Assessment of acacia plantation status in Quang Ninh province

Abstract

Acacia mangium and Acacia hybrid are the two main species for planting in
Quang Ninh province, with a total area of 167,215.4 hectares by 2019,
accounting for 67.5% of the total plantation area of the province, of which
Acacia mangium accounting for over 80% of the province's acacia
plantations. After many cultivation cycles, the quality of the site of acacia
plantations in Quang Ninh has been reduced, the soil layer is thin (the soil
thickness of 50 - 70cm accounts for 86.9% of the total area of hilly and
mountainous land in the province). Poor nutrition has reduced productivity of
plantation. Acacia species in Quang Ninh are planted with density ranging
from 1,100 trees/ha to more than 4,000 trees/ha, of which the common
planting density is 2,000 - 2,500 trees/ha. The volume of acacia plantations at
the common harvesting age (5 - 7 years) has a large variation, from 80.0 -134.1 m
3
/ha, equivalent to the average annual growth volume ranging from
14.2 - 23.3 m
3
/ha/year, an average of 113.3 m
3
/ha for Acacia mangium
plantations and 102.6 m
3
/ha for acacia hybrid plantations. The percentage of
trees affected by pests and diseases in Acacia mangium platation averaged
22.7%, much higher than that of acacia hybrid plantations, only 6.4%.
However, the level of pests and diseases in Acacia plantations in Quang Ninh
is not really serious when most of the damaged trees in acacia plantations are
only at level 1 (rate of leaf canopy being pests and diseases ≤ 25% or the rate
of branches being pests and diseases ≤ 10%).