Project Amazonia: Monitoring - Flora

Above Ground Biomass Density and Complexity

Analyzing above ground biomass density and complexity in this fashion is an important tool in studying animal and plant habitat associations. We will quantify the density and complexity of above ground flora of old growth forest and of selectively logged forest, fragmented, and regrown forest. Then we will randomly select various study points (forests previously mentioned) and we will take photographs in the north, south, east and west directions from the points selected. The photographs will be displayed such that only the borders and interiors of vegetation become significant

 We will use the following parameters and then calculate correlations between those parameters:

Epiphytes

Epiphytes and orchids are well suited to be indicators of the health and biodiversity of the rainforest, not only because they are an important source of nutrients for other flora and fauna, but because they are very sensitive to shifts in microclimate and they have slow growth. The performance, survival, and distribution of epiphytes is dependent on stand density, microclimate, distance from seed source, tree size and species, type and history of disturbance, population dynamics of epiphytes and trees, and epiphyte physiology ¹(Hietz 1999).

Epiphytes are far more vulnerable to deforestation than other flora. For example, 26% of vascular plant species present in 1900 are now extinct, but 62% of epiphyte species are extinct. Epiphytes are completely dependent on their host plants, so if a tree is cut down, all of the epiphytes residing on that tree will die. In addition, they have very specific zoning constraints, so secondary vegetation might not have all of the necessary micro sites for different epiphyte species.

In addition to complete deforestation, epiphytes are hurt by fragmentation. Their wellbeing depends on the distance from their fragment to closed forest, and the shape of the fragment (this affect seed dispersal).
They are also affected more adversely by increased CO2 levels in the atmosphere. Raised CO2 levels shift climate zones, forcing flora and fauna to migrate. Although epiphytes could migrate more easily than trees, many models of the effect of fluctuating CO2 levels predict increased seasonality of precipitation, and thus a reduction of the per humid area containing the highest epiphyte diversity (Hietz 1999).

Specific species or groups have been identified as good bioindicators:

As we mentioned before we will state the health of these indicator species by looking at their metabolism processes, more specifically at the levels of polyamines². Because polyamines are synthesized by amino acid decarboxylation reactions, where H+ is consumed, polyamine accumulation may function as a way for plants to keep their pH at a constant value. Polyamines also serve as precursors of various alkaloids that play important roles in plants defense. Adequate levels of polyamines are necessary for optimal growth and replication of plants, bacteria and fungi. Their levels of concentration increase greatly when the environment suffer changes; especially when there is potassium deficiency. In order to measure the levels of polyamines we will measure level of ODC (Ornithine decarboxylase) and ADC (Arginine decarboxylase), which are the enzymes that synthesized polyamines. The process to measure these levels is not complicated, nor expensive.

Litterfall

Litterfall, the plant matter that falls to the forest floor, plays an important role in the nutrient cycling of rainforest plants.  Plants recycle the nutrients in the litterfall by reabsorbing them through their roots.  A sharp decrease in the amount of litterfall is indicative of deforestation, and any major changes in the nutrient richness of the litterfall in an area can act as a sign that the area is in trouble.

Litterfall is measured both for its biomass and for its chemical composition, and is collected in either conical traps or long troughs.  Neither the conical traps nor the long troughs are very large (80 – 100 cm in diameter for the cones), and many of them will be spread throughout the area marked for observation.  Both traps are constructed of mesh to prevent the accumulation of water.

During the rainy season, litterfall accumulates more rapidly and needs to be measured at least once a week.  During the dry season, measurements can be lessened to once a month.  In collecting samples,  only the portions of plant matter that are within the trap should be included – for example,  long twigs should be cut, so that only the portion of twig that was over the trap is collected.

Once the sample has been collected, it has to be seperated into leaves, reproductive parts, fine woody material, and residue, discarding any animal material or scarce adhering mineral material.  Then  the samples are dried and weighted - adding them to obtain the biomass – and stored for chemical analysis.

Chemical Analysis

There are three main kinds of tests run on the litterfall samples once they have been dried and their biomass measures.  The first of these, plasma emission spectrometry is the most widely used and can account for the presence of most elements and ions that require study.  It cannot, however, account for all of them, which is why Redox potentiometry and ion liquid chromatography are also employed.

Plasma emission spectrometry is used to detect concentrations of Si, Al, Ti, Fe, Mn, Ca, Mg, Na, K, P, Ba, Sr, Ge, and Y.   Generally, the sample is exposed to a high energy source, exciting the electrons of the various atoms to specified higher energy levels.  Once the electrons fall back into their ground states, they emit specific wavelengths of radiation.  Determination of emitted wavelengths demonstrates what elements are present in the sample.  Further comparison of the intensities of the emitted wavelengths with given standards allows determination of the concentrations of different atoms.

Redox Potentiometry is used to determine the presence of NH⁴⁺ By forming a reaction with oxalacetate and malate,  the concentrations of NH⁴⁺ can be determined- setting up the half equations and determining the number of electrons consumed.

Ion liquid chromatography is used to determine the presence of Cl^- and SO₄^2-The chromatography is the separating of the mixtures into their respective elements or ions.  This separation occurs because the components of the mixture have different partition ratios between their mobile and solid phases, and have different rates of travel through the solid phase.  All forms of liquid chromatography use liquids for the mobile phase (as opposed to using a gas, which cannot separate all the elements).

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