Expert interview: eucalyptus drought? Lack of basis!

People's Daily published the Yanshu Research Center of the State Forestry Administration

Expert interview: Is eucalyptus causing drought? No scientific basis!

Interview Guests

Xie Yaojian: Chairman of the China Forestry Society Eucalyptus Professional Committee

Chen Shaoxiong: Researcher, Yushu Research and Development Center, State Forestry Administration

Is eucalyptus really a "water pump" as some people claim? Xie Yaojian, chairman of the China Forestry Society's Eucalyptus Professional Committee, explains that eucalyptus plantations cover around 2.6 million hectares in China, mainly in coastal provinces like Guangdong, Guangxi, Hainan, and Fujian, with smaller areas in Yunnan, Sichuan, Hunan, and Jiangxi. According to data, for every kilogram of dry biomass produced, pines consume about 1,000 liters of water, while eucalyptus only needs 510 liters. This shows that eucalyptus has high water use efficiency. Although it may consume more water overall due to its fast growth, it doesn’t cause a water crisis in suitable regions.

Chen Shaoxiong, a researcher at the State Forestry Administration’s Eucalyptus Research and Development Center, also denies the idea that eucalyptus is a “water pump.” From 1999 to 2003, Chinese and Australian experts conducted studies on eucalyptus and water in Tunxi and Leizhou, Guangdong. The results showed that during the rainy season, eucalyptus uses less than half the amount of rainfall. In the dry season, its water consumption is roughly equal to the rainfall. Eucalyptus roots are mainly found within 0.5 to 1 meter underground. In areas with annual rainfall over 800 mm, they don’t tap into groundwater. Even in droughts, eucalyptus only absorbs moisture up to 4 meters deep. Its small leaf area index limits transpiration, keeping water use low.

Xie Yaojian adds that forests can improve local microclimates, but their impact on large-scale climate is minimal. The southwest region, where monsoons meet, has distinct wet and dry seasons. Forests there act as a buffer, not a major factor. Claims that eucalyptus caused droughts in the southwest lack scientific support.

Eucalyptus, along with poplars and pines, is known as one of the world’s fastest-growing tree species. It was introduced to China in 1890, and after the 1980s, eucalyptus plantations expanded rapidly. By 2009, eucalyptus had become a key species for fast-growing and high-yield forests in southern China. It plays a crucial role in the pulp and timber industry. By 2015, China’s wood demand was expected to reach 330–340 million cubic meters, with domestic supply covering only 190 million. Eucalyptus plantations, using less than 3% of forest land, would meet 18% of this demand.

Attachment: State Forestry Administration Yanshu Research Center: Eucalyptus is Not a Water Pump

Eucalyptus is native to Australia, Indonesia, and the Philippines. China has grown eucalyptus for over 110 years and now considers it a strategic tree species for fast-growing and high-yield forests in southern China. Alongside poplars and pines, it is one of the world’s three fastest-growing trees. Eucalyptus has strong adaptability, grows quickly, and requires fewer pests and diseases. Existing plantations cover 2.3 million hectares, or 8% of China’s planted forests. Despite rumors like “eucalyptus is a water pump,” “it’s toxic,” or “no birds or grass under the trees,” we, as a specialized research center, aim to provide objective and scientific explanations.

Ecological Impact of Eucalyptus

(1) Eucalyptus is not a “water pump.” Scientific studies show that for every kilogram of dry biomass, eucalyptus uses 510 liters of water, far less than pines (1,000 liters) and other species like acacia (over 800 liters). While eucalyptus may use more water due to its rapid growth, it doesn’t cause a water shortage. For example, in Leizhou Peninsula, eucalyptus transpiration accounts for only about 1/3 of annual rainfall, and total evaporation plus transpiration is 1,000–1,100 mm/year—far below the 1,500 mm rainfall. Groundwater recharge is even observed, showing positive water conservation effects.

(2) Eucalyptus is not toxic. It is safe for both humans and animals. Koalas in Australia eat eucalyptus leaves exclusively, proving it is non-toxic. Major Australian cities rely on eucalyptus forests for clean water sources. Additionally, eucalyptus oil, used in cosmetics and medicine, confirms its safety and value.

(3) With proper management, eucalyptus does not degrade soil fertility. Intensive planting may temporarily reduce nutrients, but this is manageable through scientific fertilization and litter return. Soil fertility loss is not as severe as claimed, and with correct practices, eucalyptus plantations remain sustainable.

Comparison of Nutrient Uptake and Removal by Eucalyptus and Other Crops

The table shows that eucalyptus does not absorb more minerals than other crops, so there is no scientific basis for claims that it causes serious soil degradation.

Taking Zhanjiang as an example, the Leizhou Forestry Bureau, established in 1954, has planted eucalyptus for over 50 years, covering 700,000 mu. Despite claims that the land would be ruined, the forest land has improved over time. Eucalyptus yields have increased significantly due to scientific management, including new varieties, formula fertilization, and returning litter to the soil.

(4) Eucalyptus forests support biodiversity. Though they are artificial ecosystems, they still host a variety of plants and animals. Surveys in the Leizhou Peninsula found 150 species under eucalyptus forests, proving that biodiversity is not reduced. In Australia, eucalyptus forests are rich in flora and fauna, with kangaroos, birds, and reptiles thriving among dense vegetation.

Some areas may have sparse undergrowth due to factors like dense planting, lack of sunlight, or excessive weeding. These are not inherent issues with eucalyptus but result from improper management.

Eucalyptus provides significant social, economic, and ecological benefits. It creates jobs in rural areas, boosts local economies, and improves the environment. As a carbon sink, it absorbs CO₂ and releases oxygen. Replanting degraded land with eucalyptus improves soil quality and microclimate. Once barren, the Leizhou Peninsula now boasts a 24% forest coverage rate, proving eucalyptus’ environmental value.

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