In Asian tropical forests, Dipterocarpaceae is the most ecologically and economically important tree family. Due to their economic importance, dipterocarps are widely planted in tropical Asia. To well manage the dipterocarp plantations, water consumption and hydrological implications from such commercial plantations need to be assessed. However, the seasonal water use and stand-level transpiration of Dipterocarpaceae have not been well investigated.

Together with his teacher Prof. CAO Kunfang, Mr. Zafar Siddiq, a Ph.D candidate of Xishuangbanna Tropical Botanical Garden (XTBG), measured the seasonal behavior of sap flow in eight evergreen dipterocarp species in six monoculture stands and in one-mixed plantation stand in Xishuangbanna, the northern tropics of Southwest China. The researchers aimed to see whether water use in dipterocarp trees differed between in wet and dry seasons. Then what were the main environmental factors that drove the differences? They also measured the water used by the dipterocarp plantation stands.

The researchers selected eight dipterocarp species grown in plantations from six monoculture stands and one mixed stand of two species to investigate their seasonal behaviors of sap flow and water use. They placed two data loggers and a power source for measuring sap flow in 22 trees in those seven plantation stands.

They found that the dipterocarp species and their plantation stands increased water use in dry season (February to April) in Xishuangbanna. The higher water use in the dry season was explained by higher vapor pressure deficit and increased effect of photosynthetic active radiation on canopy transpiration.

Compared with fast-growing Eucalyptus and Acacia mangium plantations in Xishuangbanna, the dipterocarp plantations consumed much less water. It was due to a combination of favorable conditions both above and below ground, by the frequent and cloudy days in the ever-wet tropical rain forests.

 The study thus provided important insights for planning forest plantation, especially in the context of predicted increases in drought and in managing the hydrology of watershed areas.

   The study entitled “Increased water use in dry season in eight dipterocarp species in a common plantation in the northern boundary of Asian tropics” has been published online in Ecohydrology.

KEY WORDS

Dipterocarps, forest plantation, tree water use, stand-level transpiration, Xishuangbanna

Contact

Zafar Siddiq

Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences,
Mengla, Yunnan 666303, China 
E-mail: zafarbot@yahoo.com