Canopy development

The photo synthetic aquatic biomass comprises cyanobacteria (formerly called blue-green algae), planktonic, filamentous and macrophytic algae, and vascular macrophytes. The net productivity of the floodwater depends on the level of primary production by the photosynthetic biomass versus its consumption by grazing animals, particularly cladocerans, copepods, ostracods, insect larvae and molluscs. Their role will change as the canopy develops and at a leaf area index of about 6-7 there will be no more photosynthetically active radiation available to them. 

We have already mentioned that rapid canopy development Is an Important competitive advantage and minimizes the time during which young leaves are vulnerable to herbivores. 

Proteln-conq>lexlng polyphenols are broadly effective against herbivores, especially those not specifically adapted to eat plants containing polyphenols (47). They may constitute 10% or more of the leaf dry weight (12, 37, 44), and this requires allocation of significant amounts of carbon and energy to their construction. The use of limited reserves for such quantitative defenses must be balanced against the requirements of rapid canopy development and new shoot extension. 

To summarize, specific toxins are effective deterrents to generalist herbivores, but polyphenols produced In relatively large quantities are the only effective deterrent to specialists. Since leaf toughness and lower nitrogen content also deter many herbivores, deciduous forest trees are especially vulnerable to attack during the period of canopy development, which occurs yearly at a predictable time. Gsnopy development Is heavily dependent on available reserves of carbohydrate and nitrogen, and the production of quantitative... 

Stem number is partly determined by the size of the seed tuber (Barloy, 1988 Louis, 1985) and is closely related to the early canopy development and leaf area index (Baillarge, 1942 Cors and Falisse, 1980). Branching type is genetically controlled, although the number of branches is largely regulated by plant density. 

Gimenez C., Connor, D.J., and Rueda, F., Canopy development, photosynthesis and radiation-use efficiency in sunflower in response to nitrogen, Field Crop Res., 38, 15-27, 1994. 

Aggrading forests contribute to surface-water acidification in a number of ways. Water discharge decreases because of enhanced evapotran-spiration, causing evaporative concentration of pollutants. Hydrological pathways become modified (Waters and Jenkins, 1992), and coniferous afforestation commonly raises DOC. Dry deposition of acidifying pollutants to a forest canopy increases as the canopy develops. Total deposition of sulfur and other pollutants in throughfall in forests is typically several times higher than bulk deposition outside the forest (Beier et al., 1993 Hansen et al., 1994 Rustad et al., 1994). Episodic acidification caused by marine aerosols... 

Carlxdiydrale transport Water trail s[KM t Full canopy development Carlxdiydrate accumulation Litter production Growth slows down Leaf and fine root shedding... 

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