Vietnam has set the target of growing around 200,000 ha of forest each year while in reality, the country still has 600,000-700,000 ha (1.48-1.73 million acres) of land that could be afforested, said Vuong Van Quynh, former head of the Institute for Forest Ecology and Environment at the Vietnam National University of Forestry.

Forests could additionally be cultivated alongside roads, around residential areas, within industrial parks and even besides field barriers, he told VnExpress in an interview.

Forests with low density plantation normally have 1,600 trees per hectare.

As for production forests, areas designated primarily for the production of wood, fiber, bio-energy and/or non-wood forest products, the ratio could rise to 2,500-3,000 trees per hectare. With a mangrove forest, the density could reach 3,000-4,000 trees per hectare.

Quynh said he believes the target of planting one billion trees in the next five years is "doable."

At a meeting of the legislative National Assembly last week, Prime Minister Nguyen Xuan Phuc suggested Vietnam target planting one billion trees in the next five years since the nation has been suffering from more extreme weather conditions, resulting in deadly floods and landslides.

The country currently has 14.6 million hectares of forest, of which 4.3 million are grown forest and the rest natural.

The nation’s forest coverage makes up more than 41 percent of its total area compared to 58 percent in Cambodia, 68 percent in Laos, and around 21 percent in China and India.

Worldwide, it is now understood the ideal percentage of forest cover is 33 percent.

As for the PM's plan, Quynh said: "In the immediate future, we need to identify areas at high risk of landslides and flash floods to prioritize afforestation. The government should plan such efforts according to the structure of existing natural forests, ensure a variety of tree species and layers, and keep the vegetation zone untouched."

Regarding the ability to help ease the impacts of flash floods and landslides, he said it is the land where the plants stand that help hold back the water and not the trees, and that 1,000 ha of forest land could work as a reservoir with a capacity of several million cubic meters of water.

However, he noted the ability to hold water among planted forests would not be as good as that of natural equivalents.

To put it into perspective, if natural forests could hold 100 percent of water, planted forests can only keep 60-80 percent at most, he noted.

For planted forests, root systems have not grown big enough to retain soil while on the other hand, timber trees would be harvested for different purposes to replant new trees, which could boost the process of erosion and leaching, reducing the soil's ability to hold water, Quynh explained.

In October, central Vietnam was hit by floods thrice along with a series of landslides that claimed 159 lives and left 71 missing, with questions raised over the excessive construction of hydropower plants in areas of natural forest.

Trinh Xuan Hoa, deputy head of the Vietnam Institute of Geosciences and Mineral Resources under the Ministry of Natural Resources and the Environment, said earlier this month deforestation and construction, among other factors, were to blame for triggering landslides in the central region.