Testing liana cutting and controlled burning as silvicultural treatments for a logged forest in the eastern Amazon

Abstract

Summary1. In the eastern Brazilian Amazon, logged forests frequently include patches where liana density is particularly high. In these so-called liana tangles, competition from lianas is predicted to reduce tree growth significantly, thus effectively impeding future timber production. To begin to develop a silvicultural strategy for these patches, the impact of liana cutting and controlled burning on liana density, tree growth and tree regeneration in liana-dominated patches was investigated in a logged forest in the eastern Brazilian Amazon. 2. The two treatments (liana cutting and controlled burning) and a control were installed in 40 × 40-m plots in a randomized complete block design of six blocks. Treatments were conducted during October 1997, and tree diameter growth and mortality, canopy cover, regeneration and liana density were monitored over 2 years. 3. Mean mortality following burning was significantly higher for lianas (79%) than for trees (48%), as was the mean coppicing rate of top-killed stems (42% for lianas vs. 20% for trees). Coppicing combined with some recruitment from seed resulted in liana densities in the burned plots returning to 70% of the values in the control plots only 2 years post-treatment. 4. Canopy light transmittance, estimated from hemispherical canopy photographs taken at 1 m above the ground, increased significantly from c . 4% in controls to 8% in cut and 12% in burned treatments, and these differences persisted over the 2-year study period. 5. In the absence of silvicultural intervention, mean tree diameter increments were low (1·3 mm year -1 ), suggesting that the successional transition to higher stature forest was occurring very slowly. Each of the treatments resulted in a more than doubling of mean annual tree growth (3 and 2·8 mm year -1 for liana-cut and burned treatments, respectively). The treatments also significantly reduced the occurrence of trees that showed no growth over the study period, from 56% in controls to 30% in cut and 32% in burned treatments. 6. The results of this study suggest that although burning resulted in increased tree growth, rapid recolonization of surviving trees by lianas and the high vulnerability of burned stands to unwanted repeat burns are likely to cancel out any of the possible benefits of controlled burning as a silvicultural treatment for liana-dominated patches. Liana cutting, on the other hand, showed promise and its adoption as part of a larger strategy for the recuperation of the timber production potential of logged tropical forests seems warranted.

Lianas have a greater competitive effect than trees of similar biomass on tropical canopy trees

“…Our results may provide a physiological explanation for the increased growth of canopy trees following liana cutting observed in many studies (e.g., Pérez-Salicrup and , Gerwing 2001, Grauel and Putz 2004, Campanello et al 2007, Schnitzer and Carson 2010. The increase in sap velocity of canopy trees we observed in response to liana cutting during the dry season suggests that lianas have the potential to reduce canopy tree growth.…”

“…To assess the unique competitive impact of the liana growth form on canopy trees, liana cutting must be compared directly with cutting treatments of other woody plants, primarily trees. Of the numerous liana-cutting experiments (e.g., Barker and Pérez-Salicrup 2000, Gerwing 2001, Grauel and Putz 2004, Campanello et al 2007, Peña-Claros et al 2008, Schnitzer and Carson 2010, none have explicitly included a cutting treatment to compare the competitive effect of lianas to that of trees. The relative effect of liana and tree competition is a critical issue because as lianas increase in abundance and biomass relative to trees in tropical forests , lianas will likely have a much greater effect on canopy trees than would be predicted by their biomass.…”

Remnant Trees in Enrichment Planted Gaps in Quintana Roo, Mexico: Reasons for Retention and Effects on Seedlings

“…That there was no effect of lianas on seedling growth is also counterintuitive and contrasts markedly with their observed deleterious impacts on large trees [37][38][39][40][41][42]. We believe that this result is related to the recency of the liana infestations and that their ill-effects on seedling growth and stem form will soon become evident.…”

Espèces lianescentes à fruits comestibles du Togo

“…Depuis une dizaine d'années, plusieurs études se sont intéressées à l'écologie et au rôle des lianes dans la dynamique forestière [17][18][19][20][21][22][23][24]. Au Togo, en dépit de très nombreuses études relatives à la flore et à la végétation [25][26][27], les informations relatives aux lianes en général, et à leurs fruits en particulier, restent fragmentaires et peu détail-lées en raison du peu de travaux qui leur sont consacrés.…”