Water Relations of Juniperus virginiana and Andropogon Gerardii in an Unburned Tallgrass Prairie Watershed

1993 ◽  
Vol 38 (4) ◽  
pp. 325 ◽  
Author(s):  
Beverly D. Axmann ◽  
Alan K. Knapp
Keyword(s):  
Water Relations ◽  
Tallgrass Prairie ◽  
Andropogon Gerardii ◽  
Juniperus Virginiana

Land cover change in eastern Kansas: litter dynamics of closed-canopy eastern redcedar forests in tallgrass prairie

2001 ◽  
Vol 79 (2) ◽  
pp. 214-222 ◽  
Author(s):  
Mark D Norris ◽  
John M Blair ◽  
Loretta C Johnson
Keyword(s):  
Tallgrass Prairie ◽  
Lignin Content ◽  
Forest Litter ◽  
Decay Rates ◽  
Andropogon Gerardii ◽  
Juniperus Virginiana ◽  
Ecosystem Structure ◽  
Big Bluestem ◽  
Eastern Redcedar ◽  
Litter Dynamics

In the Great Plains region, eastern redcedar (Juniperus virginiana L.) abundance has increased dramatically in areas historically occupied by tallgrass prairie. This shift in dominant vegetation is likely to be accompanied by changes in ecosystem structure and function, including quantity, quality, and location (above- vs. below-ground) of litter inputs and subsequent effects on decomposition dynamics. The purpose of this study was to quantify and compare patterns of litterfall and decomposition in mature redcedar forests and adjacent prairie. Annual redcedar litterfall was 500 g·m-2·year-1, a large increase in foliar litter inputs compared with annually burned grassland (52 g·m-2·year-1). Using a reciprocal transplant decomposition study with four substrates, redcedar leaves and roots, and big bluestem (Andropogon gerardii Vitman) foliage and roots, we found marginal habitat effects, but greater differences between species, presumably owing to litter quality (including both C:N and lignin content). Decay rates were significantly higher in the prairie relative to the forest for each substrate. Additionally, within any particular habitat, grass litter had significantly faster decay rates than forest litter. These results suggest a shift in patterns of litter input and decomposition processes with afforestation of tallgrass prairie, which may result in long-term changes in C sequestration and storage.Key words: litter dynamics, eastern redcedar (Juniperus virginiana), big bluestem (Andropogon gerardii), decomposition, tallgrass prairie, nitrogen immobilization.

Competition and coexistence in grassland codominants: responses to neighbour removal and resource availability

2004 ◽  
Vol 82 (4) ◽  
pp. 450-460 ◽  
Author(s):  
Andrea M Silletti ◽  
Alan K Knapp ◽  
John M Blair
Keyword(s):  
Tallgrass Prairie ◽  
Competitive Exclusion ◽  
Net Photosynthesis ◽  
Andropogon Gerardii ◽  
Sorghastrum Nutans ◽  
Konza Prairie ◽  
Plant Removal ◽  
Anthropogenic Alterations ◽  
Prairie Plant

We examined the role of interspecific competition in the regulation of abundance and coexistence of the dominant grasses in tallgrass prairie using a removal experiment with Andropogon gerardii Vitman and Sorghastrum nutans L. Nash, two of the most abundant grasses in tallgrass prairie. Plant removal treatments (using foliar herbicide), applied to 0.3-m2 plots at the Konza Prairie Biological Station (northeast Kansas, USA), included removal of all A. gerardii, removal of all S. nutans, and no removal. To determine whether soil fertility altered the outcome, we included a fertilizer addition treatment (10 g N·m–2) fully crossed with the removal treatments. Andropogon gerardii removal resulted in significantly increased net photosynthesis, stomatal conductance, and tiller mass in S. nutans. Sorghastrum nutans removal had little effect on A. gerardii, suggesting asymmetric competition. Fertilizer significantly increased tiller mass and flowering stalk production in S. nutans, but had little effect on A. gerardii. The ability of A. gerardii to suppress the performance of S. nutans is consistent with the greater abundance of A. gerardii over much of the tallgrass prairie, while the ability of S. nutans to take advantage of increased resources may be one mechanism by which it avoids competitive exclusion. Because of the greater variability in the performance of S. nutans than in that of A. gerardii, any natural or anthropogenic alterations to this grassland that lead to shifts in dominance between these species may affect ecosystem productivity and stability.Key words: Andropogon gerardii, competition, grassland, neighbour removal, photosynthesis, Sorghastrum nutans, tallgrass prairie.

Assessing changes in biomass, productivity, and C and N stores following Juniperus virginiana forest expansion into tallgrass prairie

2001 ◽  
Vol 31 (11) ◽  
pp. 1940-1946 ◽  
Author(s):  
Mark D Norris ◽  
John M Blair ◽  
Loretta C Johnson ◽  
Robert B McKane
Keyword(s):  
Land Cover ◽  
Land Cover Change ◽  
Tallgrass Prairie ◽  
Woody Plant ◽  
Net Primary Productivity ◽  
Plant Biomass ◽  
Plant Cover ◽  
Juniperus Virginiana ◽  
Aboveground Net Primary Productivity ◽  
Closed Canopy

An increase in woody plant abundance in regions historically dominated by grasses is a recent land cover change in grasslands worldwide. In tallgrass prairies of North America, this increase in woody plant cover includes the development of dense stands of eastern redcedar (Juniperus virginiana L.). To evaluate the consequences of this ongoing land cover change for ecosystem functioning, we developed allometric equations, using data from Kansas and Oklahoma, to estimate aboveground biomass and productivity in closed-canopy redcedar stands. We then applied these equations to three closed-canopy redcedar stands, 35–80 years old, which developed on sites formerly dominated by tallgrass prairie in eastern Kansas. Aboveground plant biomass for these redcedar-dominated sites ranged from 114 100 kg/ha for the youngest stand to 210 700 kg/ha for the oldest. Annual aboveground net primary productivity (ANPP) ranged from 7250 to 10 440 kg·ha–1·year–1 for the oldest and younger redcedar stands, respectively. Estimates of ANPP in comparable tallgrass prairie sites in this region average 3690 kg·ha–1·year–1 indicating a large increase in C uptake and aboveground storage as a result of the change from prairie to redcedar forests. Therefore, the widespread occurrence of redcedars across the woodland–prairie ecotone suggests that this land-cover change may have important consequences for regional net C storage.

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