Orzell, Steve L.

Pell, William F.

Tucker, Gary E.

English

ScholarWorks@UARK

Journal of the Arkansas Academy of ScienceVolume 39 Article 431985Notes on Three Palustrine Natural CommunityTypes in the Arkansas OzarksSteve L. OrzellArkansas Natural Heritage CommissionWilliam F. PellArkansas Natural Heritage CommissionGary E. TuckerArkansas Tech UniversityFollow this and additional works at: http://scholarworks.uark.edu/jaasPart of the Forest Sciences Commons, and the Terrestrial and Aquatic Ecology CommonsThis article is available for use under the Creative Commons license: Attribution-NoDerivatives 4.0 International (CC BY-ND 4.0). Users are able toread, download, copy, print, distribute, search, link to the full texts of these articles, or use them for any other lawful purpose, without asking priorpermission from the publisher or the author.This General Note is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Journal of the ArkansasAcademy of Science by an authorized editor of ScholarWorks@UARK. For more information, please contact scholar@uark.edu, ccmiddle@uark.edu.Recommended CitationOrzell, Steve L.; Pell, William F.; and Tucker, Gary E. (1985) "Notes on Three Palustrine Natural Community Types in the ArkansasOzarks," Journal of the Arkansas Academy of Science: Vol. 39 , Article 43.Available at: http://scholarworks.uark.edu/jaas/vol39/iss1/43Arkansas Academy of Science Proceedings, Vol. XXXIX,1985 141Arkansas Academy of ScienceThe activity of phosphodiesterase in the starting medium and in a partially purified ammonium sulfate pellet is shown in Table 1.The sametable also shows that this enzyme is heat stable, retaining up to 84% of the unheated activity after exposure to a boiling water bath for 5 min.Extracellular cyclic AMPphosphodiesterase from the same organism was previously shown toalso be heat stable (Lynch and Farrell, 1985). Table1 shows heat resistance at 5 min but gives no indication of how long the enzyme can withstand exposure to 100°C. Figure 1 shows cyclic GMPphosphodiesterase activity remaining after heating for up to twenty minutes in a boiling water bath. Both the starting medium and the ammoniumsulfate pellet retained almost full phosphodiesterase activity even after twenty minutes of exposure to heat.The effect of various compounds on partially purified cyclic GMP phosphodiesterase activity is shown in Table 2. MIX, theophylline andcaffeine are all competitive inhibitors of phosphodiesterase. All three compounds inhibited enzyme activity withMIXbeing the most potent. Chlor-promazine (a phenothiazine) and Compound 48/80 (a condensation product of N-methyl-p-methoxy-phenethylamine with formaldehyde) are thoughtto inhibit calmodulin dependent phosphodiesterase by binding to calmodulin (Levin and Weiss, 1976; Gietzen et al., 1983). Both of these com-pounds stimulated plasmodial cyclic GMP phosphodiesterase. The mode of action of these two compounds on this enzyme is unknown.Table 3 shows cyclic GMP phosphodiesterase activity at various pH values, a pH of 7.0 showed maximum enzyme activity with markedlyreduced activity at pH4.0 and 5.0. This is similar to cyclic AMP phosphodiesterase from the same organism in that the optimum pH for enzymeactivity does not coincide with the optimum pH for growth. Uninoculated growth medium had a pHof 4.3 and after inoculation and growth,the pHof the medium rose to between 5 and 6. Under the growth conditions, cyclic GMP phosphodiesterase should be relatively inactive duringthe early stages of growth (the first few days after inoculation). Then, as the pH increases and approaches 5.0, the enzyme should become increas-ingly active.All the previous enzyme assays were done using the resin assay which measures 3H-guanosine as the end product. To insure the validity ofour heat stability data, an alternate procedure for measuring phosphodiesterase activity was utilized. This procedure involved separating the pro-duct of phosphodiesterase (3H-5 '-GMP) by paper chromatography. Figure 2 shows a continuous assay of cyclic GMP phosphodiesterase for bothheated and unheated samples as measured by paper chromatography. As can be seen, the heated sample retained enzymatic activity and productaccumulation was linear with time.As mentioned previously, extracellular cyclic AMPphosphodiesterase from the same organism is also heat stable. Work is presently under-way in our laboratory to determine ifthe cyclic AMPenzyme is a di tintt protein from the cyclic GMP phosphodiesterase reported here and whetherthe two enzymes are indeed one and the same protein.ACKNOWLEDGMENTSWe would like to thank Mrs. Ann Durgun for excellent clerical assistance. This research was supported by NSF EPSCORGrant #ISP-801 1447, by an Altheimer Foundation Grant and by the College ofSciences ORST (Office of Research in Scienceand Technology).LITERATURE CITEDGIETZEN, K., E. SANCHEZ-DELGADO, and H. BADER. 1983.Compound 48/80: Apowerful and specific inhibitor ofcalmodulin-dependent ca2 + -transport ATPase. IRCS Medical Sci. 11:12-13.LYNCH,T. J., and M. E. FARRELL. 