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Our Staff

Environmental scientists, designers, and landscape architects working together to transform landscapes

Our interdisciplinary team of environmental science, landscape architecture, and ecological design experts examine problems from multiple perspectives. We create individualized solutions tailored to each of our clients’ specific needs. Great Ecology’s staff members are trained in ecology, environmental sciences, landscape architecture, ecological design, hydrology, and planning. Our field staff are OSHA-certified to conduct work on hazardous sites.

Executive Management

Mark S. Laska, Ph.D. – President & Founder
Dr. Mark Laska is the Founder and President of Great Ecology. He has over 25 years of experience as an ecologist, focusing on wetland and habitat restoration, habitat and species assessments, ecological planning and design, and Natural Resource Damage (NRD) Assessments and Planning. His work in ecological restoration involves the planning, design, evaluation, permitting, and management of restoration projects. The author of more than a dozen scientific papers, Dr. Laska has developed a niche practice at the intersection of business and science with significant focus on environmental credit trading of habitat restoration projects. Dr. Laska holds a Doctorate in Ecology and Evolution from Rutgers University.

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Timothy Hoelzle, M.S. – VP, Technical Services
Timothy Hoelzle specializes in the repair of degraded ecosystems, with particular focus in the reclamation of lands disturbed by mining and energy extraction. His expertise also includes invasive species management, and wetland habitat restoration. Timothy is active in regional habitat restoration initiatives and is on the Board of the Central Rockies Chapter of the Society for Ecological Restoration. He holds a Master’s degree in Rangeland Ecosystem Science and a Bachelor’s degree in Restoration Ecology from Colorado State University.

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Jessa Spainhower_web

Jessa Spainhower – Director, Operations
Jessa Spainhower manages Great Ecology’s project, operations, and IT administration. She has over six years of experience as an operations and research analyst. Jessa applies her expertise in data analytics and organization to inform short-term and long-term planning and strategy. She leads the development and implementation of new information systems, infrastructure, and operational protocols and policies to support the firm’s continued growth. Jessa has a double major in Business Management and Marketing from Northwest Missouri State University.

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Regional Directors

Nick Buhbe

Nick Buhbe, M.S. – Director, Ecology and Regional Director, Western
Nick Buhbe has 18 years of experience, specializing in sediment testing, ecological health assessments of various biological communities, water quality studies, preparation of environmental planning compliance documents, and freshwater wetland-related project work. His portfolio includes physical, chemical, and biological evaluations of sediments in three major southern California harbors, as well as ports across the Pacific. He is well-versed in the Clean Water Act and the Marine Protection, Research, and Sanctuaries Act. His extensive knowledge of the marine environment has been instrumental in informing environmental planning, National Environmental Policy Act compliance, and California Environmental Policy Act documents. He holds a Master’s degree in Biology and a Bachelor’s degree in Marine Biology.

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Linda Gumeny






Linda B. Gumeny, RLA, LEED AP-ND  Director, Design and Regional Director, Eastern
Throughout Linda Gumeny’s 30-year career she has worked on a wide variety of public and private sector projects ranging from large-scale master planning to small-scale site design. She has served as both project director in the prime consultant role, and project landscape architect in a sub-consultant role for complex, multi-disciplined projects. Her work is focused on developing sustainable design solutions for parks, open space, residential, commercial, and institutional developments. Linda holds a Bachelor of Science degree in Landscape Architecture from Cornell University, and is a licensed landscape architect in NY, NJ, & CT. She is also a LEED AP-ND, accredited professional in neighborhood development.

