The number of marijuana plants that have been eradicated nationwide has dropped over the past three years, while the amount of bulk processed marijuana seized by authorities has doubled.

California, where a majority of marijuana plants are eradicated, saw a 46.5 percent drop in plants that were destroyed between 2010 and 2011, bringing down the nation’s totals, the Associated Press reports.

The decrease in plant eradication can be attributed to a number of factors, including changes in growers’ tactics, changing weather patterns and budget cuts to local and state enforcement agencies, according to Drug Enforcement Administration (DEA) and local officials.

Nationwide, the number of marijuana plants from outdoor and indoor growing operations decreased by 35 percent from 2010 to 2011, the article notes. A total of 37 states saw a decrease in eradication results.

DEA data shows the number of pounds of confiscated bulked processed marijuana rose from 53,843 pounds in 2009, to 113,167 pounds in 2011.

Authorities use helicopters to look for secret marijuana growing operations in forests and wild lands. Some of these operations are part of Mexican drug organizations, which used the forced labor of immigrants, while others use local labor.

Casey Rettig, spokeswoman for the DEA in San Francisco, said growers are transitioning from large forest farms to smaller plots that are less visible. These smaller plots can accommodate fewer plants, but they are bigger and higher-yielding, Rettig added.