1984. Comparison of cAMPphosphodiesterase from the haploid and diploid stages of the myx-omycete Physarum flavicomum. Cytobios. 39:71-79.LEVIN, R. M., and B. WEISS. 1976. Mechanism by which psycho-tropic drugs inhibit adenosine cyclic 3 ' 5 '-monophosphatephosphodiesterase of brain. Mol. Pharmacol. 12:581-589.LYNCH, T. J., and M. E. FARRELL. 1984. Extracellular phos-phodiesterase from the growth medium of the tnyxomycetePhysarum flavicomum. Proc. Ark. Acad. Sci. 38 p. 60-63.LYNCH, T. J., and W. Y.CHEUNG. 1975. Underestimation ofcyclic3 ',5 '-nucleotide phosphodiesterase by a radioisotopic assay usingan anion-exchange resin. Anal. Biochem. 67:130-138.THOMAS J. LYNCH and MARKS. ROSS, Department of Biology, University of Arkansas at Little Rock, LittleRock, AR 72204.NOTES ON THREE PALUSTRINE NATURAL COMMUNITY TYPES INTHE ARKANSAS OZARKSWithin the last five years three distinct palustrine (sensu Cowardin et al., 1979) community types not previously described in the literatureas occurring in Arkansas have been recognized by the authors. The two fen community types have been reported previously in the Ozark Plateausofsoutheastern Missouri (Orzell, 1983). Each of the recognized community types occur within the Ozark Natural Division(Pell, 1983) and is largelyrestricted to that part of the state. This paper represents an attempt to describe and classify these little-known natural communities.The basis forour classification is the repeated occurrence on the landscape ofparticular combinations ofvegetation structure and physiognomy,soil moisture regime, soil reaction, geologic substrate, topographic position, and species composition. Species composition, though obviously im-portant, is not an overriding concern; in fact, examples of a given "natural community type" may vary considerably in this respect. A naturalcommunity classification emphasizes consistent ecological differences, not those due to the vagaries of dispersal or disturbance history. Inmanycases, more traditionally defined "plant community types" may be recognized within each natural community type.The natural community descriptions presented here include information on distribution, topography, soils, community size and structure,natural processes, status and threats, and dominant and characteristic plant species. Dominant plants are species consistently occurring as majorvegetation components (relative cover > 25 percent, based on visual estimates) of the type, though they need not dominant every example of thattype. Characteristic plants are those typical or representative species that provide a reliable indicator of a given type. Dominant and characteristicspecies are not necessarily restricted to the types but, when considered together with other natural features, are diagnostic. Characteristic specieswere identified by constructing synthesis tables from species checklists compiled during field surveys (Mueller-Dombois and Ellenberg 1974). Four-141Journal of the Arkansas Academy of Science, Vol. 39 [1985], Art. 43Published by Arkansas Academy of Science, 1985Arkansas Academy off Science Proceedings, Vol. XXXIX,1985142General Notesteen streamside seep-fens, one sedge-shrub fen (only known example in Arkansas), and ten upland hydric forests served as the study sites. Specificlocations and voucher specimen data for these sites are available from the Arkansas Natural Heritage Commission. Plant nomenclature followsKartesz and Kartesz (1980).STREAMSIDE SEEP-FENSTopography, Hydrology, and SoilsStreamside seep-fens are located along second and third order Ozark streams, usually within deeply dissected, relatively small drainage basins.These streams have a permanent flow of clear, cold, minerotrophic water, sustained by diffuse seepage or discrete seep-springs. They are usuallymedium- to high-gradient streams of shallow depth, with a bedrock floor of Ordovician dolomite. Potholes, shallow pools alternating withshallowruns, rock terraces withsmall cascading waterfalls, and small sand-gravel alluvial deposits are common features.Seep-fens are generally along the upper reaches of these streams, either on adjacent sideslopes, along narrow streamside corridors, or onexposed bedrock in the stream bed. Soil moisture is dependent upon seasonal fluctuations; in dry weather free surface water may be absent butsoil remains damp, with pockets of permanent seepage. Shallow organic muck or mineral soil or a mixture of muck, sand, and cherty residuumderived from weathered dolomitic parent material forms the substrate. Bedrock strata—primarily Powell, Cotter, orJefferson City dolomite (LowerOrdovician), but sometimes St. Peter Sandstone (Middle Ordovician) —are occasionally exposed.Natural ProcessesThe rooting zone is occasionally to constantly saturated by cold, minerotrophic groundwater. Chemical and physical weathering of the bedrockproduces a calcareous substrate. The microclimate is strongly moderated by cold water