The 'Herbivory Uncertainty Principle': application in a cerrado site

Ca Gadotti,Ma Batalha

doi:10.1590/s1519-69842010005000018

Abstract

Researchers may alter the ecology of their studied organisms, even carrying out apparently beneficial activities, as in herbivory studies, when they may alter herbivory damage. We tested whether visit frequency altered herbivory damage, as predicted by the 'Herbivory Uncertainty Principle'. In a cerrado site, we established 80 quadrats, in which we sampled all woody individuals. We used four visit frequencies (high, medium, low, and control), quantifying, at the end of three months, herbivory damage for each species in each treatment. We did not corroborate the 'Herbivory Uncertainty Principle', since visiting frequency did not alter herbivory damage, at least when the whole plant community was taken into account. However, when we analysed each species separately, four out of 11 species presented significant differences in herbivory damage, suggesting that the researcher is not independent of its measurements. The principle could be tested in other ecological studies in which it may occur, such as those on animal behaviour, human ecology, population dynamics, and conservation.

Highlights

In 1927, the German physicist Werner Heisenberg introduced the “Uncertainty Principle”, according to which the act of measuring the physical properties of a particle alters its behaviour; that is, locating it in a small region of space makes the momentum of the particle uncertain, whereas measuring precisely its momentum makes the position uncertain (Heisenberg, 1927)
Cahill et al (2001) called this phenomenon the “Herbivory Uncertainty Principle” (HUP), to which little attention is paid in plant science (Boeck et al, 2008)
When we analysed the treatments without distinguishing species identity, we did not find significant differences (P = 0.27; H = 3.89; df = 3), with herbivory proportion of 0.029 ± 0.073 in the control, 0.030 ± 0.064 at low visitation intensity, 0.033 ± 0.074 at medium visitation intensity, and 0.029 ± 0.063 at high visitation intensity

Summary

Introduction

In 1927, the German physicist Werner Heisenberg introduced the “Uncertainty Principle”, according to which the act of measuring the physical properties of a particle alters its behaviour; that is, locating it in a small region of space makes the momentum of the particle uncertain, whereas measuring precisely its momentum makes the position uncertain (Heisenberg, 1927). If this occurs, the way that a physicist understands a problem and how conclusions are drawn from his or her study are affected (Heisenberg, 1927). The implications could be similar to those of physicists studying particles: the act of measuring herbivory in target plants could change the herbivory rate, that is, the researcher would not be independent of the outcomes of the study (Cahill et al, 2001). Cahill et al (2001) called this phenomenon the “Herbivory Uncertainty Principle” (HUP), to which little attention is paid in plant science (Boeck et al, 2008)

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