The influence of canopy, sky condition, and solar angle on light quality in a longleaf pine woodland
| Autor: | Stephen D. Pecot, Michael Battaglia, Stephen B. Horsley, Robert J. Mitchell |
|---|---|
| Rok vydání: | 2005 |
| Předmět: | |
| Zdroj: | Canadian Journal of Forest Research. 35:1356-1366 |
| ISSN: | 1208-6037 0045-5067 |
| DOI: | 10.1139/x05-069 |
| Popis: | Light transmittance estimates under open, heterogeneous woodland canopies such as those of longleaf pine (Pinus palustris Mill.) forests report high spatial and temporal variation in the quantity of the light environment. In addition, light quality, that is, the ratio of red to far-red light (R:FR), regulates important aspects of plant development including stem extension, specific leaf area, and seed germination. We conducted two experiments to document sources of variation in R:FR (using a LI-COR 1800 portable spectroradiometer with a cosine-corrected light sensor) in a 70- to 90-year-old natural longleaf pine woodland in southwest Georgia, USA. The first experiment compared instantaneous measurements of R:FR over a 3-day period (March) with annual estimates of canopy transmittance (using gallium arsenide phosphide photodiodes) across the range of observed overstory abundance. The second experiment examined the effect of wiregrass cover (above or below), sky condition (blue sky or overcast), and solar angle (four sampling periods between October and March) on R:FR using a multifactorial repeated measures design. We found that (1) R:FR was significantly (p 2 = 0.72) related to annual estimates of canopy transmittance (percent photosynthetic photon flux density, %PPFD); (2) R:FR and %PPFD showed significant negative relationships with increasing overstory stocking (R2 = 0.20, p = 0.028 for R:FR, and R2 = 0.87, p |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|