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:;^r; . f-:ji *v-
<br />^••*‘ . . ... .
<br />:e into account man's
<br />ion and siiiation of
<br />0 must do more* than
<br />k'ctland.s. VVe cannot
<br />ns or nutrient traps.
<br />0 that wetlands wiU
<br />ssible, and we must
<br />to that wetlands will
<br />™off. By regulating
<br />) maintain healthy
<br />il communities.*
<br />rr Supply
<br />inity because they
<br />They retain water
<br />luring flood i. thus
<br />'ely stable. Anyone
<br />>w in a w'indow box
<br />•is function. Peat,
<br />>ttom of a wetland
<br />arge quantities of
<br />5 window !k>x soil
<br />effects of the sun
<br />y moisture for the
<br />the peat makes
<br />uce the risks of
<br />•n marshes and
<br />cated; here, wet*
<br />iracteristics:
<br />ffroimdwater. (See
<br />id's basin extends
<br />the top surface of
<br />r>n, much of the
<br />lly to be absorbed
<br />indwat«r supply,
<br />hold the Water,
<br />o replenish the
<br />periods, the |»eat
<br />ase water, thus
<br />ly stable.
<br />!■;
<br />i
<br />w
<br />#•
<br />The h*\ el.s of water in the two systems, however, will not
<br />b.' etpial After a hard rain, es|HVMlly if overland flow
<br />• oa-urs, water will be higher in the wetlands. Surface water
<br />will ptTcolate into the groundwater until both levels are
<br />about the .same. After a drought, the water level is down in
<br />the wetland due to evaporation, but may be replenished
<br />somewhat by groundwater. Eventually, however the
<br />^und wau, been*, low ,„<».gh «, that wotlaad ly
<br />up. Ihis process IS often the most dramatic with sed^
<br />meadows or shallow marshes. These areas «rp
<br />••temporary'' wetlands-with standing water durTng ram^
<br />that dry up during other periods. Because of their semidrv
<br />hun.n.oclu. of vcgetatioii. they have greater absorpttoil
<br />capacity during periods of preciplution and then depend
<br />drouffht Tk ** ^undwater during periods of
<br />fuT thPv drain or
<br />to destruction, but damaging
<br />them means draining the groundwater supply.
<br />19 1 iu/K * fi^“"dwater discharge. (See Figure
<br />overlaid nlf*‘ '^*tor fromoverland How it also obtains water from streams and
<br />rSion^of fhimportant in the arid regions of the West, since other land wUl be quickly dried
<br />Slcaurtr*^"’ r“i r *"*P®^ton"t elsewhere
<br />f fed from clean underground water, thev
<br />arc likely to supi^rt different plant populations and be of
<br />higher quality than wetlands which are dependent on
<br />r.Th for their water. Many plants depend on the
<br />8t.able water level maintained by groundwater flow.
<br />j» A T^®_''®‘‘®"d is "perched" above the water table, but
<br />Its basin floor is sealed by a layer of impermeable clay. In
<br />this case, there is minimal linkage between the wetland
<br />and the water table. The wetland simply acts as a catch
<br />.^sin for overland flow. During periods of heavy
<br />precipitation the basin will fill untU it overflows, sending
<br />the rest of the water downstream or into an adjacent lake
<br />In this way ,t functions like a small dam by reducing the
<br />total amount of water in lower areas of the watershed.
<br />thereby rcrlucing flood risk. During period, of drought, it
<br />liKSes water through evaporation like the uplands, but at a
<br />slower rate because of soil and plant condition., and thus
<br />acts as a water hole for farm animals or wildlife.
<br />1 he cycling of water is important to a wetland's
<br />Mabdity. as well as providing man with a natural
<br />mechanism which moderates the extreme.s of flooding and
<br />drought. Many wetland plants and animals depend on
<br />fluctuations water level for their existence. For
<br />exjampic hip.h spring waters stimulate the growth of
<br />level for effective growth, they depend upon the gradual
<br />subsKlence of spring flood waters. Likewise, the lowering
<br />tor ducks and
<br />flue .r ' r “"""toral patlei ns of waterfluctuation, however, seriously damage these spccie.s.
<br />Mans influence on water hydrology generally
<br />exaggerates these fluctuations. This can be seen in Figure
<br />13. Under na^tural conditions, upland runoff is slowed by
<br />vegetation. The percolation of this water into the ground
<br />rwluces the amount of water entering the marsh and also
<br />rlXA ‘n " ® or urbanconditions tins process change.s. Greater amounts of
<br />precipitation are released to overland flow, covering
<br />wetlands with much higher water in the .spring and in turn
<br />demanding more of its water for groundwater recharge in
<br />dry periods. If a community is pumping groundwater for
<br />recbcTtipm™
<br />and w rcduc,.. ... chances of drou,.ht in the “dfau"^
<br />l artinilarly temporary wetlands, the low prairies the
<br />I art of the y, ar. must be presetted. These areas are often
<br />ncuREU. effectofubbanization on wetland water levels
<br />1^
<br />Light runoff
<br />Ffei«'<*alef Itlie
<br />dQlrutttfouqrv ■S.X
<br />1
<br />V
<br />1
<br />n
<br />w-
<br />i
<br />m
<br />»
<br />m
<br />■
<br />W
<br />I 4- 4 r
<br />f h
<br />m
<br />\Vi*ll>ii\<K, ttviieriil Fi
<br />Wetl.nut. piov l<lc (
<br />*aiid feeding groimils i
<br />kinds of fish ami wildl
<br />water are nm.l intiina
<br />(hii> iin|M)rtunt for su|
<br />and wafer aiiiinuls. L
<br />tor n wide rangi; of vi
<br />not exist without thei
<br />the benefits of a healt
<br />recreation, research, a
<br />and game for hunting,
<br />to the aesthetics of t
<br />.should be concerned al
<br />intricately connected v
<br />suitable use of land, tc
<br />which harm common r
<br />quality and the econor
<br />To a large extent,
<br />various water-related fi
<br />and environmental hea
<br />However, it is impoi
<br />diversity works and
<br />ecological theory ur,
<br />environment is in terra
<br />tnore stable it is. Stabil
<br />of large fluctuations du
<br />Species diversity ensur
<br />for diverting and disper
<br />le.ss likely it is that
<br />changes.
<br />This process can b
<br />opposite, monoculture,
<br />plant species by one—a
<br />arc attacks by pests.
<br />Since the most imports
<br />species in a natural co
<br />food web, it is easy to
<br />among the crops. With
<br />available, the plant-eat
<br />rapidly along with the
<br />farmer sprays pesticides
<br />process kills or harms tl
<br />the pests, making the si
<br />It is reasonable to ass
<br />prey and predator aninu
<br />The racoon, for example
<br />species of marsh birds
<br />numerous other foods, h
<br />the brunt of the raccooi
<br />point of view, if one prey
<br />survive. The presence of
<br />will also be important ir
<br />for example, can be eat
<br />osprey, among others. I
<br />the others will keep
<br />abundant. The same
<br />throughout the marsh
<br />herbivore, keeps the cat
<br />will not choke the marsh
<br />Within a healthy, di’
<br />animal species will have
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