Effects of human disturbances and plant invasion on liana community structure and relationship with trees in the Tinte Bepo forest reserve, Ghana

摘要

There are conflicting reports on the role of disturbances in maintaining liana community structure, and in determining their relationship with trees. The effects of plant invasion on these attributes of lianas are not known. The study investigated the effects of human disturbances and plant invasion on liana community structure and relationship with trees in the Tinte Bepo forest reserve, Ghana, in three distinct forest types to reflect both human disturbances and invasion: Undisturbed, Disturbed-Invaded and Disturbed Forests (UF, DIF and DF respectively). Trees >=10cmdbh were identified and their dbh measured in two 0.25ha plots in each forest type. The trees were examined for the presence of lianas (>=2cmdbh) and their dbh measured. A total of 380 lianas >=2cmdbh belonging to 20 genera and 12 families were identified in the 1.5ha forest. Twelve liana species were unique to the DIF suggesting the probable positive influence of plant invasion on their colonisation. Liana density differed significantly across the forest types (df=2, p =0.043) with the UF recording the greatest number. The mean liana stem diameter and basal area were greater in the DF. Large diameter lianas were absent in the UF. Tree density and number of trees hosting lianas were greater in the UF followed by the DIF and DF. Liana infestation was generally high with 90% in the DF, 88.2% in the UF, and 85.7% in the DIF. Both liana load per tree species and mean liana load per infested tree were highest in the UF followed by the DIF and then the DF. Liana density was highly dependent on tree density in all the forest types (df=1, r po =0.50, p =0.007; df=1, r po =0.99, p =0.000 and df=1, r po =0.72, p =0.000 in the UF, DIF and DF respectively). There was a significant positive relationship between liana dbh and host dbh in the UF (df=1, r po =0.096, p =0.000), DIF (df=1, r po =0.11, p =0.000) and DF (df=1, r po =0.16, p =0.008). There was no significant relationship between host dbh and liana loads in all the forest types.