Rev. Dr. J. Ludwig Krapf’s scientific contributions

... These rules only allowed access to sacred forests for religious reasons i.e. to pray and appease the gods. Tabiko instilled fear that a bad omen would befall any unauthorized intruders of Kaya forests (KI4; KI13; Krapf and Ravenstein, 1860). Forests with such shrines were believed to have a 'rain-calling' function (Van Binsbergen, 1979;p. ...

Reference:

From centralization to decentralization: Evolution of forest policies and their implications on mangrove management in Kenya