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Joshua Eldridge, M.S. – Regional Director, Mountain
Joshua Eldridge is an ecologist with ten years of experience, including seven years as an ecological consultant. He specializes in the management, development, and evaluation of habitat restoration and ecological research projects. His extensive portfolio includes more than 80 reclamation or rangeland monitoring projects across the Western U.S. and Australia. He assessed disturbed riparian and upland systems, performed erosional soil stability modeling, mine land reclamation, evaluated acid rock drainage, surveyed rare or endangered species, and sampled surface and ground water. Joshua is skilled in the principles of restoration ecology, quantitative assessments, statistical analysis, and technical writing. He received both his Bachelor’s and Master’s degrees from Colorado State University in Restoration Ecology with a minor in Watershed Science.

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David J. Yozzo, Ph.D. – Senior Ecologist
Dr. David Yozzo is a nationally recognized estuarine scientist with 19 years of experience. His portfolio includes navigation improvement projects throughout the Hudson-Raritan Estuary, New England, Chesapeake Bay and the Gulf of Mexico. Dr. Yozzo has conducted research on tidal wetland fish/invertebrate communities in the New York-New Jersey Harbor and has conducted baseline and post-construction environmental surveys for habitat restoration projects conducted by USACE, NYSDEC, NYCDEP, NYCEDC, NOAA, and the Port Authority of NY-NJ. In addition, Dr. Yozzo co-authored the USACE National Guidebook to Hydrogeomorphic Assessments in Tidal Fringe Wetlands and has participated in several regional applications of the HGM methodology in the New Jersey Meadowlands and in the north-central Gulf of Mexico. Recent projects include the planning, design and implementation of several ecosystem restoration pilot projects for the NYCDEP CSO-PlaNYC project; a programmatic review of habitat restoration within NOAA’s National Estuarine Research Reserve System, developing an Ecological Site Profile for the Hudson River Reserve, and remedial dredging/habitat restoration at Springfield Gardens Lake, Queens, NY, for NYCEDC and NYCDEP. Dr. Yozzo is Past-President of the Atlantic Estuarine Research Society, and has served on the Governing Board of the Coastal and Estuarine Research Federation. He also serves as an Adjunct Associate Professor of Environmental Studies at Purchase College, SUNY. Dr. Yozzo holds a Master’s degree and a Doctorate in Environmental Science from the University of Virginia.

Dr. Ioana Petrisor - Senior Ecologist

Ioana G. Petrisor, Ph.D. – Senior Biochemist
Dr. Ioana Petrisor is a biochemist with more than 20 years of experience specializing in environmental forensics and litigation support. Dr. Petrisor has served as an expert witness in California, testifying on issues associated with environmental contamination. She is the Editor-in-Chief of the Environmental Forensics Journal and her extensive publications include an invention patent, a text book, various published book chapters, more than 70 research and review articles, as well as multiple editorials and technical guidelines. Dr. Petrisor also is an environmental forensic instructor for the Association for Environmental Health & Sciences (AEHS) Foundation and the Environmental, Outreach, & Stewardship (EOS) Alliance. She has directed and conducted innovative research projects for the U.S. Departments of Energy and Defense, as well as for the European Community. Dr. Petrisor has a Doctorate in Biochemistry from the Romanian Academy of Sciences and a Bachelor’s degree in Chemistry from Bucharest University, Romania.

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Michelle Landis

Michelle M. Landis, RLA – Senior Landscape Architect
Michelle Landis has a well-established design portfolio that includes weaving regionally appropriate habitat elements into complex landscape architectural projects. Her experience of 30 years in the development industry includes work in the habitat restoration, construction industry and landscape architecture sectors. She regularly works in a prime or sub-consultant role on large multi-disciplinary projects and also specializes in design-build team projects. Michelle’s portfolio of work includes leading the design for New Naval Hospital at Camp Pendleton, San Marcos Boulevard Complete Streets, ecologically sensitive upgrades to many local parks in the San Diego region and she is currently part of the Great Ecology design team working on the mitigation banking design for pond 20 on the San Diego Bay. She holds a Bachelor of Science degree in Landscape Architecture from California State Polytechnic University, Pomona and is adjunct faculty for the Landscape Architecture courses at Southwestern College, located in Southern California.

