Ecological Setting of the Wind River Old-growth Forest

Abstract

The Wind River old-growth forest, in the southern Cascade Range of Washington State, is a cool (average annual temperature, 8.7°C), moist (average annual precipitation, 2223 mm), 500-year-old Douglas-fir 4 -western hemlock forest of moderate to low productivity at 371-m elevation on a less than 10% slope. There is a seasonal snowpack (November-March), and rain-on-snow and freezing-rain events are common in winter. Local geology is characterized by volcanic rocks and deposits of Micocene/Oligocene Micocene-Oligocene 5 (mixed) Micocene and Quaternary age, as well as intrusive rocks of Miocene age. Soils are medial, mesic, Entic Vitrands 6 that are deep (2-3 m), well drained, loams and silt loams, generally stone free, and derived from volcanic tephra. The vegetation is transitional, between the Western Hemlock Zone and the Pacific Silver Fir Zone, and the understory is dominated by vine maple, salal, and Oregon grape. Stand structural parameters have been measured on a 4-ha plot. There are eight species of conifers, with a stand density of 427 trees ha )1 and basal area of 82.9 m 2 ha )1 . Dominant conifers include Douglas-fir (35 trees ha )1 ), western hemlock (224 trees ha )1 ), Pacific yew (86 trees ha )1 ), western red cedar 7 (30 trees ha )1 ), and Pacific silver fir (47 trees ha )1 ). The average height of Douglas-fir is 52.0 m (tallest tree, 64.6 m), whereas western hemlock averages 19.0 m (tallest tree, 55.7 m). The regional disturbance regime is dominated by high-severity to moderateseverity fire, from which this forest is thought to have originated. There is no evidence that fire has occurred in the forest after establishment. Primary agents of stand disturbance, which act at the individual to small groups of trees scale, are wind, snow loads, and drought, in combination and interacting with root-rot and butt-rot fungi, heart-rot fungi, dwarf mistletoe, and bark beetles. The forest composition is slowly shifting from dominance by Douglas-fir, a shade-intolerant species, to western hemlock, western red cedar, Pacific yew, and Pacific silver fir, all shade-tolerant species. The Wind River old-growth forest fits the regional definition of Douglas-fir ''old growth'' on western hemlock sites.

Contributions of evaporation, isotopic non‐steady state transpiration and atmospheric mixing on the δ18O of water vapour in Pacific Northwest coniferous forests

“…Oxygen isotope measurements were collected in the summer of 2002 in an old-growth (≈ 500 years old) coniferous forest in the southern Washington (45°49′N, 121°58′W; elevation = 371 m), roughly 160 km from the Pacific coast (Shaw et al 2004). The dominant overstory species are Pseudotsuga menziesii (Douglas-fir), Tsuga heterophylla (western hemlock) and Thuja plicata (western red cedar).…”

“…The average tree height was 52 m for Douglas-fir and 19 m for western hemlock (Shaw et al 2004). A 75-m-tall construction crane was installed in 1995, providing access to the upper canopy.…”

“…This region is characterized by a maritime Pacific climate with dry summer and wet winter periods. The long-term mean annual temperature is 8.7 °C, and mean annual precipitation in this region is 2467 mm with < 5% falling between June and August; hence a significant decline in surface soil moisture occurs through the summer (Shaw et al 2004). Stand leaf area index was estimated as 8.6, with ≈ 56% distributed in the middle and upper canopy (Thomas & Winner 2000).…”

Rarity and abundance in a diverse African forest

“…One or a few species sometimes approach abundances observed in temperate forests (e.g. Sankovski and Pridnia 1995; Shaw et al 2004), where a single dominant tree comprises more than half the forest (Makana 1998;Hart unpublished, 1990). This is known as monodominance, and although it is known in tropical forests elsewhere, it is most important in Africa (Marimon et al 2001;Nascimento and Proctor 1997).…”

Influence of concurrence of extreme drought and heat events on carbon and energy fluxes in dominant ecosystems in the Pacific Northwest region

“…Munger Research Natural Area, a protected section of the Gifford Pinchot National Forest (45.8205 N,121.9519 W; see Shaw et al (2004) for more site description) in southern Washington. The site was co-dominated with Doulas-fir (Pseudotsuga menziesii (Mirbel) Franco) and western hemlock (Tsuga heterophylla (Raf.)…”