springs, late spring frosts, and early autumn frosts. Fluctua-tions in stream discharge periodically scour the streamside, creating areas almost "permanently" in a pioneer stage of succession.Community StructureMicroassociations of fen calcicoles occur along narrow streamside corridors or on exposed bedrock in the streambed. The prevailing coverconsists of sedges or mixed graminoids. The sedges are usually less than 30 cm tall and often form tussocks. Grasses and heliophytic forbs aremedium to tall in height and often are most conspicuous in autumnal aspect. Shrubs may be present as well.Dominant PlantsGravelly seepage areas - Fuirena simplex Vahl, Parnassia grandifolia DC, Rudbeckia fulgida Ait. var. umbrosa (C.L. Boynt. & Beadle)Cronq., Senecio aureus L., and Calamintha arkansana (Nutt.) Shinners. Seep springs - Justicia americana (L.) Vahl, Nasturtium officinale R. Br.,and Carex torta Boott.Characteristic PlantsCarex hystricina Muhl. ex Willd., C. lurida Wahlenb., Equisetum hyemale L., Oxypolis rigidior(L.)Raf., Scirpus americanus Pers., S. lineatusMichx., S. atrovirens Willd., Selaginella apoda (L.) Fern., Cornus amomum P. Mill. ssp. obliqua (Raf.) J.S. Wilson, Helenium autumnale L.,Lobelia siphilitica L., Lysimachia quadriflora Sims, and sometimes Rhynchospora capillacea Torr.Itappears that streamside seep-fens provide migrational routes for fen calcicoles in the Ozark region and refugia for extraneous taxa havingnorth-central, northeastern, and southeastern geographic affinities. Plant taxa generally found in the Arkansas Ozarks only in streamside seep-fensinclude R. capillacea (Marion, Baxter, Stone, and Sharp counties), Scleria verticillata Muhl. ex Willd. (Sharp Co. and, historically, Benton Co.),Mimulus ringens L. (Baxter, Fulton, and Sharp counties), Solidago riddellii Frank (Sharp Co.), Plantago cordata Lam. (Baxter and Randolphcounties), Spiranthes lucida (H.H.Eat.) Ames (Baxter, Stone, Marion, and Izard counties), and Pycnanthemum virginianum (L.)Durand &Jackson(Sharp and Fulton counties). IfSalixsericea Marsh. (Fulton Co., historically) is relocated in the state, it probably willbe associated with seep-fens.Distribution and SizeStreamside seep-fens are found principally in the Salem Plateau subdivision and less frequently in the Springfield Plateau subdivision of theOzark National Division. Seep-fens presently are known to occur in Marion, Baxter, Fulton, Izard, Sharp, Stone, and Randolph counties. Theyare to be expected in surrounding counties, especially Independence, Lawrence, and Searcy. Seep-fens are well developed along second- or third-order streams in the North Sylamore Creek watershed (Stone Co.) and the Spring River watershed (Fulton and Randolph counties). Seep-fens inthe Salem Plateau of adjacent southeastern Missouri were recently described by Orzell (1983). Individual streamside seep-fens are generally smallin extent, ranging from 0.1 ha to 2.0 ha in size, but may occur intermittently along several miles of stream.Status and ThreatsThe type is uncommon, and undisturbed high-quality examples are becoming increasingly rare. Threats include clear-cutting, siltation, waterpollution, grazing, and reservoir construction. Some seep-fens in the Sylamore District of the Ozark National Forest are fairly wellprotected aspart of a special interest area but these may eventually become subject to recreational pressures.SEDGE-SHRUB FENTopography, Hydrology, and SoilsSedge-shrub fens are located on toeslopes near upper to middle reaches of gaining streams of moderately to deeply dissected valleys. Thegroundwater arises from a shallow, unconsolidated aquifer in the weathered porous residuum of the surrounding uplands and is minerotrophicand circumneutral. Soils are saturated, bog-like, and produce a quaking sensation when traversed by foot. Poor internal drainage may result inshallow pooling of water. Depth of the saturated muck or mucky peat may exceed 2 m. Underlying material is gravelly alluvium and colluvium.Natural ProcessesThe soil is constantly saturated by minerotrophic water. Fens are rarely inundated and would be destroyed by prolonged flooding. Inpreset-tlement time fires retarded invasion by woody plants; windthrow and anaerobic soil conditions continue toafford this community some resistanceto woody invasion.142Journal of the Arkansas Academy of Science, Vol. 39 [1985], Art. 43http://scholarworks.uark.edu/jaas/vol39/iss1/43Arkansas Academy of Science Proceedings, Vol. XXXIX,1985 143Arkansas Academy of ScienceCommunity StructureSedge-shrub fens consist ofa sedge mat with rushes, cattails, and forbs intermixed, mats of dense "brown mosses," and patches ofmediumto tall shrubs. The sedges are short to medium in height and either caespitose or tussock-forming. Shrubs, mostly Salix spp., form thickets orare scattered throughout. Species diversity in undisturbed sedge-shrub fens is relatively high.Dominant Plants (based on one known example in Arkansas)Rhynchospora capillacea, Carex stricta Lam. var