El grupo busca contribuir a la sostenibilidad de la ciudad, la región y el país, mediante la generación de conocimiento que permita comprender la estructura y el funcionamiento de los sistemas socioecológicos, con el fin de proponer soluciones estratégicas que lleven estos sistemas hacia la sostenibilidad. Para ello desarrollamos investigación tanto disciplinar como inter y transdiciplinar, integrando métodos de diferentes disciplinas y co-produciendo el conocimiento con las comunidades locales.
PROYECTOS DE INVESTIGACIÓN
The PREDICTS database: a global database of how local terrestrial biodiversity responds to human impacts
Fecha de publicación: 02/12/2014
Biodiversity continues to decline in the face of increasing anthropogenic pressures such as habitat destruction, exploitation, pollution and introduction of alien species. Existing global databases of species’ threat status or population time series are dominated by charismatic species. The collation of datasets with broad taxonomic and biogeographic extents, and that support computation of a range of biodiversity indicators, is necessary to enable better understanding of historical declines and to project – and avert – future declines. We describe and assess a new database of more than 1.6 million samples from 78 countries representing over 28,000 species, collated from existing spatial comparisons of local-scale biodiversity exposed to different intensities and types of anthropogenic pressures, from terrestrial sites around the world. The database contains measurements taken in 208 (of 814) ecoregions, 13 (of 14) biomes, 25 (of 35) biodiversity hotspots and 16 (of 17) megadiverse countries. The database contains more than 1% of the total number of all species described, and more than 1% of the described species within many taxonomic groups – including flowering plants, gymnosperms, birds, mammals, reptiles, amphibians, beetles, lepidopterans and hymenopterans. The dataset, which is still being added to, is therefore already considerably larger and more representative than those used by previous quantitative models of biodiversity trends and responses. The database is being assembled as part of the PREDICTS project (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems – http://www.predicts.org.uk). We make site-level summary data available alongside this article. The full database will be publicly available in 2015.
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The database of the PREDICTS (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems) project
Fecha de publicación: 05/01/2017
The PREDICTS project—Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (www.predicts.org.uk)—has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used this evidence base to develop global and regional statistical models of how local biodiversity responds to these measures. We describe and make freely available this 2016 release of the database, containing more than 3.2 million records sampled at over 26,000 locations and representing over 47,000 species. We outline how the database can help in answering a range of questions in ecology and conservation biology. To our knowledge, this is the largest and most geographically and taxonomically representative database of spatial comparisons of biodiversity that has been collated to date; it will be useful to researchers and international efforts wishing to model and understand the global status of biodiversity.
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Structure and diversity of secondary tropical dry forests in Mexico, differing in their prior land-use history
Fecha de publicación: 15/12/2007
We compared the structure and diversity of secondary tropical dry forests, growing in sites cleared by bulldozer 30 years ago and subjected to different land uses prior to abandonment: (a) housing development (HD), (b) pasture (P), and (c) no use (NU). We sampled two forest sites representing each of the three former land-use types (i.e., a total of six sites) and measured the diameter at breast height (dbh) of all stems with dbh ≥1 cm and at least 2 m in height. All individuals were identified to species and classified into each of four dbh sizes-classes: 1–3, 3–5, 5–10, and >10 cm. No major differences in structure or diversity were evident among land-use types. Total tree densities varied from 2575 ± 55 to 4745 ± 985 individuals/ha and total basal areas ranged from 12.5 ± 2.6 to 14.6 ± 0.3 m2/ha (mean and S.E.). Neither one differed significantly (p < 0.05) among land-use types. Overall, the most abundant tree size-class was the 1–3 cm dbh (47% of the total number of trees), whereas trees greater than 10 cm dbh were the least abundant (4%). We found significantly higher density and basal area (p = 0.01) in NU than in HD and P only in the smallest trees (1–3 cm dbh). We identified a total of 87 species in 28 families. The Leguminosae plant family had the greatest species richness and number of individuals in all land-use types. The HD land-use type showed lower total species richness than P and NU only with two of the four nonparametric estimators. Observed species richness decreased as dbh increased in all land-use types. At least 5 legumes were among the 10 most dominant species in all land-use types, of which the non-native Mimosa arenosa was the most dominant one. It represented between 42% and 52% of the total basal area in each land-use type. The secondary forests have reached, on average, 74% and 22% of the total density and basal area, respectively, of an average primary tropical dry forest of Mexico. The high number of individuals 1–3 cm dbh (48% of the total and 83% of the species) suggest that regeneration is occurring in all land-use types, although to different degrees. The absence of small individuals of M. arenosa and a high abundance of primary forest species at NU, suggest that M. arenosa is being replaced at these sites.
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Resilience of Soil Properties to Land‐Use Change in a Tropical Dry Forest Ecosystem
Fecha de publicación: 13/02/2018
Land‐use change in tropical dry forests can dramatically alter soil properties, but little is known about their resilience. We assessed soil resilience by examining resistance to, as well as recovery from, pasture use by smallholder farmers in western Mexico. We measured 25 soil and vegetation properties and compared old‐growth forest (OGF) sites and pastures to evaluate resistance to pasture use. We assessed whether those properties recovered to OGF reference values after pasture abandonment by analyzing the trajectories of properties along a chronosequence of secondary vegetation. Finally, we assessed whether recovery of soil properties could be inferred from the recovery of vegetation properties. Nine out of 25 properties differed significantly between the OGF sites and pastures. From these nine nonresistant properties, six (i.e., penetration resistance, soil C concentration, soil C/N, basal area, individual density, rarefied species richness of woody vegetation) showed recovery as a significant positive relationship with forest age. In contrast, surface litter C, litter C/N, and soil available P showed no resistance and no recovery within the successional period examined (up to 35 y). The best vegetation indicator for the recovery of some soil properties was woody species richness. This may suggest that functional differences of colonizing plants matter for recovery after pasture use. Our findings indicate that soil was overall resilient to pasture use, but some properties did not recover synchronously with vegetation properties during succession. Thus, more attention should be paid to soil function, because full ecosystem recovery is often inferred from the recovery of vegetation properties.
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Patterns of distribution of orchids in a high Andean forest relict, Cundinamarca-Colombia
Fecha de publicación: 01/02/2020
Colombia is one of the countries with greatest diversity of orchids, with 4270 native estimated species, of which 199 present some kind threat. Knowing the characteristics that determine their distribution is necessary to design conservation programs. This study aims to know the influence of biotic and abiotic factors on the distribution of orchids in a relict of high Andean forest in the region, of Cundinamarca, Colombia, for this purpose information was collected on the orchids found in nine transects of 50 m × 4 m. The environmental factors that had the greatest influence on the distribution of orchids were the altitude and the percentage of moss cover, as well as the characteristics inherent to the communities of forophytes, in the case of epiphytic species. Establishing orchid distribution patterns will allow, in the future, to design conservation programs for this particular flora and the high Andean forest in general. © 2020 Universidad Distrital Francisco Jose de Caldas. All rights reserved.
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