Water Holding Capacity of Litter and Soil Organic Matter in Mixed Prairie and Fescue Grassland Ecosystems of Alberta

Abstract

Litter and organic matter accumuiations can reduce soil water through interception of precipitation and subsequent evaporation of absorbed water. Interception varies with mass and water hoiding capacity (WHC) of litter and organic matter, and is highest from small precipitation events. WHC varies with vegetation type, which is affected by grazing regime. Thus long-term grazing could affect WHC of litter and organic matter and would be important in the hydrologic assessment of rangelands subjected to many small precipitation events throughout the growing season. The study was conducted in mixed prairie, parkland fescue, and foothills fescue grasslands in Alberta, Canada. Grazing regimes were of light to very heavy intensities, grazed early, Me, and continuously during the growing season. Litter and organic matter were sorted by sieving into various sized categories. Litter-soil cores were also evaluated. WHC of litter and organic matter was lower in mixed prairie than in fescue grasslands. WHC increased with increazed particle size, being higher for roots and standing and fallen litter than for organic matter. WHC of iarge particle-sized material decreased with heavy intensity and/or early season grazing. WHC was affected more by intensity than season of grazing. Grazing affected WHC through species composition changes, since species have different WHC, and through trampling which affected particle size. It was concluded that litter and organic matter WHC were important in rangeland hydrologic assessments.

Surface runoff response of native and introduced grasses under simulated rainfall in southern Alberta

“…However, WHC for litter from RWR and CWG (ranging from 2.40 to 2.88 g g (1 ) were similar to that for litter in parkland fescue and foothills fescue environments (1.80 to 2.58 g g (1 , Naeth et al 1991). A greater mass of large sized litter fragments together with high ground cover is likely to lead to higher interception and retention (Naeth et al 1991) and so the ABN treatment, having nearly double the litter mass of any other treatment, had a high initial abstraction of 13.3 mm and a low RLF of 0.13.…”

“…(1 ) were considerably higher than 1.72 to 2.16 g g (1 for litter of similar fragment sizes from mixed prairie (Naeth et al 1991). However, WHC for litter from RWR and CWG (ranging from 2.40 to 2.88 g g (1 ) were similar to that for litter in parkland fescue and foothills fescue environments (1.80 to 2.58 g g (1 , Naeth et al 1991).…”

“…The mass of each fraction was determined and expressed on a DM basis. The water-holding capacity (WHC) of each fraction was determined using the method of Naeth et al (1991), who reported that WHC of litter, and so initial abstraction, was influenced by the size of litter pieces. Briefly, for each litter fraction, a 250 mL plastic vial was packed with 5 g of air dry litter and covered with plastic gauze and secured by an elastic band.…”

“…Pastures grazed at higher intensity have lower proportions of ground cover and lower amounts of litter and these parameters can be related to increased volume and higher peak flow rate of runoff (Hart and Frasier 2003;Murphy et al 2004). Naeth et al (1991) found that the size and proportion of litter fragments determined their water-holding capacity and so influenced storage of rainfall and the runoff response. Studies of surface runoff water quality from fescue-(Festuca spp.)…”

Grazing Management Effects on Sediment and Phosphorus in Surface Runoff

“…Damage caused by treading (Elliott et al 2002), decreased soil organic matter (Naeth et al 1991b;Betteridge et al 1999), and reduced leaf litter results in a reduction of aboveground water-holding capacity of the soil (Naeth et al 1991a), decreasing infiltration rate and increasing the volume of surface runoff. Management practices that reduce the total volume of surface runoff and encourage infiltration will reduce the potential for sediment and P losses from pastures (Gburek et al 2000).…”