strictior (Dewey) Carey, Rudbeckia fulgida var. umbrosa, Typha latifolia L., Boehmeriacylindrica (L.) Sw., Impatiens capensis Meerb., and Salix spp. (the last three occur primarily in thickets). Other plants found at this site, but notdominant in the community, include Oxypolis rigidior, Senecio aureus, Lobelia siphilitica, Lysimachia quadrifolia, Carex hystricina, C. lurida,Scirpus atrovirens, S. lineatus, Castilleja coccinea (L.) Streng., and Helenium autumnale.Status and ThreatsHigh quality, undisturbed fens are extremely rare. Threats include grazing pressure, ditching, clearing for cultivation, road-, pond-, and reservoir-construction, excessive well drilling, pumping, dewatering of shallow aquifers, and damage by off-road vehicles. The single Arkansas example isprotected, insofar as possible, by the U.S. Army Corps of Engineers (Little Rock District).UPLAND HYDRIC FORESTSTopography, hydrology, and soilsUpland hydric forests occur in shallow depressions isolated on broad saddles or benches at elevations of 335 to 580 m (ca. 1100-1900 ft).They are underlain by the basal sandstone member of the Atoka Formation (Pennsylvanian). Soils are deep, poorly drained, slowly permeable,and nearly level. They usually form in siltyor clayey deposits and are underlain by a fragipan. The source of water for these communities is precipitation,which pools generally 0.3 to 0.9 m during the winter for several months. Water levels are considerably lower during the summer, except after periodsof heavy rainfall, and the depressions often lack standing water during the summer.Natural ProcessesThe degree of wetness is variable, largely dependent on precipitation and evapo-transpiration.Community Structure» Upland hydric forests in the Boston Mountains have a semi-open canopy ofmedium height (19-27 m) and generally lack an understory. Vinesten form a tangled thicket near the edge of the saturated soil zone, especially ifheavily disturbed historically by timber practices. Ground coversometimes consists of vines, bryophytes, and mixed sedges or spikerushes, but is generally species-poor.Dominant PlantsQuercus lyrata Walt, and/or Quercus palustris Muenchh. in the overstoryCharacteristic PlantsLiquidambar styraciflua L.,Nyssa sylvatica Marsh., Acer rubrum L.,Fraxinus pennsylvanica Marsh., and species ofSphagnum and Polytrichummoss. Other plants found in association include Cephalanthus occidentalis L., Lyonia ligustrina (L.) DC, Eteocharis obtusa (Willd.) Schultes,Cyperus strigosus L., Carex lurida Wahlenb., Bidens aristosa (Michx.) Britt., and Helenium autumnale L.Distribution and SizetThis community type is known from Johnson, Pope, Madison, and Newton counties and has been reported from Searcy, Van Buren, and;burne counties, all in the Boston Mountain subdivision of the Ozark Natural Division. Ithas also been reported from Magazine Mountain3gan County) in the Arkansas Valley Natural Division. Representative stands are 0.4 ha to 1.8 has in size. Similar upland communities dominatedQuercus phellos L. have been observed in the Arkansas Valley (Cleburne Co.)., the Boston Mountains (Searcy and Van Buren counties), andiOuachita Mountains (Saline and Perry counties). Because additional research is needed to document the species composition, hydrologic rela-ns, and distribution of these upland willow oak forests, they are not discussed further in this paper.Status and Threats¦ Unaltered examples are rare. Threats include timber cutting, artificial drainage, and damming to create year-round wildlifeponds. Two quali-occurrences of this type in Pope County are protected as part of the recently-designated East Fork Wilderness Area.LITERATURE CITEDrWARDIN, L.W., V. CARTER, F. C. GOLET, and E. T. LAROE.1979. Classification of wetlands and deepwater habitats of theUnited States. Office ofBiological Services. Fish and Wildlife Ser-vice, U.S. Dept. of the Interior. Washington, D.C. 103 pp.MUELLER-DOMBOIS, D. and H. ELLENBERG. 1974. Aims andmethods of vegetation ecology. John Wiley &Sons, Inc., NewYork. 547 pp.ORZELL, S. L.1983. Natural area inventory and floristic analysis offens in selected southeastern Missouri counties. Masters thesis.Southern IllinoisUniversity, Carbondale, 111. 203 pp.rRTESZ, J. T., and R. KARTESZ. 1980. A synonymized checklistof the vascular flora of the United States, Canada, and Greenland.Vol. II.The biota of North America. Univ. of North CarolinaPress, Chapel Hill. 498 pp.PELL, P. 1983. The natural divisions of Arkansas: A revised class-ification and description. Natural Areas Journal 3(2):12-23.IEVE ORZELL and BILLPELL, Arkansas Natural Heritage Commission, The Heritage Center, 225 East Markham, LittleRock, AR 72201,iGARY TUCKER, Department of Biological Sciences, Arkansas Tech University, Russellville, AR 72801.143Journal of the Arkansas Academy of Science, Vol. 39 [1985], Art. 43Published by Arkansas Academy of Science, 1985

Notes on Three Palustrine Natural Community Types in the Arkansas Ozarks

UARK (University of Arkansas )

