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Spatial and temporal variability of canopy cover and understory light in a Cerrado of Southern Brazil
- Source :
- Brazilian Journal of Biology, Vol 70, Iss 1, Pp 19-24, Brazilian Journal of Biology v.70 n.1 2010, Brazilian Journal of Biology, Instituto Internacional de Ecologia (IIE), instacron:IIE
- Publication Year :
- 2010
- Publisher :
- FapUNIFESP (SciELO), 2010.
-
Abstract
- Canopy cover has significant effects on the understory environment, including upon light availability for seedling growth. The aim of the present study was to verify spatial heterogeneity and seasonal changes in the canopy cover of a dense Cerrado area, and their relationship to understory photosynthetic active radiation availability. Leaf area index (LAI) values in the rainy season varied from 0.9 to 4.83, with 40% of the values ranging from 4.0 to 5.0, while in the dry season LAI varied from 0.74 to 3.3, with 53% of the values oscillating from 2.0 to 3.0. Understory light (Q(i)) and the Lambert-Beer ratio (Q(i)/Q(o)) were taken around noon on sunny days (between 11:00 AM and 1:00 PM). They were also statistically different (p0.01) between the dry and wet seasons, with 72% of sampled points in the rainy season presenting photosynthetic photon flux density (PPFD) values lower than 250 micromol x m(-2)/s around noon, whereas in the dry season, most PPFD values varied from 1500 to 1817 micromol x m(-2)/s, thus providing high light availability for understory plants. In most of the studied sites, understory plants did not even receive enough light for 50% of their photosynthetic capacity in the wet season. In contrast during the dry season, Q(i)/Q(o) values of 0.8 to 1.0 were observed in more than 50% of the points, thereby allowing for photosynthetic light saturation. Thus, light variability around noon was higher during the dry season than in the wet season, its heterogeneity being related to spatial complexity in the canopy cover.
- Subjects :
- Wet season
Canopy
Biology
Trees
seedling growth
lcsh:Botany
lcsh:Zoology
Dry season
Botany
lcsh:QL1-991
Leaf area index
lcsh:Science
lcsh:QH301-705.5
photosynthesis
leaf area index
Understory
Photosynthetic capacity
lcsh:QK1-989
Plant Leaves
tropical savanna
lcsh:Biology (General)
Agronomy
Seedlings
Photosynthetically active radiation
Sunlight
lcsh:Q
Spatial variability
Seasons
Lambert-Beer ratio
General Agricultural and Biological Sciences
Brazil
Subjects
Details
- ISSN :
- 15196984
- Volume :
- 70
- Database :
- OpenAIRE
- Journal :
- Brazilian Journal of Biology
- Accession number :
- edsair.doi.dedup.....405a40b04f283a8065818804f998b95f
- Full Text :
- https://doi.org/10.1590/s1519-69842010000100005