ON'.rOGENY 01!' ACCJ:DENTAL AND IIYDRJ:C SOJ:L DEVELOPMENT :IN StJRl!'ACE MJ:NED LANDSCAPES by Robert B. Atkinson, W. Lee Daniels, and John Cairns, Jr. Abstract. Reducing conditions are periodically present in hydric and are essential for chemical processes that support functions and values. Indicators of these conditions, i.e., redoximorphic features, can be useful in determining the presence of a hydric . However, young wetlands, i.e., those recently formed, may not possess reducing conditions and/or may not exhibit redoximorphic features. Few studies have addressed the time needed for hydric soil development. In this study, we present data on redoximorphic features, including chroma and oxidized rhizospheres, gathered from two sets of wetlands in southwestern Virginia, including (1) constructed wetlands that are 3 years old and (2) accidental wetlands that are 10 to 30 years old. Under conditions described for these sites, there is strong evidence that discernable redoximorphic features form in accidental wetlands within 10 years, but not within 3 years in constructed wetlands. Since accidental wetlands have been in existence for longer than most man-made wetlands, they provide clues to the development of hydric soils in recently systems. Additional Key Words: litter, hydrophytic vegetation, redoximorphic features, sedimentation, SMCRA, wetlands.

Introduction indicators for "hundreds of years." A more accurate and precise estimate of Small depressions that formed time required for establishment of accidentally following contour surface hydric soil indicators is needed ( 1) mining in southwestern Virginia may to aid in delineation of recently meet all three criteria to be formed wetlands and (2) to aid in considered wetlands, according to the structural and functional assessment Cor s of En ineers Wetlands of constructed wetlands by providing De ineation Manua Environmenta evidence of functions that depend on Laboratory 1987), which is the reducing soil conditions. delineation manual currently in use. According to this manual, accidental Many wetland functions depend wetlands (referred to as "man- upon hydric soils. Hydric soils induced") may not exhibit hydric soil influence decomposition rate (Reddy et al. 1986) and distribution of organic matter (Megonigal and Day 1988), as well as distributions (Pearsall 1Paper presented at the 1996 Annual 1938). Many nutrients and other Meeting of the American Society for chemicals are transformed in wetlands, Surface Mining and Reclamation, including nitrogen (Broadbent and Knoxville, Tennessee, May, 1996. Clark 1965), phosphorus, and iron (Gambrell and Patrick 1978). 2 Rob Atkinson is currently in the Pesticide and metal transformations Department of Biology, Chemistry, and also take place in hydric soils Environmental Science at Christopher ( Gambrell and Patrick 197 8) . Newport University, Newport News, VA Considerable methane is oxidized in 23606. Lee Daniels is in the hydric soils and may influence Department of Crop and Soil atmospheric gas balances (King et al. Environmental Sciences, Virginia Tech, 1990). and John Cairns is in the Department of Biology at Virginia Tech, Under certain conditions, soil Blacksburg, VA 24061. redox potential decreases and hydric

