China's decision to lower its forecast for growth in 2012 knocked resource companies from the off today, with mining stocks being down an average 3.42 percent in afternoon trade.Wen Jiabao, the Premier of the world's second-largest economy, revealed that the country had reduced its gross domestic product (GDP) target for 2012 to 7.5%, the first time below the 8% level in the last eight years. The economy expanded by 9.2% in 2011. Wen also noted that the Chinese government would maintain its 4% inflation target and attempt to keep the yuan "stable". Copper, gold and silver futures took a tumble after the news on the back of concerns over how slower economic activity will affect demand for commodities. As such, miners dominated the fallers list on the FTSE 100 before the close on Monday, with heavyweights Xstrata, Kazakhmys, Glencore and Vedanta Resources all registering losses of at least 4%.Commodities trader and producer Glencore was falling despite announcing a 28% increase in full-year revenue for 2011 to $186bn, helped by higher average prices in crude oil (Brent crude up 39%), copper (+17%), wheat (+22%) and gold (+28%). On the FTSE 250, Irish mining company Kenmare was also a heavy faller, losing over 5%, after it said final output for January was lower than expected as poor weather conditions and problems in the mining path caused a delay in production at the Moma Mine on the coast of Mozambique. On the rise was the pharmaceuticals and biotechnology sector, with big hitters GlaxoSmithKline and AstraZeneca making gains of at least 1% as investors sought relatively 'safer', more defensive, assets.BCTop performing sectors so far todayPharmaceuticals & Biotechnology 9,744.59 +1.10%Beverages 11,528.14 +0.95%Food Producers & Processors 5,482.71 +0.70%Industrial Transportation 2,460.80 +0.57%Gas, Water & Multiutilities 4,866.55 +0.31%Bottom performing sectors so far todayMining 21,262.24 -3.42%Industrial Metals & Mining 4,412.57 -2.75%Automobiles & Parts 4,982.42 -2.43%Technology Hardware & Equipment 732.62 -2.07%Industrial Engineering 7,847.36 -1.94%