Initial Effects of Prescribed Fire on Morphology, Abundance, and Phenology of Forbs in Big Sagebrush Communities in Southeastern Oregon

Abstract

Historic fire return intervals in Artemesia tridentata (big sagebrush) ecosystems have been altered by livestock grazing, fire suppression, and other land management techniques resulting in ecological changes in these areas. Increases in abundance of woody vegetation may be causing declines in native herbaceous understory species. We examined the effects of prescribed fire on the morphology, abundance, and phenology of nine abundant forb (herbaceous dicot) species used selectively by Centrocercus urophasianus (Sage Grouse). In September 1997 prescribed fire was applied to four of eight randomly assigned 400‐ha A.t. wyomingensis (Wyoming big sagebrush) study plots at Hart Mountain National Antelope Refuge, Oregon. Livestock had not grazed experimental plots since 1991. Burning caused morphological changes such as significantly greater numbers of racemes and flowers per raceme in Astragalus malachus (shaggy milkvetch‐Legumoideae) (9 in burn vs. 6 in control; 23 in burn vs. 21 in control, respectively). Also, prescribed burning caused greater numbers of flowers in Phlox gracilis (microsteris‐Polemoniaceae) (57 vs. 13), greater numbers of umbels and umbelletts in Lomatium nevadense (Nevada desert parsley‐Umbellifereae) (4 vs. 2 and 59 vs. 31, respectively), greater numbers of flower heads in Crepis modocensis (Modoc hawksbeard‐Compositae) (32 vs. 21), and greater number of flowers/cm3 in Phlox longifolia (longleaf phlox‐Polemoniaceae) (0.11 vs. 0.06). Crown volume of Crepis modocensis (7,085 vs. 4,179 cm3) and Astragalus malachus (2,854 vs. 1,761 cm3) plants was greater in burned plots than control plots. However, burning resulted in a smaller crown area of Antennaria dimorpha (low pussytoes‐Compositae) (20 vs. 37 cm2). Phenology and time of flowering were also affected by fire. The period of active growth for each species was extended later into the summer in burned plots ( p < 0.01). In addition, Crepis modocensis and Lomatium nevadense flowered 12 to 14 days earlier in burned plots. Fire had no effect on frequency, density, and relative abundance of seven of the nine studied species. Fire reduced the frequency and relative abundance of A. dimorpha and Phlox longifolia and reduced the density of A. dimorpha.

Long-term effects of wildfire on greater sage-grouse - integrating population and ecosystem concepts for management in the Great Basin

“…Connelly and others (2000a) described a significant decline in lek attendance following a prescribed fire that removed nearly 60 percent of existing sagebrush, while other studies have reported prescribed fire-related reductions in forage availability and quality (Nelle and others, 2000;Rhodes and others, 2010). However, low intensity prescribed fire followed by higher-than-normal annual precipitation has been associated with increased flowering and extended phenology of several forb taxa selected by sagegrouse and their chicks (Wrobleski and Kauffman, 2003). In addition, approximately 66 percent of sagegrouse leks tend to occur in sagebrush habitats with low to moderate R&R that are being subjected to larger and more persistent wildfire scars according to our models.…”

Effects of an accidental dry-season fire on the reproductive phenology of two Neotropical savanna shrubs

“…However, although after-fire plant mortality in savanna vegetation such as the Brazilian cerrado tends to be low (Hoffmann and Solbrig, 2003), fires may decrease plant biomass (Hoffmann and Solbrig, 2003) and reproductive output (Hoffmann, 1998) as well as alter plant population dynamics (Hoffmann, 1999). Fires may be spatially heterogeneous, resulting in a mosaic of burnt and unburnt patches within an area (Wrobleski and Kauffman, 2003;Werner, 2010;Dodonov et al, 2014). Spatial variation in fire incidence may lead to spatial variation in plant characteristics such as plant allometry (Dodonov et al, 2011), size structure and distribution of resprouts (Silva et al, 2009;Dodonov et al, 2014), seedbank (Xavier, 2011), and plant phenology (Lucena et al, 2015).…”

Greater sage-grouse science (2015–17)—Synthesis and potential management implications

“…Past studies have provided extensive information about postfire response and recovery of vegetation in the sagebrush ecosystem (for example, Nelle and others, 2000;Wrobleski and Kauffman, 2003;Beck and others, 2009) and documented the negative effects of increasing fire frequency on sagegrouse habitats, including loss of shrub cover and potential conversion to annual grasslands (Nelle and others, 2000). Sage-grouse population trends and lek persistence also can be negatively affected by wildfire (Connelly and others, 2000a;Blomberg and others, 2012;Hess and Beck 2012).…”