Title: Species functional traits and the response of populations to disturbance govern the rate and trajectory of succession, and the functioning of high latitude ecosystems.
1Species functional traits and the response of
populations to disturbance govern the rate and
trajectory of succession, and the functioning of
high latitude ecosystems. Consequently, climate
change will alter successional dynamics and
ecosystem function primarily through its effects
on disturbance regime and on those species that
govern successional/ecosystem processes.
2 Actinorhizal plants 25 genera 220 perennial
dicotyledonous plants (mostly woody) within 8
families (Betulaceae, Casuarinaceae,
Coriariaceae, Datiscaceae, Elaeagnaceae,
Myricaceae, Rhamnaceae, Rosaceae) Associated
with the filamentous actinomycete Frankia
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4Thin-leaf alder (Alnus incana subsp. tenuifolia)
Green alder (Alnus viridis subsp.
fruticosa)
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10Factors that influence plant growth and plant
demand for N, also influence N fixation rates
Climate (temperature, ppt.) Resource supply
(light, water, nutrients) Phenology
ontogeny Disturbance (herbivory)
Plant Growth Rate Plant N Demand (NP
ratio) Nodule production and growth Nitrogenase
activity Whole-plant N2-fixation
rate Ecosystem N Inputs
Autoregulation The down-regulation of nodule
production and nitrogenase activity via a
N-sensitive, phloem-transported signal inhibitor
Plant density Nodule biomass/plant
11Alnus incana subsp. tenuifolia
Alnus viridis subsp. fruticosa
Mitchell and Ruess (in prep)
(Uliassi and Ruess 2002)
N Fixation ? (julian day, soil temperature,
soil moisture)
12Alnus incana subsp. tenuifolia
(Uliassi and Ruess 2002)
13Woolly alder sawfly, Eriocampa ovata
Ruess et al. (submitted)
14Effects of Frankia genetic structure on N
fixation rates
White Spruce Stands
Early Successional Stands
RF Pattern
RF Pattern
Anderson et al. (in prep)
15Phylogeography of Frankia
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17How will alder expansion in the arctic (Sturm et
al. 2001) affect ecosystem function??
pictures stolen from Ken Tape
18Increase in Alnus pollen percentages from 10 to
70 circa 8000-7000 BP.
Hu et al. (2001)
19Mack et al. (2004)
20Mitchell and Ruess (in prep)
21So what's the quick and dirty way to assess N
fixation inputs at the ecosystem scale??
Anderson et al. (2004)
Ruess et al. (submitted)
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23- Research/Monitoring Tasks
- Establish long-term vegetation monitoring plan
for tracking the expansion of alder (low-level
aerial photography). - Among landscapes where alder is know to be
expanding, can we model/predict hot-spots for N
fixation? (e.g. climate, soil P, pH, soil ?15N) - What are the long-term consequences of N inputs
to ecosystem structure and function in landscapes
where alder is expanding? (changes in vegetation
composition, NPP and forage quality soil C and N
stocks watershed biogeochemistry). - Monitor outbreaks of herbivorous insects and
plant pathogens.
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