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;irv!>i-ntutjvo Wt»Ka:ior. •South) )
<br />5es, iKispaluma, btcakrusht'S
<br />____I
<br />ru*. sHWgrass. arrowhead, pickerel
<br />hes. cattails
<br />the (.aim* .speems. plu-* water
<br />nml water primrose in some areas
<br />lus water hyacinth I
<br />. overcup oak, tupelo gum, swamp ’
<br />. cypress
<br />?rseM, Kurdonia. sweeihay.’pond- !
<br />I^inin chciitifern. insectivorous i
<br />J
<br />lardstiin bulrushes, wi^'e«)iigrass, :
<br />vfcsi
<br />ih nriirlencane
<br />iih water hyariiuh and water
<br />Lirbid waters: pond weeds, naiads,
<br />. ccMintail. water milfoils, mu^k- j
<br />tCThy^cinih j
<br />th saltflat ^lass and salt wort
<br />hoalgrass. man itf e^rasb. turtle-
<br />d some btaek mangrove
<br />39
<br />m
<br />mm
<br />? t
<br />•1'
<br />' i*»■ r ■f:'. - r . ... ..ri^‘•'i/ vl; - - i:
<br />fOMiimie Then, the ctmummity must tleterniine the
<br />»|H*c»fu- values it is most interested in.
<br />3. It must then eh.Mse a method of reti«lation based on
<br />these imhaes. If the |)oIicy is U> Buarantee that the
<br />s. .UK n « f.H,t of water one set of regulatory procedurt s
<br />Tnl J r I T as wildareas, then it must develop a different wetlands program.
<br />dtcide.s that it wants to maintain, it is first necessary to
<br />understand how the wetlands function .so that^thc
<br />regu atory program can achieve those goals. The closer the
<br />ecological nature of the
<br />wetlands, the more effective it will lie.
<br />The following discussion of wetlands ecology and the
<br />way It smes the public interest focuses primarily on
<br />inland wetlands, since these have received less attention
<br />than coastal wetlands. A recent publication of the
<br />Conservation Foundation, Coastal Ecosystems, by John
<br />Clark, IS an excellent study of the ecolog>* and functions of
<br />saltwater wetlands.* Though much of what follows applies
<br />to all ivetlands. there is an additional section at the end of
<br />the s|H*nal functions of coastal wetlands
<br />Wetlands Protect Water Quality
<br />Wetlands affect water quality by trapping and storing
<br />the nutrients from upland runoff in plant tissue and
<br />serving as a settling basin for silt from upland ero.sion.
<br />This natural filtering function of wetlands can be seriously
<br />damaged, however, by poor land-use practices. Since
<br />every wetland has a unique tolerance for filtering runoff
<br />from the uplands around it, development in the upland can
<br />create more nutrient and sediment inflow than the marsh
<br />IS able to absorb. Moreover, development in and around
<br />the fringe of the marsh itself can destroy its ecological
<br />health and thus its filtering ability.
<br />Due to their contribution to water quality and their
<br />vulneraliility to destruction from runoff, wetlands fall
<br />within the regulatory function of local government. The
<br />broad objectives of social, political, and economic
<br />well-being that give communities the power to zone land
<br />and regulate subdivisions are designed to promote the
<br />most suitable use of land, as well as to protect, con.servu,
<br />and promote the orderly development of land -and
<br />water-resources. Protecting water quality is part of this
<br />mission. Since wetlands are an important link in the entire
<br />hydrological system, the community's interest in larger
<br />^les of water requires it to be interested in the wetlands
<br />When a community has to close its Inaches becnu.se of
<br />dangerous bacteria, it knows the natural wetland ’.s
<br />assimilative capacity is overloaded. Thus, there are al.so
<br />long-range health and safety considerations in a wetlands
<br />program.
