We generally use 50 X 50 m or 100 X 100 m quadrats to calculate the basic ecological parameters within a hectare of land. Within 50 X 50 m or 100 X 100 m quadrats, we used to laid 10 X 10 m quadrats for sampling tree species, 5 X 5 m for shrubs & seedlings, and 1x 1 m for herbs.
You may use 10-20 quadrats x 3 replicates for trees, 25quadrats x 3 replicates for shrubs and 50 Quadrats x 3 replicates for herbs in a forest stands
In 100x100m quadrat, you can sub divide 25 quadrat of 20*20m and randomly selected half (13) quadrat of 20x20 m, and in each 20*20m quadrat 3 quadrat 5*5m for shrubs and 3 quadrat of 1 m2 in each 5*5m quadrat (total 9 quadrat 1m2).
El esfuerzo óptimo estaría en función de muchos factores relacionados con la naturaleza del ambiente y forma de vida que estés estudiando. Como sugerencia, para determinar que tan eficiente fue tu muestreo (si ya lo realizaste) puedes determinar la cobertura de la muestra obtenida, el paquete iNEXT (https://cran.r-project.org/web/packages/iNEXT/vignettes/Introduction.html) puede ayudarte. Ahora, si ya tienes muestreos hechos (previos) y quieres complementar el trabajo (nuevos muestreos), puede usar el paquete SSP (https://cran.r-project.org/web/packages/SSP/index.html) que justamente te indica cuanto de esfuerzo es el necesario para ser el considerado óptimo. De esta manera, tomas una decisión respaldada estadísticamente sobre el tamaño muestral.
I think depends upon the forest type and its elevation and community structure. In the hilly mountain region the diversity patterns form a hump-shaped structure, so need to consider many factors. In plain, the homogenous managed forest requires fewer replicates to present the community structure an overall variation.
The research papers shared by Marco Aurelio are very much relevant and useful in ecological studies.
Thanks for sharing
Regards
Quadrat size could vary according to study priorities. If keeping the size of the quadrat aside for a while, the answer to this question is multifaceted as the quadrat method is used frequently for several ecological studies (assessment of populations, communities, species diversity and biomass estimation etc.) and the number of plots may vary accordingly.
For ecosystem studies (E.g. species diversity studies), it depends on the saturation level of species-accumulation curves. If the species accumulation curve of the sampling dataset shows exponential growth, it means you need to continue sampling in a given area until the point where the curve reaches its saturation (flat) level. Indeed, pre-defined standard sampling protocols play a crucial role in the saturation of species-accumulation curves and the number of quadrats to be studied.
I hope it is helpful to some extent.
Cheers
It definitely has to be at least 30 quadrats so the distribution of the sample estimates of the mean tends to a normal distribution :)
If it is pure forest less quadrats seems possible, but if it is mixed deciduous forest it must be bigger and numerous.
We used a transect of 2 km length and six plots (each plot was subdivided into 10 subplots of 20 m * 50 m) each of 1 ha at a successive interval of 300 m to study the changes in the structural assemblages caused by the interaction between anthropogenic disturbances and forest management activities in the mixed sal forests. Please find the link to the paperArticle Changes in the Ecological Parameters of Mixed Forests of Sal...
Minimum 25% area should be covered to get atleast all species representation from all sides, and accordingly quadrat number should be divided converting them into hectares
I think plot the grid of whole area using some GIS tools and then sampling at least one quadrat in each grid.
I think the decision of making quadrates is depends on the optimum and saturation level of species-accumulation curves.