Contrasting modes of survival by jack and pitch pine at a common range limit

Abstract

Freezing tolerance, reproductive development, and seed germination of jack pine (Pinus banksiana Lamb.) and pitch pine (Pinus rigida Mill.) were compared in a small sympatric population in Acadia National Park in Maine, at the southern range limit of the former and the northern limit of the latter. Freezing tolerances of vegetative shoots and roots were similar for both species. Both species flower prolifically, and there was no evidence of differences in either pollen viability, cone survival, or proportion of viable seed (65–70% of the total). Regeneration success (established seedlings ranging from 1 to 13 years old) was similar overall for both species, but success by species varied greatly in some years. Jack pine regeneration was significantly associated with thinner soils, while pitch pine regeneration was associated with thicker soils in hollows. Jack pine seed germinated significantly faster than pitch pine seed, especially when day–night temperature was reduced. Pitch pine seedlings always exhibited a significantly higher shoot/root ratio than those of jack pine. The most northerly provenances of jack pine germinated significantly faster than those from the most southerly provenances. Jack pine also germinated at a significantly higher percentage than pitch pine in exposed granite sand. Thus relatively cool, dry conditions may favor establishment of jack pine seedlings, while pitch pine establishment may be favored in warmer, wetter conditions.

Importance of colonization and competition in forest landscape response to global climatic change

“…There are many possible drivers including seed production (Greenwood et al 2002;LaDeau and Clark 2001); seed dispersal (Higgins et al 2003); seedling establishment ); competition for nutrients; water and light (Gleeson and Tilman 1990); forest diebacks (Auclair 1993;Cox et al 2004); herbivores (Howlett and Davidson 2003); pathogens and parasites (Moorcroft et al 2006); and genetic adaptation (Bradshaw and Holzapfel 2006). In our study, response of species' colonization ability to climatic change was governed by the modification of seedling establishment probability.…”

Influence of seedbed, light environment, and elevated night temperature on growth and carbon allocation in pitch pine (Pinus rigida) and jack pine (Pinus banksiana) seedlings

“…In these populations, Conkey et al (1995) found that mature trees of both species showed good growth and no signs of speciesspecific stress. We have shown that neither freezetolerance nor reproductive efforts are limiting for either species where their populations overlap at ANP (Greenwood et al, 2002). However, the two species differ in their seed germination trajectories with respect to temperature, with jack pine germinating faster at relatively lower temperatures.…”

“…However, the two species differ in their seed germination trajectories with respect to temperature, with jack pine germinating faster at relatively lower temperatures. This may provide an early growth advantage to jack pine when soil temperatures are low (Greenwood et al, 2002).…”

“…Within these energy environments we identified two common surface substrates: a fine organic duff that resembles ground peatmoss and a moderately course granitic sand. Transect counts of regenerating seedlings indicated the presence of regeneration pulses that were asynchronous between these species (Greenwood et al, 2002). However, low numbers of seedlings surviving from any particular cohort precluded explicit analysis of interspecific differences in seedbed preference.…”

Forest Disturbance History from ‘Legacy’ Pitch Pine (Pinus rigida) at the New River Gorge, West Virginia

“…Pitch pine was selected as the prime recorder of forest history, given its site age and the fact that much of dendroecological record in this region has either been logged or consumed by fire. Additionally, pitch pine is generally shade-intolerant and establishment is best on bare mineral soil (Greenwood et al 2002), such that its presence within the contemporary mesophytic forest is an indicator, or legacy, of past disturbance. Specifically, my objectives were to (1) develop the first large sample tree-ring record that pre-dates industrialization in the New River Gorge region; (2) reconstruct the fire and canopy disturbance history of a mixed pine-oak community embedded within the mesophytic forest region; and (3) test the relationship between climate and disturbance in the context of land use change and industrialization.…”