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http://home.howstuffworks.com/definesunflower.htm http://www.wnmu.edu/academic/nsp ages/gilaflora/kochia_scoparia.html Role of Phytotoxin Tolerators and Hyperaccumulators in Plant Community Ecology Chuck Casper BZ 572 Phytoremediation 12/4/2012 http://www.ndsu.edu/pubweb/famulari _research/commonSearch.php?plant _letter=R Presentation outline 1) Plant community development a) differences on phytoxic sites 2) Mechanisms influencing plant community dynamics a) Plant-Plant interactions (+ and -) b) Regeneration and reproduction i) seed dispersal mode ii) reproduction method http://www.downtoearth.org.in/content/just-forest http://www.rustyparts.com Metals and organic compounds alter successional dynamics • • • • Many articles report significant differences in the initial colonization of bare ground on contaminated and uncontaminated sites “Pioneer” species differ Rate of colonization or succession slowed, even inhibited on contaminated sites Perhaps evidence for multiple stable states theory http://www.iteachbio.com/Life%20Science/life.htm Early seral or “pioneer” species The first species to colonize site devoid of vegetation, thought to facilitate other species, ameliorate conditions to allow establishment of future species Phytotoxic compounds inhibited invasion by Chinese Tallow, willow, rattlebrush, and salt cedar which are typical early seral or pioneer species. (Olson and Fletcher 2000) Grasses planted for restoration were weak, died when soil eroded, did not spread to bare unrestored plots Unintroduced grasses were more vigorous and spreading 2 reasons plants can not colonize bare tailings 1) substrate lacks the appropriate microbiota such as mycorrhizae 2) vegetative reproduction is much slower than by seed Ryszka and Turnau 2007 Plant community characteristics 40 years post-disturbance urban brownfield contaminated w/ As, Cd, Cr, Cu, Pb, Zn, V Betula populifolia, Populus deltoides occurred on areas of increasing soil metal load Other species like emergent marshes restricted to areas with low soil metal loads B. populifolia, P. deltoides accumulate Zn in leaf tissue at extremely high levels Leaf litter re-deposits Zn, creates potential feedback loop maintaining dominance by B. populifolia and P. deltoides Gallagher et al. 2008, Gallagher et al. 2011 Pb/Zn tailing 1-30 years old in Poland Highest grass diversity on oldest plots Ryszka and Turnau 2007 Pb/Zn tailings in China 4 separate community types, with diversity increasing with time Wang et al. 2011 Community Composition Former industrial sludge basin contaminated by PAHs in Texas The three most prominent species based on area of ground covered were mulberry tree (36%), Bermuda grass (19%), and sunflower (9%), accounting for 64% of the total cover on the basin (known accumulators) Composition much different from disturbed but uncontaminated site Olson and Fletcher 2000 Site polluted with Pb, Cd, Zn and sulphur dioxide since 15th century Species number increased with distance from pollution source (proxy for time) Willow were the only woody species present at the most degraded plots (known accumulator) Regvar et al. 2006 Composition cont’d River valley in Spain w/ high pH (2.3 avg) and heavy metal concentration, mining over 5,000 years (Fe, Cu, Zn, As, and Pb) Species richness decreases as degradation stage advances Flora comprised of Fe, Cu, Zn, Ni, and Pb excluders Rufo and de la Fuente 2010 Rio Tinto, Spain http://tourismplacesworld.blogspot.com/2011/06/acid-lake-rio-tinto-in-spain.html Comparison of hydrocarbon contaminated site with uncontaminated site Robson et al. 2004 Robson et al. 2004 Altered development trajectory After 20 years of natural and artificial rehabilitation of Pb/Zn minelands (China) naturally invaded species were mostly herbaceous (69.4% of total) especially from Poaceae and Asteraceae families Succession theory predicted different community type Li et al. 2007 Pb/Zn mine waste in Wisconsin Species composition changes with mine age, but successional change in vegetative cover is minimal The relative proportion of open and closed turf communities does not change significantly with time Kimmerer 1989 Croplands unsuitable b/c heavy metal contamination in China One species pioneers and dominates croplands up to 13 years after abandonment Zhang et al. 2012 Slowed or inhibited succession Rio Tinto, Spain In unaltered areas vegetation progresses toward steady plant community or climax vegetation while slowed or inhibited on altered sites Rufo and de la Fuente 2010 Abandoned mine sites France, high levels of Zn, Pb, Cd, As, TI 700 year old, 100 year old, and 10 year old sites Oldest site still not colonized by trees even though surrounded by Castanea sativa (chestnut) forest In other nearby sites such as abandoned vineyards, bare soil is colonized by annuals and eventually trees within a century Escarre et al. 2011 Question 1 How is succession or plant community development different on phytotoxin contaminated sites? Positive interactions Soils highly polluted with Zn, Cd, and Pb + interaction b/t Fabaceae anthyllis, and two grasses F. anthyllis regeneration highest when planted w/ grass grass cover provides shade facilitating F. anthyllis germination Facilitation is critical to early succession in this area, phytostabilization is most effective when legumes and grasses planted together. Frerot et al. 2006 Zn and Pb tailings 