The Liukuei Experimental Forest (LEF) is the largest experimental forest in Taiwan in which
about 10,000 ha of natural and artificial forestlands are administered. To understand the climatic
and hydrological conditions of this vast area so as to provide necessary information for forestry
management, phenology, hydrology, afforestation, and ecological conservation, the Division of
Watershed Management has successively set up 3 second-grade agricultural weather stations in
the northern, central, and southern parts of the LEF since 1980 respectively named the Fonkang,
Shanping, and Donna stations, as well as 5 gauged watersheds in the Shanping area since 1964.
This report summarized the effective electronic records of these 3 stations from 1986 to 2017,
and presents LEF’s climatic conditions in monthly resolution. Average annual rainfall amounts in
the Fonkang, Shanping, and Donna areas were 3429.8, 3435.9, and 3536.1 mm, respectively. The
average annual rainfall for the entire area was close to 3500 mm (3467.3 mm), which was much
higher than that for Taiwan as a whole (about 2500 mm) and indicates that the LEF receives abundant
rainfall. However, rainfall in the LEF mostly occurs in April to October, and this period can
be defined as the wet season. Rainfall in the wet season accounted for 92.8, 94.5, and 94.7% of
the total annual rainfall for the Fonkang, Shanping, and Donna areas, respectively. This shows that
rainfall is extremely temporally unevenly distributed. There are a clear wet season and dry season
in the LEF. Numbers of rainfall-days (defined as a day with ≥ 0.5 mm of rainfall) in a year for the
Fonkang, Shanping, and Donna areas were 142.5, 135.1 and 126.0 d, respectively. The number of
rainfall-days in the northern part of LEF was greater than that of the southern part, while the rainfall
amount in the north was less than that in the southern part, indicating that rainfall was more
unevenly temporally distributed in the southern part of the LEF. Annual average temperatures in
the Fonkang, Shanping, and Donna areas were 16.7, 20.7, and 19.7℃, respectively. The entire LEF
area belongs to a cool climate zone, based on the annual average temperature. The difference in
annual average temperature is mainly determined by elevation. The average monthly temperature
differences for the Fonkang, Shanping, and Donna areas in a year cycle were 7.7 (12.3~20.0), 8.3
(15.8~24.1), and 8.6 (14.7~23.3)℃, respectively. Compared to the monthly average temperature
difference of the Fushan, Lienhuachih and Taimali experimental forest of ITRI, the average monthly
temperature difference of the LEF was relatively low. The highest monthly average temperature
for the entire LEF area was in July, and the lowest average monthly temperature was in January.
Average daily temperature differences in January for the Fonkang, Shanping, and Donna areas
were 7.04, 6.87, and 6.42℃, respectively; and those of July were 5.73, 6.50, and 7.32℃, respectively.
Other meteorological parameters monitored in the LEF were humidity, solar radiation, wind
speed and direction, and evaporation. The physical quantities of these meteorological factors are
also presented in monthly statistics. In addition, the yearly average temperatures of the air, stream-
72 Lu et al.─Climatic and hydrologic characteristics of the Liukuei Experimental Forest
flow, topsoil at 5, 30, and 50 cm in depth of the riparian zone of Chungliao Creek were 19.53,
19.04, 18.99, 19.39, and 19.38℃, respectively, for the monitoring period of 2005~2008. The yearly
average rainfall, streamflow discharge, and baseflow for the period 2000~2003 of the Shanping no.
2 experimental watershed were 3316.5, 2043.1, and 487.3 mm, respectively. It was also noted that
streamflow discharge in the period from November to April mainly originated from deep seepage
water and groundwater and was approximately equal to that of baseflow.