FRST 200 Lecture Notes - Lecture 24: Shade Tolerance, Ecophysiology, Experiment
Document Summary
Experimental science that seeks to describe the physiological basis that underlies ecological observations. Availability of light and differences in shade tolerance. Photosynthetic capacity peaks when leaves reach full size, then declines towards senescence (may take several years for evergreen leaves) Evergreen leaves have a higher cause of formation than deciduous leaves to last longer. Lower n content which lowers photosynthetic capacity; inversely related to leaf longevity. **photosynthesis may continue all winter on the coast in evergreen trees (also green bark) In interior, stops after a few frosts; chlorophyll concentration often lower. Recovers after a few warm days in spring (long before bud breaks) From cold storage, photosynthesis in seedlings recovers within a few days; can reach compensation within a few hours. Long days & high solar angle and high soil moisture content combined with low soil temperatures make spring great for net photosynthesis. Especially so for evergreens because they"re there ready to go & spring ephemerals.
