Forest Vegetation of the Montane and Subalpine Zones, Olympic Mountains, Washington

FOREST VEGETATION OF THE MONTANE AND SUBALPINE ZONES, OLYMPIC MOUNTAINS, WASHINGTON R. W. FoNnA1 AND L. C. BLiss2 Dopartment of Botany, University of Illinois, Urbana, Illinois 61801 TABLE OF CONTENTS INTRODUCTION 271 .Abies amabilis-Tsuga mertensiana Type 280 STUDY AREA 272 .Abies lasiocarpa Type .......... 281 Location 272 Communities on Recently Disturbed Sites 281 Geology 272 Soils ..................... 283 Climate 273 Morphology .................. 283 METHODS 274 Chemical Properties .......... 284 Vegetation 274 DISCUSSION . ....... 286 Ordination 275 Forest Pattern . ...... 286 Community Type Diversity . ........... 287 Soils ................................... 275 Distribution of Important Tree Species .. 289 RESULTS 276 Understory Pattern ......... 291 Montane Forests .............. 276 Forest Zonation ..... 292 Abies amabilis-Tsuga heterophylla/Oxalis Fire ...... 294 Type ...................... 276 Tree Invasion into Late-Melting Snow Abies amabilis-Tsuga heterophylla Type 277 Basins ........... 295 Tsuga heterophylla-Pseudotsuga menziesii Avalanche Effects . ................. 296 Type ........................ 278 Comparison of the Olympic Forests with Pseudotsuga menziesii-Tsuga heterophylla Forests of Other Mountain Systems in the Type .......................... 278 Northwest ................ 296 Pseudotsuga menziesii Type ....... 279 SUMMARY ................... 299 Subalpine Forest . ....... 280 LITERATURE CITED . ....................... 300 INTRODUCTION and luxuriant vegetation, never extend to an ele One of the last frontiers for large scale ecological vation above 300 m. Sharpe's work was taxonomic research in the United States has been the Pacific in format, although a considerable portion was con Northwest. Foresters have conducted silvicultural cerned with the phytosociology of carefully selected and narrowly defined plots. research in the area for many years, but until the This study is concerned with the forest vegetation late 1950's there had been few basic ecologic studies of the montane and subalpine zones, part of a larger especially in the mountains near the coast. Dauben project to investigate the plant ecology of the Olym mire (1952, 1956) had done considerable work in the pic Mountains massif. Dense coniferous forests cover northern Rockies. Krajina and his students (Krajina the slopes of the Olympics from sea level to 1800 m, 1965) began research during the late 1950's in the but this investigation is limited to those between 550 coastal and interior mountains in British Columbia, and 1800 m. Because so little was known about the and Whittaker (1960) investigated the ecology of the ecology of these fore11ts, several different kinds of Siskiyou Mountains in southern Oregon-northern data and observations were needed. Information California. Synecological studies in the Cascade was desired on the location, composition, and struc Range began with the work of Franklin (1965, ture of the montane and subalpine forests; the re 1966). lationships of the different community types to each Some pertinent points concerning the ecology of other and how the pattern of species and communi the Olympic Peninsula were first stated by Jones ties is affected by temperature and precipitation. (1936), although the book was basically a flora. Additional information was sought on the role of fire Sharpe (1956) studied the rain forests, which are in these forests; the effect of vegetation, environ narrowly confined to three broad river valleys open mental factors, and slope exposure on soil develop to the Pacific Ocean. The rain forest, dependent ment; and the relationship of parent material and Upon the ocean influence and typified by huge trees soil fertility levels to forest pattern. Finally, we Accepted for publication March 26, 1969. wanted to know the position of the Olympic Moun 'Present address: Department of Biology, Western tain forests in the ecology and phytogeography of Washington State College, Bellingham, Washington the Pacific Northwest mountain systems. 98225. The nomenclature in this study follows the treat 'Present address: Department of Botany, University mPnts of several authors, because of the Jack of a of Alberta, Edmonton, Alberta, Canada. comprehensive flora for the Pacific Northwest. Ecological Monographs 272 R. W. FoNDA AND L. C. BLiss Vol. 39, No. 3 Nomenclature is that of U.S. Forest Service (1965) for Gymnospermae, Hitchcock, et al. (1955, 1959, 1961, 1964) for Dicotyledonae, Hitchcock and Chase (1950) for grasses, and Peck (1961) for the lo.wer Monocotyledonae. Exceptions vascular plants and FORKS are the treatments of Blechnum spicant and JJ1 aian 2974mm 9.6' themum dilatatum, which follow Munz (1959). • Pseudotsuga menziesii var. menziesii is the only variety of Douglas fir found in ~he ~lympics .. C~ tation of the binomial elsewhere m this work mdi cates, therefore, only this variety. Voucher s~eci mens are deposited in the Herbarium of the Umver sity of Illinois. Grateful acknowledgment is made to the National Science Foundation for support of this project ( GB-2240). Thanks are due to the staff of Olympic National Park for their cooperation; to Mr. T. Nash and Dr. R. Kuramoto who helped with portions of this study; and to Mrs. Arline Fonda who assisted with the field work and did the illustrations for this manuscript. The University of Wisconsin, Depart NI ment of. Soils, and the Nu-Ag Soil Testing Labora ~ tory performed the soil chemical analyses. 