Seasonal and Spatial Variation in Leaf Area Index, Litter Production, and Light Levels in Myrica Cerifera,Shrub Thickets Across a Barrier Island Chronsequence

Leaf area index (LAI), litter production and understory light levels of Myrica cergera shrub thickets were assessed on Hog Island, Virginia to quantify spatial and seasonal variations in leaf area and light attenuation among four thickets representing a successional chronosequence and compare methods of estimating LA1 in shrub- dominated systems. Seasonal LA1 estimates were made seven times throughout the year with a portable integrating radiometer (Li-Cor LAI-2000) and three times by measurement of photosynthetically active radiation (PAR) and use of the Beer-Larnbert law. Leaf area index was also estimated through leaf litter collection and use of allometric relationships between stem diameter and leaf area. The oldest of the four thickets had the lowest LA1 and litter production throughout the year. Peak LA1 measurements with the portable integrating radiometer ranged from 2.0 ± 0.2 to 4.0 ± 0.3 for the oldest and youngest thickets, respectively which appear to be substantial underestimates of the actual values. According to annual litterfall, LA1 ranged from 4.1 ± 0.5 for the oldest thicket to 10.2 ± 0.4 for a 20 year old thicket. Leaf area index varied from 6.4 ± 0.2 for the oldest thicket to 1 1.4 ± 2.1 for the 40 year old thicket according to the allometric relationships, which may overestimate LA1 in stands with many large stems. The high light attenuation by the shrub canopy and heavy litterfall may contribute to the low diversity within thicket canopies by inhibiting germination and growth of other species. The study demonstrates that these low diversity shrub thickets have a higher LA1 and litter production, and thus higher potential for primary productivity, than many temperate forested systems and that stand age may be the major determinant of productivity.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Biology

Year dc:date.available

2005

Author dc:creator

• Brantley, Steven T.

Contributors dc:contributor

• Dr. Donald R. Young

• seasonal variation
• Hog Island
• Beer-Larnbert
• allometric
• LAI
• radiometer
• Biology
• Life Sciences

Statement dc:rights

• © The Author

Identifier

https://scholarscompass.vcu.edu/etd/1507

OAI identifier oai:identifier

oai:scholarscompass.vcu.edu:etd-2506