Michael E. Loik, Associate Professor

Department of Environmental Studies , University of California, Santa Cruz , CA 95064

Tel: (831) 459-5785, Fax: (831) 459-4015, mloik (at) ucsc (dot) edu

Prospective Graduate Students, please click here

Research Interests

•    Plant Physiological Ecology
•     Climate Change
•     Ecohydrology
•     Snow ecology
•     Arid land ecology
•     Plant water relations
•     Photosynthesis
•     Recruitment processes
•     Carbon dynamics
•     Nutrient cycling
•     Rainfall
•     Snowfall

My research examines the physiological responses of plants and ecosystems to climate change.  The primary focus is on the effects of anthropogenically altered patterns of rain and snowfall on plant and ecosystem functions.  My research group also studies how other global changes (including elevated carbon dioxide, increased temperature, and nitrogen deposition) will affect plants and ecosystems.  

Our main research site is at the Valentine Eastern Sierra UC Reserve, near Mammoth Lakes, CA.  We work closely with the Bureau of Land Management, the National Park Service, the National Forest Service, Caltrans, the City of Los Angeles Department of Water and Power, Inyo County Water, and the Mammoth Community Water District, to help inform managment decisions.

1. Plant Responses to Altered Precipitation at the Sierra Nevada conifer forest - Great Basin Desert ecotone. This research examines the influence of altered precipitation patterns on plant ecophysiology, communities, and ecosystem processes. In arid ecosystems typical of much of the western U.S., water availability affects plant survival, photosynthesis, growth, reproduction, and migratory potential. Experiments are being conducted at the Valentine Eastern Sierra UC Reserve in eastern California, where we have been applying water in the summertime to simulate enhanced levels of monsoonal rainfall that some climate models predict will occur in the southwestern Great Basin Desert in the future.  We are also utilizing 50 yr old snowfences constructed by Caltrans as simulations of increased and decreased snow depth scenarios, such as envisioned by some climate change models for the future. Altered snow depth results in more (or less) soil water available for shrub and tree growth in the subsequent spring and summer, effects which can then resonate to higher order processes in the ecosystem (such as litterfall, root growth, soil C storage, and soil N content.)  Whereas we are continuing our work on carbon, water and nutrient fluxes as driven by snow depth and melt timing in this system, we have recently embarked on a project to study community-level responses to snow depth changes.  We are measuring natural recruitment of Jeffrey and Lodgepole Pines (Pinus jeffreyi and P. contorta, respectively), as well as Great Basin sagebrush and antelope bitterbrush (Artemisia tridentata and Purshia tridentata, respectively) as a function of snow depth treatment and microhabitat (i.e., shrub canopies vs open intershrub spaces).

While it may seem intuitive that plants will grow more when supplied with extra water - especially in a desert - not all plants respond to rain and snowmelt water in an equal manner.  For example, some deep-rooted trees of the arid western United States will only take up water, conduct photosynthesis, and grow following the melting of snow and the soaking of deep soil layers.  In contrast, certain species - such as cacti and many ephemeral wildflower species - have very shallow roots and are quite opportunistic at taking up and using water.  Still other desert species have both shallow and deep roots, and are able to make use of winter snow melt and summer rainfall. 

Our work is conducted on lands managed by the University of California Natural Reserve System, the Inyo National Forest, Caltrans, the Mammoth Community Water District, the Bureau of Land Management, and the City of Los Angeles Department of Water and Power.  Results help us to interpret and understand how climate change will affect the interaction of natural and human systems, such as water availability, fire risk at peri-urban and natural interfaces, wildlife habitat quality, agriculture, water quality, and recreational uses of lands in the western United States.    

This research is supported by the National Institute for Climate Change Research.

2.  Carbon and Water Dynamics of the US Deserts.  This study is motivated by the potential for altered precipitation regimes (an element of climate change) to greatly impact water-limited ecosystems of the Southwest. Existing field studies exploring the effects of variation in precipitation on C (carbon) and H₂O (water) dynamics in deserts of the Southwest have produced large datasets. However, no syntheses have been conducted with respect to these datasets to explore the broader implications of altered precipitation for arid and semiarid ecosystems. This is a collaborative project with Kiona Ogle (University of Wyoming), Travis Huxman (University of Arizona), David Tissue (Texas Tech), and Stan Smith (University of Nevada, Las Vegas). Our objective is to synthesize existing data related to C and H₂O fluxes, spanning leaves to ecosystems, across four major deserts in the Southwest. A second objective is to use the synthesis results to identify novel questions and hypotheses and to help direct future, cross-site experiments.

