I would like to study herbaceous vegetation, especially, Among the grass species composing this vegetation, Know which one is the most abundant, I heard about Braun-Blanquet J.,(1932) methods. and I would like to know how to apply it to find dominance-abundance of the area studied.
thank you!
If you have the availability of a good camera, I think there software that after taking a picture of a set of vegetation you can estimate how much percentage occupied by each species; but you have to give the scale for the data area. Unfortunately I dont know any software. Just look for.
Know another way but it takes longer.
Simply take a picture knowing the actual area of land shown on the photo or at least have a known area on the same scale; then manually pints those species of interest and cut the paper separating them by color. Parallel you cut an area that you know and weights; then together those fragments of the same color and weight. By rule of thumb you know how much area occupies.
Pe. 4 m2 (known area) weigh 5g and Xm2 weigh 10 g (pieces of the same color).
For the classical Braun-Blanquet visual estimates you may have a look at my papers halfway between today and your citation, that is in the 70s. A more recent approach with segmentation of the research area based on satellite image classification, subsequent random site selection followed by point-line-intercept ground measurement is described in my 2006 article from south Africa (sorry attach functionality is dysfunctional again since new lay out of RG). A basic reference to such methods is included as well.
To characterise the vegetation the method of phytosociological relevés is usually employed. The species abundance is estimated by clasical Braun-Blanquet (1964) method, which means that total coverage for each species is estimated visually and recorded using cover-abundance scale within seven cover classes r: 1 or 5 individuals; +: few individuals (
I think the Braun-Blanquet method is good if you want both a global overview of the abundance / dominance patterns and an exhaustive list of the plants in your plot.
If you intend to do some calculations, the point intercept technique recommended by Hein van Gils is better, the only drawback is that you'll need a lot of points to reach (sub)-exhaustivity.
An intermediate option would be to divide your plot into a number of subplots, let's say 9, and record the number of subplots in which each species is present. In my opinion it's a good compromise between accuracy, exhaustivity and time spent in the field.
Right, the classic Braun-Blanquet (1964) method is just for general overview of abundance of particular species in a plot.
To establish the abundance of flowering, the density of stems per unit area can be calculated by counting stems in randomly selected areas. I use circular with a diameter of 36.7 cm (= 0.1·m-2). In the case of the high-stem species (Tanacetum vulgare, Artemisia vulgaris, Solidago gigantea and S. canadensis), I count all stems in an area of 1·m-2 defined plots.
Usually, the method depends on the study point
Best regards
The method of outhred (1984) is good for vegetation that all occurs within the same strata, it gets messy comparing life firms in different strata. You create annuli within a plot. I have used 32x32 m outer annuli which equate to 0.1 ha with 9 annuli within.each annuli is logarithmically smaller in area. This is a quick way to obtain a frequency score that is statistically shown to represent proper abundance. Described in one of my papers on my profile .... Hunter & Clarke (1998).
For a published case of Olivier's answer see attached.
The Br-Bl. cover-abundance is a scale for measurement once you have located a sample plot/site. For any stats the location of the plot needs to be unbiased (random or systematic, in short). The selection of the sample sites is the Achilles heel of the Br-Bl. or phytosociological approach.
Article Nitrogen and phosphorus limited production of cereals and se...
- Badges
- Science topic
- Similar topics
- Computer Communications (Networks)
- Simulators