QUANTITATIVE PHENOLOGY AND LEAF SURVIVORSHIP OF RHODODENDRON MAXIMUM IN CONTRASTING IRRADIANCE ENVIRONMENTS OF THE SOUTHERN APPALACHIAN MOUNTAINS

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Abstract
Seasonal plant growth patterns were compared forRhododendron maximumL. in two contrasting subcanopy environments. The two subcanopy, above ground environments differed only in their quantity of irradiance by virtue of the relative dominance of evergreen or deciduous trees in the canopy. A third site had no canopy influence. Overall growth (shoot elongation, woody increment, leaf production) was maximized under the open (BMO) and deciduous dominated canopy (PCD). The leaf pool was significantly smaller under the evergreen dominated canopy (PCE) but average leaf area per leaf was slightly larger at PCE. Individual age‐specific leaf cohorts, identified from shoot morphology, indicated increased leaf survivorship with a decreased irradiance environment. Leaf production was synchronous and rapid (1 week), followed by three weeks of leaf expansion, which created the even‐aged leaf cohorts. Wood growth (diameter increment), in contrast, continued through the beginning of the winter. Reproductive effort increased with increasing irradiance environment. Significant variation in growth was observed between canopy shoot types at all three research sites. The significance of these phenological patterns is discussed in view of the variable subcanopy environment of southwestern Virginia.
Funding Information
  • VPI Arts (1895490)