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Old-growth forests of Engelmann spruce (Picea engelmannii Parry ex. Engelm.) and subalpine fir (Abies lasiocarpa (Hook.) Nutt.) dominate much of the landscape of the Rocky Mountains. We characterized the structure, biomass and production of 18 old-growth (200?450-year-old) spruce/fir forests in Rocky Mountain National Park, Colorado, as well as the stand-level supply and use of light and nitrogen. Stands were chosen to span a broad range of elevation, aspect, and topography. Aboveground tree biomass in these old-growth forests averaged 253 Mg/ha (range 130?488 Mg/ha), with aboveground net primary production of 3700 kg ha?1 yr?1 (range from 2700 to 5200 kg ha?1 yr?1). Within stands, trees >35 cm in diameter accounted...
In many temperate and annual grasslands, above-ground net primary productivity (NPP) can be estimated by measuring peak above-ground biomass. Estimates of below-ground net primary productivity and, consequently, total net primary productivity, are more difficult. We addressed one of the three main objectives of the Global Primary Productivity Data Initiative for grassland systems to develop simple models or algorithms to estimate missing components of total system NPP. Any estimate of below-ground NPP (BNPP) requires an accounting of total root biomass, the percentage of living biomass and annual turnover of live roots. We derived a relationship using above-ground peak biomass and mean annual temperature as predictors...
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Percent change in the average net primary production for each HUC5 watershed between historical (1971-2000) and future (2071-2100) time periods. The MC1 dynamic vegetation model was run under the CSIRO, MIROC, and Hadley climate change projections and the A2 anthropogenic emissions scenario. Simulated mean net primary production (in g m-2 per yr), was determined for each HUC5 watershed by averaging values of original ~ 4 km raster data. Watersheds represent 5th level (HUC5, 10-digit) hydrologic unit boundaries and were acquired from the Natural Resources Conservation Service. Background: The dynamic global vegetation model MC1 (see Bachelet et al. 2001) was used to simulate vegetation dynamics, associated...
Recent reports of net ecosysytem production >100 gCm?2 yr?1 in deserts are incompatible with existing measurements of net primary production and carbon pools in deserts. The comparisions suggest that gas exchange measurements should be used with caution and better validation if they are expected to indicate the magnitude of carbon sink in these ecosysytems. Published in Global Change Biology, volume 15, issue 6, on pages 1488 - 1490, in 2009.
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Global climate change is predicted to alter growing season rainfall patterns, potentially reducing total amounts of growing season precipitation and redistributing rainfall into fewer but larger individual events. Such changes may affect numerous soil, plant, and ecosystem properties in grasslands and ultimately impact their productivity and biological diversity. Rainout shelters are useful tools for experimental manipulations of rainfall patterns, and permanent fixed-location shelters were established in 1997 to conduct the Rainfall Manipulation Plot study in a mesic tallgrass prairie ecosystem in northeastern Kansas. Twelve 9 x 14–m fixed-location rainfall manipulation shelters were constructed to impose factorial...
Understanding spatial and temporal variation in net primary production (NPP), the amount of carbon fixed into biomass by vegetation, is a central goal of ecosystem ecologists. Optical remote sensing techniques can help address this need by providing accurate, consistent, and reliable approximations of photosynthetic activity at large scales. However, converting photosynthetic activity into NPP requires estimates of light-use efficiency, which has been shown to vary among vegetation types. In this study, we compare remotely sensed estimates of absorbed photosynthetically active radiation with ground-based NPP estimates to determine appropriate light-use efficiency values for grasslands and croplands. We contrast...
    map background search result map search result map Altering Rainfall Timing and Quantity in a Mesic Grassland Ecosystem: Design and Performance of Rainfall Manipulation Shelters Simulated percent change in net primary production between historical and future time periods under three climate change projections for OR and WA, USA Altering Rainfall Timing and Quantity in a Mesic Grassland Ecosystem: Design and Performance of Rainfall Manipulation Shelters Simulated percent change in net primary production between historical and future time periods under three climate change projections for OR and WA, USA