USA NPN National Phenology Network

Taking the Pulse of Our Planet

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National Coordinating Staff pictured at a Winter, 2017 retreat in Tucson, Arizona.


The USA-NPN's National Coordinating Office (NCO) guides the development of the Network, facilitates communication between scientists, land managers, policy-makers, and the public who are interested in assessing the effects of global change on natural ecological systems. Staff members work for the US Geological Survey and The University of Arizona.

Jake WeltzinJake Weltzin
Executive Director
USA National Phenology Network
National Coordinating Office
1311 E 4th St., Tucson, AZ 85721
(520) 626-3821
Fax: (520) 621-7834
Full CV - Résumé
Phenology Publications
An Interview with Jake on LiveScience

Jake Weltzin assumed his position as Executive Director of the USA-NPN in August 2007. Jake’s interest in natural history developed as he grew up in Alaska and served as an exchange student in the Australian outback. He obtained his B.S. from Colorado State University, M.S. from Texas A&M University, and Ph.D. from the University of Arizona. Following a post-doctoral fellowship at the University of Notre Dame, Jake went to the University of Tennessee, where he served as Assistant and then Associate Professor.

Jake is interested in how the structure and function of plant communities and ecosystems might respond to global environmental change, including atmospheric chemistry, climate change, and biological invasions. His research spans temperate and tropical grasslands and savannas, temperate woodlands, deciduous forest, and sub-boreal peatlands. His recent experience as a science administrator at the National Science Foundation underscored the need to foster large-scale science initiatives such as the USA-NPN. As its first Executive Director, Jake’s vision for USA-NPN is “to develop a continental-scale instrument for integrative assessment of global change that simultaneously serves as an outreach and educational platform for citizens and educators.”

Theresa CrimminsTheresa Crimmins 
Assistant Director
(520) 621-8523
Full CV
Phenology Publications
Follow me on Twitter @TheresaCrimmins

Theresa Crimmins assumed the role of Assistant Director in August, 2015. For nearly seven years prior to this, she served as the USA-NPN’s Partnerships & Outreach Coordinator. Theresa works enthusiastically to support involvement in Nature’s Notebook, the growth and use of phenology data and resources curated by the USA-NPN, and a broader appreciation of phenology among scientists and non-scientists alike.

Theresa obtained a B.S. in biology and an M.A. in geography from Western Michigan University and a Ph.D. in natural resources from the University of Arizona. Her research interests encompass plant response to global change, spatial analysis, and engaging citizen scientists of all ages in scientific discovery. 

LoriAnne Barnett
Education Coordinator
(520) 621-1803
Full CV - Resume
Phenology Publications
Follow me on Twitter @loriannebarnett

LoriAnne Barnett coordinates the USA-NPN's education activities, focused on engaging a variety of formal and non-formal audiences in experiential education and phenology via the Nature's Notebook program.  She has worked in a number of educational settings over the last two decades, teaching both youth and adults the importance of place and connections to the natural world, and serves as an advocate for citizen science, education and stewardship of the land.

LoriAnne holds a B.A. in Environmental Studies from Shippensburg University in Pennsylvania and a M.A. in Environmental Science and Environmental Education from Prescott College in Arizona.  She has led workshops on leadership development, Wilderness First Aid, outdoor adventure safety, and risk management.  Her areas of experitise include youth development, curriculum development, and environmental education. Current Board service includes President of the Arizona Association for Environmental Education and founding board member of the Arizona Master Naturalist Association

Ellen DennyEllen Denny
Monitoring Design & Data Coordinator
Full CV
Phenology Publications

Ellen Denny coordinates the design and development of the USA-NPN’s protocols for the collection of standardized ground-based plant and animal phenology observations across the nation.  She also serves as the scientific data manager for Nature’s Notebook data and other phenology data sets included in the National Phenology Database.
Ellen has a B.S. in Aquatic Biology from Brown University, an M.F.S. (Forest Science) from the Yale School of Forestry & Environmental Studies, and spent a decade working at the interface of ecosystem ecology and information management before coming to the USA-NPN. Her interaction began as the co-founder and coordinator of the Northeast Regional Phenology Network, established in 2007 to support the efforts of the USA-NPN. Since then she has served the USA-NPN in various capacities, including helping to advise other developing regional phenology networks across the nation and internationally.

