Biological Richness, An Introduction James A. Danoff-Burg Dept. Ecol., Evol., & Envir. Biol. Columbia University

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Today: Introduction to Biological Richness  Designing Surveys – Review of assignment 1  Why Study Biological Diversity?  Types & Aspects of Diversity  Evenness  Species Richness Indices  Rarefaction

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Application of Techniques – An Exercise  Design a study, avoiding pseudoreplication  Include visual representations of sampling method  Include:  Experimental question  Manipulations  Hypotheses (null, alternatives)  Target organisms  Censusing design  Censusing method

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Last Week’s Assignment  Project of your own design  Write up a short (2-3 paragraphs) description of your proposed study in normal scientific prose  Include question and hypotheses (including null and all alternative hypotheses)  Include sampling design, sampling method  Be specific and thorough  to before the start of class next

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Types of Censusing Designs  Grid  Using regular intervals along a 2-dimensional design  Transect  Sampling with reference to a straight line  Random  Can be used to site point-quarters, quadrats, other sampling methods

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Choosing Between Censusing Designs  How to choose between sampling layouts?  Depends on experimental question  Gradients  Probably best to use a transect  Ensures comparability  Relatively uniform sampling area  Random probably best – if done frequently enough, get equal representation of areas included  Grid may be useful when need to uniformly sample area

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Surveying Design  Need to equally capture / census entire community (or subset) to be studied  Be consistent  Have equal sampling effort in different areas  Time, area, quantity sampled  Appropriately represent area studied  Equally sample disparate constituent areas  Random vs. orderly (grid, transect)?

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Surveying Techniques  In short: Any viable form of collecting or sampling  Need to be sited at a level appropriate to the question  Examples:  Point-Quarter Proximity to a central point within a cross  Quadrat Sampling within a small area  Pitfall traps  Beating Sheets  Mist netting  Seining  Etc…

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Pseudoreplication Example  Question – What is the affect of treatments A & B?  Pseudoreplication = treating stars of the same color as replicates  Replication = include only a single star of each color, or their average Treatment ATreatment B Site 1 Site 2 Site 3 Site 4

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Today: Introduction to Biological Richness  Designing Surveys – Review of assignment 1  Why Study Biological Diversity?  Types & Aspects of Diversity  Evenness  Species Richness Indices  Rarefaction

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Diversity is Interesting  Stimulated many poets, artists, naturalists, etc.  Ecotourism is prompted by biological diversity  Or at least biological, geological, climatological diversity  Continual novelty is a key feature  Increasing probability of novelty, because of high biodiversity, leads to increasing visitation rates  E.g., most ecotourism is to tropics

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Diversity as an Indicator  Diversity = health of the ecosystem  Diversity and stability relationship  Example of Shahid Naeem’s work on trophic redundancy and stability  Diversity and recovery from perturbations, erosion, etc.  Diversity as a detective tool of the past  Use to determine how long ago land was altered by human or natural activity

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Diversity is controversial  Define diversity  Simple definitions work well  Richness  Abundance  BUT these are not really “Diversity”  More complicated ones are less clear  What does it mean?  More we try to define it, the less definable it is  Some have argued that it is meaningless (Hurlbert 1971)

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Today: Introduction to Biological Richness  Designing Surveys – Review of assignment 1  Why Study Biological Diversity?  Types & Aspects of Diversity  Evenness  Species Richness Indices  Rarefaction

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Types of Biological Diversity  Point: diversity at a single point or microenvironment  Alpha: within habitat diversity  Beta: species diversity along transects & gradients  High Beta indicates number of spp increases rapidly with additional sampling sites along the gradient  Gamma: diversity of a larger geographical unit (island)  Epsilon: regional diversity

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Aspects of Biodiversity  What can we measure?  Possibilities  Species (richness)  Abundance  Diversity relationship between richness & abundance  Guild  Trophic structure  Evolutionary diversity  Within species diversity (genetic, morphological)  Others?

