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Effects of Management on Carbon Sequestration in Forest Biomass in Southeast Alaska
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The Tongass National Forest (Tongass) is the largest national forest and largest area of old-growth forest in the United States. Spatial geographic informa- tion system data for the Tongass were combined with forest inventory data to estimate and map total carbon stock in the Tongass; the result was 2.8±0.5PgC,or8%of the total carbon in the forests of the conterminous USA and 0.25% of the carbon in global forest vegetation and soils. Cumulative net carbon loss from the Tongass due to management of the forest for the period 1900–95 was estimated at 6.4–17.2 Tg C. Using our spatially explicit data for carbon stock and net flux, we modeled the potential effect of five management regimes on future net carbon flux. Estimates of net carbon flux were sensitive to projections of the rate of carbon accumulation in second-growth forests and to the amount of carbon left in standing biomass after harvest. Projections of net carbon flux in the Tongass range from 0.33 Tg C annual sequestration to 2.3 Tg C annual emission for the period 1995–2095. For the period 1995–2195, net flux estimates range from 0.19 Tg C annual sequestra- tion to 1.6 Tg C annual emission. If all timber harvesting in the Tongass were halted from 1995 to 2095, the economic value of the net carbon sequestered during the 100-year hiatus, assuming $20/Mg C, would be $4 to $7 million/y (1995 US dollars). If a prohibition on logging were extended to 2195, the annual economic value of the carbon sequestered would be largely unaffected ($3 to $6 million/y). The potential annual economic value of carbon sequestration with management maxi- mizing carbon storage in the Tongass is comparable to revenue from annual timber sales historically authorized for the forest.
Key words: carbon sequestration; geographic information system; climate change; forest management; Alaska.
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Elevation-dependent influence of snow accumulation on forest greening
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Rising temperatures and declining water availability have influenced the ecological function of mountain forests over the past half-century. For instance, warming in spring and summer and shifts towards earlier snowmelt are associated with an increase in wildfire activity and tree mortality in mountain forests in the western United States (1,2). Temperature increases are expected to continue during the twenty-first century in mountain ecosystems across the globe (3,4), with uncertain consequences. Here, we examine the influence of interannual variations in snowpack accumulation on forest greenness in the Sierra Nevada Mountains, California, between 1982 and 2006. Using observational records of snow accumulation and satellite data on vegetation greenness we show that vegetation greenness increases with snow accumulation. Indeed, we show that variations in maximum snow accumulation explain over 50% of the interannual variability in peak forest greenness across the Sierra Nevada region. The extent to which snow accumulation can explain variations in greenness varies with elevation, reaching a maximum in the water-limited mid- elevations, between 2,000 and 2,600 m. In situ measurements of carbon uptake and snow accumulation along an elevational transect in the region confirm the elevation dependence of this relationship. We suggest that mid-elevation mountain forest ecosystems could prove particularly sensitive to future increases in temperature and concurrent changes in snow accumulation and melt.
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Enhanced Seasonal Exchange of CO2 by Northern Ecosystems Since 1960
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Seasonal variations of atmospheric carbon dioxide (CO2) in the Northern Hemisphere have increased since the 1950s, but sparse observations have prevented a clear assessment of the patterns of long-term change and the underlying mechanisms. We compare recent aircraft-based observations of CO2 above the North Pacific and Arctic Oceans to earlier data from 1958 to 1961 and find that the seasonal amplitude at altitudes of 3 to 6 km increased by 50% for 45° to 90°N but by less than 25% for 10° to 45°N. An increase of 30 to 60% in the seasonal exchange of CO2 by northern extratropical land ecosystems, focused on boreal forests, is implicated, substantially more than simulated by current land ecosystem models. The observations appear
to signal large ecological changes in northern forests and a major shift in the global carbon cycle.
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Extreme contagion in global habitat clearance
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Habitat clearance remains the major cause of biodiversity loss, with consequences for ecosystem services and for people. In response to this, many global conservation schemes direct funds to regions with high rates of recent habitat destruction, though some also emphasize the conservation of remaining large tracts of intact habitat. If the pattern of habitat clearance is highly contagious, the latter approach will help prevent destructive processes gaining a foothold in areas of contiguous intact habitat. Here, we test the strength of spatial contagion in the pattern of habitat clearance. Using a global dataset of land-cover change at 50 50 km resolution, we discover that intact habitat areas in grid cells are refractory to clearance only when all neighbouring cells are also intact. The likelihood of loss increases dramatically as soon as habitat is cleared in just one neighbouring cell, and remains high thereafter. This effect is consistent for forests and grassland, across biogeographic realms and over centuries, constituting a coherent global pattern. Our results show that landscapes become vulnerable to wholesale clearance as soon as threatening processes begin to penetrate, so actions to prevent any incursions into large, intact blocks of natural habitat are key to their long-term persistence.
Keywords: habitat loss; global change biology; conservation; wilderness
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Fact Sheet: Habitat - Forested Stream and/or Seepage
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Forested stream environments are typically found in the buffer zones between forested land and stream banks, often known as riparian zones. Stream headwaters and seepage areas occur where ground water percolates to the surface through muck, mossy rock, and nettles. It can also be found under rocks, among gravel, or cobble where water has begun to percolate in areas near open water. Breeding grounds are commonly found beneath mosses growing on rocks, on logs, or soil surfaces in these types of seepage areas.
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Fact Sheet: Habitat - Forest/Woodlands
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Forest/Woodland habitats describe large areas primarily dominated by trees, with moderate ground coverage, such as grasses and shrubs. Density, tree height, and land use may all vary, though woodland is typically used to describe lower density forests. A forest may have an open canopy, but a woodland must have an open canopy with enough sunlight to reach the ground and limited shade.
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Federal Programs Offer Opportunities for Wildlife, Forestry Improvements
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For persons interested in performing active management on their property to establish or improve wetlands, riparian (streamside) areas, forest lands, or other upland habitats for wildlife and pollinators, now is the time to request a plan and apply for financial assistance if desired.
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Finite Carbon
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Finite Carbon is North America’s leading developer and supplier of forest carbon offsets.
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First Friday All Climate Change Talks
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Frank Thompson, research wildlife biologist with the Forest Service Northern Research Station in Columbia, MO, will discuss “Changes in the abundance of tree species under climate projections for the Central Hardwoods and Central Appalachians.”
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First-ever Report on USDA Efforts to Expand Agroforestry Practices
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Agriculture Secretary Tom Vilsack today released the first-ever report on USDA's role advancing agroforestry. Agroforestry: USDA Reports to America details how agroforestry practices are helping farmers, ranchers and woodland owners enhance agricultural productivity, protect the environment and increase profits.
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