Geoscience Reference
In-Depth Information
water ranges from slightly acidic to alkaline
-
conditions that are suitable for a wide
range of plants and which give rise to greater
l oristic diversity compared with bogs. The
terms oligotrophic and eutrophic refer
respectively to nutrient-poor and nutrient-
rich fens.
the diverse resources provided to sustain them-
selves, while later riverine civilizations from
Egypt to Mesopotamia and the Indus l ourished
on their contributions. Today, few wetland
habitats exist without some form of anthropo-
genic inl uence or modii cation. Numerous
extractive and service industries are based on
the resources and functions provided by wet-
lands. These ecosystems support a wide diver-
sity of l ora and fauna, they contribute to
biogeochemical cycling of nutrients, sequester
carbon and other greenhouse gases regulating
climate, act as natural i lters to purify water,
and protect against destruction from l oods
and storm events.
Humans extract a wide array of economic
goods and services from these ecosystems. In
some regions of the world, wetlands provide for
basic needs of food, fuel, water and shelter. In
other areas, technology has allowed humans to
mimic wetland functions and take advantage of
the ecosystem services they offer by construct-
ing artii cial wetlands where none existed, or
restoring and rehabilitating other sites that may
have been degraded. In still other regions, wet-
lands provide intrinsic aesthetic value to com-
munities dependent on tourism and recreation.
Given the multiple uses and services of wet-
lands, managing this resource requires an inte-
grated systems approach. Such an approach
recognizes the complex and latticed nature of
2.7 Anthropogenic dimensions of wetlands
Human settlement across wetland ecosystems
dates back millennia. Our early ancestors used
Figure 2-24.
High air humidity combined with smoke
from autumn burning of agricultural wastes form a
haze over Männikjärve Bog (foreground) and Endla
Lake (left background) in eastern Estonia. Ash settles
and contributes to nutrients and inl uences surface-
water chemistry in the bog environment. Kite airphoto
by J.S. Aber and S.W. Aber.
A
B
Figure 2-25.
Nigula Bog and Salupeaksi mineral island, southwestern Estonia. A. Overview of the raised bog with
the mineral island on right side. B. Close-up view of tree-covered mineral island developed on a drumlin (see Color
Plate 2-25B). Note distinct vegetation zones: (a)
Sphagnum
moss, (b) pine, (c) birch (partly bare), and (d) ash, elm,
maple and other deciduous hardwoods, some of which display fall colors. Kite aerial photo; Aber et al. (2002).
