The total value of China’s timber imports — rough logs, timber or wood pulp — has increased more than 10 times since China began restricting logging at home in 1998, reaching $23 billion in 2017, the highest ever, according to IHS Markit’s Global Trade Atlas.

The government extended a regional ban to the rest of the country at the end of 2016. It now allows commercial logging only in forests that have been replanted, a policy that environmentalists say other countries should emulate.

The problem is that many have not, and Chinese companies have pursued these opportunities.

More than 500 companies operate in Russia now, often with Russian partners, according to a report by Vita Spivak, a scholar on China for the Carnegie Moscow Center. Russia once delivered almost no wood to China; it now accounts for more than 20 percent of China’s imports by value.

“If the Chinese come, nothing will be left,” Marina Volobuyeva, a resident of the Zamensky region south of Lake Baikal, told a television channel after a Chinese company secured a 49-year lease to log in the area.

Russia sells such logging concessions at prices that vary by region and type of wood, but on average, they cost roughly $2 a hectare, or 80 cents an acre, per year, according to Mr. Shmatkov of the World Wildlife Fund. That is far below the cost in other countries.

In 2017, China imported nearly 200 million cubic meters of wood from Russia.

Artyom Lukin, a professor of international studies at the Far Eastern Federal University in Vladivostok, noted that government corruption, criminality and the lack of economic development in Siberia and the Far East have also made the crisis worse.