This research is also supported by the National Institute for Climate Change Research.


3. Impacts of Global Change on Freezing Tolerance and Cold Acclimation.  My laboratory has been developing this method to measure in situ the impacts of various treatments -- namely global warming, precipitation increases, and elevated CO₂ -- on the ability to survive episodic freezing events.  For species that have processes (growth, survival, reproduction, recruitment, migration) limited by sub-zero temperatures, an altered ability to survive freezing under anthropognic global change may be one mechanism by which community composition and species distributions change.  We are examining hypotheses regarding such effects via In situ Cold Experiments ("ICE").  This involves cooling leaves with evaporant from a liquid nitrogen tank, and simulataneous measurements of chlorophyll fluorescence, photosynthetic assimilation, and membrane integrity.  Studies examining the role of enhanced downward infrared radiation on snowmelt and plant development during spring are being carried out at the Rocky Mountain Biological Laboratory .  Companion studies on the role of elevated CO₂ on freezing and heat stress tolerance, xanthophyll cycle activity, and photosynthetic productivity for shrubs of the Mojave Desert ecosystem are being conducted at the Mojave Global Change Facility.
 

4. PrecipNet: A National Network for Precipitation and Ecosystem Change Interdisciplinary Research. The purpose of this network is to encourage and foster communications and collaborations across research groups with common interests regarding the impacts of climate change on future precipitation patterns, ecosystem processes, and the human enterprise. The goals are to: (1) encourage an integrated effort that promotes studies and comparisons of the effects of altered timing and magnitude of rain and snowfall across ecosystems; (2) coordinate exchange of graduate students and postdoctorals between research groups to enhance skills development and technology transfer; (3) train both early-career and under-represented scientists in the latest methodologies and quantitative modeling and analytical tools; (4) to produce meetings and workshops to explore the latest climate model predictions, to develop strategies for comparing methods, and to conduct meta-analyses of results; (5) promote interdisciplinary research between natural and social scientists regarding the impacts of climate change on natural ecosystems and the interrelationships with human systems and institutions; (6) development of common experimental, modeling, scaling, and integration approaches for the simulation of future increases and decreases in rain and snow, measurement of impacts on ecosystem processes, and effects on society; (7) encourage interactions with other relevant research networks, such as BASIN (Biosphere-Atmosphere Stable Isotope Network) and SAHRA (Sustainability of semi-Arid Hydrology and Riparian Areas); and (8) development of databases on the world wide web that would be available for all global change studies.

This program is currently funded by the National Science Foundation.

Laboratory Personnel

Graduate Students
Alden Griffith
Holly Alpert
Amy Concilio

Postdoctoral Fellow
Sharon Martinson

Research Assistants
Jack Rusk
Dustin Johnston
Lucy Lynn

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Student Research Projects

Student research and training are an important part of the activities in my laboratory.  Our field campaigns regularly include high school, undergraduate, graduate, and postdoctoral research assistants.

Examples of current and past graduate student and senior thesis research projects:

Impacts of snow depth and N deposition on cheatgrass, Bromus tectorum.

Impacts of snow depth changes on Jeffrey Pine recruitment.

Impacts of climate change on invasion by Bromus tectorum.

Effects of enhanced precipitation on high temperature tolerance for the Great Basin shrub Purshia tridentata .  

Freezing tolerance and cold acclimation for Artemisia tridentata seedlings along an elevation gradient.

Patterns of reproductive allocation for different varieties of Yucca whipplei.

Publications

Smith SD, Tissue DT, Huxman, TE, Loik ME. (2008) Ecophysiological Responses of Desert Plants To Elevated CO₂: Environmental Determinants and Case Studies. In: de La Barrera E. and Smith WK (eds) Perspectives in Biophysical Plant Ecophysiology. Academic Press, San Diego, CA. [in press]

Lambrecht SC, Shattuck AK, Loik ME (2007) Combined drought and episodic freezing effects on seedlings of low- and high-elevation subspecies of sagebrush (Artemisia tridentata) Physiologia Plantarum 130 (2): 207-217 JUN 2007

Lambrecht, SC, Loik ME, Inouye DW, Harte J. (2007) Reproductive and physiological responses to simulated climate warming for four subalpine species. New Phytologist 173 (1): 121-134