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Jill Steed Ph.D

Jill McGrady, Ph.D. – Associate Ecologist
Dr. Jill McGrady has over 10 years of experience in the fields of ecology and ecosystem studies.  Her work focuses on restoration evaluation, planning, and development of Natural Resource Damage (NRD) strategy following environmental impacts from mining, refinery, oil spill, and other contamination events.  Dr. McGrady currently manages a large-scale, comprehensive restoration planning project spanning several coastal states. She has multiple publications in leading academic journals and holds a Bachelor’s degree in Biology from Allegheny College, a Master’s degree in Ecology and Evolutionary Biology from Purdue University, and a Doctorate in Ecology and Evolution from Rutgers University.

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George Patten – Associate Ecologist
George Patten is an environmental scientist with experience in water quality assessments and watershed planning in Colorado. He has extensive experience assessing ecological and human health risks of contaminated soils, sediments, and groundwater. His portfolio includes field investigations and technical support to evaluate Superfund and other contaminated sites, as well as Natural Resource Damage Assessments and litigation support for environmental injuries. George also has a strong background in geospatial analysis, GIS, and other data visualization tools. He has a Bachelor’s degree in Environmental Science from the Colorado College and a degree in Urban and Regional Planning from the University of Colorado at Denver.

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Ashley Tuggle

Ashley Tuggle, M.E.M. – Associate Ecologist
Ashley Tuggle is an environmental scientist specializing in freshwater ecology and stormwater management. She has significant experience in water quality modeling, wetland field surveys, and land use planning in North Carolina and the Appalachian region. Ashley also has a strong technical background in geospatial analysis, GIS, and statistical analysis. She holds a Bachelor’s degree in Environmental Studies from Franklin College Switzerland and a Master’s degree in Environmental Management and Certificate of Geospatial Analysis from the Nicholas School of the Environment at Duke University.

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Marlene Tyner

Marlene Tyner, M.E.S.M. – Ecologist
Marlene has over 6 years of experience in ecological research and environmental analysis. She specializes in GIS and spatial analysis, climate change science, species distribution modeling, land use planning, market-based conservation strategies, corporate sustainability strategic planning, and environmental law and policy. Her past work includes coastal and near-shore sedimentation modeling, responses of ecosystem processes and communities to climate change, and global habitat modeling under various climate change predictions. Marlene holds a Bachelor’s degree in Ecology & Evolutionary Biology from the University of Michigan and a Master’s degree in Environmental Science & Management from the Bren School of Environmental Science & Management at the University of California, Santa Barbara.

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Emily Callahan, M.A.S. – Ecologist
Emily Callahan is an ecologist, with experience in conducting both international and domestic environmental impact assessments, her key area of expertise is in offshore oil and gas development and decommissioning- with a focus on the economic and environmental impacts of developing and implementing international Rigs-to-Reefs programs. She specializes in ecological evaluations of offshore resources, kelp forests and wetland restoration projects, and biodiversity baseline management studies. Ms. Callahan has had diverse experience in marine and terrestrial field sampling as well as a strong background in biological monitoring programs. She holds a Bachelor’s degree in Environmental Studies from Connecticut College and a Master’s degree in Marine Biodiversity and Conservation. She is a PADI certified dive master and an AAUS Scientific Diver with over 800 hours of logged dives.

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Charles Howe

Charles Howe – Associate Designer
Charles Howe is a landscape designer and environmental scientist specializing in ecosystem restoration and site planning. Charles excels in the graphical representation of environmental data to aid decision making for ecosystem management and land-use issues. His diverse portfolio includes design and construction of salt marshes, wooded wetlands, riparian and stream systems, vernal pools, tree inventory/value assessment, forest management, as well as agro-forestry plantings and resort planning. Charles is an ISA Certified Arborist and brings an extensive knowledge of woody plant species in the Tri-State area. Charles served on the New York Metropolitan Waterfront Alliance’s design guidelines team on the development of a rating system for resilient, multi-functional coastlines. He received a certification in wetland delineation from Rutgers University, a Masters of Landscape Architecture from the Harvard University Graduate School of Design, and a Bachelor’s degree in Environmental Science and Biology, magna cum laude, from Allegheny College.

