Environmental Engineering Reference
In-Depth Information
Table 2.1
Ranges of Phytomass Densities of Terrestrial Ecosystems
Biomes and Ecosystems
Phytomass Density (dry matter, t/ha)
Tundra
<
5
Grasslands
Temperate
10-20
Tropical
10-35
Wetlands
20-60
Forests
Boreal
40-100
Temperate
50-1,000
Richest communities
1,700-3,500
Tropical
100-400
Richest communities
700-1,100
Note:
For data sources, see the text.
Temporal differences are even greater: a satellite pass may record the minimum
phytomass density in a freshly clear-cut or burned forest, but rapid regrowth might
occur in the following years and decades, and new stocking records may be set by
the secondary growth.
Most of the biosphere's standing phytomass (nearly 90%) is in forests, and most
of the forest phytomass (nearly 75%) is in the tropics, about three-i fths in the
equatorial rain forests and the rest in seasonally green formations (table 2.1). Tropi-
cal rain forests can be rather monotonous—especially those dominated by the family
of dipterocarp trees in Southeast Asia and in the northeastern basin of the Congo
River (Connell and Lowman 1989), but most of this biome has an admirably high
biodiversity, and its richest communities contain 200-300 species/ha, with maxima
in excess of 600 plant species.
The standing phytomass is concentrated mostly in tall, massive, often buttressed
trees forming the forest's dense canopy and in a smaller number of emergent trees
whose crowns rise above the closed-canopy level. Long woody vines (lianas), aggres-
sively growing strangler species, epiphytic plants (orchids, bromeliads), and rela-
tively bare forest l oors (a result of rapid decomposition of the litter) are other
notable hallmarks of this biome (Gay 2001; Carson and Schnitzer 2008). Dense
tropical rain forests have between 150 and 180 t C/ha of aboveground phytomass,
and their total storage (including living, dead, and underground biomass) is com-
monly between 200 and 250 t C/ha (Keith, Mackey, and Lindenmayer 2009).
