Issue link: http://winesandvines.uberflip.com/i/116287
G RA P E G R O W I N G or simply the number of species present in a habitat. Even this simple method can be challenging depending on the boundaries put on counting. Should we only count the birds and mammals? Should all the plant species be included? How about the insects? What about the fungi? Then there are the soil microbes. In terms of biodiversity in relation to vineyards, I am aware of studies that at best counted the mammal and bird species as well as a few important insects but no more. The other two methods of measuring biodiversity are accomplished using mathematical formulae. One is called the Simpson Index, which was first published in 1949. It is the probability that a second individual sampled from a population/ community should be the same species as the first one sampled. The Simpson Index (C) is calculated as follows: ST C= ∑ i pi2 where pi2 = Ni(Ni-1) NT(NT-1) Where pi is the proportion of individuals in the ith species, ST is the total number of species present in the community, i is the ith species, Ni the number of individuals in the ith species and NT the total individuals in the sample. I do not think I need to explain why I have never seen anyone use the Simpson Index to measure biodiversity in and around vineyards. The third biodiversity index is called the Shannon–Wiener Index, or sometimes the Shannon Weaver Index, which is calculated (H) as follows: ST H= ∑ p log p i i e i It is clear from the difficulty of calculating the above indices that biodiversity presents a dilemma. It is a great concept and an important characteristic of an ecosystem, but even the scientifically inclined do not use the long-established metrics to measure it because they are too involved and costly to carry out. An indicator species offers one solution to this dilemma. An indicator species is a species of plant or animal that through scientific analyses has been determined to be representative of a community or ecosystem. If one is confident of this designation, then monitoring a single species to get an indication of biodiversity or the health of a community or ecosystem is much simpler than calculating with one of the above diversity indices. The challenge is to figure out what qualifies a species to be an indicator species. Often it is a species that is particularly sensitive to change or environmental disturbance. Unfortunately, while designating an indicator species can be done scientifically, the validity of choosing a particular one is often debated. Furthermore, it is not quite the same as measuring the biodiversity of a biological community. I would have liked to present a simple yet robust method for calculating biodiversity, but it should be clear from the above discussion that this is not possible. The next best thing is to expand awareness about the complexity of measuring biodiversity, allowing for a more informed interpretation of presentations and articles on this important subject. Dr. Cliff Ohmart is vice president of professional services for SureHarvest and author of "View from the Vineyard: A practical guide to sustainable winegrape growing," due to be published this month by Wine Appreciation Guild. Previously he served as research/IPM director at the Lodi-Woodbridge Winegrape Commission. He has been writing about sustainable winegrowing issues for Wines & Vines since 1998. Anderson Valley Winegrowers Association presents Search Online for PEST CONTROL Vineyard Suppliers Vineyard Equipment Vineyard Services Vineyard Supplies Sixteenth Annual Anderson Valley Pinot Noir Festival May 17–19 2013 Taste Pinot Noir produced by California's finest vintners from grapes grown exclusively in Anderson Valley. Enjoy local foods, live music, educational events, winery open houses and more. For more information and tickets visit: www.avwines.com ONLINE SEARCH W W W. W I N E S A N D V I N E S B U Y E R S G U I D E . C O M 84 W in es & V i ne s APR I L 2 013