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Vegetation measures (植生測度)

Mount Usu / Sarobetsu post-mined peatland
From left: Crater basin in 1986 and 2006. Cottongrass / Daylily


[ abudnance | dominance ]


The total number of individuals or amount of resources present in a specific area. Typically, used qualitative, relative, or subjective manner rather than an absolute number or amount.


For convenient use

The species is

  • A: abundant
  • C: common
  • F: frequent
  • O: occasional
  • R: rare

in the given area (or ecosystem)

Cover or coverage (被度)

The area of ground covered by plants. Usually we use the marginal projection of the aboveground parts of plants, shown below.

cover estimation frame

A: An example of frame for establishing quadrat (方形区) for the measurement of cover. ← field equipment (野外調査道具)
B: Cover is not for the absolute cover. We estiamte the projection of the plants, as indicated by interrupted lines.
Cover-abundance scale, or dominance scale

Table 2.1. A comparison of cover scales used to recording vegetation plots including the traditional Braun-Blanquet scale (1928), the original Domin scale (1928), a variant of the Domin scale by Krajina (1933), and the scales of the Carolina (Peet et al. 1998) and New Zealand vegetation surveys (Allen 1992). The brown letters indicate how the newer indices nest into the Braun-Blanquet scheme. (Modified after van der Maarel & Franklin 2013)

Range of coverBraun-BlanquetDominKrajinaCarolinaNew Zealand
Single individualr, solitary with small cover++11
Sporadic or few+, Few, with small cover (pronounced 'cross')1111
0-1%1, numerous, but less than 1/20 cover, or scattered, with cover up to 1/202121
5-10%2, any number, with 1/20-1/4 cover (5-25%)4453
25-33%3, any number, with 1/4-1/2 cover (25-50%)6674
50-75%4, any number, with 1/2-3/4 cover (50-75%)8885
75-90%5, any number, with cover more than 3/4 of the reference area (> 75%)9996
Daubenmire's cover classes

Class (%): 1 (0-5), 2 (5-25), 3 (25-50), 4 (50-75), and 5 (75-100)
(Daubenmire 1959)

Biomass (バイオマス)

The mass of living organisms in a given area (or ecosystem) at a given time. We often use dry mass for plant ecology. See also biome and productivity.
Phytomass (ファイトマス)
= plant biomass (biomass of the plants only)
Necromass (ネクロマス)
(s.s.) organic material consisting of or derived from dead organisms
(s.l.) the total mass of dead organisms (of a given type, in a given area, etc.)

The measurements of biomass (バイオマス測定法)

Destructive method: harvest

AG = aboveground, BG = belowground (root)
bm = live biomass, dm = dead mass, tm = total mass = bm + dm

nd = new dead mass, assumued to be stanidng dead mass
od = old dead mass, assumued to be litter
dm = nd + od

rd = relative rate of decomposition

Semi-destructive method ☛ allometry (アロメトリー)
Harvest (刈取)
Table. NPP estimation procedures (Scurolck et al. 2002).
Method. Calculation. Assumptions
1.    Peak live biomass = max(AGbm)

any dead mass is carried over from previous year
death in current year is neglibible
belowground production is ignored or estimated

2.    Peak standing crop (live plus dead matter)

= max(AGbm + AGdm)
= max(AGbm + AGnd) or
= max(AGtm)

any standing dead mass is formed in current year

3.    Maximum minus minimum live biomass = Max(AGbm) - Min(AGbm)

same with Method 1 +
live biomass carried over from previous year is excluded

4.    Sum of positive increments in live biomass

= ΣAGbmt), when ΔAGbmt > 0

most growth occurs between successive sampling intervals (simultaneous growth and death do not occur)
belowground production is ignored or estimated

5/6. Sum of positive increments in live and dead plus litter

= ΣAGbm + ΔAGnd)/Δt or
= ΣAGbm + ΔAGdm)/Δt, when ΔAGbm > 0

simultaneous growth, death and decomposition do not occur

7.    Sum of changes in live and dead biomass

with adjustment for decomposition

= Σ[Δ(AGbm + AGdm + AGrd × AGrd)/Δt


[ productivity ]

Biomass profile (生産構造)

Biomass profile or diagram (生産構造図)
biomass profile

RLI = relative light intensity

  1. Set up plots, of which size is dependent on vegetation height
  2. Measure vertical changes in solar radiation (must be done before harvest)
  3. Set up poles at the four corner of plot
  4. Stretch strings to any height, e.g., at 20 cm intervals
  5. Harvest the biomass from top to the bottom (leaves, stems and flowers are kept separately on each species, when possible)
  6. At the same time, count number of shoots and estimate LAI, if possible
  7. Excavate the belowground organs, when required
  8. Each sample is weighed after drying up


Dominance (優占度)

  1. The (relative) degree to which one or a few species predominate in a community in terms of numbers, crown closure, importance, and/or biomass
  2. In genetics, the ability of one allele to suppress the phenotypic expression of another allele in the heterozygote. The suppressed allele is then recessive to the dominant allele.
In my lectures, the definition #1 is used.
Density (密度)
The number of plants per unit area. Usually we use this parameter for trees and plants of which individuality is clearly recognized.
Frequency (頻度)
Number of plots that the target species occurs.
Dominant species (優占種)
Species that is (are) dominant in the given area. The dominant species often characterize the community structure and function.


Relative density (相対密度, %)
= (number of individuals of a species)/(total # of individuals) × 100
Relative dominance (相対優占度) (%)
= (dominance of a species)/(dominance of all species) × 100
Relative frequency (相対頻度) (%)
= (frequency of a species)/(sum frequency of all species) × 100
Importance value (重要度) (IV)
= Relative density + relative dominance + relative frequency

(Max = 300), or

= (Relative density + relative dominance + relative frequency)/3

(Max = 100)