Paul B. Alaback

Dynamics of Understory Biomass in Sitka Spruce‐Western Hemlock Forests of Southeast Alaska

Understory vegetation undergoes successional stages during the 1st 300 yr after logging or fire disturbance in the coastal Picea—Tsuga forests of southeast Alaska. Residual shrubs and tree seedlings increase their growth within 5 yr after overstory removal. Understory biomass peaks at 5 Mg°ha — 1 °yr — 1 °15—25 yr after logging. Shrubs and herbs are virtually eliminated (<0.1 Mg/ha) from the understory after forest canopies close at stand ages of 25—35 yr. Bryophytes and ferns dominate understory biomass during the following century. An understory of deciduous shrubs and herbs is reestablished after 140—160 yr. Thereafter, biomass of the shrubs, herbs, and ferns continues to increase, while bryophyte biomass and tree productivity decline. Departures from this developmental sequence are related to unusual types of stand establishment, soil, microclimate, or disturbance. The development and duration of the depauperate understory that succeeds canopy closure in southeast Alaska is closely related to the canopy structure of shade—tolerant Tsuga forests with their high foliar biomass. In young—growth forests (<100 yr), the decline in understory development immediately after canopy closure is significantly associated with tree basal area and percentage of tree canopy cover. In old—growth forests, in contrast, understory biomass is correlated with mean tree diameter, age, and volume. It is hypothesized that understory development over the chronosequence responds primarily to changes induced in the light environment by developments in the forest canopy. Maintenance of the most productive forests in the aggradation stages of development (0—100 yr) through forest management will minimize the development of a productive vascular understory and thus deprive herbivores of forage during 70—80% of the forest rotation.

High-latitude rainforests and associated ecosystems of the West Coast of the Americas: climate, hydrology, ecology and conservation.

Section 1. Climate, Hydrology, and History.- 1. North-South Variations in West Coast Hydrometeorological Parameters and Their Significance for Earth Systems.- 2. Factors Controlling the Climate of the West Coast of North America.- 3. Sulfur Cycling in Coastal Upwelling Systems and Its Potential Effects on Climate.- 4. Atmospheric and Geologic Constraints on the Biogeochemistry of North and South American Temperate Rainforests.- 5. Past Changes in Climate and Tree Growth in the Western Americas.- 6. Constraints on Terrestrial Primary Productivity in Temperate Forests Along the Pacific Coast of North and South America.- Section 2. Biotic Patterns.- 7. Biodiversity Patterns in Relation to Climate: The Coastal Temperate Rainforests of North America.- 8. Phytogeographic Relationships and Regional Richness Patterns of the Cool Temperate Rainforest Flora of Southern South America.- 9. A Comparative Review of Forest Dynamics and Disturbance in the Temperate Rainforests of North and South America.- 10 Patterns of Terrestrial Vertebrate Diversity in New World Temperate Rainforests.- 11. Avian Communities in Temperate Rainforests of North and South America.- 12. The Importance of Plant-Bird Mutualisms in the Temperate Rainforest of Southern South America.- 13. The Temperate Rainforest Lakes of Chile and Canada: Comparative Ecology and Sensitivity to Anthropocentric Change.- Section 3. Forest System Responses to Human Activities.- 14. Implications of Patch Dynamics for Forested Ecosystems in the Pacific Northwest.- 15. Assessing and Responding to the Effects of Climate Change on Forest Ecosystems.- 16. A Comparison of the Ecology and Conservation Management of Cool Temperate Rainforest in Tasmania and the Americas.- 17. Logging Effects on the Aquatic Ecosystem: A Case Study in the Carnation Creek Experimental Watershed on Canadas West Coast.- 18. Biodiversity of Canadian Forests, with Particular Reference to the West Coast Forests.- Section 4. Conclusion.- 19. Afterword.

Food availability and foraging near human developments by black bears

Abstract Understanding the relationship between foraging ecology and the presence of human-dominated landscapes is important, particularly for American black bears (Ursus americanus), which sometimes move between wildlands and urban areas to forage. The food-related factors influencing this movement have not been explored, but can be important for understanding the benefits and costs to black bear foraging behavior and the fundamental origins of bear conflicts. We tested whether the scarcity of wildland foods or the availability of urban foods can explain when black bears forage near houses, examined the extent to which male bears use urban areas in comparison to females, and identified the most important food items influencing bear movement into urban areas. We monitored 16 collared black bears in and around Missoula, Montana, during 2009 and 2010, while quantifying the rate of change in green vegetation and the availability of 5 native berry-producing species outside the urban area, the rate of change in green vegetation, and the availability of apples and garbage inside the urban area. We used parametric time-to-event models in which an event was a bear location collected within 100 m of a house. We also visited feeding sites located near houses and quantified food items bears had eaten. The probability of a bear being located near a house was 1.6 times higher for males, and increased during apple season and the urban green-up. Fruit trees accounted for most of the forage items at urban feeding sites (49%), whereas wildland foods composed <10%. Black bears foraged on human foods near houses even when wildland foods were available, suggesting that the absence of wildland foods may not influence the probability of bears foraging near houses. Additionally, other attractants, in this case fruit trees, appear to be more important than the availability of garbage in influencing when bears forage near houses.

Biodiversity patterns in relation to climate: the coastal temperate rainforests of North America.

The west coast of North America presents a rich array of climatic, geologic, and historical environments in which a relatively rich flora and fauna have developed. In contrast to South America, the west coast of North America is part of a large temperate zone and as such shares serveral species with continental and in particular the montane biota of inland portions of the continent. Many species are confined to the coastal region, suggesting an adaptation to the relatively unique, mild marine climate, especially that of the temperate rainforest region. Subtleties in climatic differences between North America and other temperate rainforest types are hypothesized as a critical factor in explaining differences in structure and composition of vegetation (Alaback, 1991).