Kathy Gerst
Associate Research Scientist
Data Product Coordinator
(520) 621-1740
Full CV
Phenology Publications

Kathy Gerst is an ecologist conducting research and development for phenology data products derived from the National Phenology Database. Previously, she was a liaison with the California Phenology Project facilitating the implementation of plant phenology monitoring in California National Parks. In this role, she collaborated with agency and academic partners to develop project documentation, protocols, data summary and analysis products, and outreach materials.

Kathy received a B.S. in Ecology, Behavior and Evolution from UCLA in 2001. She completed her PhD in Ecology and Evolutionary Biology in 2011 at the University of Arizona where she carried out research on the evolutionary ecology, reproductive biology, and physiology of desert annual plants. Broadly, she is interested in understanding how species, communities, and populations respond to a variable and changing environment.

Patty Guertin
(520) 621-1838

Patty Guertin is an in-house botanist at the National Coordinating Office in Tucson, Ariz. She assists with developing USA-NPN's plant and animal species’ profiles, focusing on gathering the necessary details for developing plant phenological protocols.

Having lived in many regions of the United States, and having investigated the local and regional flora of each area, Patty subsequently completed a B.S. in Plant Sciences at the University of Arizona. As a non-degree graduate student, she focused on field botany, GIS experience, and vegetation mapping and measurements. For the last 15 years, she has worked on vegetation and botanical projects as a field botanist and GIS specialist in the Southwest US, Texas and California, primarily for the national parks, focusing on non-native invasive plants and/or local flora.

Lee MarshLee Marsh
IT Coordinator
Applications Programmer
(520) 621-1636

Lee Marsh manages the development of tools and infrastructure, including servers, the National Phenology Database, web services, mobile apps and websites. He develops, enhances and maintains the USA-NPN's PHP and Java web applications, as part of the USA-NPN's IT team. He also plays a key role in data output and integration efforts.

Lee graduated from the University of Illinois, Springfield campus, with a B.S. in computer science, and spent the several years working for the private industry, including a regional startup and a Fortune 500 consulting firm. His interests include artificial intelligence and computer gaming systems.

Sharon Oliver

Administrative Associate
(520) 621-8571

Sharon Oliver, Administrative Associate, manages the administrative details of the National Coordinating Office, including budget and travel processes, supports the planning of conferences and meetings, and works on special projects.

Sharon received a B.A. in psychology from the University of Arizona and brings a wide range of experience to her position. She worked for a number of years in the federal sector in administrative, professional and management positions. Most recently, she worked at the U.S. Embassy in Athens, Greece where she was part of the administrative team supporting the Ambassador and Deputy Chief of Mission.

Erin Posthumus

Erin Posthumus
Outreach Coordinator and US Fish & Wildlife Service Liaison
(520) 621-1670
Full CV
Phenology Publications

Erin leads USA-NPN's outreach and engagement efforts through communication with observers and resource development. She is also the USA-NPN's liaison to the US Fish & Wildlife Service, and is working with National Wildlife Refuges across the country to implement phenology monitoring to meet their resource management and outreach goals.

A Seattle native, Erin received her B.A. in Environmental Biology from the University of Colorado at Boulder, then worked on a variety of field biology projects around the US and abroad. She first came to the USA-NPN as a Peace Corps Fellow in 2010, during her graduate program in the University of Arizona's School of Natural Resources and the Environment. In 2013 she was awarded a Master of Science for her research on wildlife species diversity at endangered red squirrel middens. 

Alyssa RosemartinAlyssa Rosemartin 
Partner & Application Specialist
Full CV 
Phenology Publications

Alyssa Rosemartin supports partnerships with resource management agencies and researchers to advance the USA National Phenology Network's mission to improve scientific understand and decision-making. She also contributes to in-house data product development, including quality control.

