Opportunities, Constraints and Perceptions of Rural Communities Regarding Their Potential to Contribute to Forest Landscape Transitions Under REDD+: Case Studies from Mexico

In Mexico, REDD+ is being presented as a win-win policy enabling forest communities to benefit financially and diversify their income sources while preserving and increasing their forest carbon stocks through more sustainable management. Under the national programme, it is expected that forest communities will have opportunities to tailor their own approaches. However, to date there is little understanding about what opportunities and constraints exist in reality for forest communities to contribute to REDD+, and even less about how their members perceive these opportunities. We assess potential and constraints at community level and investigate perceptions about opportunities in REDD+ and strategies that communities are currently envisaging for participation, in seven communities in the Ayuquila River Basin and around the Chamela-Cuixmala Biosphere Reserve in Jalisco, and in the area surrounding the Monarch Butterfly Reserve in Michoacan. We find that there is more opportunity for reduced degradation and forest enhancement than for reduced deforestation, in all the communities; that it may be difficult to establish additionality for REDD+ activities in some communities; that the amount of forest resource per community may greatly affect the potential to participate; that the presence of people with no land rights may complicate the distribution of benefits; that communities expect REDD+ in general to follow the Payment for Environmental Services model, and that lack of information about what activities may count as REDD+ activities and what level of financial rewards may be expected mean that communities cannot at present adequately appraise whether REDD+ will be worth their while or no

Conservation of the endemic dwarf carnivores of Cozumel Island, Mexico.

Cozumel Island, Mexico, harbours two endemic species of dwarf procyonids: the Pygmy Raccoon Procyon pygmaeus and the Dwarf Coati Nasua nelsoni. Both species are Critically Endangered, and are among the world&rsquo;s most threatened Carnivora. Here we summarise the research we have been conducting on their ecology, evolution, genetics, and conservation. We also summarise the conservation initiatives we have been undertaking and promoting in order to advance the conservation of these unique species and their habitats. This effort illustrates the importance of an interdisciplinary approach in conservation science and action in maximising effectiveness. Nevertheless, the precarious status of the species make it imperative to continue and expand the work we have carried out in Cozumel to prevent two imminent global extinctions.<br /

Effect of liana cutting on tree regeneration in a liana forest in Amazonian Bolivia

Lianas, woody climbing plants, are a conspicuous component of tropical forest canopies that might affect prevailing conditions in the forest floor and thus impact tree seedling regeneration. The effects of lianas on tree seedling survival, growth, and density were studied in a lowland liana forest in Bolivia. Gravimetric soil water content and canopy openness were measured to evaluate whether these factors changed as a result of liana cutting. I established 24 square plots of 900 m2 each, and after an initial set of measurements, all lianas were cut in half of them, while the others plots were used as controls. Tree seedling growth and survival of two tree species were evaluated: Clarisia ilicifolia and Astronium fraxinifolium. Eighteen months after liana cutting, seedlings in liana-cut plots grew significantly taller and produced more leaves than did seedlings in control plots, but survival was not affected by treatment. Seedling growth following liana cutting was significantly higher in A. fraxinifolium than in C. ilicifolia seedlings. Densities of tree and liana seedlings did not change after liana cutting. Gravimetric soil water content was apparently not affected by liana-cut treatment. Canopy openness increased significantly in liana-cut plots, but only by 4%, and only after 26 mo. I conclude that lianas hinder the growth of tree species seedlings differentially, which in turn might shift the balance in competitive interactions between seedlings. Thus, at the study site lianas could affect tree regeneration

Effect of liana cutting on water potential and growth of adult Senna multijuga (Caesalpinioideae) trees in a Bolivian tropical forest

Lianas, or woody climbing plants, are a major constituent of seasonally dry tropical forests, and are thought to impact negatively their host trees. In this study we evaluated whether liana presence was associated with reduced leaf water potentials and growth in adult Senna multijuga trees during the dry season in a lowland Bolivian forest. We used leaf water potentials in trees as a first approach to assess trees\u27 water status, under the assumption that leaf water potentials become more negative when water losses (via transpiration) exceed gains (by uptake). We measured relative growth in girth at 1.5 m height (gbh) to quantify tree growth. At the beginning of the 1996 dry season (early June), we selected 20 S. multijuga trees 10-20 cm dbh, and measured their gbh. We also recorded pre-dawn and mid-day leaf water potentials in these trees. In ten experimental trees all lianas were then cut, while the remaining trees were used as controls. Pre-dawn and mid-day water potentials were re-measured 1 day after liana-cutting, and then every week in all trees for 1 month and then at 3 and 5 months, until the beginning of the next rainy season (November); gbh was measured again in July 1997 to estimate relative growth rate. Liana removal was associated with less negative pre-dawn (-0.3 vs -0.4 MPa) and mid-day (-0.5 vs -0.7 MPa) water potentials in trees during the dry season. This difference appeared as early as 1 day after cutting, and disappeared once the rainy season began. Liana-cut trees grew more (0.4 mm/mm year) than liana-uncut trees (0.2 mm/mm year). These findings suggest that lianas may interfere with water availability to these trees during the dry season, and may also hinder tree growth

Comparative water relations of mature mahogany (Swietenia macrophylla) trees with and without lianas in a subhumid, seasonally dry forest in Bolivia

