Nitrogen (N) in the Environment

   ~It's everywhere! 

   ~Often the limiting factor in terrestrial systems

Biological Nitrogen Fixation (BNF)

   ~Symbiotic nitrogen (N) fixation occurs in root nodules

   ~Energetically costly, but strong competitive advantage

Fixation Strategies

   ~Spectrum of regulation- Facultative to Obligate

Hawai‘i Pacific Weed Risk Assessment System (HPWRA)

   ~Tool to help predict whether a plant will likely become invasive

   ~Uses published research and experts to answer 49 ?????

   ~High Risk or Low Risk evaluation

Seed collection & germination

     ~Extract seeds from pods

   ~Scarify and imbibe seeds

   ~Sew

Growth & measurements

   ~Repot seedlings

   ~Randomized block design

   ~Fertilization

   ~Stem diameter, height, & number of leaves

Harvest

   ~Separate plant parts: roots, shoots, & root nodules

   ~Take dry mass measurements & grind

   ~Elemental analyzer & Isoptope ratio mass spectrometer

High Risk

   ~Acacia confusa

    ~Falcataria moluccana

   ~Leucaena leucocephala 

 ~Senna siamea (control)

Low Risk

   ~Caesalpinia pulcherrima

   ~Pterocarpus indicus

   ~Samanea saman

   ~Bauhinia variegata (control)

Coming up...

   ~Four more species of each High Risk & Low Risk

   ~Data analysis

Thank You!

Dr. Rebecca Ostertag, UHH 

Dr. Jennifer Funk, Chapman University

Dr. Jon Price, UHH

  Molly Murphy, BIISC