Evaluation of Some Man-Made Forests at Al-Jabal Al-Akhdar in Libya

Abstract

This study aimed to investigate the growth dynamic, litterification, wood yield and dendroclimatology of Aleppo pine (Pinus halepensis) trees growing in five different plantations, namely, Hemre, Marawah, Madwar Ziton East, Madwar Ziton West and Kashaf, located at Al-Gabal Al-Akhdar region, Libya.The results obtained have demonstrated that the planation of Marawah displayed the highest diameter at breast height (dbh) (21.55 cm), mean annual increase in dbh (0.66 cm/ year), basal area (BA) (19.25 m 2 /ha) , log volume (1.02 m 3 /tree), mean annual increase in log volume(0.02 m 3 /tree/year) , log yield /ha (307.47 m 3 /ha) and mean annual increase in log yield/ ha (8.54 m 3 / ha/ year). Hemre, however, displayed the tallest tree (14.61m) crown diameter (5.23 m) , with no significant differences in dobh, (21.70 cm) , BA (21.20 m 2 /ha) and log yield /ha (256.22 m 3 / ha ) with those manifested in Marawah plantation. On the contrary, Kashaf plantation, however, has exhibited the lowest values of the growth and yield as mentioned above.The average of annual litter fall gained in the plantations floor was 10.51 ton/ ha / year, as a mean for all plantations studied, with non significant differences among each other. There were also non significant differences among all plantations in specific gravity of the wood (0.45 as a mean for all plantations). The bark coefficient was also the same for all plantations inspected (0.93).Monitoring the rainfall rate since 1960 up till now ( 2019), there was a slight decrease in rainfall rate with the time that averaged 394.34 mm/year, concomittant with a slight increase in temperature that averaged 18.47°C at Al-Gabal Al-Akhdar region. The dendroclimatological studies have revealed that either the width of early wood, latewood or annual ring thickness was inversely proportional with the simultaneous temperature in all sites investigated. Except for Kashaf plantation, the rainfall rate was neithersignificantly impacting on the width of early wood, latewood nor annual ring thickness developed in the stem of the trees in all plantations analyzed. Upon the prospected negative climate changes and its detrimental impacts on the forest growth, it recommended to improve silvicultureal practices to keep it fit.

Dendrochronological studies in North Africa: reality and prospects

“…Due to the occurrence of false and missing rings, it was not possible to synchronize the single samples (on an annual basis) for the interval of practically regular growth. Mohamed et al (2019) studied the growth of the cultivated Aleppo pine trees (P. halepensis) growing in five different plantations in the Aljabal Al-Akhdar region, Libya. They found that there was a negative relationship between temperature and the width of earlywood or latewood or the thickness of the annual rings of the species.…”