Successional trends and biomass of mosses on windthrow mounds in the temperate rainforests of Southeast Alaska

We investigated successional trends on windthrow mounds in two old-growth Tsuga heterophylla-Picea sitchensis forests in northern southeast Alaska to determine the influence of windthrow disturbance on the maintenance of plant diversity. We were particularly interested in assessing the value of mosses in detecting long-term effects of disturbance in temperate rainforests. Mosses established a dense carpet on windthrow mounds within the first few decades after the disturbance. No consistent changes were noted in total moss and vascular plant cover, moss biomass, or species diversity between young mounds (±50 yrs), intermediate mounds (±150 yrs) or old mounds (> 200 yrs), or between mounds and the undisturbed forest floor, despite consistent differences in soils development. Classification and ordination of the vegetation data did not show a consistent relationship between soil surface age or soil depth and overall species composition on the two sites. Young mounds were the most compositionally distinctive, primarily due to moss species. Pogonatum alpinum var. sylvaticum, P. contortum and Polytrichum formosum were generally confined to young mounds with unstable substrata, while Dicranum majus and Sphagnum girgensohnii were associated with old soil surfaces and deep organic soils. Vascular plant species with affinities for riparian or deep shade habitats (Tiarella trifoliata, Coptis asplenifolia and Dryopteris expansa) showed a general preference for the forest floor. Gymnocarpium dryopteris was the only vascular plant with a significant association with young mounds. Mosses comprised approximately 25% of understory plant biomass and as much as 50% of understory productivity. In cool temperate forests, the inclusion of mosses in vegetation analysis may provide valuable insights into the nature of vegetation patterns over subtle environmental gradients. The distinctiveness of the temperate rainforest type and the unique ecological effects of windthrow disturbance in this type are also suggested by this study.

Temperate and Boreal Rainforests of the Pacific Coast of North America

The world’s most expansive stretch of coastal temperate and boreal rainforest issandwiched between the Pacific Ocean and a chain of coastal mountains spanning 23 degrees of latitude and some 3,600 kilometers. Here, rainforests extend from northern Kodiak Island and Prince William Sound, Alaska (61°N latitude)to just south of San Francisco Bay, California (38°N latitude; see figure 2-1). Along the coastline, rainforest is limited to moist climates extending to as muchas 160 kilometers inland in southeast Alaska and adjacent British Columbia to 60 kilometers or less in California and the Pacific Northwest. A secondary beltof rainforest up to 100 kilometers wide occurs along the western slopes of the Cascades from southern British Columbia to central Oregon.

Temperate and boreal rainforest relicts of Europe

European temperate rainforests are disjunctly distributed from ~45° to 69°N latitude, where they are influenced by maritime climates (see figure 6-1). Storms originating in the North Atlantic and the Mediterranean (Balkans) provide for mild winters, cool summers, and adequate precipitation to sustain rainforests throughout the year. Due to extensive deforestation, however, today’s European rainforests are mere fragments of primeval rainforests. A reminder of a bygone era when rainforests flourished, they are barely hanging on as contemporary rainforest relicts (see box 6-1).

Temperate and Boreal Rainforests of Inland Northwestern North America

On the windward slopes of the Columbia and Rocky Mountains is a 7 million-hectare disjunct rainforest (see figure 3-1) that arguably includes the largest expanse of inland temperate and boreal rainforests on Earth (but also see Inland Southern Siberia, chapter 9). Most rainforests here are temperate except at the most northerly latitudes, where they grade to boreal rainforest. Although early biogeographers noted the unexpected presence here of numerous species typical of coastal regions (e.g., Daubenmire 1943), only recently have ecologists recognized these forests as a distinct entity: an inland counterpart to coastal rainforests of the Pacific Northwest (Alaback et al. 2000; Goward and Arsenault 2000; Goward and Spribille 2005).

Climatic and Human Influences on Fire Regimes in Temperate Forest Ecosystems in North and South America

Fire plays an integral role in regulating ecosystem structure and processes including biodiversity, nutrient cycling, ecosystem structure, resiliency, stability, and carbon flow (Boerner 1982; Agee 1993). These effects of fire on ecosystems are extremely sensitive to all components of the disturbance regime (frequency, intensity, scale, predictability; Pickett and White 1985). To properly evaluate the impact of human activities on fire — both now and in the future — it is critical that we have an accurate baseline of past fire occurrences. In particular, we need to understand the natural role of fire in ecosystems across a range of scales from stands or sites to broad regions (Turner et al. 1994). In addition, we need to understand the controls that govern fire regimes across landscapes, so that we can better understand both how natural systems worked in the past and how fire regimes might be changed in the future (Franklin et al. 1991; Veblen and Lorenz 1991; Alaback and McClellan 1993).

Just What Are Temperate and Boreal Rainforests

When most people think of rainforests, they think of lush, tropical “jungles”teeming with poison arrow frogs (Dendrobates spp.), toucans (e.g., Ramphastos sulfuratus), mountain gorillas (Gorilla gorilla beringei), and jaguars (Panthera spp.).Tropical rainforests are indeed special places, as they account for over half the terrestrial species on Earth (Meyers et al. 2000) while representing just 12 percent of the world’s forest cover (Ritter 2008). Their temperate and boreal counterparts are another story, though, one yet to receive the kind of global recognition rightfully merited by tropical rainforests. Their story is told here,beginning with historical and recent accounts to define and map the temperate and boreal rainforests of the world.