516 soil indicators begin to develop. The Table 1. Indicator categories and rate of oxygen diffusion in soil probability of a plant species decreases by a factor of approximately occurring in a wetland (Reed 1988) 10,000 once a soil becomes saturated (Gambrell and Patrick 1978). Aerobic soil microbes consume organic matter Indicator Wetland and use oxygen preferentially as an Category Frequency electron acceptor. Some oxygen demand can also be attributed to oxidation of reduced elements diffusing up from Obligate anaerobic layers (Simpson 1978). wetland >99% Microbial activity and chemical Facultative transformations continue to occur wetland 67-99% under anaerobic conditions and the Facultative 34-66% redox potential of the soil is Facultative lowered, i.e., reducing conditions upland 1-33% become established (Ponnamperuma Obligate 1972). upland <1% Once reducing conditions become established for sufficient frequency and duration each year, several years Appalachian Mountains prior to may be required for redoximorphic enactment of the Surface Mining features such as low chroma and Control and Reclamation Act of 1977 oxidized rhizospheres (iron oxide (SMCRA). Topographic features left by coatings on fine roots) to develop. mining included vertical "high walls" and fairly flat 11 benches 11 consisting Naturally occurring wetlands of severely compacted spoil with bulk typically exhibit redoximorphic density of 1.7 g/cc (Daniels and Amos features within 25 cm of the surface 1982). Sediment was deposited over or just below the A horizon, which are compacted mine spoil in many small used in wetland delineation (Vepraskas depressions on benches. As a result, 1995). Specifically, matrix chroma wetland hydrology became established must be 1 or less if no color pattern and hydrophytic vegetation colonized (depletions and masses) occurs the depressions (Atkinson and Cairns (Environmental Laboratory 1987; 1994). Over time, these conditions Federal Interagency Committee for led to lowered soil redox potential Wetland Delineation 1989). According and establishment of redoximorphic to the Environmental Laboratory features in the accidental wetlands we ( 1987), wetlands that have been studied. "incidentally created by human activities" are considered "atypical Sites were located in Wise situations." This section states that County in southwestern Virginia. hydric soil indicators may be lacking, Selection criteria included the and delineation may not require that presence of hydrophytic vegetation and hydric soil indicators be present. depressional wetland hydrology and the Thus, assessments of constructed absence of significant acid mine wetlands, including wetlands drainage inputs. Each wetland constructed as mitigation for exhibited two plant community types: destruction of natural wetlands, may (1) a community dominated by obligate not currently consider soil chroma and wetland and (2) a community oxidized rhizospheres for measuring dominated by facultative wetland success. This paper provides plants (Table 1). information on the time required for development of redoximorphic features Year of accidental wetland in small depressions in southwestern formation ranged from 1965 to 1986. Virginia. Maximum water depth in accidental wetlands ranged from 89 cm in site 3 Site Description to 8 cm in site 2 (Table 2). Aboveground biomass estimates in 1994 Accidental Wetlands for the facultative wetland community were 442 g/m2 and were 398 g/m' for the Contour surface mining for coal obligate wetland community. Total disturbed over 385,000 ha in the precipitation over a 7-year period

517 Table 2. Site reference number, hydrology (sources of water, duration dry, and hydrology modifier), and age (year formed) for 12 accidentally formed wetlands in this study

Site Inlets/ Water Draw- Hydrology' Year outlets depth1 down2 formed

1 No/no 40 o.o PEMe 1978 2 Temp/temp 7.9 66 PEMb,a 1986 3 Temp/perm 89 0.0 PEMe 1974 4 No/temp 18 25 PEMc 1974 5 No/no 18 13 PEMc 1973 6 No/temp 62 13 PEMc 1973 7 Temp/temp 20 4.2 PEMd 1983 8 Perm/perm 44 0.0 PEMe 1974 9 Temp/temp 8.4 21 PEMc 1965 10 Temp/temp 60 4.2 PEMd 1970s 11 No/no 32 8.3 PEMd 1970s 12 Temp/temp 73 0.0 PEMe 1970s

1Maximum measured depth in cm 'Percent of three growing seasons without inundation 'Modifiers based on Cowardin et al. (1979) include PEM=palustrine system and emergent class; water regime modifiers include: a=temporarily flooded, b=seasonally flooded, c=semipermanently flooded, d=intermittently exposed, and e=permanently flooded

( 1988 to 1994) in Wise, VA, showed were Echinochloa walteri, Eleocharus significantly low precipitation in obtusa, Scirpus cyperinus, and Typha 1989 and 1993 (Fig. 1). Mean monthly latifolia. maximum temperatures during that period ranged from a low in February The Powell River Project (PRP) of 7°C to a high in July of in Wise County, VA, was the site of 27°C (National Weather Service three constructed wetlands. Cooperative Observer, Wise, VA; Fig. Sedimentation rates were low since 2) • wetland construction occurred after the site had been revegetated with the Most of the adjacent uplands perennial ryegrass Lolium perenne and were characterized by herbaceous various legumes (Fabaceae). Three species, including Festuca elatior, wetlands were also constructed near Lespedeza cuneata, Trifolium repens, Wise, VA. Sedimentation rates were and Solidago gigantea. Terrestrial much higher at this site since wetland vegetation dynamics in the region are construction coincided with final discussed elsewhere by Holl and Cairns grading and preceded revegetation (1994). efforts.

