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Physiognomy, structure and floristic composition of one hectare of lowland tropical rain forest was studied in detail at Los Tuxtlas, Mexico. Physiognomically, the Los Tuxtlas forest should be classified as 'lowland tropical high evergreen rain forest'. The forest showed a closed canopy at 30-35 m. Of all woody, non-climbing species with aDBH >_ 1.0 cm 89.407o (94.5070 of all individuals) were evergreen, 25.4070 (59.5 070 of the individuals) had compound leaves, and over 80070 of species (and individuals) had leaves in the notophyll and mesophyll size classes. The forest structure was characterized by a low density (2976 individuals with a DBH >_ 1.0 cm, 346 individuals with a DBH >_ 10.0 cm, per ha, excluding vines) with an average basal area (38.1 m 2, DBH>_ 1.0 cm, 34.9 m 2, DBH>_ 10.0 cm, per ha, excluding vines). This was attributed to the relative maturity of the forest on the study plot. The study plot contained 234 species (11 208 individuals with a height >0.5 m), of which 55.1070 (34.8o70 of individuals)were trees, 9.4070 (6.8070)shrubs, 3.4070 (44.3070)palms, 20.1°/0 (5.207o) vines, 6.8070 (8.707o) herbs and 5.10/0 (0.307o) of unknown lifeform. Furthermore, 58 species of epiphytes and hemi-epiphytes were found. Diversity of trees, shrubs and palms with a DBH _> 1.0 cm was calculated as Shannon-Wiener index (4.65), Equitability index (0.65), and Simpson index (0.10). The dominance-diversity curve showed a lognormal form, characteristic for tropical rain forest. The community structure was characterized by a relative dominance of Astrocaryum mexicanum in the understorey, Pseudolmedia oxyphyllaria in the middle storeys, and Nectandra ambigens in the canopy. Species population structures of 31 species showed three characteristic patterns, differentiated by recruitment: continuously high, discontinuously high, and continuously low recruitment. Height/diameter and crown cover/diameter diagrams suggested a very gradual shift from height growth to crown growth during tree development. Forest turnover was calculated as 138 years. Compared to other tropical rain forests the Los Tuxtlas forest had 1. similar leaf physiognomical characteristics, 2. a lower diversity, 3. a lower density, 4. an average basal area, and 5. a slow canopy turnover.Nomenclature is given in Appendix I 56

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Question How to evaluate and integrate relevant ecological, social and technical criteria to select species to be introduced in restoration projects of highly diverse ecosystems such as tropical riparian forests. Location Riparian forest, Marqués de Comillas municipality, southeast Mexico (16°54′N, 92°05′W). Methods We proposed a 'species selection index' ( SSI) using five independent criteria related to ecological, social and technical information. SSI targeted species that (1) are important in the reference forest; (2) are less likely to establish following disturbance; (3) are not specific to a particular habitat; (4) are socially accepted; and (5) their propagation requires a reasonable time and financial investment. SSI may range between zero and 50, with higher values meaning higher potential for restoration purposes. Results Out of a local pool of 97 species, we identified 30 target tree species that together represented >60% of total importance value index in the reference riparian forests. SSI averaged 28.3 ± 1.0 over the studied species, suggesting that species with high values are not frequent. For 20 species, reintroduction by means of active forest restoration was deemed necessary. Species that established through natural regeneration, following secondary regrowth, had lower social value among local farmers. Nearly half of the identified species showed technical constraints for easy propagation and seeding. Conclusions The proposed procedure is useful for selecting species to initiate forest restoration projects and of other woody ecosystems that harbour high biodiversity, and is suitable for several stakeholders interested in restoration

Decisionmakers need updated, scientifically sound and relevant information to implement appropriate policy measures and make innovative commitments to halt biodiversity loss and improve human well-being. Here, we present a recent science-based synthesis on the biodiversity and ecosystem services of Mexico, intended to be a tool for policymakers. We describe the methodological approach used to undertake such an assessment and highlight the major findings. Organized into five volumes and originally written in Spanish (Capital Natural de México), it summarizes the available knowledge on the components, structure, and functioning of the biodiversity of Mexico; the threats and trajectories of anthropogenic impact, together with its conservation status; and the policies, institutions, and instruments available for its sustainable management. We stress the lessons learned that can be useful for similar exercises in other megadiverse developing countries and identify major gaps and strategic actions to conserve the natural capital in light of the challenges of the Anthropocene.

In spite of the profound deterioration of Mexican natural ecosystems and the negative effects that this process has caused on the quality of life of the human population, environmental restoration has not yet become a priority public policy. Restoration activities such as reforestation and soil improvement have been promoted since the beginning of the 20th century; however, the priority has been put on reforestation of green urban areas and on the recovery of agricultural soil. It was not until the mid 1990’s that an integral vision of restoration was included. For example, regarding reforestation, compact rural areas were prioritized through the introduction of native species. Although this was an important step, production and planting is still emphasized and not enough attention has been put on survival rates of the plants or the consolidation of reforested areas. Other important programs are the recovery of threatened priority species, the elimination of exotic species, and the recovery of degraded lands in priority regions such as the humid tropics, among others. There is significant progress in the programmatic platform, allocation of economic resources, and institutional strengthening. However, there is a need to consolidate and harmonize an adequate legal framework, increase efforts to build technical and scientific workgroups with a long term, interdisciplinary and integral vision that influence and promote innovative public policy for environmental restoration

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Anthropogenic disturbances frequently exceed resilience of riparian forests. In small-scale 25 restoration projects revegetation is a common technique, but its success depends on the plant 26 species used and some environmental filters. We experimentally investigated whether grass 27 competition and soil compaction together with seasonal drought and flooding limit the 28 establishment of seven tree species experimentally planted in abandoned riparian pastures in 29 Southeast Mexico. We tested the effects of grass clearing and soil tilling and analyzed 30 seasonal variation of vertical distance to water level, and changes in tree performance, 31 microclimate, and vegetation biomass after planting. Seedling survival was low (19±3%), 32 ranging between 3% (Brosimum alicastrum, Moraceae) and 38% (Pachira aquatica, 33 Bombacaceae). Survival was negatively correlated to vertical distance to water level, 34 highlighting the importance of the short but severe dry season that may occur in the humid 35 tropics, which reduced survival by >60%. Flooding events also produced high seedling 36 mortality (80% after the two first events). Clearing but not tilling enhanced seedling survival. 37Clearing also significantly increased seedling growth of some species, suggesting competition 38 release. Tilling did not have any consistent effect on growth, but it appears to counteract the 39 positive effects of clearing. Both pre-existing and planted trees ameliorated microclimate to 40 produce better conditions for establishment of new trees following natural regeneration. We 41 conclude that clearing can enhance seedling establishment in riparian abandoned tropical 42 pastures, but other revegetation treatments intended to reduce soil drying and uprooting by 43 flooding during early establishment should be evaluated to improve the cost-benefit of 44 restoring riparian forest. 45