Bios 431
Essay 1: Above and Below-ground Herbivory Effects (Mundim et al 2017)
It appears that until recently, studies on the effects of herbivory have been relatively limited to the study of aboveground biomass. Recent findings by Fabiane Mundim and colleagues stress the importance of studying the effects of herbivory on both above and below ground biomass in order to better understand how plants allocate resources. From their findings herbivory above and below ground affected where and how resources were allocated. The main findings, in a controlled setting, showed that plants that suffered aboveground herbivory responded in a way that promoted aboveground growth but also elevated belowground defense. This inverse was also found to be true – plants that had belowground herbivory responded by allocating resources that promoted root growth but also elevated defenses in the aboveground leaves. Plants infected by nematodes had greater terpenoids concentrations in leaves instead of the roots and in plants were herbivory was aboveground root terpenoids concentrations were 2.4-fold higher than in other treatments (Mundim et al 2017). The allocation of resources for defenses and growth allow for the plant, Solanum lycocarpum, to survive after herbivory to above and below-ground has occurred.
One natural factor in plant growth that Mundim and colleagues did not touch upon was the role of shade in plant growth. Shade treatment may have differing consequences on above and below ground growth when combined with herbivory effects. Unequivocally, photosynthesis is important to plant metabolism. If plants in the experiment had been limited in the amount of sunlight that they received it would have added yet another variable that in the end may have had impacts on total biomass and eventual maturation. Solanum lycocarpum, as described in Mundim’s paper, is common to Brazil’s cerrados which are open physiognomies (Mundim et al 2017). Even its scientific name, Solanum lycocarpum, refers to the sun – surely if shade was introduced as a variable it would have varying effects for the biomass of the plant both above and below ground. Lack of sun may result in stunted plant fitness relative to plants that obtained sunlight, this is because the plant would not be able to fully obtain all the materials needed for metabolism. Other factors that a controlled experiment may not be able to fully duplicate is resource limitation imparted by resource completion with conspecifics or other plants.
Herbivory above and below ground was tested in a controlled setting, in a natural setting other variables could have lasting effects on plant growth and eventual production of seedlings. As mentioned previously shade could have been another natural variable affecting growth. This is important especially when one considers how in class we briefly talked about how loss of energy at one level of the food chain can spell loss of energy for other consumers. In young plants, resources...