Constructed Wetlands Methods In 1992, six wetlands were Twelve accidental wetlands in constructed at two sites by excavating Wise County, VA, were studied between depressions and creating small berms. 1992 and 1995. Parallel transects and Mean wetland size was approximately 10 permanent plots were established and m x 30 m, and maximum depth was monitored for 3 years. Accidental approximately 1 m. Because of the wetland sampling was conducted within small size, data collection was two communities: (1) a community limited to nondestructive techniques, dominated by obligate wetland plants e.g., vegetation cover estimates and and (2) a community dominated by soil probes. Species with highest facultative wetland plants. modified importance values (sum of Constructed wetland sampling was not relative cover and relative frequency) conducted on a community basis due to

518 200 ~ Ci Cl) + 150 E ~" 0" -~ 100 ·5. ·;:;- ".... "" 0 '"E--

1988 1989 1990 1991 1992 1993 1994 Year

Fig. 1. Annual precipitation totals during a 7-year period (1988-1994) recorded in Wise, VA

30 ".... = 25 -E! 0. " 20 E ~ E-" Ci Cl) =E + 15 E 0u -~ ~ 10 2 " 5 2"

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month Fig, 2. Mean monthly maximum temperatures during a 7-year period (1988-1994) recorded in Wise, VA small dimensions and poorly defined wetland. Soil samples were extracted vegetative zonation. Several by shovel and were broken open parameters were studied and those that manually for inspection. Value and aid in characterizing soils are chroma estimates were made using a described here. wetted sediment sample in full sun using a Munsell Soil Color Chart. Soil value and chroma, Oxidized rhizosphere frequency and prevalence of oxidized rhizospheres, intensity were assessed by visual and presence of iron depletions and inspection. No iron depletions and masses were assessed at a minimum of masses were detected in any soil two plots within each accidental samples in this study, although low wetland community and within the chroma matrices were commonly deeper portion of each constructed described.