Journal of the Arkansas Academy of Science Volume 39 Article 43 1985 Notes on Three Palustrine Natural Community Types in the Arkansas Ozarks Steve L. Orzell Arkansas Natural Heritage Commission William F. Pell Arkansas Natural Heritage Commission Gary E. Tucker Arkansas Tech University Follow this and additional works at: https://scholarworks.uark.edu/jaas  Part of the Forest Sciences Commons, and the Terrestrial and Aquatic Ecology Commons Recommended Citation Orzell, Steve L.; Pell, William F.; and Tucker, Gary E. (1985) "Notes on Three Palustrine Natural Community Types in the Arkansas Ozarks," Journal of the Arkansas Academy of Science: Vol. 39 , Article 43. Available at: https://scholarworks.uark.edu/jaas/vol39/iss1/43 This article is available for use under the Creative Commons license: Attribution-NoDerivatives 4.0 International (CC BY-ND 4.0). Users are able to read, download, copy, print, distribute, search, link to the full texts of these articles, or use them for any other lawful purpose, without asking prior permission from the publisher or the author. This General Note is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Journal of the Arkansas Academy of Science by an authorized editor of ScholarWorks@UARK. For more information, please contact scholar@uark.edu. Arkansas Academy of Science Proceedings, Vol. XXXIX,1985 141Arkansas Academy of ScienceThe activity of phosphodiesterase in the starting medium and in a partially purified ammonium sulfate pellet is shown in Table 1.The sametable also shows that this enzyme is heat stable, retaining up to 84% of the unheated activity after exposure to a boiling water bath for 5 min.Extracellular cyclic AMPphosphodiesterase from the same organism was previously shown toalso be heat stable (Lynch and Farrell, 1985). Table1 shows heat resistance at 5 min but gives no indication of how long the enzyme can withstand exposure to 100°C. Figure 1 shows cyclic GMPphosphodiesterase activity remaining after heating for up to twenty minutes in a boiling water bath. Both the starting medium and the ammoniumsulfate pellet retained almost full phosphodiesterase activity even after twenty minutes of exposure to heat.The effect of various compounds on partially purified cyclic GMP phosphodiesterase activity is shown in Table 2. MIX, theophylline andcaffeine are all competitive inhibitors of phosphodiesterase. All three compounds inhibited enzyme activity withMIXbeing the most potent. Chlor-promazine (a phenothiazine) and Compound 48/80 (a condensation product of N-methyl-p-methoxy-phenethylamine with formaldehyde) are thoughtto inhibit calmodulin dependent phosphodiesterase by binding to calmodulin (Levin and Weiss, 1976; Gietzen et al., 1983). Both of these com-pounds stimulated plasmodial cyclic GMP phosphodiesterase. The mode of action of these two compounds on this enzyme is unknown.Table 3 shows cyclic GMP phosphodiesterase activity at various pH values, a pH of 7.0 showed maximum enzyme activity with markedlyreduced activity at pH4.0 and 5.0. This is similar to cyclic AMP phosphodiesterase from the same organism in that the optimum pH for enzymeactivity does not coincide with the optimum pH for growth. Uninoculated growth medium had a pHof 4.3 and after inoculation and growth,the pHof the medium rose to between 5 and 6. Under the growth conditions, cyclic GMP phosphodiesterase should be relatively inactive duringthe early stages of growth (the first few days after inoculation). Then, as the pH increases and approaches 5.0, the enzyme should become increas-ingly active.All the previous enzyme assays were done using the resin assay which measures 3H-guanosine as the end product. To insure the validity ofour heat stability data, an alternate procedure for measuring phosphodiesterase activity was utilized. This procedure involved separating the pro-duct of phosphodiesterase (3H-5 '-GMP) by paper chromatography. Figure 2 shows a continuous assay of cyclic GMP phosphodiesterase for bothheated and unheated samples as measured by paper chromatography. As can be seen, the heated sample retained enzymatic activity and productaccumulation was linear with time.As mentioned previously, extracellular cyclic AMPphosphodiesterase from the same organism is also heat stable. Work is presently under-way in our laboratory to determine ifthe cyclic AMPenzyme is a di tintt protein from the cyclic GMP phosphodiesterase reported here and whetherthe two enzymes are indeed one and the same protein.ACKNOWLEDGMENTSWe would like to thank Mrs. Ann Durgun for excellent clerical assistance. This research was supported by NSF EPSCORGrant #ISP-801 1447, by an Altheimer Foundation Grant and by the College ofSciences ORST (Office of Research in Scienceand Technology).LITERATURE CITEDGIETZEN, K., E. SANCHEZ-DELGADO, and H. BADER. 1983.Compound 48/80: Apowerful and specific inhibitor ofcalmodulin-dependent ca2 + -transport ATPase. IRCS Medical Sci. 11:12-13.LYNCH,T. J., and M. E. FARRELL. 