02488nas a2200265   4500008004100000245011800041210006900159300001300228490000800241520163600249653001801885653001001903653001001913653001501923653002301938653001901961100001801980700001701998700001702015700001602032700001702048700001602065700001302081856012802094       1996                        eng d00aThe relationship of floods, drying, flow and light to primary production and producer biomass in a prairie stream0 arelationship of floods drying flow and light to primary producti  a151 -1590 v3333 aFactors related to autochthonous production were investigated at several sites along a prairie stream at Konza Prairie Research Natural Area. Primary production, algal biomass, litter input, and ability of floods to move native substrate were measured. Additional experiments were conducted to establish the influence of light and water velocity on primary production rates and recovery of biomass following dry periods. The study period encompassed two extreme (> 50 year calculated return time) floods, thus we were able to analyze the effects of scour on periphyton biomass and productivity. Biomass of sedimentary algae was reduced greatly by flooding and did not reach preflood amounts during the 2 months following the first flood. Rates of primary production associated with sediments recovered to levels above preflood rates within 2 weeks. Biomass of epilithic periphyton was not affected as severely as that of sedimentary algae. Little relationship was observed between water velocity and photosythetic rates. Production reached maximum rates at 25% of full sun light. Epilithic chlorophyll levels recovered within eight days following a dry period, and chl a was an order of magnitude greater on rocks than sediments 51 days after re-wetting. Estimated annual rates of primary production were 2.6 times greater in the prairie than in the forest reaches of the stream. The ratio of annual autochthonous:allochthonous carbon input was 4.81 for prairie and 0.32 for the forest. Periphyton production in prairie streams is resilient with regard to flooding and drought and represents a primary carbon source for the system.10aautochthonous10aFlood10alight10aperiphyton10aPrimary production10awater velocity1 aDodds, W., K.1 aHutson, R.E.1 aEichem, A.C.1 aEvans, M.E.1 aGudder, D.A.1 aFritz, K.M.1 aGray, L.  uhttp://lter.konza.ksu.edu/content/relationship-floods-drying-flow-and-light-primary-production-and-producer-biomass-prairie02663nas a2200289   4500008004100000245010400041210006900145300001300214490000700227520173600234653001601970653002201986653001602008653001402024653001002038653002102048653001902069653001202088653002002100653001202120653002502132653002602157653002502183100001402208700002002222856013102242       1995                        eng d00aStomatal and photosynthetic responses to variable light in sorghum, soybeans and eastern gammagrass0 aStomatal and photosynthetic responses to variable light in sorgh  a613 -6200 v943 aWe studied photosynthetic and stomatal responses of grain sorghum (Sorghum bicolor [L.] Moench cv. Pioneer 8500), soybean (Glycine max L. cv. Flyer) and eastern gamagrass (Tripsacum dactyloides L.) during experimental sun and shade periods simulating summer cloud cover. Leaf gas exchange measurements of field plants showed that short-term (5 min) shading of leaves to 300–400 μmol m−2 s−1 photosynthetic photon flux density reduced photosynthesis, leaf temperature, stomatal conductance, transpiration and water use efficiency and increased intercellular CO2 partial pressure. In all species, photosynthetic recovery was delayed when leaves were reilluminated, apparently by stomatal closure. The strongest stomatal response was in soybean. Photosynthetic recovery was studied further with soybeans grown indoors (maximum photosynthetic photon flux density 1 200 μmol m−2 s−1). Plants grown indoors had responses to shade similar to those of field plants, except for brief nonstomatal limitation immediately after reillumination. These responses indicated the importance of the light environment during leaf development on assimilation responses to variable light, and suggested different limitations on carbon assimilation in different parts of the soybean canopy. Photosynthetic oxygen evolution recovered immediately upon reillumination, indicating that the light reactions did not limit soybean photosynthetic recovery. While shade periods caused stomatal closure and reduced carbon gain and water loss in all species, the consequences for carbon gain/water loss were greatest in soybean. The occurrence of stomatal closure in all three species may arise from their shared phenologies and herbaceous growth forms.10aA:Ci curves10aeastern gamagrass10aGlycine max10ainduction10alight10aoxygen evolution10aphotosynthesis10asorghum10aSorghum bicolor10asoybean10aStomatal Conductance10aTripsacum dactyloides10aWater use efficiency1 aFay, P.A.1 aKnapp, Alan, K.  uhttp://lter.konza.ksu.edu/content/stomatal-and-photosynthetic-responses-variable-light-sorghum-soybeans-and-eastern-gammagrass