Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Data were sampled at three-week intervals through 2013. Values each time point are means based on 20x 1m2 quadrats, with dark shading showing 95% confidence limits.