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Diversity of Diversities  Difference between the diversities is usually one of relative emphasis of two main envir. aspects  Two key features  Richness  Abundance  Each index differs in the mathematical method of relating these features  One is often given greater prominence than the other  Formulae significantly differ between indices

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Today: Introduction to Biological Richness  Designing Surveys – Review of assignment 1  Why Study Biological Diversity?  Types & Aspects of Diversity  Evenness  Species Richness Indices  Rarefaction

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Evenness  Definition of Evenness  How equally abundant are each of the species?  A simple way to combine abundance and richness  Rarely are all species equally abundant  Some are better competitors, more fecund, more abundant in general than others

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Evenness increases diversity  Increasing evenness  greater diversity  True for all indices Site 1 Site 2 S = 4 N = 8 S = 4 N = 8 Higher Evenness, Diversity

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Evenness as an Indicator  For many ecosystems, high evenness is a sign of ecosystem health  Don’t have a single species dominating the ecosystem  Often invasives dominate  Paradox of enrichment E.g., polluted / enriched Lake Okeechobee, Florida  Disturbed areas are mostly edge species Simple biodiversity Dominance of a few species ecologically, numerically

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Evenness Across Locations  Between ecosystem comparability is usually not possible  Some areas have lower biodiversity naturally than others Tiaga is naturally much less even than the deciduous forest Tiaga is often dominated by a single species (e.g., Blue Spruce)  Seasonality may confound the comparison as well Earlier in temperate growing season, less even than later  This is a general principle for most all indices this term  When would you want to compare across locations?  Trying to prioritize areas for conservation  Based largely on biodiversity (not ecol. uniqueness)

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Today: Introduction to Biological Richness  Designing Surveys – Review of assignment 1  Why Study Biological Diversity?  Types & Aspects of Diversity  Evenness  Species Richness Indices  Rarefaction

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Species Richness Indices  Richness has largely been the variable of interest for many conservationists  There are many ways to treat species richness  Two main ones  Raw Richness  Species Density

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Numerical species richness = Raw Richness  Works best with complete surveys (everything taken)  These can be destructive  Need equal sampling effort  Popular in aquatic studies  species seen per 1000 individuals

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Species Density  Useful in botanical surveys, sometimes in aquatic surveys  Species / m 2 if on a 2D plane  Mostly botanical surveys, some arthropod surveys  Species / m 3 if in a 3D space  Aquatic or botanical canopy surveys

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Today: Introduction to Biological Richness  Designing Surveys – Review of assignment 1  Why Study Biological Diversity?  Types & Aspects of Diversity  Evenness  Species Richness Indices  Rarefaction

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Rarefaction  Method to post-hoc treat data to correct for lack of standardization of sampling effort  Not always possible to collect in a standardized manner  Particularly true with “Natural Experiments”  May have some treatment areas larger than others  Able to collect in some areas for more time than others  Outcome  To calculate the # of spp expected in each sample  If hypothetically, all samples were of a standard size

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Rarefaction  Designed by Sanders (1968), modified by Hurlbert (1971)  Drawbacks  Loss of information through data loss Expected number of abundance / species is all that is left Loss of abundance, richness data  See Worked example #1 in Magurran for more information on how to do the calculation  We will work through this next week  Read the example before hand

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, After Standardizing Efforts  Can now conduct simple richness comparisons between sites  Need to be comparable  Can do Margalef, Menhinick, Shannon, Simpson analyses  We’ll begin these in two weeks

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Our Data This Term I  Relationship between plant biodiversity, pest insect biodiversity, and beneficial insect biodiversity  Read website at pages/gardens_main.htm pages/gardens_main.htm  Has a pretty good amount of background on the topic  Field sites were in Manhattan and Brooklyn community gardens  Data collected during summer 2001  I will also you the data matrix Please begin looking it over so that you are comfortable with it

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Our Data This Term II  Influence of Hemlock Woolly Adelgid on carrion beetle biodiversity  Separated by many (at least 3) trophic levels  Adelgid is a phloem-feeding insect  Carrion beetles are detritivores or predators on fly larvae on carrion  Field sites at Black Rock Brook, Black Rock Forest  Data collected during summer 2001  I will also you these data Please begin looking over the data set

Lecture 2 – Introduction to Biological Richness© 2003 Dr. James A. Danoff-Burg, Next week:  Abundance, An Introduction  Read  Magurran Ch 2  Magurran Worked Examples 1-6  Southwood & Henderson 2.1, 2.2, 13.1  We will conduct a few evenness and species abundance models next week  Decide which of the two projects on which you are interested in working collaboratively  3 people per group