Agriculture would be the "single most interest opportunity over the next 10 to 20 years," Diggle said.
Vulpes favors investments in metals, energy and food, and "dislikes" government bonds, he said.
"Being long stuff in the ground is going to be a better place to be than holding pieces of paper," Diggle said.
The firm's Testudo Fund, which is heavily invested in precious metals and the mining industry, has gained 2.5 percent this year. The Russian Opportunities Fund has declined about 10 percent in the same period.
'Biggest Risk'
Governments and their policies represent the biggest threat to investors, he said. "The biggest risk will come from governments: government interference in markets, government debt and government manufacturing of paper money to pay off the debt," he said.
Diggle said he's focusing on "new exciting commercially viable technology" in the life sciences industry that will find cures for illnesses including cancer and Parkinson's disease.
"We certainly see a lot of interest by big pharma in small innovative biotechnology," Diggle said. "If we can find those small new exciting biotechnology companies before big pharma gets to them, there's a big uptick in terms of valuation if they can prove their work."