Job Opportunity
 

Intern: Patterns, causes, & consequences of variation in liana infestation in tropical forests in Panama

Project Title: Patterns, causes, and consequences of variation in liana infestation in tropical forests in Panama

Mentor Name: Helene Muller-Landau, mullerh@si.edu

Location: Barro Colorado Island and/or Gamboa, Panama (Smithsonian Tropical Research Institute)

Duration: 8-12 months, with possible start dates between January and June 2022 (NOTE: If pandemic-related measures prevent in-person field work and other on-site activities at any time during the internship period, activities will continue fully virtually.)

Compensation: $1,000 per month + funds for roundtrip travel to Panama if/when relevant

**This internship will remain open until filled. 


Project Summary & Objectives: The abundance of lianas (woody vines) varies widely within and among tropical forests. Forest stands vary in the proportion of trees that are liana-infested, and infested trees vary in the proportions of their crowns that are covered by lianas.  The abundance of lianas is critically important to determining tropical forest carbon stores and cycling: where there are more lianas, trees grow more slowly, tree mortality rates are higher, forests store less carbon, and recovery from disturbance is slowed.  The effects of lianas differ among tree species, and thus liana abundance also affects tree species composition.  Complicating matters, there is a large diversity of liana species in tropical forests, and liana species vary in their traits and effects on trees.

Our objectives are to

  • Quantify patterns of variation in the levels of liana infestation and in liana colonization and loss rates of host trees within and among forest sites and host tree species. 
  • Evaluate the consequences of liana infestation for trees, including analyses of effects of liana gain and loss over time on individual tree growth (or shrinkage) in height, crown area, and trunk diameter, and how this varies with tree and liana traits. 
  • Investigate the mechanisms underlying differences in liana infestation rates through studies of differences in liana “behavior” with tree size, environmental conditions, and liana and tree species traits. 

We pursue these objectives through a combination of analyses of pre-existing datasets, new data collection, and modeling.  Pre-existing datasets include precise annual measurements of tree diameter growth with dendrometers on >3000 trees for which liana load scores are available, time series of high-resolution drone imagery of a 50-ha plot in which individual tree crowns are mapped enabling quantification of tree height and crown area change, and functional traits datasets for Panama plant species.  New data collection opportunities include measurements and observations of 3D liana growth patterns using a mobile laser scanner (Geoslam ZEB Horizon) and STRI’s canopy cranes

Ultimately, this research seeks to contribute to a mechanistic understanding of variation in the abundance of lianas (woody vines) in tropical forests, an understanding that can inform better vegetation models and enable us to more accurately predict forest responses to global change.   

Mentorship Goals: Interns will have the opportunity to gain experience in tropical forest field data collection, laser scanning data collection and processing, data analysis in R, reading and discussing scientific literature, and oral and written presentation of scientific research.

List of Suggested Readings: 

Muller-Landau, H. C., and S. W. Pacala. 2020. What determines the abundance of lianas and vines? Pages 239-264 in A. Dobson, D. Tilman, and R. Holt, editors. Unsolved Problems in Ecology. Princeton University Press, Princeton, NJ.

Visser, M. D., H. C. Muller-Landau, S. A. Schnitzer, H. de Kroon, E. Jongejans, and S. J. Wright. 2018. A host-parasite model explains variation in liana infestation among co-occurring tree species. Journal of Ecology 106:2435-2445.

Visser, M. D., S. A. Schnitzer, H. C. Muller-Landau, E. Jongejans, H. de Kroon, L. S. Comita, S. P. Hubbell, and S. J. Wright. 2018. Tree species vary widely in their tolerance for liana infestation: A case study of differential host response to generalist parasites. Journal of Ecology 106:781-794.

Muller-Landau, H. C., and M. D. Visser. 2019. How do lianas and vines influence competitive differences and niche differences among tree species? Concepts and a case study in a tropical forest Journal of Ecology 107:1469-1481.

Schnitzer, S. A., S. A. Mangan, J. W. Dalling, C. A. Baldeck, S. P. Hubbell, A. Ledo, H. Muller-Landau, M. F. Tobin, S. Aguilar, and D. Brassfield. 2012. Liana abundance, diversity, and distribution on Barro Colorado Island, Panama. PLOS ONE 7:e52114.


Candidate Profile: The ideal candidates have a bachelor’s degree in a relevant field, strong quantitative skills including statistics coursework and programming experience, strong English oral and written communication skills, and good Spanish oral communication skills.  The positions are particularly well suited for candidates seeking more research experience prior to graduate school.  

Application Instructions: Please email a (1) CV, (2) an unofficial undergraduate transcript (with an explanation of the grading scheme if from a non-US university), (3) a scientific writing sample, preferably in English but can be in Spanish (e.g., undergraduate thesis, lab report, research paper), (4) a sample of code you have written (in R, Python or another language with commenting), and (5) a cover letter describing your qualifications, interest in the position, potential start dates, and contact information for 3 references to mullerh@si.edu

Job Locations: 
Panama City, Panama