How will rapid climate change affect species and ecological communities?

• Species phenology and growth • Phenotypic expression of species • Species’ population dynamics • Gene frequencies in populations (evolution) • Species distributions • Species interactions • Disturbance processes and community dynamics • Ecosystem structure and dynamics

Biomes: global patterns of plant response to climate • Biomes are general ecosystem types that occur under a particular climate regime, and exhibits characteristic vegetation structure, community organization, and ecosystem processes.

Cold needle-leaved woodland (lodgepole pine) and cold shrub steppe (Great Basin sagebrush), Yellowstone National Park, 24 years after fire

Boreal needle-leaved evergreen forsst Montane tropical broadleaved evergreen forest Temperate deciduous broadleaf forest Humid tropical broadleaved evergeeen forest

The Mediterranean Biome SW Australia CA Crete

Climate and Terrestrial Biomes, circa 1960 R. Whittaker

Biomes, circa 2000:Coupled vegetation-climate interactions at the global scale Bonan et al. Global Change Biology 2003

Temperature and biological patterns

• Species and community range limits • local distribution patterns • population age structure • genetic differentiation • ecosystem processes

Physical Constraints on organisms

• Microclimate – Radiation – Temperature – Energy – Water & humidity • Nutrients • Toxins • Mechanical stress Dresig. 1980. Oecologia.

Climate and Habitat

• Habitat is “the resources and conditions present in an area that produce occupancy” (Hall et al. 1997. Wildlife Soc. Bull. 25: 173-182) • Climate space – radiation, wind, temperature, humidity • Microclimate

Post et al. Science, September 2009

Nemani RR, White MA, Cayan DR, Jones GV, Running SW, Coughlan JC, Peterson DL

Asymmetric warming over coastal California and its impact on the premium wine industry. Climate Research Nov 01.

Janzen, F.J. Proc. Nat. Acad. Sci. 1994. ages/Species/Turtles/paintedhead.jpg

Heat balance of an animal

Energy balance of an organism

M + Q a =


+ C +  E + G + X M Q a


C  E G X Metabolic energy absorbed radiation emitted radiation energy exchanged by convection latent heat energy energy exchanged by conduction net energy loss or gain

Some considerations in bioclimatology of animal species • Endotherms vs. ectotherms – 99.9% of species are ectotherms that rely primarily on external sources for body heat • Behavior – Diurnal vs. nocturnal – Fossorial, semi-fossorial vs. non-fossorial – Hibernation, torpor • Nutritional status • Age and stage of development

Climate space (“Fundamental niche”) modeling • Organism – Body mass – Voluntary min and max T – Selected body T – Latent heat transfer rate – Resting metabolic rate – Degree days for egg development • Environment – Solar radiation – Wind profile – Air Temperature profile – Relative humidity – Soil temperature profile

Scales of environmental temperature variation

• Global • Regional – Land/water – Elevation • Local – Slope angle and aspect • Microsite – Vegetation canopy, soil moisture, etc.

Bay checkerspot butterfly

Murphy and Weiss (1992) Chapter 26 in Global Warming and biological diversity, ed. R. L. Peters and T. E. Lovejoy. Castleton, New York: Hamilton Printing.

Climate change and plant species

• Temperature • Soil water balance • Carbon dioxide • Dispersal and adaptation Wollemia nobilis

Climate and Photosynthesis

• Photosynthesis 6 CO 2 + 6 H 2 O ----sunlight----> C 6 H 12 O 6 + 6 O 2 • Rate controlling factors – Radiation – Temperature – Water – Carbon dioxide – Nutrients (nitrogen)

Photosynthesis and plant water balance

Absorption depends on :

soil water soil water osmotic potential root osmotic potential soil temperature, oxygen

Transpiration depends on :

leaf water, temp.

air temp, humidity leaf shape, resistance

H 2 O



CO 2 response curve of photosynthesis • Diffusion limitation affected by stomata • Biochemical limitation affected by light/enzymes • Plants equalize physical and biochemical limitations

Inherent tradeoff between CO 2 gain and H 2 O loss

Influence of different parameters on the efficiency of the carbon dioxide uptake (ordinate) of a C 3 and a C 4 plant (

Atriplex rosea

plant (

Atriplex patula

, yellow line) , green line). Measured parameters (from left to right): light intensity, leaf temperature and concentration of carbon dioxide within the intercellular space (according to O. BJÖRKMAN and J. BERRY, 1973).

Water use efficiency

• C3 plants 1-3 g CO 2 intake / kg H2 0 loss 20-35 ° C optimal temperature • C4 Plants 10-40 g/kg 30-45 C • CAM Plants 20-40+ g/kg 20-35 C


• Photosynthesis usually measured in units of moles carbon/leaf area/time (usually reported as net photosynthesis) • Gross Primary Production (GPP) is a measure of photosynthetic activity – carbon uptake per ground area per time – Around 50% of GPP is used in respiration • Net primary production (NPP) = GPP – Respiration – Net carbon (or biomass) per ground area per time • Net ecosystem production (NEP) measures change in total organic matter per area per time – NEP = GPP – Respiration of Autotrophs and Heterotrophs

Components of NPP Components of NPP % of NPP

New plant biomass Leaves and reproductive parts (fine litterfall) Apical stem growth Secondary stem growth New roots Root secretions Root exudates Root transfers to mycorrhizae Losses to herbivores, mortality, and fire Volatile emissions 0-5 40-70 20-40 1-40 10-30 0-10 0-30 30-40 10-30 10-30

What do we usually measure??

Litterfall Sometimes stem growth



Patterns of NPP vary strongly with climate

Possible responses of plants to increased atmospheric CO

2 • Decreased stomatal conductance • Decreased transpiration • Increased water use efficiency • Increased photosynthetic rate • Decreased nitrogen concentration • Increased phenolic concentration • Long term Acclimation

Predicting plant species responses to rapid climate change

• Plants can – Tolerate – Adapt – Disperse • Issues – Local phenotypic and genotypic variation?

– Rate of adaptation vs. rate of climate change?

– Dispersal rates in fragmented landscapes?

– Photoperiod vs. climate controls on phenology

Predicting future plant species distributions • Lessons from the past • Approaches – Bioclimatic modeling (realized niche models) – Physiological models (fundamental niche models) – Spatial population and community models – Dynamic [global or regional] vegetation models • Dispersal through fragmented habitats

Neotoma sp. (packrat) Packrat midden, Grand Canyon, 13000 yrs. BP

Alder pollen

Present potential veg Vegetation 15,000 YBP

Measured rates of spread for tree genera during postglacial period

• Oak • Spruce • Hemlock 7 km/generation 0.3-1(8) km/generation 0.5-3 km/generation • Dispersal in fragmented habitats?

Summary points

• Microclimate is the climate experienced by organisms • Species occupy distinctive habitats that reflect their physiology, interactions with other species, and dispersal. Species respond individualistically to climate variation • Species persistence under a changing climate can occur through tolerance, adaptation or dispersal

A few summary points (2)

• • • • Oceans and humid forests account for roughly 2/3 of the earth’s net primary production.

Gross and net primary production increase in warmer and wetter climates Plants interact with the atsmophere to modify local, regional and even global climate.

Increased CO2 increases water use efficiency of plants, especially C3 plants