1984. Comparison of cAMPphosphodiesterase from the haploid and diploid stages of the myx-omycete Physarum flavicomum. Cytobios. 39:71-79.LEVIN, R. M., and B. WEISS. 1976. Mechanism by which psycho-tropic drugs inhibit adenosine cyclic 3'5 '-monophosphatephosphodiesterase of brain. Mol. Pharmacol. 12:581-589.LYNCH, T. J., and M. E. FARRELL. 1984. Extracellular phos-phodiesterase from the growth medium of the tnyxomycetePhysarum flavicomum. Proc. Ark. Acad. Sci. 38 p. 60-63.LYNCH, T. J., and W. Y.CHEUNG. 1975. Underestimation ofcyclic3 ',5 '-nucleotide phosphodiesterase by a radioisotopic assay usingan anion-exchange resin. Anal. Biochem. 67:130-138.THOMAS J. LYNCH and MARKS. ROSS, Department of Biology, University of Arkansas at Little Rock, LittleRock, AR 72204.NOTES ON THREE PALUSTRINE NATURAL COMMUNITY TYPES INTHE ARKANSAS OZARKSWithin the last five years three distinct palustrine (sensu Cowardin et al., 1979) community types not previously described in the literatureas occurring in Arkansas have been recognized by the authors. The two fen community types have been reported previously in the Ozark Plateausofsoutheastern Missouri (Orzell, 1983). Each of the recognized community types occur within the Ozark Natural Division(Pell, 1983) and is largelyrestricted to that part of the state. This paper represents an attempt to describe and classify these little-known natural communities.The basis forour classification is the repeated occurrence on the landscape ofparticular combinations ofvegetation structure and physiognomy,soil moisture regime, soil reaction, geologic substrate, topographic position, and species composition. Species composition, though obviously im-portant, is not an overriding concern; in fact, examples of a given "natural community type" may vary considerably in this respect. A naturalcommunity classification emphasizes consistent ecological differences, not those due to the vagaries of dispersal or disturbance history. Inmanycases, more traditionally defined "plant community types" may be recognized within each natural community type.The natural community descriptions presented here include information on distribution, topography, soils, community size and structure,natural processes, status and threats, and dominant and characteristic plant species. Dominant plants are species consistently occurring as majorvegetation components (relative cover > 25 percent, based on visual estimates) of the type, though they need not dominant every example of thattype. Characteristic plants are those typical or representative species that provide a reliable indicator of a given type. Dominant and characteristicspecies are not necessarily restricted to the types but, when considered together with other natural features, are diagnostic. Characteristic specieswere identified by constructing synthesis tables from species checklists compiled during field surveys (Mueller-Dombois and Ellenberg 1974). Four-141Journal of the Arkansas Academy of Science, Vol. 39 [1985], Art. 43Published by Arkansas Academy of Science, 1985Arkansas Academy off Science Proceedings, Vol. XXXIX,1985142General Notesteen streamside seep-fens, one sedge-shrub fen (only known example in Arkansas), and ten upland hydric forests served as the study sites. Specificlocations and voucher specimen data for these sites are available from the Arkansas Natural Heritage Commission. Plant nomenclature followsKartesz and Kartesz (1980).STREAMSIDE SEEP-FENSTopography, Hydrology, and SoilsStreamside seep-fens are located along second and third order Ozark streams, usually within deeply dissected, relatively small drainage basins.These streams have a permanent flow of clear, cold, minerotrophic water, sustained by diffuse seepage or discrete seep-springs. They are usuallymedium- to high-gradient streams of shallow depth, with a bedrock floor of Ordovician dolomite. Potholes, shallow pools alternating withshallowruns, rock terraces withsmall cascading waterfalls, and small sand-gravel alluvial deposits are common features.Seep-fens are generally along the upper reaches of these streams, either on adjacent sideslopes, along narrow streamside corridors, or onexposed bedrock in the stream bed. Soil moisture is dependent upon seasonal fluctuations; in dry weather free surface water may be absent butsoil remains damp, with pockets of permanent seepage. Shallow organic muck or mineral soil or a mixture of muck, sand, and cherty residuumderived from weathered dolomitic parent material forms the substrate. Bedrock strata—primarily Powell, Cotter, orJefferson City dolomite (LowerOrdovician), but sometimes St. Peter Sandstone (Middle Ordovician)—are occasionally exposed.Natural ProcessesThe rooting zone is occasionally to constantly saturated by cold, minerotrophic groundwater. Chemical and physical weathering of the bedrockproduces a calcareous substrate. The microclimate is strongly moderated by cold water springs, late spring frosts, and early autumn frosts. Fluctua-tions in stream