Alyssa has fourteen years of experience working in the field of natural resources, in IT, research, education and project management.  Alyssa received a B.A. in Spanish and environmental science in 2000 from Smith College and an M.S. in wildlife conservation and management from the University of Arizona's School of Natural Resources and the Environment in 2008. Her thesis explores the relationship between food availability and reproductive investment in terns, as well as breeding bird use of wetlands in the northern Gulf of California. 

Sara Schaffer
Web Designer & Developer
(520) 621-1631

Sara Schaffer works for the USA-NPN as a Website designer and developer, working on website modifications using drupal.  She has experience with graphic design, photography and publishing. She creates, formats and edits several of the documents produced by the NPN. Sara also provides support by completing various tasks related to daily operations and procedures. Her work varies depending on the tasks and events occurring in the NCO.

Sara is a born and raised Tucsonan, and received her B.S. in Microbiology from the University of Arizona in May 2010. In her free time, she enjoys the company of her dog, traveling, canyoneering, yoga and cycling.  Sara teaches indoor cycling, weightlifting and yoga for a local gym, and rides the annual Tour de Tucson.

Jeff Switzer
Systems Analyst
(520) 621-1636

Jeff Switzer will be using his programming skills to enhance and debug all aspects of the USA-NPN's IT infrastructure. His duties will range from solving problems with the mobile apps, to creating features for the website to optimizing the database. He will assist the USA-NPN team in making processes and functionalities more efficient and more adept to handling observer’s needs.  

Jeff graduated from the University of Wyoming with B.S. degrees in computer science and mathematics. As a graduate student he researched resource bounded dimension and joined a startup where he developed an electronic medical records system. He then spent two years teaching in Africa before joining the NPN team. When he's not coding you can find him camping, mountain biking, making music, and drinking tea.


Travis DennisTravis Dennis Photo
Youth Educator

Travis Dennis is a junior at the UA, studying Ecology and Evolutionary Biology as well as Natural Resources. He is currently working with the Nature’s Notebook program as a youth educator and is excited to get kids interested in local ecology. Travis helped bring Nature's Notebook to youths at the UA's Insect Festival, and is working with Manzo School.

Ryan HoffmanRyan Hoffman
Outreach Assistant

Ryan Hoffman is a senior in Plant Sciences and is excited to use his position as Outreach Assistant in the USA-NPN office as a platform to communicate ideas related to both plants and phenology. He hopes to use his botanical knowledge to help people gain a better understanding of the implications human activities have on plants and the environment, and increase awareness of environmental changes taking place.

 Jenny Moscato Jenny Moscato Photo
Community Outreach Associate
(520) 621-1803

As the 2016-2017 Coverdell Peace Corps Fellow working with the USA-NPN, Jenny Moscato will be working to facilitate Nature’s Notebook programming at Manzo Elementary School and the Mission Garden, two new sites established on the Tucson Phenology Trail to help increase access to underserved communities. Her job duties include program planning and development, in addition to community engagement and curriculum development. 

Jenny received a B.A. in Environmental Studies from Emory University in 2009. During a Peace Corps service assignment as a Natural Resource Conservation volunteer in Ecuador from 2011-2013, she lived in a rural, fishing village where her work in elementary and middle schools focused on environmental education activities. In addition, she formed a women’s artisan group that sold products made from recycled materials. She is pursuing a Masters in Landscape Architecture which will give her the opportunity to work on projects she is passionate about in the Southwest such as restoration of retired mining sites, access to public spaces, watershed management, and native ecosystems.

Julianna Renzi
Julianna RenziNASA Space Grant Intern

Julianna is a research intern who started with the NPN in the Fall of 2015 through the NASA Space Grant program, and is now her second year as a NASA Space Grant Student. She is currently a senior at the University of Arizona working on a B.S. in Environmental Science as well as two minors in Arabic and Marine Science. Julianna is analyzing the phenology data from the Tucson Phenology Trail with the National Phenology Database. Her broad research interests involve understanding changes in species life-cycles, as well as their effects on human populations.

Carrie StienCarrie Stien Photo

Carrie Stine is a sophomore majoring in Biochemistry and Molecular Biology. She grew up in Montana with a love for the outdoors and a passion for its preservation. She is excited to be working with USA-NPN, so she can study the impacts of climate change and help students discover an interest in the environment.