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Model Estimates Of Net Primary Productivity, Evapotranspiration, And Water Use Efficiency In The Terrestrial Ecosystems Of The Southern United States During 1895–2007, Hanqin Tian, Guangsheng Chen, Mingliang Liu, Chi Zhang, Ge Sun, Chaoqun (Crystal) Lu, Xiaofeng Xu, Wei Ren, Shufen Pan, Arthur Chappelka Mar 2010

Model Estimates Of Net Primary Productivity, Evapotranspiration, And Water Use Efficiency In The Terrestrial Ecosystems Of The Southern United States During 1895–2007, Hanqin Tian, Guangsheng Chen, Mingliang Liu, Chi Zhang, Ge Sun, Chaoqun (Crystal) Lu, Xiaofeng Xu, Wei Ren, Shufen Pan, Arthur Chappelka

Chaoqun (Crystal) Lu

The effects of global change on ecosystem productivity and water resources in the southern United States (SUS), a traditionally ‘water-rich’ region and the ‘timber basket’ of the country, are not well quantified. We carried out several simulation experiments to quantify ecosystem net primary productivity (NPP), evapotranspiration (ET) and water use efficiency (WUE) (i.e., NPP/ET) in the SUS by employing an integrated process-based ecosystem model (Dynamic Land Ecosystem Model, DLEM). The results indicated that the average ET in the SUS was 710 mm during 1895–2007. As a whole, the annual ET increased and decreased slightly during the first and second half …


Long-Term Tillage Frequency Effects On Dryland Soil Physical And Hydraulic Properties, Andrew W. Lenssen, J. D. Jabro, U. M. Sainju, W. B. Stevens, R. G. Evans Jan 2008

Long-Term Tillage Frequency Effects On Dryland Soil Physical And Hydraulic Properties, Andrew W. Lenssen, J. D. Jabro, U. M. Sainju, W. B. Stevens, R. G. Evans

Andrew W. Lenssen

Soil tillage is considered one of most important practices in agricultural production due to its influence on physical, chemical, and biological properties of the soil environment. The effect of a long-term tillage [no-till (NT), spring till (ST), and fall and spring till (FST)] was investigated on soil penetration resistance (PR), bulk density (BD), gravimetric water content (GWC) and saturated hydraulic conductivity (Ks) under dryland conditions. Tillage effects on these physical properties were tested after 22 years on a Dooley sandy loam (fine-loamy, mixed Typic Argiborolls) derived from glacial till parent material. The statistical design used was a randomized complete block …


The Effect Of Water Level Management On The Soils And Vegetation Of Two Coastal Louisiana Marshes, Brian J. Wilsey, K. M. Flynn, I. A. Mendelssohn Jan 1999

The Effect Of Water Level Management On The Soils And Vegetation Of Two Coastal Louisiana Marshes, Brian J. Wilsey, K. M. Flynn, I. A. Mendelssohn

Brian J. Wilsey

Wetland degradation and loss is the result of a combination of natural causes and anthropogenic activities and is a serious problem in coastal Louisiana, where approximately 80% of the total US coastal wetland loss since the 1930’s has occurred. One method currently used to address this wetland loss problem is structural marsh management,which is the use of levees and water control structures to control hydroperiod. The effects of structural marsh management on two managed marshes in Southern Louisiana (Unit 4 of the Rockefeller Wildlife Refuge and the Fina LaTerre Mitigation Bank) were evaluated by comparing the soils and the dominant …


Influence Of Summer Storms On The Solution Geochemistry In A Coastal Plain Hydrosequence, Jeffrey M. Novak, C. Lee Burras Jan 1994

Influence Of Summer Storms On The Solution Geochemistry In A Coastal Plain Hydrosequence, Jeffrey M. Novak, C. Lee Burras

C. Lee Burras

An understanding of factors which influence wetland soil solution chemistry is important for soil solutions are known to influence some chemical properties of surface waters. The influence of summer storms on the solution geochemistry in a South Carolina riverine wetland soil was evaluated by comparing pore water collected 2,4 hr after five summer storm events with pore water acquired during five nonstorm periods. Pore water was collected by tension lysimeters buried at 15 to 152 cm in two locations along a hydrologic gradient. Samples of rain, throughfall and stream water were also collected. Overall, summer storms had no significant influence …


A Survey Of Water Flow In Drainage Ditches And Streams In South Central Minnesota, Clay L. Pierce, Bill Thompson Jan 1981

A Survey Of Water Flow In Drainage Ditches And Streams In South Central Minnesota, Clay L. Pierce, Bill Thompson

Clay L. Pierce

Discharge was monitored on 13 agricultural drainage ditches and 4 small rivers in south central Minnesota. Derived data were categorized by response to hydrologic events and stream order. Stream order was found to be the most reliable predictor of hydrologic event response. Peak flows in drainage ditches were found to correspond to peak flows in rivers.