How can I use the "countif" function in excel, and not have the output change when I sort the data?

I have created a database in sheet 1 that I want to sort as I add more data. I organize & sort my data by a variable called "tag #" which refers to the identification # of a certain plot of trees. Every time I get a new tree plot, I enter more lines of data into my database (one for every tree) all of them with the same tag #. Due to the way that the numbering of the plots works, I don't get the data in numerical order. So I want to enter the data of a plot into an existing database and then sort it so that the tag #s are in order. This is simple enough, but I need to use the "countif" function (in another sheet) to count certain variables (ex. tree species) within a given tag #. I can do this, and the function works fine until it's time to sort the data again. At that point the "countif" function yzes whatever data is then in the cells that used to contain data of a different tag #. How do I solve this? Can I somehow have the "countif" func. follow the cells as I sort them?