0 km 25 STUDY AREA l<'IG. 1. Mean annual precipitation (mm) ancl tcm·; LOCATION perature CO C) for selected stations on the Olympic Peninsula, Washington. Data are for observation per· The Olympic Peninsula, covering an area of ca. iocls of varying length. 10 400 km2 in the northwest corner of Washington, is 'bounded on the west by the Pacific Ocean, on the this same period form a minor part of the geology. north bv the Strait of .Juan de Fuca, and on the Metchosin Formation volcanics, formed during Eo· <>ast by .Hood Canal and Puget Sound. The Olympic cene inundation, constitute the rim of the mountains Mountains constitute the center of the peninsula, and on the north, east, and south. This formation covers are one of the last true wilderness areas of the considerably less area. than the Soleduck Formation, United States (Fig. 1). Figure 2 shows the major and most of it lies in the X ational I<'orest. Along the drainages in the Olympics, and some important land east and south this formation is almost 19 km wide, marks. but it is relatively narrow along the north~rn edge. Olympic National Park, officially established in Sediments deposited near the close of Eocene con 1938, occupies nearly 364,000 ha of the central moun stitute the Crescent Formation, and are most obvious tains and a coastal strip. Olympic National Forest, along this northern rim. Previously, rocks of this ca. 252,000 ha adjoins the National Park boundary formation covered most of the Olympic Peninsula, in many places. The National Forest and private but they have been subsequently eroded away. land-owners carry on extensive Jogging operations, The present topographic features of the Olympics but the National Park boundaries were established were largely produced by two intervals of diastro before logging operations had penetrated the moun phism, but were somewhat modified by glacial action tains very far, so that no forests within Olympic and erosion during the Pleistocene. The mountains National Park have been cut. ~Iost of the sampling have a basic northwest-southeast course, over which for this stud~· was conducted within the "!\ational has been imposed a north-south trend wrought by Park boundaries, although some work was carried the Cascadian Revolution. The western mountains out in th<> National Forest on leave strips from clear rise gently eastward from the ocean, with long cutting operations. ridges, 300 to 600 m high, stretching for 30 to 50 km before culminating in high peaks, such as Mt. GEOU)GY Olympus and the Bailey Range. (Fig. 1). The cen Weaver (1937, 1945) and Danner (1955) have tral body of mountains from Mt. Olympus east for studied the geology of the Olympic Mountains, and 40 km averages 1800 m in elevation. The north<>ast their publications have served as the basis of the dis and southeast slopes are cut by deep valleys with cussion below. Most of the rocks in the mountains steep sides and intervening sharp crests, so that originated in either of two geologic ages. The central the rugged eastern Olympics present a marked con and largest part of the Olympics consists of sedi trast to the western portion. As a result of the Puget mentary rocks of the Soleduck Formation, deposited Sound downwarping, the eastern Olympics plunge about 126 million years ago during the early Creta from 2100 m to sea level at Hood Canal in a dis ceous period. Some volcanic rocks laid down during tanee of 13 km. Summer 1969 FOREST VEGETATION OF THE MONTANE AND SUBALPINE ZONES 273 IN .... 48 Stand number •• .A. Montone stand • Subalpine stand km n~. ~. Location of important geographic features and stands sampled in the Olympic Mountains . .?~fountain glaciers have been the main sculpturing The peninsula is about 120 km wide from the agents in the mountains. During maximum Pleisto Pacific Ocean to Hood Canal; Mt. Olympus is only cene glaciation, many mountain glaciers pushed down 51 km from the ocean. The ameliorating effect of their valleys, some probably reaching the ocean. Most the Pacific reaches far inland, keeping the general of the major

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