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Liz Clift B&W

Liz Clift, MFA – Copy Editor
Liz Clift is responsible for copy editing of deliverables. She has worked as a technical writer, editor, and grant writer for more than six years, and has taught college composition courses. She is also a creative writer, and has published a variety of short stories, poems, and essays. She holds a Bachelor’s degree in Environmental Studies from Elon University and a Master of Fine Arts in Creative Writing & Environment from Iowa State University.

Lilia Gavrilenko, Controller

Lilia Gavrilenko, M.S. – Controller
Lilia Gavrilenko handles the daily accounting activities for Great Ecology. She has over seven years of experience in accounting and budgeting. Lilia holds Master’s degree in Mathematics and Bachelor’s in Accounting.

Julie Nelson, Operations Assistant

Julie Nelson – Operations Analyst
Julie Nelson is responsible for supporting overall operational tasks that enable continual business performance and improvement. Previously, Julie assisted top executives with reporting and data analysis to measure productivity and increase efficiency. Julie holds a Bachelor’s degree in Business Administration with a concentration in finance from Salem State University.

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Julien Jollon BW

Julien Jollon – Marketing Coordinator
Julien Jollon handles the day to day marketing initiatives for Great Ecology. He has over five years of experience in digital marketing and design, including creating and executing marketing campaigns. Julien holds a Bachelor’s degree in Marketing from the University of San Diego.

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Alejandro Baladrón Julian, M.S. 
Alejandro Baladrón Julian is an environmental scientist specializing in hydrology. Before receiving his Certificate in Conservation Biology from Fordham University, he worked as an environmental consultant in Spain for five years. He has extensive experience performing Environmental Impact Assessments and hydrology modeling, including the design of drainage networks for highway and railway lines, the analysis of evacuation capacity in wastewater drainage systems, and flood risk studies. In addition, he has developed technical reports and cost-benefit analyses for European water supply projects, including the European Regional Development Funds (ERDF) and Cohesion Fund Programs. Alejandro holds a Bachelor’s degree in Environmental Sciences, a Master’s degree in Applied Hydrology, and a Master’s of Advanced Studies in Environmental Sciences.

Daniel R. Brumbaugh, Ph.D.
Dr. Daniel R. Brumbaugh, a marine ecologist with over 20 years of experience, specializing in coral reef ecology, focusing on reef monitoring techniques, studies of coral recruitment, and the science and management of marine protected areas. For 12 years, Dan studied coral reef and other marine ecosystems in The Bahamas and applied this knowledge to Bahamian marine conservation and education. During this time, he led a number of interdisciplinary investigations, including the Bahamas Biocomplexity Project, to study how an expanding system of marine protected areas in the country could function. He also participates on the governing Council and Scientific Advisory Committee of the Bahamas National Trust, and has advised the Bahamas Department of Marine Resources (then Fisheries) on applications of marine science to reserve planning. In the U.S., Dan has served on the stakeholder Advisory Council of the Channel Islands National Marine Sanctuary and as a Visiting Scientist with the U.S. National Marine Protected Areas Center. He also is also an individual member of the World Commission on Protected Areas (WCPA, part of the World Conservation Union, or IUCN) and is on the Advisory Board of the non-profit OneReef, which facilitates reef conservation agreements between funders and reef-owning communities in Micronesia.