519 Water depth at the deepest point matrices and oxidized rhizospheres in each accidental wetland was were common in accidental wetlands; measured biweekly during each growing however, no pattern of iron depletions season from 1992 through 1994. Each and masses was observed in any accidental wetland was assigned a wetlands in this study (Fig. 3). water regime modifier based on the classification scheme set forth in Hydric soil criteria for chroma Cowardin et al. (1979). Elevation in were met in all 12 obligate wetland all plots was measured using a transit communities and 11 of 12 facultative and stadium rod, and the mean of three wetland communities (Fig. 4). A estimates was calculated for each chroma of O was common in the obligate plot. Plot depth was calculated based wetland community of all four on elevation and biweekly water depth accidental wetlands that exhibited estimates. Water depth in constructed permanent inundation and in site 11, wetlands was also measured biweekly. which was inundated throughout the Sediment depth was measured using a study except for July, 1993, during a soil probe penetrated to depth of drought. Only the facultative wetland compacted mine spoils, and the mean of community at site 10 failed to meet three estimates was determined for the chroma criterion of 1 or less. each plot. Grand means were Mean soil chroma in the obligate calculated for each community in the wetland community (0.67; SD 0.70) was accidental wetlands and for each somewhat lower than for the constructed wetland site. Soil facultative wetland community (1.1; SD particle size analyses were conducted 0.68) (Fig. 4). at each accidental wetland and were compared to published data on upland Oxidized rhizospheres were soils that was also collected at PRP present at all accidental wetlands by Daniels and Amos (1982). except site 12. Obligate wetland communities that exhibited chroma Litter estimates were made in greater than O were found to have both communities within the 12 "prevalent and bright" oxidized accidental wetlands in 1994. Litter, rhizospheres. Oxidized rhizospheres including surficial organic material were described as "absent" (sites 8, as well as standing dead biomass, was 10, and 12) or "present and dull" collected in 0.25-m' quadrats, dried, (sites 1, 3, and 11) in obligate and weighed. No quantitative wetland communities that exhibited estimates of litter were made in chroma of 0. Oxidized rhizospheres in constructed wetlands; however, cover the facultative wetland community were estimates were made from 1-m2 quadrats described as "prevalent and bright" along two belt transects in each of for all accidental wetlands except the six constructed wetlands. site 12, which exhibited dense growth of a moss, Sphagnum sp., associated Belowground biomass estimates with negligible mineral material above were made in both communities within compacted mine spoil. the 12 accidental wetlands in 1994. All plant biomass between underlying The duration criterion for compacted mine spoils and the litter wetland hydrology (Environmental layer were collected within O. 25-m' Laboratory 1987) was exhibited by all quadrats. No attempt was made to accidental wetlands except site 2. separate live and dead roots. Water regime modifiers for accidental Material was washed and sieved through wetlands included permanently flooded a #10 seive, dried, and weighed. ( 4 sites) , intermittently exposed ( 3 Because of the small dimensions of sites), semipermanently flooded (4 constructed wetlands, no estimates of sites) , and seasonally flooded (site belowground biomass were made at these 2) (Table 2). After August, 1992, sites. inundation was not detected at site 2, which is the youngest of the 12 Results accidental wetland sites (formed 1986) (Table 2). Precipitation totals Accidental Wetlands for 1993 were the second lowest on record in Virginia (National Oceanic Redoximorphic features were and Atmospheric Administration 1993). present in all 12 accidental wetlands Surface water disappeared from 8 of in this study. Low chroma (1 or less) the 12 accidental wetlands during

520 2.5 Ill! Facultative Wetland D Obligate Wetland I 2 ·C "'E 8 ..c u 1.5 " ·s -Cl) 1 § -

~" 0.5 . "

~ '-- ~ ~~ ~~ 0 -~ '--- '-- '-- -- - ~~ 1 2 3 4 5 6 7 8 9 10 11 12 Accidental Wetlands

Fig. 3. Mean soil chroma for facultative wetland and obligate wetland conununities at 12 accidental wetlands

Jl O .,__ __ (F acu ltative (Obligate Constructed 1987 Wetland) Wetland) Wetlands Delineation Accidental Wetland Communities Manual

Fig. 4. Mean soil chroma for accidental wetlands, constructed wetlands, and maximum according to the 1987 delineation manual

1993, but inundation was reestablished facultative wetland conununities than during the 1993 growing season except for obligate wetland conununities in at sites 2, 4, and 9. Precipitation most sites. Soil saturation may have in 1994 was within the range persisted longer than inundation, but considered normal, and inundation was was not quantified in this study. reestablished at sites 4 and 9, but not site 2. Sediment depth in accidental wetlands differed both among and Hydrology also differed within within the two conununities. Mean accidental wetlands. Mean water depth sediment depth for both conununities in obligate wetland conununities (25 was greatest at site 10, which cm) was 24 cm deeper than mean functioned as a sediment retention facultative wetland conununity water throughout this study. Sediment depth (1 cm) (Fig. 5). Thus, depth exceeded the maximum measured inundation periods were shorter for depth of 80 cm in five of the six

521 80 ,------·- 1 I - L~!ac~ltative Wetland OObligate Wetland j ------' 60 l-- - 40 +--,=------! 20 - a i 0 I ----~ ~ -iT I -20 J -f}-- -- _, 2 3 4 5 6 7 8 9 10 11 12 a=based on I estimate Accidental Wetlands

