790 to 1,040 Abies grandis, Pinus ponderosa Ochoco Divide Ochoeo 777 1,250 to 1,650 Pseudotsuga menziesii Rainbow Creek Umatilla 170 1,100to 1,440 Abies grandis, Pseudotsuga menziesii WASHINGTON Meeks Table Wenatchee 27 1,280 to 1,585 Pseudotsuga menziesii, Calamagrostis rubescens Salmo Colville 563 1,158 to 2,080 Thuja plicata, Tsuga heterophylla

are Pseudotsuga menziesii, Abies grandis, Thuja plicata, monitoring. Permission to utilize an area for research and Pinus monticola. may be obtained through the National Forests and the All Research Natural Areas are available to the scientific Forest Service Research Stations. community for nonmanipulative research and ecological

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