Status of dieback of Juniperus Procera (African pencil cedar) in natural stands and plantation in Alsouda highlands, Saudi Arabia

Abstract

The natural habitat of Juniperus procera is a unique ecosystem in Saudi Arabia. The ecosystem of Aseer highlands is an important habitat for flora and fauna. Alsouda Highlands, situated in the south-western part of Saudi Arabia, is claimed to be the highest peak in Saudi Arabia. These forests suffered varying degrees of degradation. Juniperus trees in these highlands have experienced widespread decline with substantial dieback for 35 years. The aim of the study is to evaluate the status of J. procera dieback in Alsouda natural stands (2400-2950 m). The results showed that >80 % J. procera trees within the natural stands had symptoms of dieback but >65% was not severely affected. Tree recovery signs of new lateral shoots, leaves, sprouts and flowering were evidently observed even among the severely affected trees. The plantation showed no symptoms of dieback, but their growth rate was relatively low. The NDVI showed an increasing trend of greenness with time, especially in the seasons with high rainfall. The effect of slope aspect was evident in the severity of dieback and greenness of the vegetation as detected by the NDVI data. The west facing slopes were higher in NDVI values than the east-facing slopes, due to higher precipitation in the west - facing slopes by the southwestern monsoons. The results indicate significant effect of seasonal rainfall with respect to tree health.