Fig. 5. Mean water depth from April through September, 1994, for facultative wetland and obligate wetland communities at 12 accidental wetlands

l!IFacultative Wetland OObligate Wetland a

ci'rn + 8 60 ------~----- ~ I 130Cl rn

0 1 2 3 4 5 6 7 8 9 10 11 12 a=based on I estimate Accidental Wetland Sites

Fig. 6. Sediment depth for facultative wetland and obligate wetland communities at 12 accident wetland sites plots where measurements were taken at cm compared to 23 cm for obligate site 10. Mean sediment depth was wetland communities (Fig. 6). lowest at site 6 for both the Particle size analyses for accidental facultative wetland (6 cm) and wetlands indicated a significantly obligate wetland (14 cm) communities. higher percent clay (31%) than that In 10 of the 12 accidental wetlands, for upland areas (15%). Silt content obligate wetland sediment depth in accidental wetlands (58%) was also exceeded that for the facultative somewhat higher than that for uplands wetland. Median sediment depth for (41%) (Fig. 7). facultative wetland communities was 13

522 80.------;=~~~~~~~~~~~ ll!lAccidental Wetlands OUplands ! 60 ------·--··· ---·-

40 -·-

20 ···----

0 Sand Silt Clay Particle Size

Fig. 7. Particle size analysis for accidental wetlands (this study) and for uplands at the Powell River Project (Daniels and Amos 1982) 1800-r--;======:::;-~~~~~~,=--~---i 5 1600 . -~ fill F~~~~ative Wetland D 0-~~ate_'.Vetland I __ Cl) ·--- + 1400 --·- -- 1200 -··- - - --·-- ---·-··--·------a------· ----- .:g, 1000 - ~ 800 c 600 Q 400 200 0 2 3 4 5 6 7 8 9 IO 11 12 a=based on I estimate Accidental Wetland Sites Fig. 8. Mean dry weight of litter for facultative wetland and obligate wetland communities at 12 accidental wetlands

Mean litter content in fa cul tati ve wetland plant community. accidental wetlands was 621 g/m2 in Belowground biomass in accidental 1994. Facultative wetland litter wetlands was higher in the facultative 2 content (730 g/m ) was significantly communities, 442.5 g/m2 , than in greater than litter content in obligate wetland communities, 398.4 obligate wetland communities (514 g/m'. Site 2 was the most recently g/m') . Litter content was lowest in formed accidental wetland (1986) and 2 ·site 8 (184 g/m ), which was found to exhibited the lowest mean belowground have the highest diversity and biomass in the facultative wetland abundance of aquatic community (135.2 g/m') (Fig. 9). macroinvertebrates (Jones 1995; Fig. 8). Constructed Wetlands

Dense root mat formations with Soil chroma was 3 to 4 in all negligible accumulated mineral six newly constructed wetlands in this material were common in the study. In all three constructed

523 1200-r;:::======::::-~~~~~~~~~~~~~~~--, lmFacultative Wetland[ a 1000 --'~obligate Wetland i 6'

600 --

400 --

200

0

2 3 4 5 6 7 8 9 10 11 12 a=based on I estimate Accidental Wetland Sites

Fig. 9. Mean dry weight of biomass (belowground) for facultative wetland and obligate wetland communities at 12 accidental wetlands

wetlands near Wise, VA, oxidized this study. Oxidized rhizospheres may rhizospheres were present, but were form more quickly. They were described as "infrequent and dull." described as "present and dull" in two No oxidized rhizospheres were found in of the newly constructed wetlands. the three constructed wetlands at PRP. Mean vegetative cover (68%) was The minimum time required for significantly greater at the Wise development of low chroma is probably constructed wetlands than at the PRP even shorter, since site 2 failed to constructed wetlands (9%). exhibit inundation during or after drought conditions began in spring Sediment depth in constructed 1993; and, since precipitation in 1989 wetlands was significantly different was even lower than for 1993 in Wise among the PRP and Wise constructed County (National Weather Service wetlands. The mean sediment depth for Cooperative Observer, Wise, VA), site PRP constructed wetlands was 5. 8 cm 2 probably was not inundated in 1989. compared to 19.3 cm for the Wise constructed wetlands (Fig. 10). The issue of low chroma color development in these materials is Discussion complicated by the fact that some of the mine spoil strata encountered are The hydric soil criteria for reduced and gray when mined and chroma (1 or less) and, to a lesser freshly deposited (Daniels and Amos extent, oxidized rhizospheres 1981). However, these reduced (Environmental Laboratory 1987) were sandstones and silts tones are met by both facultative and obligate typically chroma 2 or higher, and wetland communities in all 12 weathering for even a few years raises accidental wetlands, including site 2. the matrix chroma to 3 or 4 under well Since site 2 was formed in 1986, one drained conditions. Thus, the higher can infer that a low soil chroma can chroma sediment colors observed in the be exhibited in less than 10 years constructed wetlands corroborates our after a depression becomes assumption that the low chromas (<1.0) established. The minimum time observed in the accidental wetlands we required for chroma of 1 to be surveyed reflect the development of exhibited within small depressions is hydric soil conditions rather than greater than 3 years, based on the simple preservation of relic parent survey of six constructed wetlands in material colors.

