e.g. moment one: square in its normal state moment two: square after cutting large trees and replacing them with dwarf trees.
To compare biodiversity in a square (e.g., a quadrat) at two different times, you can use various analysis methods. Here are a few:
1. *Species richness*: Compare the number of species present in the quadrat at both times.
2. *Species turnover*: Calculate the change in species composition between the two times, using metrics like Jaccard's index or Simpson's index.
3. *Shannon diversity index*: Compare the diversity of species using the Shannon index (H'), which considers both species richness and evenness.
4. *Species abundance*: Compare the number of individuals of each species present at both times.
5. *Community composition*: Use ordination techniques like Principal Component Analysis (PCA) or Non-metric Multidimensional Scaling (NMDS) to visualize and compare the community composition at both times.
These analyses can help you understand changes in biodiversity over time, such as species gain or loss, changes in community structure, and shifts in species abundance.
Ateef Ullah already gave a good advice, there are many indices. But you cannot do any statistics on only one quadrat to calculate biodiversity indices and compare them before and after manipulation. So, I assume you have many quadrats (replicates). Is there any ecological gradient involved? it is important for understanding beta-diversity patterns and ordination results. Download PAST4 (free) software and under Diversity tab you can find lots of tools for comparing diversity, while ordination methods are under Multivariate tab.
Zaal Kikvidze, soo, the square is not too big and i decide to sample without doing quadrat... instead, i doo some time replicates (3 times after the cutting and 3 times before...)
so, it will work??
Pretty unusual design, but if the effect is strong, you might test it.
Dear Guilherme Moura,
the analysis methods mentioned above are important for
you analyze your data.
On this website, there are several articles and methods that you can follow, as there are several studies that tested the fragmentation of biodiversity in the Amazon at different times.
https://ppbio.inpa.gov.br/publicacoes/artigos/2024
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