Dear Keron,

I am not sure if I understood your question correctly. If you want to compare the samples would be enough, a previous analysis a comparison between means.

Is there also any way of deciphering if for example an invasive species had a significant impact on the changes if the other abiotic parameters remained constant?

Hola Keron,

cualquier paquete estadístico te sirve, SPSS, SAS o los más específicos para estudios ecológicos. Creo que lo importante es el tratamiento o análisis que pretendes hacer con tus datos, qué piensas comparar y para qué? con esto en mente, revisas los supuestos estadísticos que deben cumplir tus datos para aplicar pruebas paramétricas o no paramétricas. Para las comparaciones de diversidad prueba con los modelos y varios índices, por ejemplo el alpha de Fisher es muy potente, pero lo ideal es calcular varios indicadores, Si piensas analizar patrones, entonces debes pensar en los métodos de clasificación y ordenación. Hay un trabajo clásico de Magurran 1985, sobre este tema.

Dear Keron,

maybe you can use linear models or generalized linear mixed models to test whether specific parameters have significant effects upon species richness and diversity. Using those models you are able to apply random factors to test whether the year of data collection has any effects upon the result. Or maby you could do a timeline analysis? I recommend using R.

Books that might help you:

1. Crawley: The R Book

2. http://eu.wiley.com/WileyCDA/WileyTitle/productCd-1405190086.html

3. http://www.highstat.com/BGGLM.htm

4.Farrawy: Extending the linear model with R (https://github.com/clamm/R_dev/blob/master/Faraway%20-%20Extending%20the%20Linear%20Model%20with%20R.pdf)

Thanks much Luiz, Nestor and Vanessa! I'll look into the suggestions made. 

Hello Keron:

I think you could try an ANOVA test only should see if (as Nestor says) your data meet the assumptions of normal distribution and considering the number of your "n" among others, because this is a test can give you lots of information and a program which serves a lot is "Statistica", give him some treatment to your data. I hope you find it useful comment.

Greetings!

Gume

Hello Karen

Are you looking for a change in species diversity over 35 years period? Use species turnover (beta diversity), please check papers listed below.

http://dx.doi.org/10.1111/j.1461-0248.2004.00636.x

http://dx.doi.org/10.1890/06-1730.1

 http://dx.doi.org/10.1111/j.1466-8238.2009.00490.x

Regards

Hi Keron

Not sure exactly what parameters you want to look at for shifts over time, but if it involves community change you might like to have a look at the approach we took in attached.

Cheers

Kevin