524 30

oen 25 ---·· ------·- ····--.--- + I 20 t 15 ------· ------·--·-----·---- 0 ij 10 s 5 iien 0 PRP I PRP2 PRP3 Wise I Wise2 Wise3 Constructed Wetland Sites

Fig. 10. Mean sediment depth in constructed wetlands at two sites, Power River Project (PRP) and near Wise, VA (Wise)

Mitsch and Gosselink (1993) list and Amos 1981), which may have limited three conditions for establishment of infiltration rates. Constructed low chroma: (1) sustained anaerobic wetlands at PRP failed to form an conditions, ( 2) sufficient organic impervious layer in the first 2 years matter to support microbial activity, after construction, and there was and (3) adequate soil temperature. considerable fluctuation in water These conditions were met to differing depth. The shrink-swell extents in all 12 accidental wetlands characteristics of sediments appeared and influence the time required for to permit infiltration following development of hydric soil indicators. drawdown events. Wetland hydrology, especially Vepraskas and Wilding (1983) the duration of inundation, appeared noted that soils saturated for 120 to influence soil chroma. Sites days failed to show chroma below 3 having permanently flooded water when organic matter content was less regimes were found to exhibit lower than 1%. Organic matter was measured chroma than sites with either in both litter and belowground biomass intermittently exposed or compartments for both communities in semipermanently flooded conditions the 12 accidental wetlands. The (Fig. 11). Water depth did not appear supply appears to be ample to support to influence chroma, except for the microbial metabolism, but may have fact that deeper portions of a wetland been limiting during early stages of may be inundated for longer periods of wetland development. There are two time. For example, facultative possible roles for organic matter in wetland communities were not inundated hydric soil development in accidental for as long as the associated obligate wetlands. First, organic matter is wetland communities and exhibited required for microbial metabolism, higher chroma. which leads to iron reduction and lower chroma. Organic matter may have The actual duration of wetland been available early in accidental hydrologic conditions cannot be wetland development since wind quantified for the accidental wetlands dispersed seeds, e.g., Typha latifolia since there is no data to indicate how and Scirpus cyperinus, could colonize much time was required for an sediments quickly. impervious layer to form. Particle size analysis in accidental wetlands Second, the water holding indicated a significantly higher clay effects of organic matter can increase content when compared to spoil the duration of soil saturation. material on upland benches (Daniels Since accidental wetlands form in

525 3 100 lill'/ll!IDFacultative Wetland

~ Ci c::::JObligate Wetland 75 C: ~ "'+ 0 C: ., 2 0 E 'i .,~ "O

0 0 Pennanently Intennittently Semipennanently Seasonally flooded exposed flooded flooded

