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Effects of long-term rainfall inter-annual variation on regeneration dynamics of tropical dry forests (TDF) are still poorly understood. Such understanding is particularly important to assess the regeneration potential of TDF in landscapes subjected to slash-and-burn farming management. Here, we studied from 2004 to 2016 the effects of inter-annual rainfall variation on the dynamics of regenerative communities of woody species during the old-field succession of a TDF in Western Mexico. Over the study period a severe drought, caused by an El Niño Southern Oscillation (ENSO) event in 2005, and two hurricanes (Jova, 2011, magnitude 2; Patricia, 2015, magnitude 4) were experienced. In 2004, we established a chronosequence of abandoned cattle pastures and old-growth forest sites, which were assigned to four successional categories, each one with three sites: Pasture (0–3 years fallow age), Early (3–5 years), Intermediate (8–12 years), and Old-Growth Forest (without any human disturbance). At each site, seedlings, saplings and resprouts 10–100 cm height of shrub and tree species were tagged, taxonomically identified, measured in height and monitored over 12 continuous year intervals. At each year, all new plants reaching 10 cm height were recorded and considered as recruits. Community rates (recruitment, relative growth rate in height, mortality, species gain and species loss) were calculated per year, considering all plants combined and separating shrub from tree species. All community rates varied notoriously in response to temporal rainfall variability, with almost null interaction with successional category. As expected, mortality and species loss rates declined as the amount of rainfall increased, especially when precipitation of the current and the previous year were taken into account; these rates peaked in the ENSO year and were still high in the following year. Unexpectedly, recruitment and species gain rates also declined with the increase in rainfall, especially with the amount of rainfall in the current year. Overall, community rates of tree species were more responsive than those of shrub species to temporal rainfall variation. The ENSO-related drought event produced a short and transient instability in the plant density and species density of regenerative communities. However, ENSO effects were smoothed out by subsequent rainy years, leading to a net increase in plant density and species density in all successional categories, especially in the younger one. Overall, our study shows that global (e.g. ENSO) and regional (e.g. storms, hurricanes) climate factors play a key role on forest succession, modulating the speed of the TDF regeneration dynamics. We conclude that low impact agricultural land use and the presence of good levels of remnant forest cover in the landscape confers a high potential for regeneration in abandoned agricultural fields, even under the impact of severe droughts and severe hurricanes. [ABSTRACT FROM AUTHOR]

Abstract: Understanding the patterns and processes driving biodiversity maintenance in fragmented tropical forests is urgently needed for conservation planning, especially in species‐rich forest reserves. Of particular concern are the effects that habitat modifications at the landscape scale may have on forest regeneration and ecosystem functioning: a topic that has received limited attention. Here, we assessed the effects of landscape structure (i.e., forest cover, open area matrices, forest fragmentation, and mean inter‐patch isolation distance) on understory plant assemblages in the Los Tuxtlas Biosphere Reserve, Mexico. Previous studies suggest that the demographic burst of the strong competitor palm Astrocaryum mexicanum in the core area of this reserve limits plant recruitment and imperils biodiversity conservation within this protected area. Yet, the local and landscape predictors of this palm, and its impact on tree recruitment at a regional scale are unknown. Thus, we used structural equation modeling to assess the direct and cascading effects of landscape structure on stem and species density in the understory of 20 forest sites distributed across this biodiversity hotspot. Indirect paths included the effect of landscape structure on tree basal area (a proxy of local disturbance), and the effects of these variables on A. mexicanum. Density of A. mexicanum mainly increased with decreasing both fragmentation and open areas in the matrix (matrix contrast, hereafter), and such an increase in palm density negatively affected stem and species density in the understory. The negative direct effect of matrix contrast on stem density was overridden by the indirect positive effects (i.e., through negative cascading effects on A. mexicanum), resulting in a weak effect of matrix contrast on stem density. These findings suggest that dispersal limitation and negative edge effects in more fragmented landscapes dominated by open areas prevent the proliferation of this palm species, enhancing the diversity and abundance of understory trees. This “positive” news adds to an increasing line of evidence suggesting that fragmentation may have some positive effects on biodiversity, in this case by preventing the proliferation of species that can jeopardize biodiversity conservation within tropical reserves. [ABSTRACT FROM AUTHOR]

