Geoscience Reference
In-Depth Information
from.low.elevations.over.the.previous.decades.(C.D..Thomas,.pers..comm.;.
R.J..Wilson.and.D..Gutiérrez,.pers..obs.).
4.
Changes to species composition
.. Uphill. shifts. in. species'. ranges. imply.
elevational.changes.to.species.richness.and.composition,.and.many.studies.
have.identiied.systematic.changes.of.this.kind.(Table 6.1)..Measurements.
of. the. cover. of. different. alpine. plants. show. that. species. associated. with.
low. elevations. are. increasing,. and. in. some. cases. species. associated. with.
high.elevations.are.becoming.less.abundant.(Keller.et.al..2000;.Klanderud.
and.Birks.2003;.Pauli.et.al..2007;.Vittoz.et.al..2008)..Faunal.studies.show.
declines. in. the. distribution. or. abundance. of. species. associated. with. high.
elevations,.and.increases.or.no.change.in.species.associated.with.low.eleva-
tions.(Pounds.et.al..1999;.Moritz.et.al..2008;.Rovito.et.al..2009)..Two.stud-
ies. have. quantiied. these. elevational. changes. in. community. composition..
There.was.an.uphill.shift.of.42.m.in.the.mean.elevational.associations.of.
moth.species.per.sampling.location.on.Mount.Kinabalu.(Borneo).between.
1965.and.2007.(Chen.et.al..2009)..This.upward.shift.was.rather.less.than.
that.reported.for.individual.species,.for.two.probable.reasons:.irst,.species.
that.had.colonized.the.sampled.elevations.from.below.by.the.second.survey.
could.not.be.included.in.the.analysis;.second,.upper.elevation.expansions.
were.truncated.by.the.tops.of.the.mountain,.or.by.the.upper.elevation.lim-
its.of.moths'.larval.host.plants..Butterly.community.composition.in.cen-
tral.Spain,.quantiied.using.multivariate.statistics,.shifted.uphill.by.290.m.
between.1967-1973.and.2004-2005,.as.isotherms.shifted.upward.by.
c.
225.
m.(Wilson.et.al..2007).
IDENTIFICATION OF UPHILL RANGE SHIFTS
Studies.of.changes.to.species'.ranges.have.employed.historical.baseline.data.that.
were.collected.for.a.variety.of.reasons,.using.a.variety.of.approaches..As.a.result,.
means.to.account.for.changes.to.sample.effort.may.be.required.(e.g.,.Rowe.2005;.
Tingley. and. Beissinger. 2009).. Where. point. counts. or. quadrats. have. been. estab-
lished,.these.can.be.repeated.with.the.same.sampling.effort.(e.g.,.Archaux.2004;.
Pauli.et.al..2007)..But.in.many.other.cases.repeat.surveys.designed.to.detect.cur-
rent. species. distributions. are. likely. to. employ. more. rigorous. sampling. protocols.
and. greater. sampling. effort,. and. sampling. effort. may. increase. most. at. relatively.
inaccessible.high.elevations..Recent.atlas.surveys.may.also.include.larger.numbers.
of. distribution. records. than. historical. data. (Hill. et. al.. 2002).. Simply. based. on.
increases.in.sampling.effort,.range.extensions.should.be.expected.at.both.high-.and.
low-elevation.limits.(Shoo.et.al..2006)..Therefore,.techniques.must.be.employed.to.
ensure.that.reported.uphill.range.expansions.are.independent.of.sampling.bias.and.
that.increased.sampling.effort.does.not.obscure.low-elevation.contractions..Most.
commonly,.data.from.more-intensive.(usually.recent).surveys.have.been.subsam-
pled.so.that.the.total.number.of.samples.from.each.site,.region,.or.elevation.inter-
val.are.the.same.in.both.surveys.(Hill.et.al..2002;.Wilson.et.al..2005,.2007;.Lenoir.
et.al..2008;.Raxworthy.et.al..2008;.Chen.et.al..2009)..Alternatively,.analyses.have.
been. restricted. to. abundant,. widespread,. or. well-recorded. taxa. in. both. surveys.
