PLS 147 Lecture Notes - Lecture 16: Pinus Ponderosa, Sequoia Sempervirens, Longhorn Beetle
Plant communities on harsh soils
Closed-cone forests, serpentine outcrops & pygmy forests
Sierra redwoods
●groves embedded in lower montane forests
○low lying places
○moist swales or near streams
●fire needed for establishment
○serotiny: dryness opens cones
■from heat or shoot death from douglas squirrel and longhorn beetle
larva
■dispersal
○prepares mineral soil seed bed
■free of competition
●ponderosa pine, sugar pine, incense cedar, and white fir???
●sub dominants
○…
●herb layer
Coast redwood:
●tallest tree
●fire resistant
●requires fog
●douglas fir/western hemlock
Sierra redwood:
●largest tree
●requires fire
●needs groundwater
●lower montane mixed-conifer
both are ancient relics
many of these conditions are associated with invasion resistance
Closed cone forests/stands (grove of trees, or isolated smaller patches, a few acres)
●Often relatively coastal
○isolated stands
●low nutrient/stressed soils
○slow growth
●dominated by single species of tree, single-aged
○so characterized by stand replacing fire bc regenerate at the same time
●low interval fire
○predictable, infrequent (>100 years)
○ignition limited
●dense, w/ ladder fuels
○designed to burn up
Document Summary
From heat or shoot death from douglas squirrel and longhorn beetle. Lower montane mixed-conifer both are ancient relics many of these conditions are associated with invasion resistance. Closed cone forests/stands (grove of trees, or isolated smaller patches, a few acres) Dominated by single species of tree, single-aged. So characterized by stand replacing fire bc regenerate at the same time. Delayed seed release occurring in response to an environmental trigger. Cones are closed until triggered (fire or death) and may stay on the trees for many years. Pinaceae : heat (fire) opens cones, resin melts. Eg coulter pine, big-cone pine (pinus coulteri) Monterey pine (pinus radiata), bishop pine (pinus muricata), asymmetrical, Fire is only one source of stem death (herbivory) Sierra redwoods/sequoias, sargent cypress (cupressus sargentii), gowen cypress (hesperocyparis goveniana, mcnabb cypress (c. macnabiana) wait for fire bc fire gets rid of competition (light, space)