Shane Cherry, M.S.
Shane Cherry has served as a principal investigator on geomorphology and hydraulic studies for watersheds, large rivers, and streams in diverse settings around the United States. He has worked as a professional geomorphologist and consultant since 1996 leading projects involving river process modeling and analysis, environmental permitting, mitigation strategy, and ecosystem restoration. Shane works on airport and transportation infrastructure projects, mining projects, and sediment remediation sites. Shane’s river and stream restoration experience includes over 80 projects. Shane engenders tremendous confidence in clients, and is a strong consensus builder through his calm articulation of ideas and concepts. Shane employs level-headed wisdom to solve problems directly and efficiently with a talent for building consensus among internal and external stakeholders. This style makes him especially effective in contentious situations around large capital project permitting and multi-party environmental remediation. He offers comprehensive skills in applied science, environmental permitting strategy, and project management that he applies to watershed studies, ecological restoration, habitat design, flood studies, and river process modeling.

Joseph Ehrenberger, M.S.
Joseph Ehrenberger’s career of 11 years as an ecologist includes a broad diversity of skills and experiences, with an emphasis on wildlife and habitat assessments. His portfolio includes assisting with husbandry and breeding of rare species in the U.S., Dominican Republic, and Grand Cayman. His field experiences concentrated on general wildlife and habitat assessments, as well as special-status species surveys (e.g. Greater sage grouse, Lesser prairie chicken, Mexican spotted owl, Indiana bat, Swift fox, raptor nest monitoring, Ricord’s iguana, and plants such as the Ute’s ladies tresses and Colorado butterfly plant). His habitat work includes restoration for Preble’s meadow jumping mouse and Kremmling milkvetch, as well as rangeland noxious weed management, mountain pine beetle control, and energy development mitigation. Most recently, he conducted focused surveys throughout Colorado for amphibians and reptiles, including rattlesnake management projects and safety training for governments and the private sector. He has authored numerous technical publications and agency documents. Furthermore, his coordination of volunteers has proven essential to non-profit and federal species and habitat monitoring programs. Joseph received his Bachelor’s degree in Teaching from Virginia Tech and his Master’s degree in Ecology from Indiana State University.

Kim Raby Lennberg, M.S
Kim Raby Lennberg is a watershed scientist with 14 years of experience investigating the scientific, technical, and policy aspects of a broad range of environmental subjects, specializing in using an interdisciplinary approach to watershed science and characterization. Kim’s professional expertise includes monitoring and assessing watershed health by examining the chemical, physical, biological, and hydrological characteristics of aquatic ecosystems; designing, coordinating, managing, and conducting extensive ecological and aquatic field investigations; and authoring technical reports communicating the results of short- and long-term studies, as well as substantial portions of NEPA- and CERCLA-related documents. Her current areas of study and interest focus are on stream restoration and aquatic habitat evaluation and improvement. Kim’s most recent project work includes evaluation of river restoration projects through aquatic and riparian habitat quality assessment, monitoring and reporting assistance related to flood recovery, and management of fishery and aquatic resource monitoring and reporting projects in areas impacted by phosphate mining. Kim holds a Bachelor’s degree in Environmental Systems Technology from Cornell University, a Master’s degree in Environmental Studies (with a focus on alpine hydrology) from the University of Colorado at Boulder, and a Professional Certificate in River Restoration from Portland State University.

John C. Lovio, M.S.
John Lovio is a field and conservation planning ecologist with over 30 years of professional experience in biological assessments, species surveys, environmental regulatory compliance, and ecological research in the western states, particularly California. He specializes in the habitat relations, biogeographies, and landscape ecologies of wildlife, particularly birds, with special interest in establishing ecological baselines and perpetuating long-term ecological studies to measure effects of land use changes and climate change. He is experienced in assessing land condition and conservation value, as well as anticipating and evaluating habitat disturbance (including wildfire) effects and restoration efforts in a wide range of aquatic, estuarine, and terrestrial natural environments. John Lovio holds a Master’s degree in Biology-Ecology from San Diego State University and a Bachelor’s degree in Wildlife Biology from the University of California at Davis.