Loik, ME (2006) Sensitivity of water relations and photosynthesis to summer precipitation pulses for Artemisia tridentata and Purshia tridentata. Plant Ecology 191 (1): 95-108

Patrick L, Cable J, Potts D, Ignace D, Barron-Gafford G, Griffith A, Alpert H, Van Gestel N, Robertson T,  Huxman TE, Zak J, Loik ME, Tissue DT (2006) Effects of an increase in summer precipitation on leaf, soil, and ecosystem fluxes of CO2 and H2O in a sotol grassland in Big Bend National Park, Texas. Oecologia DOI 10.1007/s00442-006-0621-y

Schwinning, S, Sala, OE, Loik, ME, Ehleringer JR. (2004) Thresholds, memory, and seasonality: understanding pulse dynamics in arid/semi-arid ecosystems. Oecologia141: 191-193

Loik, M.E., Breshears, D.D., Lauenroth, W.K., Belnap, J. (2004) A multi-scale perspective of water pulses in dryland ecosystems: climatology and ecohydrology of the western USA. Oecologia 141: 269-281  

Huxman, T.E., Smith, M.D., Fay, P.A., Knapp, A.K., Shaw, M.R., Loik, M.E., Smith, S.D., Tissue, D.T., Zak, J.C., Weltzin, J.F., Pockman, W.T., Sala, O.E., Haddad, B.M., Harte, J., Koch, G.W., Schwinning, S., Small, E.E., Williams, D.G. (2004) Convergence across biomes to a common rain-use efficiency. Nature 429: 651-654  

Gillespie, I.G., Loik, M.E. (2004) Pulse events in Great Basin Desert shrublands: Responses of Artemisia tridentata and Purshia tridentata seedlings to summer rainfall pulses. Journal of Arid Environments 59: 41-57  

Loik, M.E., Still C.J., Huxman, T.E., Harte, J. (2004) In situ photosynthetic freezing tolerance for plants exposed to a global warming manipulation in the Rocky Mountains, Colorado, U.S.A. New Phytologist 162: 331-341.

Naumberg, E., Loik, M.E., Smith, S.D. (2004) Stomatal conductance of Larrea tridentata dominates photosynthetic temperature responses under elevated CO₂. New Phytologist 162: 323-330.

Weltzin JF, ME Loik, S Schwinning, DG Williams, P Fay, B Haddad, J Harte, TE Huxman, AK Knapp, G Lin, WT Pockman, MR Shaw, EE Small, MD Smith, SD Smith, DT Tissue, JC Zak. (2003).  Assessing the response of terrestrial ecosystems to potential changes in precipitation. BioScience.  53:941-952

Loik, ME and SP Redar (2003) Freezing tolerance and cold acclimation for seedlings of Artemisia tridentata along an elevation gradient. Journal of Arid Environments.  54:769-782

Parker, IM, Rodriguez, J and ME Loik (2003) An evolutionary approach to understanding the biology of invasions: local adaptation and general purpose genotype in the weed Verbascum thapsus. Conservation Biology . 17: 59-72.

Dole, KP, Loik, ME and LC Sloan (2003) The relative importance of climate change and the physiological effects of CO₂ on freezing tolerance for the distribution of Yucca brevifolia. Global and Planetary Change. 36: 137-146.

Naumburg, E, Housman DC, Huxman TE, Loik ME and SD Smith (2002) Photosynthetic response of Mojave Desert shrubs to Free Air Carbon Dioxide Enrichment over four years with differing precipitation regimes. Global Change Biology 9: 276-285

Loik, ME and KD Holl (2001) Photosynthetic responses of tree seedlings in grass and under shrubs in early-successional old fields, Costa Rica. Oecologia 127: 40-50.

Holl, KD, ME Loik, EV Lin, and IA Samuels. (2000) Tropical montane forest restoration in Costa Rica: obstacles and opportunities. Restoration Ecology 8: 339-349.

Loik, ME, TE Huxman, EP Hamerlynck, and SD Smith (2000) Low-temperature tolerance and cold acclimation for three Mojave Desert Yucca species exposed to elevated CO₂. Journal of Arid Environments 46: 43-56.

Loik, M.E., St. Onge, C.D. and J. Rodgers (2000) Post-Fire Recruitment of Yucca brevifolia and Yuccaschidigera in Joshua Tree National Park, California. In: J. Keeley (ed.) Proceedings of the 2nd Interface Between Ecology and Development in California. USGS Open-File Report 00-62.

