To many people, investing in commodities is about capitalizing on short-term price swings. To MacKenzie Davis, one of the managers of the RS Global Natural Resources Fund, it's about getting down and dirty to find stocks worth holding on to for the long haul.

The 39-year-old manager pokes around mines, wells and fields in both the U.S. and Canada, as well as in more far-flung locales such as Vietnam or even the Arctic Circle, to get a complete view of companies and their natural resources. On a recent whirlwind tour of Australia, Davis and portfolio manager Ken Settles visited with 16 companies, scrambled around two iron ore mines, and toured a port facility, all in just a few days.

"The only way to really know about a company's natural resource assets is to put a hard hat on and take a look at them," says Davis. "What it comes down to is geology that was put in place millions of years ago and good management that knows how to allocate capital."

The goal of these investigations is to find companies with low production costs and attractive geological assets that allow them to make money even if commodity prices stagnate or drop. It's a timely strategy at a time of slow economic growth, when commodity prices are likely to be constrained and it's essential to keep down costs.

That wasn't the case for much of the last decade, when the growth stories in emerging markets such as China, Brazil and India pushed commodity prices higher. The prices collapsed, however, during the 2008 financial crisis, and between May and November of that year the S&P Global Natural Resources Index fell 58%. Although commodities have gained ground since then, a slower growth environment, even among burgeoning emerging market economies, has kept prices in check.

Davis cites a number of reasons for investors to maintain some exposure to natural resources. Even with the worldwide economic slowdown, emerging market countries are still seeing high-single-digit GDP growth rates. These countries' commodity needs will expand in the coming years, so they will continue to help drive demand for natural resources. Furthermore, commodity prices have held up surprisingly well in the face of sluggish economic growth in most countries.

Davis says the most convincing long-term arguments lie on the supply side of the equation, since natural resources are finite. The reserves have been well-tapped, and companies have not invested heavily in locating and developing new ones as prices sag. Until those prices rise, there is little financial incentive to spend more to increase production. The government takeover of oil, copper and other resource reserves in some countries adds another set of supply constraints, since governments almost always run them less efficiently than private enterprises.

To minimize that threat, the fund avoids companies in countries such as Russia and parts of Latin America where commodities could likely be repatriated. Otherwise, the fund spreads a wide geographic net by buying names headquartered in the U.S., Canada, Chile, Australia and any other place where regulations require reporting transparency from public companies. At 44% of the assets, energy stocks play an important role in the fund's assets, though RS Global Natural Resources holds a variety of large stakes in other sectors as well, such as copper, coal, diamonds and precious metals.