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Phenology, developmental patterns and growth cycles for multiple seed crops in Pinus elliottii

Pines are known to produce one seed crop each year and mature about 20 months after pollination. The entire life cycle may take two to three years. Recent observations, however, show that a greater number of crops may develop annually and that cone development may be faster. In Pinellas County, Florida, Pinus clausa and P. elliottii now have three seed crops annually, and consequently, more seeds during the year. Also, there is no dormant phase from pollination time to seed maturity in the primary (most abundant) crop of these species. The reason for this change in reproductive strategy is thought to be as a response to climatic changes, in particular, CO₂ levels. Pines seem to be reacting to increases of available atmospheric CO₂ that fluctuate seasonally. The gas may act as a biochemical switch for developmental stages and be a mechanism for controlling cone growth. Furthermore, there are definite phenological shifts forward in the primary seed crops of P. clausa (about 105 days) and P. elliottii (about 150 days) that present more opportunity for their hybridization. Pines are known to show sensitivity to their environment, and therefore, are climatic indicators of changes that are probably occurring in other economically valuable plants.

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Fish also help in seed dispersal in forests

London, Feb 6, 2008 A new research has revealed that fish have a remarkable role in distributing the seeds of tropical plants.

The research was carried out in Brazil’s Pantanal, the largest freshwater wetlands in the world, by a team from the Sao Paulo State University.

According to a report in Nature News, in the usual methods of animal seed dispersal, primates, rodents and birds either eat fruit and ingest seeds contained inside or get seeds from the plant stuck to their bodies. Later, the seeds are either defecated intact, or fall off.

But in recent years, ecologists have found seeds in the digestive tracts of more than a hundred fish species as well.

In the Pantanal, plants including palms and legumes tend to release their fruits during a time of year when massive flooding is common, and waters encroach over thousands of square kilometres.

The fruits fall from the trees into water and the pacu, one of the most common fish in the Pantanal, migrate deep inland during such floods and munch on the fruit.

Mauro Galetti, at Sao Paulo State University in Brazil, and his team looked to see whether these fish were carrying intact seeds, which they could defecate in areas that dry out when the floodwaters recede.

The team explored the guts of 70 fish collected at Fazenda Rio Negro, an ecologically diverse area of the Pantanal that teems with wildlife.

What they found was that there was a positive correlation between fish size and the number of intact seeds in the stomach. In fact, more than 141 seeds from the tucum palm were found in the largest individuals.

From the data collected, it seems that the tucum palm relies almost entirely on pacu services for seed dispersal, said Galetti. It is amazing that for some plant species, pacu appear to be the main dispersers, he added.

This is the first report that I know of suggesting links between aquatic and terrestrial ecosystems where fishing may be impacting tropical forests, sad ichthyologist Bill Pine at the University of Florida in Gainsville.

TheTriggering System Connected to Movements

By Brooks Salzwedel

By Edward Burtynsky, Australia