Loik, ME, SP Redar and J Harte (2000) Photosynthetic responses to light for Artemisia tridentata and Erigeron speciosus under a climate warming manipulation in the Rocky  Mountains. Functional Ecology. 14: 166-175.

Hamerlynck, EP, Huxman, TE, Loik, ME, and SD Smith. (2000) Effects of high temperature, drought and elevated CO2 on photosynthesis of the Mojave Desert evergreen shrub, Larrea tridentata . Plant Ecology 148:183-193.

Hamerlynck, E.P., T.E. Huxman, S.D. Smith, R. Nowak, L.A. Defalco, S. Redar, M.E. Loik, D.N. Jordan, S. Zitzer, and J.R. Seemann. (2000) Initial results of Free Air Carbon Enrichment on a mojave desert ecosystem: photosynthetic responses in contrasting shrub species. Journal of Arid Environments. 44: 425-436.

Shaw M.R., M.E. Loik and J. Harte. (2000) Gas exchange and water relations of two Rocky Mountain shrub species exposed to a climate change manipulation . Plant Ecology. 146:197-206

Loik, M.E. and K.D. Holl. (1999) Photosynthetic responses to light for rain forest seedlings planted in abandoned pasture, Costa Rica. Restoration Ecology. 7:382-391.

Huxman T.E., E.P. Hamerlynck, M.E. Loik, and S.D. Smith. (1998) Gas exchange responses of Yucca species to elevated CO₂ and extreme high temperature. Plant, Cell and Environment 21:1275-1283.

Huxman, T.E. and M.E. Loik. (1997) Reproductive patterns of two varieties of Yucca whipplei (Liliaceae) with different life histories. International Journal of Plant Sciences 156:778-784.

Loik, M.E. and J. Harte. (1997) Changes in water relations for leaves exposed to a climate-warming manipulation in the Rocky Mountains of Colorado. Environmental and Experimental Botany 37:115-123.

Huxman, T. E. and M.E. Loik. (1996) Seeds of Yucca whipplei var. whipplei germinate in the fruit. The Southwestern Naturalist 41:318-320.

Loik, M. E. and J. Harte. (1996) High-temperature tolerance for Artemisiatridentata and Potentilla gracilis under a climate change manipulation. Oecologia 108:224-231.

Nobel, P.S., N. Wang, R.A. Balsamo, M.E. Loik, and M.A. Hawke. (1995) Low- temperature tolerance and acclimation of Opuntia spp. after injecting glucose or methylglucose. International Journal of Plant Sciences 156:496-504.

Loik, M.E. (1995) Book Review: Scaling Physiological Processes. J. Ehleringer and C.B. Field (eds.) Climatic Change 29:463-466.

Nobel, P.S. and M.E. Loik. (1994) Low-temperature tolerance of pricky pear cacti. In: P. Felker and J.R. Moss (eds.) Proceedings, Fourth Annual Texas Prickly Pear Council. Caesar Kleberg Wildlife Research Institute, Kingsville, TX.

Loik, M. E., and P. S. Nobel. (1993) Exogenous abscisic acid mimics cold acclimation for cacti differing in freezing tolerance. Plant Physiology 103:871-876.

Loik, M. E., and P. S. Nobel. (1993) Freezing tolerance and water relations of Opuntia fragilis from Canada and United States. Ecology 74:1722-1732.

Loik, M. E., and P. S. Nobel. (1991) Water relations and mucopolysaccharide increases for a winter hardy cactus during acclimation to subzero temperatures. Oecologia 88:340-346.

Nobel, P.S., M.E. Loik, and R.W. Meyer. (1991) Microhabitat and diel tissue acidity changes for two sympatric cactus species differing in growth habit. Journal of Ecology 79:167-182.

Nobel, P.S. and M.E. Loik. (1990) Thermal analysis, cell viability, and CO₂ uptake of a widely distributed North American cactus, Opuntia humifusa, at subzero temperatures. Plant Physiology and Biochemistry 28:429-436.

Courses Taught

ENVS 80B Ecological Forecast for Global Warming (Fall 2008)

ENVS 162 Plant Physiological Ecology (Winter 2009)

ENVS 196 Environmental Electronics (Spring 2009)

Training

B.Sc., University of Toronto, 1984

M.Sc., University of Toronto, 1986

Ph.D., University of California, Los Angeles, 1992