discharge periodically scour the streamside, creating areas almost "permanently" in a pioneer stage of succession.Community StructureMicroassociations of fen calcicoles occur along narrow streamside corridors or on exposed bedrock in the streambed. The prevailing coverconsists of sedges or mixed graminoids. The sedges are usually less than 30 cm tall and often form tussocks. Grasses and heliophytic forbs aremedium to tall in height and often are most conspicuous in autumnal aspect. Shrubs may be present as well.Dominant PlantsGravelly seepage areas - Fuirena simplex Vahl, Parnassia grandifolia DC, Rudbeckia fulgida Ait. var. umbrosa (C.L. Boynt. & Beadle)Cronq., Senecio aureus L., and Calamintha arkansana (Nutt.) Shinners. Seep springs - Justicia americana (L.) Vahl, Nasturtium officinale R. Br.,and Carex torta Boott.Characteristic PlantsCarex hystricina Muhl. ex Willd., C. lurida Wahlenb., Equisetum hyemale L., Oxypolis rigidior(L.)Raf., Scirpus americanus Pers., S. lineatusMichx., S. atrovirens Willd., Selaginella apoda (L.) Fern., Cornus amomum P. Mill. ssp. obliqua (Raf.) J.S. Wilson, Helenium autumnale L.,Lobelia siphilitica L., Lysimachia quadriflora Sims, and sometimes Rhynchospora capillacea Torr.Itappears that streamside seep-fens provide migrational routes for fen calcicoles in the Ozark region and refugia for extraneous taxa havingnorth-central, northeastern, and southeastern geographic affinities. Plant taxa generally found in the Arkansas Ozarks only in streamside seep-fensinclude R. capillacea (Marion, Baxter, Stone, and Sharp counties), Scleria verticillata Muhl. ex Willd. (Sharp Co. and, historically, Benton Co.),Mimulus ringens L. (Baxter, Fulton, and Sharp counties), Solidago riddellii Frank (Sharp Co.), Plantago cordata Lam. (Baxter and Randolphcounties), Spiranthes lucida (H.H.Eat.) Ames (Baxter, Stone, Marion, and Izard counties), and Pycnanthemum virginianum (L.)Durand &Jackson(Sharp and Fulton counties). IfSalixsericea Marsh. (Fulton Co., historically) is relocated in the state, it probably willbe associated with seep-fens.Distribution and SizeStreamside seep-fens are found principally in the Salem Plateau subdivision and less frequently in the Springfield Plateau subdivision of theOzark National Division. Seep-fens presently are known to occur in Marion, Baxter, Fulton, Izard, Sharp, Stone, and Randolph counties. Theyare to be expected in surrounding counties, especially Independence, Lawrence, and Searcy. Seep-fens are well developed along second- or third-order streams in the North Sylamore Creek watershed (Stone Co.) and the Spring River watershed (Fulton and Randolph counties). Seep-fens inthe Salem Plateau of adjacent southeastern Missouri were recently described by Orzell (1983). Individual streamside seep-fens are generally smallin extent, ranging from 0.1 ha to 2.0 ha in size, but may occur intermittently along several miles of stream.Status and ThreatsThe type is uncommon, and undisturbed high-quality examples are becoming increasingly rare. Threats include clear-cutting, siltation, waterpollution, grazing, and reservoir construction. Some seep-fens in the Sylamore District of the Ozark National Forest are fairly wellprotected aspart of a special interest area but these may eventually become subject to recreational pressures.SEDGE-SHRUB FENTopography, Hydrology, and SoilsSedge-shrub fens are located on toeslopes near upper to middle reaches of gaining streams of moderately to deeply dissected valleys. Thegroundwater arises from a shallow, unconsolidated aquifer in the weathered porous residuum of the surrounding uplands and is minerotrophicand circumneutral. Soils are saturated, bog-like, and produce a quaking sensation when traversed by foot. Poor internal drainage may result inshallow pooling of water. Depth of the saturated muck or mucky peat may exceed 2 m. Underlying material is gravelly alluvium and colluvium.Natural ProcessesThe soil is constantly saturated by minerotrophic water. Fens are rarely inundated and would be destroyed by prolonged flooding. Inpreset-tlement time fires retarded invasion by woody plants; windthrow and anaerobic soil conditions continue toafford this community some resistanceto woody invasion.142Journal of the Arkansas Academy of Science, Vol. 39 [1985], Art. 43https://scholarworks.uark.edu/jaas/vol39/iss1/43Arkansas Academy of Science Proceedings, Vol. XXXIX,1985 143Arkansas Academy of ScienceCommunity StructureSedge-shrub fens consist ofa sedge mat with rushes, cattails, and forbs intermixed, mats of dense "brown mosses," and patches ofmediumto tall shrubs. The sedges are short to medium in height and either caespitose or tussock-forming. Shrubs, mostly Salix spp., form thickets orare scattered throughout. Species diversity in undisturbed sedge-shrub fens is relatively high.Dominant Plants (based on one known example in Arkansas)Rhynchospora capillacea, Carex stricta Lam. var strictior (Dewey) Carey, Rudbeckia fulgida var. umbrosa, Typha latifolia