Navigation Links
Seeing the forest through the trees and seeing the trees through the leaves
Date:1/13/2010

Since the time of the earliest humans, people have attempted to understand the natural environment. We have observed our surroundings and searched for explanations for natural phenomena. Yet despite our persistence over thousands of years, many basic questions remain to be answered. Although we understand core processes such as photosynthesis, we do not have a full understanding of issues such as how plants maximize their photosynthetic capacity.

Specific leaf area, or SLA, plays a prominent role in ecological theories that attempt to provide explanations for plant and ecosystem function. SLA, a measurement of the total leaf area to dry mass, has been found to correlate with the potential for light-resource use, the relative growth rate of a plant, and differences in essential nutrient demand and habitat preference.

Scientists also have observed that the SLA of individual leaves varies within a single plant, and this measurement often correlates with leaf maturation and position within the canopy. More recently, scientists have discovered that, as a tree increases in size, its total canopy SLA decreasesthat is to say, its total leaf surface area fails to keep pace with increases in total leaf mass.

What causes this decrease in SLA as tree size increases has remained a mystery, but recent research by Cornell University scientists Karl Niklas and Edward Cobb published in the January issue of the American Journal of Botany (http://www.amjbot.org/cgi/content/full/97/1/27) provides an explanation for this decrease in SLA with an increase in tree size.

"The traditional explanation for the size-dependent decrease in SLA was never very satisfying," Niklas said. "We wanted to look at this phenomena in greater details with more care, and we found a totally different answer to a classic ecological question."

The commonly accepted hypothesis has been that decreasing SLA in trees of increasing size is a result of leaf-by-leaf acclimation to the local environment. Physical factors such as differences in light intensity are affected by differences in leaf position within the canopy, providing different local environments. Niklas and Cobb hypothesized that changes in SLA may be a result of changes in the relative numbers of different shoot types that produce leaves differing in SLAsa developmental shift that occurs as a tree increases in size.

Niklas and Cobb examined 15 red maple trees that differed in trunk size and found that the changes in SLA can be attributed to shoot type rather than to the location of the leaves within the canopy. As the trunk diameter increased, the number of short-shoots increased rapidly relative to the number of long-shoots. Detailed analyses of the largest tree demonstrated that short shoots, on average, produce leaves with smaller specific leaf areas than those produced by long shoots. Consequently, developmental shifts occurring at the shoot and whole plant level account for size-dependent decreases in total canopy SLA, rather than leaf-by-leaf acclimation to the local environment.

Mathematical models for the distribution of light within the canopy predict that the photosynthetic rate of the entire canopy is maximized when the specific leaf area is lowest for leaves at the top of the canopy. This research provides new insight into the mechanism by which trees have evolved to obtain light and photosynthesize at the greatest rate.

"Our research shows that plants are highly integrated organisms that respond to their environments in ways that are every bit as complex as even the most sophisticated animals," Niklas said. "This research also shows that we still have plenty to learn about phenomena that we thought we understood very well."


'/>"/>

Contact: Richard Hund
rhund@botany.org
314-577-9557
American Journal of Botany
Source:Eurekalert

Related biology news :

1. Seeing Alzheimers amyloids
2. Crystal (eye) ball: Study says visual system equipped with future seeing powers
3. Seeing through the skin
4. Seeing stem cells helps in fight against peripheral arterial disease
5. Seeing the tree from the forest: Predicting the future of plant communities
6. Seeing previously invisible molecules for the first time
7. Seeing is relieving
8. Seeing without looking
9. Seeing how evolutionary mechanisms yield biological diversity
10. Seeing family for the holidays? Scientists discover how the stress might kill you
11. Tropical insects go the distance to inform rainforest conservation
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:6/21/2016)... Columbia , June 21, 2016 ... to the new role of principal product architect ... named the director of customer development. Both will ... chief technical officer. The moves reflect NuData,s strategic ... in response to high customer demand and customer ...
(Date:6/15/2016)... , June 15, 2016 ... market report titled "Gesture Recognition Market by Application Market - Global ... 2016 - 2024". According to the report, the  global ... billion in 2015 and is estimated to grow ... 48.56 billion by 2024.  Increasing application ...
(Date:6/7/2016)... , June 7, 2016  Syngrafii Inc. ... a business relationship that includes integrating Syngrafii,s patented ... branch project. This collaboration will result in greater ... the credit union, while maintaining existing document workflow ... http://photos.prnewswire.com/prnh/20160606/375871LOGO ...
Breaking Biology News(10 mins):
(Date:6/23/2016)... , June 23, 2016 Apellis ... Phase 1 clinical trials of its complement C3 ... single and multiple ascending dose studies designed to ... (PD) of subcutaneous injection in healthy adult volunteers. ... (SC) either as a single dose (ranging from ...
(Date:6/23/2016)... -- Andrew D Zelenetz , ... Published recently in Oncology & ... Andrew D Zelenetz , discusses the fact ... placing an increasing burden on healthcare systems worldwide, ... the patents on many biologics expiring, interest in ...
(Date:6/23/2016)... , ... June 23, 2016 , ... ... exhibiting at the Pennsylvania Convention Center and will showcase its product’s latest features ... will also be presenting a scientific poster on Disrupting Clinical Trials in The ...
(Date:6/23/2016)... ... June 23, 2016 , ... Velocity Products, ... tools designed, tuned and optimized exclusively for Okuma CNC machining centers at The ... of a collaboration among several companies with expertise in toolholding, cutting tools, machining ...
Breaking Biology Technology: