Landscape-scale heterogeneity in lodgepole pine serotiny

Abstract

A 1992 study of serotiny in lodgepole pine (Pinuscontorta Dougl. ex Loud. var. latifolia Engelm.) in Yellowstone National Park asked four questions: (i) are there morphological characteristics that can be used to estimate pre-fire proportion of serotinous trees in forests that burned in 1988?; (ii) at what spatial scale does percent serotinous trees vary across the landscape?; (iii) which environmental factors are correlated with serotiny?; and (iv) what is the relationship between prefire serotiny and postfire lodgepole pine seedling density? We first sampled cone characteristics in serotinous and nonserotinous trees along four 2950-m transects in unburned forests, and examined burned trees nearby. Results indicated that asymmetrical cones and an acute angle of cone attachment to the branch were reliable indicators of serotiny even in burned trees. We then sampled nine patches of lodgepole pine forest that had burned in 1988, and varied in size from 1–3600 ha. We sampled serotiny at varying intervals along two perpendicular transects that crossed in the center of each patch. At each sample point, the 12 nearest canopy lodgepole pines were classified as serotinous or nonserotinous. We concluded that the percentage of serotinous trees is most variable at intermediate scales of 1–10 km, and is relatively homogeneous at both fine scales (<1 km) and at very broad scales (tens of kilometers). Percent serotiny was generally more variable and greater at low to middle elevations. Prefire density of serotinous trees was a more important predictor of postfire seedling density than aspect, slope, or soil type. These findings have important implications for landscape-level patterns in postfire regeneration of lodgepole pine.

Conflicting selection from fire and seed predation drives fine-scaled phenotypic variation in a widespread North American conifer

“…At the community and ecosystem levels, the degree of prefire serotiny affects postfire seedling density. Following widespread fires in the GYE, lodgepole pine sapling density varied over several orders of magnitude (0-500,000+ seedlings per ha), and this variation was most strongly explained by the prefire frequency of serotiny (9)(10)(11)13). Unsurprisingly, this extreme variation in sapling density had significant community-and ecosystem-level consequences as well (9,(11)(12)(13).…”

“…Following widespread fires in the GYE, lodgepole pine sapling density varied over several orders of magnitude (0-500,000+ seedlings per ha), and this variation was most strongly explained by the prefire frequency of serotiny (9)(10)(11)13). Unsurprisingly, this extreme variation in sapling density had significant community-and ecosystem-level consequences as well (9,(11)(12)(13). Sparse recovery may allow for the colonization of other ecosystem types that would otherwise be outcompeted, increasing landscape heterogeneity (12) processes (10), and postfire annual net primary productivity and total leaf area are strongly associated with lodgepole pine sapling density (13).…”

Cone production in young post-fire Pinus contorta stands in Greater Yellowstone (USA)

“…Variability in lodgepole pine cone serotiny among stands is striking, and many studies have examined its relationship to fire (e.g., Clements, 1910;Critchfield, 1957;Lotan, 1970Lotan, , 1975Pfister and Daubenmire, 1975;Muir and Lotan, 1985a,b;Koch, 1987;Tinker et al, 1994;Schoennagel et al, 2003). In the Intermountain and Rocky Mountain regions, the percentage of trees bearing serotinous cones increases with latitude (Koch, 1987).…”

Spatial Heterogeneity and Soil Nitrogen Dynamics in a Burned Black Spruce Forest Stand: Distinct Controls at Different Scales

“…Denitrification rates vary in response to changes in interstitial soil water content (Christensen et al 1990), and nutrient levels may reflect the spacing of individual plants (Schlesinger et al 1990;Jackson and Caldwell 1993) or the distribution of vegetation types across landscapes (Fan et al 1998;Ludwig et al 2000;Beedlow et al 2004). After disturbance, patterns of forest productivity and soil nutrient availability may vary spatially at fine and coarse scales (Tinker et al 1994;Turner et al 1997;Fraterrigo et al in press).…”