L., Boehmeriacylindrica (L.) Sw., Impatiens capensis Meerb., and Salix spp. (the last three occur primarily in thickets). Other plants found at this site, but notdominant in the community, include Oxypolis rigidior, Senecio aureus, Lobelia siphilitica, Lysimachia quadrifolia, Carex hystricina, C. lurida,Scirpus atrovirens, S. lineatus, Castilleja coccinea (L.) Streng., and Helenium autumnale.Status and ThreatsHigh quality, undisturbed fens are extremely rare. Threats include grazing pressure, ditching, clearing for cultivation, road-, pond-, and reservoir-construction, excessive well drilling, pumping, dewatering of shallow aquifers, and damage by off-road vehicles. The single Arkansas example isprotected, insofar as possible, by the U.S. Army Corps of Engineers (Little Rock District).UPLAND HYDRIC FORESTSTopography, hydrology, and soilsUpland hydric forests occur in shallow depressions isolated on broad saddles or benches at elevations of 335 to 580 m (ca. 1100-1900 ft).They are underlain by the basal sandstone member of the Atoka Formation (Pennsylvanian). Soils are deep, poorly drained, slowly permeable,and nearly level. They usually form in siltyor clayey deposits and are underlain by a fragipan. The source of water for these communities is precipitation,which pools generally 0.3 to 0.9 m during the winter for several months. Water levels are considerably lower during the summer, except after periodsof heavy rainfall, and the depressions often lack standing water during the summer.Natural ProcessesThe degree of wetness is variable, largely dependent on precipitation and evapo-transpiration.Community Structure» Upland hydric forests in the Boston Mountains have a semi-open canopy ofmedium height (19-27 m) and generally lack an understory. Vinesten form a tangled thicket near the edge of the saturated soil zone, especially ifheavily disturbed historically by timber practices. Ground coversometimes consists of vines, bryophytes, and mixed sedges or spikerushes, but is generally species-poor.Dominant PlantsQuercus lyrata Walt, and/or Quercus palustris Muenchh. in the overstoryCharacteristic PlantsLiquidambar styraciflua L.,Nyssa sylvatica Marsh., Acer rubrum L.,Fraxinus pennsylvanica Marsh., and species ofSphagnum and Polytrichummoss. Other plants found in association include Cephalanthus occidentalis L., Lyonia ligustrina (L.) DC, Eteocharis obtusa (Willd.) Schultes,Cyperus strigosus L., Carex lurida Wahlenb., Bidens aristosa (Michx.) Britt., and Helenium autumnale L.Distribution and SizetThiscommunity type is known from Johnson, Pope, Madison, and Newton counties and has been reported from Searcy, Van Buren, and;burne counties, all in the Boston Mountain subdivision of the Ozark Natural Division. Ithas also been reported from Magazine Mountain3gan County) in the Arkansas Valley Natural Division. Representative stands are 0.4 ha to 1.8 has in size. Similar upland communities dominatedQuercus phellos L. have been observed in the Arkansas Valley (Cleburne Co.)., the Boston Mountains (Searcy and Van Buren counties), andiOuachita Mountains (Saline and Perry counties). Because additional research is needed to document the species composition, hydrologic rela-ns, and distribution of these upland willow oak forests, they are not discussed further in this paper.Status and Threats¦ Unaltered examples are rare. Threats include timber cutting, artificial drainage, and damming to create year-round wildlifeponds. Two quali-occurrences of this type in Pope County are protected as part of the recently-designated East Fork Wilderness Area.LITERATURE CITEDrWARDIN, L.W., V. CARTER, F. C. GOLET, and E. T. LAROE.1979. Classification of wetlands and deepwater habitats of theUnited States. Office ofBiological Services. Fish and Wildlife Ser-vice, U.S. Dept. of the Interior. Washington, D.C. 103 pp.MUELLER-DOMBOIS, D. and H. ELLENBERG. 1974. Aims andmethods of vegetation ecology. John Wiley &Sons, Inc., NewYork. 547 pp.ORZELL, S. L.1983. Natural area inventory and floristic analysis offens in selected southeastern Missouri counties. Masters thesis.Southern IllinoisUniversity, Carbondale, 111. 203 pp.rRTESZ, J. T., and R. KARTESZ. 1980. A synonymized checklistof the vascular flora of the United States, Canada, and Greenland.Vol. II.The biota of North America. Univ. of North CarolinaPress, Chapel Hill. 498 pp.PELL, P. 1983. The natural divisions of Arkansas: A revised class-ification and description. Natural Areas Journal 3(2):12-23.IEVE ORZELL and BILLPELL, Arkansas Natural Heritage Commission, The Heritage Center, 225 East Markham, LittleRock, AR 72201,iGARY TUCKER, Department of Biological Sciences, Arkansas Tech University, Russellville, AR 72801.143Journal of the Arkansas Academy of Science, Vol. 39 [1985], Art. 43Published by Arkansas Academy of Science, 1985

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Notes on Three Palustrine Natural Community Types in the Arkansas Ozarks

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