Many evergreen mahogany (Swietenia macrophylla King) trees in the seasonally dry Bajo Paragua forest in northeast Bolivia carry substantial liana loads. Evergreen lianas may impede the growth of their host trees in various ways, including competition for water. Hypotheses tested were that water relations status differs (a) between lianas and their host trees, and (b) between trees infested with lianas that were cut 3.5 months previously (treated trees) and control trees with intact lianas. Diurnal measurements of stomatal conductance (g(s)) and leaf water potential (Psi) were made on canopy leaves of treated and control trees and lianas at the start and end of the dry season. Lianas had higher (less negative) Psi values (mean and predawn) and higher diurnal g(s) (expressed as mean or sum of diurnal values) than mahogany trees, indicating that lianas had a higher demand for, and ability to obtain, water than their host trees. Control and treated trees had a similar water relations status, suggesting that removal of lianas had no effect on the water relations of the trees, even at the end of the dry season. We conclude that either both life forms have conservative water relations that were unaffected by water availability in our study, or that the trees and lianas have access to sufficient and different sources of water because of differences in their rooting depths. Our data are consistent with studies of temperate species, indicating that lianas do not interfere with water availability to their host trees

Lianas and their supporting plants in the understorey at Los Tuxtlas, Mexico

Lianas are woody climbing plants that begin their life cycles as seedlings rooted in the ground, but eventually rely on other plants for physical support in order to reach the top of the forest canopy (Holbrook & Putz 1996, Putz & Holbrook 1991). Lianas can negatively affect plants they climb by competing with them for common resources such as light, water and nutrients, and by causing them direct physical damage (Dillenburg et al. 1995, Pérez-Salicrup & Barker 2000, Stevens 1987, Whigham 1984). Yet, there is little documentation about the size at which liana individuals of different species begin to climb on other plants in nature. This information is important because the size at which a liana begins to climb on other plants will determine when lianas potentially start physically affecting their supporting plants. Furthermore, although the growth of liana seedlings might be determined by light (Sanches & Válio 2002), the availability of support will also largely influence the rate of growth of liana stems (Peñalosa 1982, 1983, 1985). Thus, information about the size at which liana species find support in the forest understorey will be useful in understanding future growth of liana individuals

Lianas and trees in a liana forest in Amazonian Bolivia

The distribution of lianas (woody climbing plants) on trees in a lowland “liana forest” of northeastern Bolivia was clumped and varied with characteristics of individual trees and tree neighbors. In twenty-four 900-m2 square plots established to estimate tree (≥10 cm DBH [diameter at breast height]) and liana (≥2 cm DBH) densities and to count the number of lianas a tree carried, we estimated a mean of 65 tree species and 51 liana species per hectare. Mean tree density at the study site (564 trees/ha, SE = 23.7) was similar to other tropical sites, but mean liana density was much higher (2471 lianas/ha, SE = 104.3). Basal area of trees ≥10 cm DBH was low in Oquiriquia (19.2 m2/ha) in comparison to other tropical forests. Liana diversity, as expressed by the ratio of liana/tree species, was higher in this forest than in any other so far reported. Of trees ≥10 cm DBH, 86 percent carried lianas. Four tree species (Astrocaryum aculeatum, Euterpe precatoria, Xylopia sericea, and Astronium fraxinifolium) had a lower proportion of liana-infested individuals than expected based on the mean percent of liana infestation in this forest. Forest plots with similar tree species composition did not have similar liana composition or liana loads per tree, which suggests that lianas and trees have no specific associations with each other. Lianas showed an aggregated distribution on trees, suggesting a facilitation process in which new lianas use already established ones to climb trees. Lianas of four different climbing mechanisms climbed a similar number of trees. Plots in the forest with high palm density also had high liana density, suggesting that palms and lianas respond positively to common forest conditions in the study site (perhaps related to successional forest status). Larger-diameter trees carried more lianas than slender trees, but this relationship was affected by the density of trees 10–30 cm DBH surrounding each tree, which suggests again that the successional stage of the forest in which a tree grows affects the number of lianas a tree carries. We found little evidence to support the idea that lianas were more likely to climb some tree species than others. Instead, larger trees and trees growing in the vicinity of trees 10–30 cm DBH, tended to have more lianas, perhaps as result of longer exposure to liana infestation

Cost and efficiency of cutting lianas in a lowland liana forest in Bolivia

Liana cutting is a commonly suggested silvicultural practice aimed at reducing the negative impacts of lianas on timber production, but few experimental studies have been conducted to evaluate the cost and efficiency of this practice. In this study, we estimated the cost of cutting lianas in 12 plots of 0.25 ha each in a densely liana-infested forest of lowland Bolivia, and evaluated the efficiency of this silvicultural treatment in terms of the proportion of lianas missed, the density of resprouting liana stumps, and the number of liana-infested trees after two years of an experimental liana treatment. The cost of cutting lianas in this forest by locally hired laborers was 23.6 (SE = 2.48) person-hours/ha. Considering local cost of labor and the U.S.–Bolivian currency exchange rate at the time of the study, this figure translates to ca $15/ha. Liana density decreased from 2471 (SE = 104.3) to 130 (SE = 24.2) liana stems ≥2 cm/ha immediately after cutting, because 5.5 percent of lianas were left uncut (missed). Slender lianas were missed more often than lianas with large-diameter stems. Liana species that grow 2–3 m before they start to twine were also frequently missed. Twenty-two percent of liana stumps ≥2 cm sprouted after cutting. Liana stumps with larger diameters sprouted more than stumps with smaller diameters. Most liana stumps produced only two sprouts. Two years after cutting, 78 percent of trees had no living lianas in their crowns, in contrast to only 13 percent liana-free trees in the control plots. Sixty-four percent of trees still had hanging dead lianas two years after cutting, but only 23 percent of trees were reinvaded by lianas using dead liana stems as trellises. Liana cutting can efficiently reduce the number of lianas in liana-infested forests, and the effects of cutting lianas last for at least two years; however, the treatment is expensive. Thus, we recommend that it is better to view liana cutting as a preventive activity to avoid liana infestation, rather than as a corrective measure after poor management. Liana cutting can be easily conducted along with other reduced-impact logging practices