Role of Phytotoxin Tolerators

and Hyperaccumulators in

Plant Community Ecology Chuck Casper

BZ 572 Phytoremediation

12/4/2012

http://home.howstuffworks.com/define-

sunflower.htm

http://www.ndsu.edu/pubweb/famulari

_research/commonSearch.php?plant

_letter=R

http://www.wnmu.edu/academic/nsp

ages/gilaflora/kochia_scoparia.html

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

http://tourismplacesworld.blogspot.com/2011/06/acid-lake-rio-tinto-in-spain.html

Rio Tinto, Spain

Robson et al. 2004

Comparison of

hydrocarbon

contaminated site

with

uncontaminated

site

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.ehleringer.net

http://www.wildflower.org

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,

diversity lower

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

http://www.greateryellowstonescience.org/topics/scien

cemanagement/tools/thresholds

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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

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Gallagher, F.J., Pechmann, I., Holzapfel, C., Grabosky, J. 2011. Altered vegetative assemblage trajectories within and urban brownfield.

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