Hi everyone,
Can someone help me to interpret the Shannon alpha diversity output? Is the H value a measure of sample richness only? And does the p-value represent the significant differences between samples based on H values?
Hello Asmaa,
Welcome to the forums! 
The H value is part of the Kruskal-Wallis test (Wikipedia).
The p-value is also part of the stat test.
(Here's my favorite explanation of p-values)
richness only
The Shannon's alpha diversity measures both the richness and evenness of the samples.
Other alpha diversity methods use richness or evenness only, if that's what you want.
Let us know if you have more questions!