Water Regime a=based on one site

Fig. 11. Soil chroma for four accidental wetlands arranged by water regime (based on Cowardin et al. 1979) small depressions, export of organic with sediment that supports color matter is low. Since mean accidental development and provides an indication wetland litter content was high (621 of oxidation and reduction processes. g/m2 in 1994), absence of inundation for short periods during the growing Other Hydric Soil Indicators season may not have led to significant soil aeration. Macroinvertebrates Oxidized rhizospheres were found were abundant in some accidental to be "prevalent and bright" in most wetlands (e.g., site 8), but they accidental wetlands. The ability of should not inhibit development of hydrophytes to aerate the soil hydric soil indicators for several adjacent to roots has been described reasons. By reducing the detritus for many species (Conway 1940, size and increasing surface area, Bartlett 1961, Armstrong and Boatman macroinvertebrates facilitate 1967). The two communities found in microbial action. The faster accidental wetlands in this study were mineralization of nutrients should identified based on the dominant also yield greater primary species. The obligate wetland productivity and organic matter community was dominated by species accumulation. which occur in wetlands >99% of the time, and the facultative wetland Thus, sedimentation appears to community is dominated by species that play an important role in accidental occur in wetlands 67-99% of the time wetland formation and development. (Reed 1988). Sediment deposition can influence hydrology by creating an impervious oxidized rhizospheres were layer that establishes inundation. missing under three distinct Sediment provides a substrate for conditions observed in this study. seeds of hydrophytes and a plant First, oxidized rhizospheres were growing medium. If plant growth either lacking, infrequent, or dull in provides adequate litter following the six newly constructed wetlands. senescence, there will be sufficient Oxidation of iron adjacent to roots of substrate to support microbial hydrophytes appears to require time to metabolism and adequate water holding become visible. Bartlett (1961) capacity to limit diffusion of oxygen. extracted reduced iron from soil to In addition, it is the supply of iron show that some iron oxidizes around

526 the surface of roots during a single have occurred in the last 10 years, growing season, but did not address and monitoring has been limited. the establishment of a visible layer Accidental wetlands provide an age of oxidized iron around roots. class from 10 to 30 years post Second, oxidized rhizospheres were formation and provide clues to absent or dull in obligate wetland depressional wetland ontogeny. In communities that exhibited a particular, redoximorphic features, permanently flooded water regime. including low chroma matrices and Oxygen may have been released by roots oxidized rhizospheres, were formed more slowly at these greater depths, within this time period. Newly and, since oxygen and redox potential constructed wetlands showed that decreases with depth, oxygen may be certain hydric soil indicators, i.e., consumed more quickly under these oxidized rhizospheres, can form within conditions. Third, oxidized 3 years. rhizospheres were absent at the facultative wetland community in site Literature Cited 12. This community exhibited high organic matter content and negligible Armstrong, W., and D. J. Boatman. mineral material; thus, iron was 1967. Some field observations probably not available for oxidation. relating the growth of plants to conditions of soil There was no evidence of iron aeration. Journal of Ecology 55: depletions and masses in this study. 101-110. These features either have not had sufficient time to form, or conditions Atkinson, R. B., and J. Cairns, Jr. are not conducive to mottle 1994. Possible use of wetlands development. Color patterns in ecological restoration of associated with iron depletions and surface mined lands. Journal of masses become established where water Health 3: 139- levels fluctuate (Ponnamperuma 1972). 144. The absence of these color patterns may, therefore, be a result of stable Bartlett, R. J. 1961. Iron oxidation water tables in the small depressions, proximate to plant roots. modulated by litter content and slow Vermont Agricultural Experiment infiltration rates. Station, Journal Series Paper No. 99. University of Vermont. Soil temperature was not measured in this study, but several Broadbent, F. E., and F. Clark. 1965. years of temperature data were Denitrification, p. 344-359. In: obtained from the local Climatological Soil nitrogen, W. V. Observer in Wise, VA. Mean monthly Bartholemew, and F. E. Clark, maximum temperatures ranged from a low eds. American Society of in February of 7°F to a high in July of Agronomy, Madison, WI. 27°F). Since water depth in the accidental wetlands ranged from 8 to Conway, V. M. 1940. Aeration and plant 89 cm, light penetration to the bottom growth in wet soils. The seems likely. However, vegetative Botanical Review 6(4): 149-163. cover of Typha latifolia was extensive in many obligate wetland communities, Cowardin, L. M., V. Carter, F. c. and shading could reduce soil Golet, and E. T. LaRoe. 1979. temperatures. It appears that the 12 Classification of wetlands and accidental wetlands were in similar deepwater habitats of the United geographic and topographic positions States. US Fish and Wildlife and would experience similar soil Service, FWS/OBS-79-31, temperatures; however, future studies Washington, DC. should monitor soil temperature. Daniels, W. L., and D. F. Amos. 1981. Conclusion Mapping, characterization and genesis of mine soils on a Wetland construction has reclamation research area in increased in the United States Wise, VA, p. 261-275. In: following implementation of Section Proceedings of the 1981 404 of the Clean Water Act (1977). Symposium on Surface Mining However, most construction attempts Hydrology, Sedimentology, and