1-30 years old in Poland Unintroduced grasses were more vigorous, spread faster, produced more litter Facilitation- Natural colonizers promote development of soil organic matter, a crucial factor in establishment of other plants Ryszka and Turnau 2007 http://www.flickriver.com/photos/stationalpinejosephfou rier/sets/72157603314028697/ Positive interactions cont’d Increased application of heavy metals altered competition Increased uptake of Zn by one species reduced the negative effect of that metal on the target species Highest concentration of Ni mitigated competive effect of Salix caprea on Carex angustifolia Salix caprea attenuated negative effect of Zn on Centaurea flava Medium Zn application enhanced competitive ability of Salix caprea on Carex angustifolia Could improve remediation capacity with species mixtures instead of monocultures Niche space filled Koelbener et al. 2008 Facilitation Selenium hyperaccumulators Higher soil Se concentration limits growth of Se sensitive species-reduces competition Facilitate Se tolerant species through reduced herbivory (El Mehdawi et al. 2011) http://www.wildflower.org http://www.ehleringer.net Regeneration and reproduction Site polluted with Pb, Cd, Zn and sulphur dioxide since 15th century Grasses propagated and colonized mostly vegetatively not via seed. Regvar et al. 2006 Self pollinating species more common on contaminated sites Seed dispersal via birds is lower, birds less likely to visit sites with low plant cover Robson et al. 2004 Pb/Zn tailings Colonization depended on rhizome strategy Wang et al. 2011 Question 2 What reproductive strategy is common on disturbed sites contaminated with phytotoxins? Conclusions Phytotoxin contamination=altered developmental trajectories Succession slowed or inhibited Community composition is different, http://www.greateryellowstonescience.org/topics/scien diversity lower cemanagement/tools/thresholds Facilitation more likely a driver than competition Evidence for multiple stable states theory? Better understanding of ecology of contaminated sites can yield more effective phytoremediation strategies http://www.williamscreekmgt.com/gallery/installation/keyston e-enterprise-park-phytoremediation References Bizecki-Robson, D., Knight, J.D., Farrell, R.E., Germida, J.J. 2004. Natural revegetation of hydrocarbon-contaminated soil in semi-arid grasslands. Canadian Journal of Botany. 82, 22-30 Escarre, J., Lefebvre, C., Raboyeau, S., Dossantos, A., Gruber, W., Marel, J.C.C., Frerot, H., Noret, N., Mahieu, S., Collin, C., Van Oort, F. 2011. Heavy Metal Concentration Survey in Soils and Plants of the Les Malines Mining District (Southern France) Implications for Soil Restoration. Water Air and Soil Pollution. 216, 485-504 El Mehdawi, A.F., Quinn, C.F., Pilon-Smits, E.A.H. 2011. Selenium Hyperaccumulators Facilitate Selenium-Tolerant Neighbors via Phytoenrichment and Reduced Herbivory. Current Biology 21, 1440-1449 El Mehdawi, A.F., and Pilon-Smits,E. A.H. 2012. Ecological aspects of plant selenium hyperaccumulation. Plant Biology 14, 1-10 Frerot, H., Lefebvre, C., Gruber, W., Collin, C., Dos Santos, A., Escarre, J. 2006. Specific interactions between local metallicolous plants improve the phytostabilization of mine soils. Plant and Soil. 282, 53-65 Gallagher, F.J., Pechmann, I., Bogden, J.D., Grabosky, J., Wies, P. 2008. Soil metal concentrations and vegetative assemblage structure in an urban brownfield. Environmental Pollution, 153, 351-361 Gallagher, F.J., Pechmann, I., Holzapfel, C., Grabosky, J. 2011. Altered vegetative assemblage trajectories within and urban brownfield. Environmental Pollution. 159, 1159-1166 Kimmerer, R.W. 1989. Environmental Determinants of Spatial Pattern in the Vegetation of Pb-Zn Mines in Southwestern Wisconsin. American Midland Naturalist. 121, 134-143 Koelbener, A., Ramseier, D., Suter, M., 2008. Competition alters plant species response to nickel and zinc. Plant Soil. 303, 241-251 Li, M.S., Luo, Y.P., Su, Z.Y. 2007. Heavy metal concentrations in soils and plant accumulation in a restored manganese mineland in Guangxi, South China. Environmental Pollution. 147, 168-175 Olson, P.E., and Fletcher, J.S. 2000. Ecological Recovery of Vegetation at a Former Industrial Sludge Basin and its Implications to Phytoremediation. Environmental Science and Pollution Research. 7, 195-204 Regvar, M., Vogel-Mikus, K., Kugonic, N., Turk, B., Batic, F. 2006. Vegetational and mycorrhizal successions at a metal polluted site: I ndications for the direction of phytostabilization? Environmental Pollution. 144, 976-984 Rufo, L., and de la Fuente, V. 2010. Successional Dynamics of the Climatophile Vegetation of the Mining Territory of the Rio Tinto Basin (Huelva, Spain): Soil Characteristics and Implications for Phytoremediation. Arid Land Research and Management. 24, 301327 Ryszka, P., and Turnau, K., 2007. Arbuscular mycorrhiza of introduced and native grasses colonizing zinc wastes: implications for restoration practices. Plant Soil. 298, 219-229 Wang, J., Zhang, C.B., Ke, S.S., Qian, B.Y. 2011. Different spontaneous plant communities in Sanmen Pb/Zn mine tailings and their effects of mine tailing physico-chemical properties. Environmental Earth Science. 62, 779-786 Zhang, C., Lie, G., Xue, S., Xiao, L., Ma, H., 2012. Rhizosphere Characteristic of Available Trace Elements During the Succession on Abandoned Croplands in the Loess Plateau, China. Soil Science. 177, 619-627