Climate records for Bulu, Ndian Division, SW Cameroon

The file ‘Bulu-Ndian_Climate_1984-2017.csv' (format: comma-separated values) contains year, month, and day number in the first columns, followed by maximum (‘maxT’, oC) and minimum (‘minT’, oC) temperatures, volume of evaporated radiometer water (‘radi’, ml/day) and rainfall (‘rain’, mm/day) at Bulu, Ndian Department, SW Cameroon (4o55’53.47” N, 8o51’32.70” E; 51 m elevation [Google Earth]). This location is close to eastern border of Korup National Park, and 7.5 km SW of the town of Mundemba. The station is operated by PAMOL Plantations Plc, Cameroon. Readings were taken manually at 07:00 h each day, a record of the previous 24 hours. The date entered into the file was accordingly that of the previous day. Rainfall was measured in a standard copper collecting gauge, temperature read on thermometers inside a Stevenson screen, and radiation measured using Gunn-Bellani radiometers (Baird and Tatlock, London), one for each of two successive periods of time.

To convert ‘radi’ [V] to radiation in W/m2 [R] the following calibration equations can be applied for the radiometers over their corresponding periods of operation:

R = 24.1 + 12.3∙V                 (01.01.1984 - 02.04.2009)

R = 21.1 + 14.7∙V                 (30.05.2011 – 31.05.2017)

(Between 03.04.2009 and 29.05.2011 no data were recorded (values ‘NA’). This was due to accidental breakage of the original instrument and a delay whilst a suitable replacement was found and installed.)

The details of the calibrations of the two radiometers are explained in an appendix to the following related paper in preparation: “Mast fruiting in Microberlinia bisulcata and further evidence for the nutrient resource limitation hypothesis”, by Newbery, D. M., Schwan, S. Chuyong, G. B., Neba, G. A., Etta, C., Norghauer, J. M. and Worbes, M. [Bibliographic details subject to updating.]

We acknowledge the help and support of their Technical Officers Cyprain Lantang and Daniel Tabi at Bulu, and the assistance of Marlise Zimmermann (IPS, Bern) with entering the data into computer files from photographed pages of the climate record books. The data were checked and curated by D. M. Newbery.

These climate data have been of invaluable use to our ecosystem and vegetation research of the forests of Southern Korup National Park, the main field site for which lies c. 12 km NW of Bulu. They are also of interest for regional climate mapping because other stations in this part of western Central Africa are very sparse and their records incomplete.

Colbertson E. Etta, PAMOL Plantations Plc, Lobe Oil Palm Estate, PMB 03, Ekondo Titi, SW Region, Cameroon.  George B. Chuyong, Department of Plant Science, University of Buea, P. O. Box 63, Buea, SW Region, Cameroon. David M. Newbery, Institute of Plant Sciences, University of Bern, Altenbergrain 21, CH-3013, Bern, Switzerland.