BIOMASS!

 WHAT IS IT?

Biomass is the term that refers to the total amount of living material in  certain area. Biomass is regarded as an important indicator of ecological and management processes in an ecosystem.

WHY TO MEASURE IT?

The university of Idaho established that some important reasons to measure biomass is because:

• Plants that dominate a site, in terms of biomass, are a reflection of the plants that are controlling the nutrient, water, and solar resources on the site.  Therefore, biomass is often measured to assess the ecological status of a site.

• Measures of standing crop also reflect the amount of energy stored in the vegetation, which can indicate the potential productivity at the site. Therefore, estimates of biomass are used in assessing rangeland condition.

• Estimates of biomass and residual biomass also strongly influence the hydrologic properties of the site including infiltration, runoff, and erosion.

HOW TO MEASURE IT?

The ideal way to measure biomass would be grouping all the organisms of certain population and take their weight. But since this feat is almost imposible, specially in large ecosystems, there are some methods to aproximate it:

Estadistically:

The transect method consists in selecting an imaginary line across the ecosystem, and counting the organisms that are in the area limited by this transect. That data can then be estimated using the proportion of the transect  to the rest of the ecosystem.

The quadrats metod uses a rectangular area and biomass is counted in that specific place.

These methods must consider that the selected area share almost the same conditions as the entire ecosystem in general; also, since they are estatisitics, as more times the measures are taken, most accurate will be the result of biomass.

Technologically:

Satelite monitoring is also used to measure biomass: Images generated are analyzed to determine total biomass productivity. but this method is only used with producers. An example of this technology is the MODIS Rapid Response System, developed to provide daily satellite images of the Earth's landmasses in near real time. It uses the MODIS Enhanced Vegetation Index (EVI) to shows the density of plant all over the entire globe. 

Also, in controlled ecosystems, there can be applied the Global Navigation Satellite Systems (GNSS), which is an animal tracking system which uses devices which send a signal to plot the position of an individuo of certain specie in their actual location.

ADVANTAGES AND DISADVANTAGES. 

So  to large ecosystems is better to use estatistic approaches because of their relative simpleness compared with the animal tracking system, but of course the second one will give an almost exact index of biomass of certain population. This method have also the disadventage that there can exist an organism missed and do not count in the actual register.

Some methods have the adventage of being used to both producers and consumers, such as the estatistical ones, but others are speciallized such as the satelite monitoring (focused on producers) or the animal tracking system (used mostly in consumers ).

BIOMASS IN THE ESTUARY:

After biomass is collected at different trophic levels, a biomass pyramid can be made. Here's an example of an estuary, more specifically, Chesapeake Bay. Taking the following food chain:

phytoplankton -> clams -> blue crabs -> sandbar sharks

Firstly, the units will be measured in kg per cubic kilometer, since it is a aquatic ecosystem. We can calculate the amount of each species in the food chain, and we get the following information:

There are 31,333,333 units of phytoplankton in 2320 cubic km of water in Chesapeake Bay.

There are 9,200,000 clams in that same area.

There are 278,666 blue crabs.

There is one sandbar shark.

Then, considering the weight of each specie and the area, we can calculate biomass, which then can be shown in what is known as a biomass pyramid.

Phytoplankton:78200000kg/2923km^3

Clams:7820000kg/2923km^3

Blue Crab:189100kg/2923km^3

Sandbar Shark: 59kg/2923km^3

"Why Biomass?." Principles of Vegetation Measurement and Assessment . University of Idaho, 2004. Web. 27 Aug 2010. <http://www.cnr.uidaho.edu/veg_measure/Modules/Lessons/Module%206/6_2_Why%20Measure%20Biomass.htm>.

"Measuring Biomass." Global Greenhouse Warming. N.p., n.d. Web. 27 Aug 2010. <http://www.global-greenhouse-warming.com/measuring-biomass.html>.