Tropical rainforests harbor a high diversity of tree species, offering a potentially rich array of timber (TFP) and non-timber (NTFP) forest products. The supply of such products has been commonly evaluated at the local (plot) scale; however, little is known about how their availability and diversity change at the landscape scale, particularly in heterogeneous environments. This information is critical in designing landscape forest management programs. Here, we assess the extent to which the frequency, abundance, diversity, composition and productivity (aboveground biomass) of tree assemblages with potential forest products (PFPs) change across three landscape units (LUs) that differ in soil and topographic conditions. The study was carried out in a well-conserved old-growth tropical rainforest in southeastern Mexico. Three plots (0.5 ha each) were established per LU, in which all trees ≥ 10 cm were inventoried, taxonomically identified and assigned to eight forest product categories. General linear models, multiple regression and ordination analysis (CCA) were used to assess structural and compositional changes in the tree assemblages supplying different PFPs among LUs and along soil physicochemical gradients. More than half (94 species, 57%) of the total number of identified species (165) had one or more PFPs, mostly related to timber products. Ordination analysis showed that the abundance of species with different PFPs has a heterogeneous distribution among LUs, mostly related to changes in soil nitrogen, pH and aluminum saturation. Variation among LUs in terms of tree biomass was strongly driven by soil available phosphorus and soil physiological depth. Each LU had a different potential to provide forest products, producing a diverse mosaic of PFPs within the landscape. Decisions concerning sustainable forest management should consider such variability in the availability and diversity of forest products across landscapes, as well as the environmental factors that govern this spatial variation. [ABSTRACT FROM AUTHOR]

Protected areas (PAs) are essential for biodiversity conservation, but their restrictive policies could accentuate poverty. Such a possibility may occur with the more restrictive PAs (e.g., national parks), which prioritize conservation while limiting the use of natural resources. However, less restrictive PAs, such as biosphere reserves, which allow the sustainable use of natural resources, may be better at alleviating poverty. However, such permissibility may reduce the effectiveness of preventing deforestation. Here, we assessed this conservation-development tradeoff by testing changes in marginalization (an indicator of poverty) and forest loss between two contrasting PAs management scheme types (MST, national parks and biosphere reserves) in Mexico. We quantified forest loss inside PAs and unprotected areas during the 2000–2019 period. Also, we contrasted marginalization changes during the 2000–2020 period between municipalities included in PAs (n = 288) and municipalities not directly influenced by PAs (n = 1615). Using a matching analysis approach, we tested for differences in forest loss and marginalization between protected and unprotected areas and between MST, in all cases controlling for the potential effects of confounding factors (e.g., slope, altitude, distance to cities, economic sector). We also evaluated potential conservation-development trade-offs resulting from the interaction of MST with the biophysical-socioeconomic context. PAs did not accentuate marginalization comparing unprotected areas. After matching, both national parks and biosphere reserves showed similar average changes in marginalization and forest loss probability. However, national parks showed higher marginalization than biosphere reserves in areas far from cities and sites with poor agriculture suitability, probably because restrictive policies in such adverse contexts might work against the development of the local communities. Also, national parks showed higher forest loss than biosphere reserves in areas suitable for agriculture. Our results suggest that, in the Mexican protected areas system, the interaction between MST and biophysical-socioeconomic contexts may lead to conservation-development tradeoffs. The more restrictive MST does not provide greater protection to the forest than the less restrictive MST and, under certain biophysical conditions, may reduce the capability of communities to cope with poverty. [Display omitted] • Protected areas by itself do not reinforce poverty of neighbor communities. • National parks are as efficient as biosphere reserves to prevent forest loss. • Poor agriculture suitability is associated with higher poverty in national parks. • Conservation-development trade-offs in protected areas depend on their context. • Under some context conservation and poverty alleviation can be compatible goals in protected areas. [ABSTRACT FROM AUTHOR]

Copyright of Tropical Conservation Science is the property of Sage Publications Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Mexico has one of the richest tropical forests, but is also one of the most deforested in Mesoamerica. Species lists updates and accurate information on the geographic distribution of species are necessary for baseline studies in ecology and conservation of these sites. Here, we present an updated list of the diversity of amphibians and reptiles in the Lacandona region, and actualized information on their distribution and conservation status. Although some studies have discussed the amphibians and reptiles of the Lacandona, most herpetological lists came from the northern part of the region, and there are no confirmed records for many of the species assumed to live in the region. After reviewing databases of scientific collections and published herpetological lists, and adding new information from our 2007 to 2013 inventories of the southeastern Lacandona rainforest, we recorded 124 species (89 reptiles and 35 amphibians) for the region. Nine amphibians (25.7%) and 2 (2.2%) reptiles are endemic to the Mayan forest (from the Lacandona, in Mexico, to the Mayan Mountains in Belize). Four amphibians and three reptiles appeared to be restricted to the Montes Azules Biosphere Reserve, suggesting that they are particularly vulnerable to habitat loss and degradation. On average, the region shares less than 60% of the species with neighboring Mexican tropical forests (e.g., Las Choapas region and Los Tuxtlas, Calakmul, and Sian-Ka'an Biosphere Reserves). Of the herpetofauna evaluated, the Mexican government threatened species list (NOM 059) indicates that seven species (20%) are under a risk category, while the IUCN indicates that only seven species (10.1%) are at risk. Our findings indicate that Lacandona is of great importance for the conservation of the Mesoamerican herpetofauna. Nevertheless, increasing deforestation levels add further uncertainties to the maintenance of amphibians and reptiles among other vertebrates in the region. [ABSTRACT FROM AUTHOR]

