I also found that community structure species composition and their abundances of lianas in ridge was distinct from that in valley because of the differential distribution and abundance of certain species along the topographic gradient.
In an attempt to explain this phenomenon deterministically, I took two approaches: 1 to explore if trait expression of leaf-based traits, wood specific gravity and stem growth rate was different among species with ridge habitat association, species with valley habitat association, and generalist species; and 2 to explore if frequencies of different whole-plant growth strategies in the forest understory—defined by whether a liana was free-standing or already climbing, by its climbing mechanism, and by its understory appearance—were different between ridge and valley.
My underlying rationale was that if certain trait expression or understory growth strategy can be associated to a given species, or group of species, and such species also drive the community structure difference between ridge and valley, then ecological insight on the biological deterministic mechanisms driving the difference can be gained. I end this one-page dissertation abstract right here and purposely leave you, the reader, perplexed—I invite you to seek answers to the liana distribution conundrum in the YFDP by perusing this dissertation.
On the positive side, it has been suggested that by growing between tree crowns, lianas help stabilize trees Smith , but the evidence is that liana infested trees actually create larger gaps when they fall.
Tree species vary in their susceptibility to liana infestations, and in their ability to shed lianas that colonize their crowns Putz b. Because of limits in the diameter of supports that lianas can use in their ascent to the canopy, fast growing trees tend to avoid liana infestations, especially if they rapidly shed their lower branches.
Thick-stemmed palms are particularly immune to lianas, and lianas that do make it into their coronas are shed along with the leaves to which they are attached. Smooth bark and bark that is shed in large flakes may also deter lianas to some extent, but given the way that most lianas attach to their supports, this mechanism would not seem to be particularly effective. Some tree species also suffer reduced threats of vine colonization because the symbiotic ants that they harbor and feed keep their host tree free of parasites, including structural parasites such as lianas Janzen Due to their vine avoiding and vine shedding characteristics, sometimes including these ant symbionts, pioneer trees are particularly common in severely vine infested areas where slower growing trees are affectively suppressed Schnitzer et al.
Herbaceous vines and lianas often play important roles during forest succession after natural and anthropogenic i. Liana proliferation on and near the edges of forests is also one of the major causes of structural deterioration in fragmented forests Laurance et al.
Vine Management. Where lianas are abundant, they represent a severe nuisance for forest managers.
Not only are crop trees suppressed and damaged by the lianas they support, but forest operations are also rendered more difficult and dangerous. Tree fellers are in particular danger when liana-laden trees pull down their neighbors, often on top of the worker. For these reasons, pre-felling liana cutting is a commonly prescribed silvicultural treatment for reducing logging damage to the residual forest and for enhancing worker safety Putz , Vidal et al. This silviculturally beneficial effect is mostly due to the removal of the fallen stems that, where lianas have not been cut, contribute the majority of stems that suppress regeneration in logging gaps Alvira et al.
The Role of Vines: Summary. Although vines can be a major problem in forests managed for timber, their beneficial roles in forest ecosystems should not be overlooked. For example, lianas provide important intercrown pathways for many canopy-dwelling animals and so are important ecosystem engineers Photo 9.
The abundant leaves, flowers, and fruits of lianas also represent important food resources for animals, and contribute substantially to biogeochemical cycles. Although many lianas have small and wind dispersed seeds, some produce delicious fruits that are important to many forest animals. Many canopy lianas also produce abundant flowers, making them an important component of pollinator communities.
A larger proportion of liana species than tree species are pollinated by large bees and beetles. Because vines are favored by forest disturbances and are more common as well as more diverse in warmer environments, human-induced disturbances and global warming are likely to promote vine abundance. Perhaps these environmental modifications are already responsible for the reported increase in the growth rates and abundance of large diameter lianas in tropical forests Phillips et al.
Forest Ecology and Management in press. Malaysian Forester Handbuch der Pflanzenphysiologie Adansonia Canadian Journal of Botany Journal of the Linnean Society Botany 9: Journal of Tropical Ecology Oecologia American Naturalist Botanical Gazette Cambridge, U. Plant Biology 3: Journal of Applied Ecology Ecological Applications Hladik A.
Ecology Forest Ecology and Management Biotropica Nature Journal of Tropical Forest Science 6: Australian Journal of Botany Journal of Ecology Putz FE, Sirot LK, Pinard MA Tropical forest management and wildlife: silvicultural effects on forest structure, fruit production, and locomotion of non-volant arboreal animals. Indeed, global change and different forms of forest disturbance have led to an increase in the abundance and biomass represented by lianas. Recent research for example shows that artificially high densities of feral pigs have a positive effect on liana abundance.
Similarly, lianas seem to be positively affected by forest fragmentation. A study in the endangered Brazilian Atlantic forest showed that liana abundance was higher in small fragments and near forest edges as a consequence of the microclimatic conditions found there e. These microclimatic conditions are similar to those found in canopy gaps , where lianas have been observed to aggregate.
This increase in liana abundance has important implications for biodiversity and ecosystem services.
Competition between lianas and trees leads to a decreased reproductive success of many canopy species , with consequences for seedling density and tree seedling recruitment. A mechanistic explanation of this finding is brought by two contributions by the same research team to Journal of Ecology.
These authors explain the greater presence of lianas on shade-tolerant trees as a combination of their inability to shed them and their ability to tolerate them. Conversely, they find that fast-growing species are able to shed lianas , yet their growth rates are reduced to a greater extent by them, and thus the individuals of fast-growing species we observe are those that survived and do not bear lianas. One of the mechanisms by which lianas outcompete trees, is their efficient water transport and physiological regulation.
Indeed, a study published in Functional Ecology , suggests that the importance of lianas for forest water dynamics might have been undervalued up to now. A method that is widely used in response to liana proliferation is liana cutting.
Liana cutting is also extensively used as a method to increase tree productivity.