527 Reclamation. University of Megonigal, J.P., and F. P. Day. 1988. Kentucky, Lexington. Organic matter dynamics in four seasonally flooded forest Daniels, W. L., and D. F. Amos. communities of the Dismal . 1982. Generating productive American Journal of Botany topsoil substitutes from hard 75 (9): 1334-1343. rock overburden in the southern Appalachians. Environmental Mitsch, w. J., and J. G. Geochemistry and Health 7: 8-15. Gosselink. 1993. Wetlands, 2nd ed. van Nostrand Reinhold, New Environmental Laboratory. 1987. York, NY. Corps of Engineers Wetlands Delineation Manual, Tech. Rep. Pearsall, W. H. 1938. The soil Y-87-1, US Army Engineer complex in relation to plant Waterways Experiment Station, communities. Journal of Ecology Vicksburg, MS. 26: 180-209. Federal Interagency Committee for Ponnamperuma, F, N. 1972. The Wetland Delineation. 1989. chemistry of submerged soils. Federal manual for identifying Advances in Agronomy 24: 29-96. and delineating jurisdictional wetlands. US Army Corps of Reed, P. B., Jr. 1988. National Engineers, US EPA, US Fish and list of plant species that occur Wildlife Service, and USDA Soil in wetlands: Virginia. US Fish Conservation Service, and Wildlife Service, st. Washington, DC. Petersburg, FL. Gambrell, R. P., and W. H. Reddy, K. R., T. c. Feijtel, and w. Patrick. 1978. Chemical and H. Patrick, Jr. 1986. Effect of microbiological properties of soil redox conditions on anaerobic soils and sediments, microbial oxidation of organic p. 375-423. In: Plant life in matter, p. 117-156. In: The role anaerobic envi"ronments, D. D. of organic matter-in modern Hook, and R. M. M. Crawford, agriculture, Y. Chen, and Y. eds. Ann Arbor Science Avnimelech, eds. Martinus Publishers Inc., Ann Arbor, MI. Nijhoff Publishers, Dordrecht, The Netherlands. Holl, K. D., and J. Cairns, Jr. 1994. Vegetational community Simpson, T. W. 1978. Soil development on reclaimed coal morphologic and hydrologic surface mines in Virginia. changes associated with Bulletin of the Torrey Botanical wastewater irrigation. Ph.D. Club 121(4): 327-337. dissertation, Pennsylvania State University, University Park, PA. J o n e s , D . H . 1 9 9 5 . Macroinvertebrate richness and Vepraskas, M. J. 1995. Redoximorphic abundance of accidental wetlands features for identifying aquic on surface mines, Masters conditions. North Carolina Thesis, Department of Biology, Agricultural Research Service Virginia Polytechnic Institute Tech. Bull. 301, North Carolina and State University. State University, Raleigh, NC. Blacksburg, VA. Vepraskas, M. J., and L. P. King, G. M., P. Roslev, and H. Wilding. 1983. Aquic moisture Skovgaard. 1990. Distribution regimes in soils with and and rate of methane oxidation in without low chroma colors. Soil sediments of the Florida Science Society of America Everglades. Applied and Journal 47: 280-285. Environmental Microbiology 56(9): 2902-2911.

528