Liana loads and post-logging liana densities after liana cutting in a lowland forest in Bolivia
Alvira D; Putz F; Fredericksen T
Forest Ecology and Management
Liana infestations can be a problem in forests managed for timber because lianas decrease rates of tree growth damage tree boles and inhibit tree regeneration. To determine the area from which lianas colonize tree crowns in a liana-rich moist lowland forest in a timber concession in the Department of Santa Cruz Bolivia we described \"liana sheds\" of individual canopy trees (the area under the crown and beyond its margins from which lianas colonize trees). In the same area we tested the hypothesis that pre-logging cutting of lianas in a harvested tree\s liana shed reduces post-logging liana infestations. Prior to logging 73% of 570 trees >10 cm in DBH representing 12 commercial species carried at least one liana >2 cm DBH. Liana-infested trees hosted an average of 9.3 lianas (+/-0.45 S.E. range: 1-68). The mean area of the crown covered by lianas was 35% (+/-29.7 S.E.) but some trees (10%) were completely covered by lianas. \"Liana shed areas\" were a function of crown area and varied among tree species. Most lianas on trees were rooted below the crown of their host (90%); the number of lianas decreased with increasing distance from the crown edge but lianas colonized trees from as far as 8 m beyond the crown. Overall there was a significant reduction in the number of lianas in 22 felling gaps 8 months after logging where lianas were cut before logging compared with 22 control gaps. In control gaps the majority of climbing lianas sprouted from the prostrate stems of fallen canopy lianas (81%) including 3.1 km/ha of stems that were rooted along the ground before logging. Liana regeneration in gaps after pre-logging liana cutting occurred mainly by stump sprouting (41%) and sprouting from prostrate stems (48%). Pre-felling liana cutting reduced liana cover in felling gaps by 9% only but reduced liana basal area by 69%. The results of this study suggest that tree crown area shape and height are among the most important factors determining the likelihood of liana colonization of canopy trees and that pre-logging liana cutting reduces post-logging liana proliferation in logging gaps.