Week 5 - 24 Sep. 2013 Forest productivity

Homework due next week: Research paper outlines.

Altitude mimics latitude.  The farther you go from the equator, the colder it is.  The higher up you go on a mountain, the colder it is.  This is why we can find boreal forests and tundra on the tops of mountains that are located in the temperate zone.

Productivity – Creation of new organic matter.

Primary producers – Use sunlight to create their own organic matter from water, CO2, and nutrients, through the process called photosynthesis.

6CO2 + 6H2O + energy = C6H12O6 + 6O2

Primary production – the synthesis and storage of organic molecules during growth and reproduction of photosynthetic organisms.  This produces new chemical compounds and tissues.  Result – new biomass = amount of CO2 that is ‘fixed’

How to measure productivity?  Measure the mass (amount) of biological matter –

weight – weigh the fish, etc,

count – number of trees, etc.

size – diameter at breast height of trees

Secondary producers cannot make their own organic matter.  They must consume it. = organisms that consume the primary producers (cattle etc.)

Secondary production – creation of biomass in the consumers – such as an animal growing.

 

What does this mean for forests?  And for forests in Haiti?

Tropical forests – high productivity, double that of temperate forests.  (So then you might think soils are very fertile, but they are not!) 

Why are tropical forests twice as productive as temperate forests?

Geography and climate.

Remember – a biome is an environmental region define by plant community – as influence by geography & climate!

Let’s look at how geography influences productivity.

Maximum intensity of sun’s radiation is at the equator, and decreases as we move toward poles.

Therefore, the equator receives:

More sunlight

Constant sunlight throughout the year

Warm temperatures

Much rain

Which means photosynthesis can occur year round!

In drier and colder biomes, productivity is lower.

If you want to learn more, see

http://www.globalchange.umich.edu/globalchange1/current/lectures/kling/energyflow/energyflow.html

Paper outlines are due Oct. 1!

The forest chapter from A Community Guide to Environmental Health was provided to students as a reference source. 

Buy it here: http://store.hesperian.org/HB/prod/B160.html

Or download it here: http://hesperian.org/books-and-resources