<br />Quite often planning documents cite these use values u.s
<br />the important functions of wetlands. It is true that thl
<br />removal of wetlands by dredging or filling will have ua
<br />immediate impact on the water quality of streams and
<br />lakes below them in the watershed sy.stein. 'I'hcse
<br />documents also suggest that by preserving mar.she.s the
<br />community will have an effective antipolliilion device. Yet
<br />this assertion may not necessarily be true, especially if
<br />W'etlands are treated as a bottomless catch basin
<br />40
<br />When nutrients are added to an aquatic ecosy.siem, the
<br />physu jl and biological result.s art* called eutrophicatio.n It
<br />1.S a n.-mir.d process which occurs in all wetlands to a
<br />greater or le.sscr extent, dejiending on local availability of
<br />mitnents. the rate at which they enter the sy.sttm, and the
<br />rate at which they leave. Kutrophicalion is a process
<br />closely associated with the aging or filling-in of lakes. As
<br />the nutrient level increases, the water sup,xirts more plant
<br />me, which m turn builds the organic bottom of the water
<br />body W etiands. bccau.se of their greater plant population
<br />and their tendency to hold water longer so that it is not
<br />flushed downstream as qui<*kly. trap the.se r.utrients
<br />which are then stored a.s muck and peat .leposits. Under
<br />n<*rinal conditions these deposits do not build up as
<br />rapidly as is often supposed. It can take thou.sand.s of
<br />years to add a few fwt to the liotiom of a bog
<br />On the other hand, human activities can comiiress the
<br />long gradual process of eutrophication from centuries to a
<br />few decades or even years. Sediments and nutrients from
<br />upland (l. vdopmunt can overload and dama,.,. tho nalural
<br />^.Slcm turn,OK tho wotlan.l into a aoltlini; basin of
<br />polluted and unpleasant-smelling water
<br />At mlvancu stages eutrophication is an unpleasant
<br />proce.ss from man's point of view. It produces smollv algae
<br />blooms or dense gn.wths of water weeds, and it depletes
<br />the oxjgen levels m the water when the plant.s start to
<br />n-spiro or dmimposc. On a hot. windle.ss night, the rate of
<br />chemical activity m a small marsh is high, no lij;ht is
<br />ON ailab t for photosynthesis, and little o.xygen is added to
<br />u .siirf.tce If the plants are re.spiring or decom.io.sing at
<br />the time, the o.vygen level m.ny get very low and kill the
<br />Siiicv a marsh is relatively smaller and shallower than a
<br />lake. I IS less aide to handle the nutrients from a given
<br />watershed. A wetland has a larger relative surface area
<br />exposed to sunlight, where algae and .suhmerged. floating
<br />or emergent plants can grow. .Since the bottom mud is
<br />wanm*r even when shaded, chemical processes occur
<br />faster than m a deep lake. Likewi.se, when agitated by
<br />winds, the bottom layer of nutrients an* stirred up and
<br />released into the* water. All of these conditions tend to
<br />make mar.sl„*s and other wetlands quite seiesitive to
<br />mitrienf. inputs.
<br />VVhile wotlarids operate as nutrient filters, they can
<br />c-a.sily he overloaded and thus destroyed, 'rhis is exactly
<br />what happens with man-caused eulrojihication. Through
<br />uu rcased ruiudf and nutrients from fertilizers and urban
<br />de^eopn,ent. the entire process of eutrophication is
<br />sp(H*(h*d up to as much as 100 time.s as fa.st as the natural
<br />process. ( onse(,uently u marsh an*a that would have acted
<br />r*..s an important nutrient filter for 1.000 years may only
<br />function that way for 10 years <„,ce it is overloaded. '
<br />I reatmg wetland.s as settling ha.sins for overland runoff
<br />Has many of the same ctualifications that apply to their
<br />> met urn as nutrient trap.s. Kc*moving wetlands will
<br />•f.*.n. *(.lately affect adjacent waters by increasing the flow
<br />Oi dirtier water into them. Wetlands act to hold du*.vn
<br />urimlity the amount of sii.spended parlieles ii. water-
<br />by slowin,: the upland runoff as it flows through the tangle
<br />of weUaiul plant roots a„d systems. The resulting
<br />reiluction III the force of water flow and the natur:.J catch
<br />basm formed by plant roots allow.s some sediment to
<br />¥:
<br />r’
<br />I
<br />.4
<br />t
<br />sett le.
<br />in il«it*|
<br />the en
<br />wet la IK
<br />I m‘ by r
<br />A .sin
<br />big jars
<br />influenc
<br />iKiltom
<br />and lea>
<br />with the
<br />take the
<br />it will cl
<br />Turbh
<br />and oth
<br />amount
<br />competit
<br />plants SI
<br />requirem
<br />also infli
<br />depend <
<br />desirable
<br />scavenge
<br />sight feec
<br />populatio
<br />constanti:
<br />and thus
<br />In thes
<br />by increat
<br />and degrt
<br />experimer
<br />developmc
<br />of erosion
<br />take 15.0C
<br />forest; an<
<br />fanner has
<br />in his field
<br />higher rati
<br />such incei
<br />const ructic
<br />ecology sin
<br />constantly
<br />figure 12.
<br />Psriodof lowp
<br />jr.
<br />jaWe»KtA
<br />Water collected
<br />and stored in the
<br />wetland filters dc
<br />tonBC/iargeihegi
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