Environmental sensors
Environmental microcontroller units, by J. Stark and M. Htet (2019).
    - Bill of materials ($30)
    - Arduino code on GitHub and sensor data display R code

Leaf function
Leaf-level photosynthesis, by J.M. Heberling (2013).
    - light response curves: R code and sample data
    - CO2 response curves: R code and sample data
Leaf construction cost, by J.M. Heberling (2011, revised 2017).
Epidermal microscopy (e.g., stomatal size, density), by A. Craddock and J. Fridley (2008).

Aboveground growth phenology
Spring foliar budbreak phenology, by J. Fridley and A. Craddock (2013).
Leaf chlorophyll monitoring, by J. Chieppa (2012).
Leaf production and shoot extension, by J. Fridley.

Chemical analysis
C and N content: NC2100 autoanalyzer protocol, by A. Fox (2016), revised K. Martinez (2017).
Ash concentration in biomass, by E. Hinman and M. Ritchie (2017).
Chlorophyll a/b extractions, by K. Martinez (2017). 
     - Porra et al. 1989 reference [PDF]

Plant propagation
Softwood cuttings protocol, by A. Ebert (2018).