Abstract: Leaves of the long-lived Dioon merolae have been harvested intensively for decades (possibly for centuries) for ceremonial purposes by Zoque and mestizo groups inhabiting the Central Depression of Chiapas, Mexico. Over a period of four years, we evaluated vital rates (stem growth, leaf production, reproductive performance, and survival) and projected population growth rates in three populations (250 plants each, divided into eight size classes: new germinants, seedlings, saplings (S1, S2), and adults, A1–A4) with different leaf harvesting histories: non-defoliated by humans for at least 55 years (or very old harvest), defoliated annually until 15 years ago (recovering from harvest), and defoliated annually for at least the past 25 years (currently being harvested intensely). Population structure was affected by leaf harvest history. Stem growth was negatively affected by the annual harvest of leaves in size classes from seedlings up to A4 (ANOVA, P <0.003); fewer leaves were produced by seedlings, saplings and adults at the annually harvested site (ANOVA, P <0.027). Survival was high at all sites across all size classes; in the annually harvested site, A4 plants showed a decrease in survival (one dead out of four plants). Sex ratio of adults that produced cones during the four years of study was 61% males to 39% females. At the non-defoliated site, adult classes A2 and A4 produced >80% of the cones; no cones were produced by the A3 and A4 adult size classes at the annually harvested site. Asymptotic estimates of population growth indicated growing populations (λ ≥1); the highest mean values of finite population growth rate were obtained in the non-harvested site (λ =1.0202). Elasticity analysis with population projection matrices indicated that stasis (L, 9–38%) was the component that most contributed to λ, followed by growth (G, 1.2–2.9%), and fecundity (F, 0.2–1.1%). We observed detrimental effects on several vital rates due to continued long-term defoliation, although population growth parameters do not currently suggest a decreased trend as a result of the annual harvest of leaves. The duration of this study of a very long-lived plant species suggests caution when setting levels and frequency of leaf harvest. The results help pinpoint practical recommendations that could be implemented in a sustainable management plan for this species, particularly to increase seed production in the annually harvested site, and recruitment of new germinants and seedlings at all sites. However, sound practices will need to consider the interests of involved stakeholders (landowners, pilgrims, conservation organizations and authorities) to effectively reduce anthropogenic pressure on this endangered species. [Copyright &y& Elsevier]

The article presents a study on the application of community structure analysis to the function of ecosystems involving carbon storage and pollination. It highlights the impact of human enterprise on species, the ecosystem and biodiversity leading to the adaption of methods for depicting evenness in the taxonomic group. An overview of crop transfer and biodiversity conservation is also presented.

Discusses the natural growth conditions that maximize height growth after transplantation from a nursery in a Mexican rainforest. Significance of multiple regression analysis in analyzing the plant growth; Effect of light on various species.

Copyright of Forest Ecology & Management is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• Ecological filters differentially affect seedlings and resprouts along succession. • Abiotic filters predominantly select for legume species. • Biotic filters on resprouts generate high clade diversity. • Secondary forests are similar to old-growth forest after 15 years of succession. • Understanding differential operation of filters during succession informs forest management. Abiotic and biotic filters may play differential roles in the plant community organization along forest succession in abandoned fields. However, little is known about how life stage-specific filters influence species replacement during succession. We approach this issue by analyzing changes in community attributes (abundance, species density, species diversity, species composition) and the phylogenetic structure of shrubs and trees at different life stages during the old-field succession of a seasonally tropical dry forest (TDF) in Western Mexico. We raised two main questions: (1) How different are the trajectories of change in community attributes and phylogenetic structure along succession for shrub and tree species at different life-stages? (2) Do different stage-specific trajectories result from differential filtering mechanisms? We used a chronosequence of abandoned pastures and forest sites, classified in five successional categories (with three sites each): Pasture (< 1.5 years fallow age), Early (3.5–5.5 y), Mid (6–8 y), Advanced (13–15 y), and Old-Growth Forest. Identity and abundance of species were recorded at five life stages: seeds in the top soil layer, seedlings (plants emerged from seeds, 10–100 cm height), resprouts (plants emerging from buds in roots or stumps, 10–100 cm height), juvenile [shrubs and trees > 100 cm height and < 2.5 cm diameter at breast height (DBH)], adults (shrubs and trees with DBH ≥ 2.5 cm). Additionally, we quantified the phylogenetic mean parwise distance (MPD) among species, and analyzed the phylogenetic community structure, for each successional category and life stage. We found that early in succession the resprout stage was more abundant and diverse than the seedling stage, while the inverse occurred late in succession. Along the first 15 years of succession, the seedling stage showed a clumped phylogenetic structure (with a strong dominance of legume species), while the resprout stage tended to have an overdispersed one (with species from a wide range of clades). Also, community attributes of the juvenile and adult stages approached those of the old-growth forest, and in both stages the phylogenetic structure changed from clustered to random. Overall, our results suggest that the assembly of shrub and trees communities along succession resulted from a combination of abiotic filtering processes, operating mostly on seedlings (selecting primarily legume drought-tolerant species), and biotic filtering processes, operating mostly in resprouts (generating a taxonomic and phylogenetically diverse regenerative pool). The implications of these results for the management of secondary TDF in human modified landscapes are discussed. [ABSTRACT FROM AUTHOR]