Restoring Riparian Corridors with Fire: Effects on Soil and Vegetation

Abstract

In many riparian corridors of the semi-arid west, stream incision has resulted in lowered water tables, basin big sagebrush (Artemisia tridentata var. tridentata Nutt.) encroachment and the loss of the dominant herbaceous vegetation. To determine the potential for restoring basin big sagebrush-dominated riparian corridors to greater herbaceous cover, a fall prescribed burn on sites with relatively shallow (-153 to -267 cm) and deep (-268 to > -300 cm) water tables was conducted. We evaluated the separate and interacting effects of water table depth and burning on total soil C and N, soil nutrient availability, and soil enzyme activities by microsite (sagebrush subcanopy, sagebrush interspace), and soil depth (ash/liter, 0-2, 2-5, and 10-20 cm). Three years after the prescribed burn, tissue nutrient content in silvery lupine (Lupinus argenteus Pursh) and Douglas sedge (Carex douglasii Boott), by microsite, growing in burned and unburned areas of 1 shallow water table site was measured. Influence of fire on soil attributes was largely limited to the top 5 cm. As a consequence of prescribed burning, deep water table sites lost relatively more N and C from litter horizons and released more aqueous-soluble Ca+2 from 0-2 cm mineral horizons than did corresponding horizons from shallow water table sites. Overall, compared to unburned controls, burning: (1) increased aqueous. extractable S04 2, K+, and KCl-extractable NH4, (2) decreased activities of the enzymes asparaginase, crease and acid-phosphatase, and (3) decreased KCl-extractable N03" and aqueoussoluble ortho-P. Out of 16 measured soil attributes reported, 7 were influenced by a microsite main effect and/or interaction. New tissue of silvery lupine on burned plots had greater N, greater Zn and Fe (only on subcanopy microsites) and less Ca than plants on control plots; new tissue of Douglas sedge had greater S and less Na, P, and Zn. The results indicate that burning alone is an appropriate restoration treatment for shallow water table sites because of minimal C and N loss and increased available nutrients for regrowth of understory herbaceous species. Deep water table sites require a burning prescription that minimizes fire severity because of higher potential C and N loss, and reseeding due to a lack of perennial understory herbaceous species and more xeric conditions.

The sensitivity of ecosystem carbon exchange to seasonal precipitation and woody plant encroachment

“…Watershed-wide, mesquite cover increased by 410% during the period 1973-1992 (Kepner et al 2000). In riparian areas, this increase likely resulted from several interacting processes that include grazing by cattle (Skartvedt 2000), changes in the flood-frequency regime and channel morphology of the river (Stromberg 1998), and declines in fire frequency (Blank et al 2003). Scott et al (2006) provide an in depth description of the research sites used in this investigation.…”

Dust supply varies with sagebrush microsites and time since burning in experimental erosion events

“…Fire generally does not have significant effects on soil texture and its spatial (i.e., microsite) patterning in sagebrush steppe [Pierson et al, 2001[Pierson et al, , 2002Davies et al, 2009;Hoover, 2010]. Fire can reduce soil organic matter and carbon, and decrease the extent to which soil bulk density and infiltration rates differ between undershrub and interspace microsites in sagebrush steppe [Blank et al, 1994[Blank et al, , 2003Pierson et al, 2001Pierson et al, , 2002Pierson et al, , 2008Davies et al, 2009;Hoover, 2010]. Direct effects of fire on soil aggregates and aggregate stability are not certain for sagebrush microsites and burned environments in general [Boix Fayos, 1997;Giovannini and Lucchesi, 1997;García-Oliva et al, 1999;Mataix-Solera et al, 2002;Arcenegui et al, 2008;Varela et al, 2010].…”

Fire effects on the spatial patterning of soil properties in sagebrush steppe, USA: a meta-analysis

“…Fire can promote the transition of sagebrush steppe from an annual grass-invaded state to an annual grass-dominated state that is exceedingly difficult to restore to shrubland (D'Antonio et al 2009). Fire also alters surface soil properties (Roundy et al 1978;Blank et al 1994Blank et al , 2003Pierson et al 2002Pierson et al , 2008aPierson et al , 2008bRau et al 2007Rau et al , 2009Davies et al 2009).…”

“…within ,1 year) is not well understood for many soil properties, although the effect is relatively predictable for some others. Fire can decrease organic carbon and organic matter at the soil surface via combustion, for example (Blank et al 2003). Fire has produced increases as well as decreases in the availability of limiting plant nutrients such as phosphorus near the soil surface, conversely (Blank et al 2003;Rau et al 2007).…”

“…In order to understand the effect of fire on soil properties and ecological condition at site or coarser geographic scales in the sagebrush steppe, it is necessary to examine the effects of fire at the scale of shrub and interspace microsites ( Fig. 1) (Blank et al 1994(Blank et al , 2003Pierson et al 2008aPierson et al , 2008bDavies et al 2009;Rau et al 2009). Much current literature describes the soil biogeochemical, hydrological and physical characteristics, as well as erosion processes, for microsites in the sagebrush steppe (Table 1 and Fig. 2).…”