Quantifying patterns of deforestation and linking these patterns to potentially influencing variables is a key component of modelling and projecting land use change. Statistical methods based on null ...hypothesis testing are only partially successful for interpreting deforestation in the context of the processes that have led to their formation. Simplifications of cause-consequence relationships that are difficult to support empirically may influence environment and development policies because they suggest simple solutions to complex problems. Deforestation is a complex process driven by multiple proximate and underlying factors and a range of scales. In this study we use a multivariate statistical analysis to provide contextual explanation for deforestation in the Usumacinta River Basin based on partial pattern matching. Our approach avoided testing trivial null hypotheses of lack of association and investigated the strength and form of the response to drivers. As not all factors involved in deforestation are easily mapped as GIS layers, analytical challenges arise due to lack of a one to one correspondence between mappable attributes and drivers. We avoided testing simple statistical hypotheses such as the detectability of a significant linear relationship between deforestation and proximity to roads or water. We developed a series of informative generalised additive models based on combinations of layers that corresponded to hypotheses regarding processes. The importance of the variables representing accessibility was emphasised by the analysis. We provide evidence that land tenure is a critical factor in shaping the decision to deforest and that direct beam insolation has an effect associated with fire frequency and intensity. The effect of winter insolation was found to have many applied implications for land management. The methodology was useful for interpreting the relative importance of sets of variables representing drivers of deforestation. It was an informative approach, thus allowing the construction of a comprehensive understanding of its causes.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Atmospheric N deposition is predicted to increase four times over its current status in tropical forests by 2030. Our ability to understand the effects of N enrichment on C and N cycles is being ...challenged by the large heterogeneity of the tropical forest biome. The specific response will depend on the forest's nutrient status; however, few studies of N addition appear to incorporate the nutrient status in tropical forests, possibly due to difficulties in explaining how this status is maintained. We used a meta-analysis to explore the consequences of the N enrichment on C and N cycles in tropical montane and lowland forests. We tracked changes in aboveground and belowground plant C and N and in mineral soil in response to N addition. We found an increasing trend of plant biomass in montane forests, but not in lowland forests, as well as a greater increase in NO emission in montane forest compared with lowland forest. The N2O and NO emission increase in both forest; however, the N2O increase in lowland forest was significantly even at first time N addition. The NO emission increase showed be greater at first term compared with long term N addition. Moreover, the increase in total soil N, ammonium, microbial N, and dissolved N concentration under N enrichment indicates a rich N status of lowland forests. The available evidence of N addition experiments shows that the lowland forest is richer in N than montane forests. Finally, the greater increase in N leaching and N gas emission highlights the importance of study the N deposition effect on the global climate change.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Mangrove deforestation threatens to release large stores of carbon from soils that are vulnerable to oxidation. Carbon stored in deep soils is not measured in national carbon inventories. Thus, ...policies on emission reductions have likely underestimated the contribution of mangrove deforestation to national emissions. Here, we estimate that emissions from deforestation and degradation of mangroves in Mexico are 31 times greater than the values used to determine national emission reduction targets for the Paris Agreement. Thus, Mexico has vastly undervaluated the potential of mangrove protection to reduce its emissions. Accounting for carbon emissions from mangrove soils should greatly increase the priority of mangrove forests to receive funding for protection under carbon trading programs.
We conducted a year-long field experiment to investigate how nitrogen addition affected decomposition of Piscidia piscipula and Gymnopodium floribundum along a precipitation gradient in the Yucatan ...Peninsula, Mexico. Nitrogen addition did not affect decomposition rates at the drier sites. However, fertilization at the wettest site increased the decomposition of Gymnopodium litter and decreased the decomposition of Piscidia litter. Water-soluble carbon and lignin, and water-soluble carbon and nitrogen concentrations were the best predictors of decomposition for Gymnopodium and Piscidia litters, respectively. We conclude that the effects of nitrogen addition on decomposition will vary from site to site as a function of mean annual precipitation, inherent soil fertility, and species identity.
•CO2 and NO2 fluxes, and net N-transformations increase with precipitation.•Soil organic C concentrations decrease with elevated N input.•Elevated N input increases CO2 and N2O fluxes in the driest ...region.•N enrichment increases only CO2 fluxes in the wettest region.
Although tropical forests play a disproportionate role in regulating global C and N cycles, the impact of elevated N-deposition on these ecosystems is not well studied. Our goal was to determine whether elevated N input had an effect on soil C and N cycling in seasonally dry tropical forests along a precipitation gradient (with mean annual precipitation ranging from 540mm to 1040mm). We used a microcosm N-fertilization experiment to explore how soil C and N dynamics respond to N addition. NO2 fluxes and net N-mineralization and nitrification rates in soils increased considerably with mean annual precipitation. In contrast, CO2 fluxes decreased with increased mean annual precipitation. Organic C concentrations in soil from both the driest and the wettest forest sites decreased significantly with elevated N input. However, microbial biomass responded to N enrichment differently across sites. In soils from the driest site, microbial biomass C and N concentrations declined significantly with elevated N input. In contrast, in soils from the wettest site, microbial biomass C and N immobilization increased. Net N-mineralization and nitrification rates did not respond to elevated N input. In soils from the driest site, elevated N input resulted in an increase in C and N losses due to CO2 and N2O fluxes. However, elevated N input to soils from the wettest site did not consistently affect CO2 and N2O fluxes. In soils from the wettest site, the main response to N enrichment was an increase only in CO2 fluxes. We conclude that the reactions of seasonally dry tropical forest soils to increases in N deposition will vary, depending on the details of the site's water limitations, which appear as a regulatory mechanism of the N cycle in these soils.
We conducted a year-long field experiment to investigate how nitrogen addition affected decomposition of Piscidia piscipula and Gymnopodium floribundum along a precipitation gradient in the Yucatan ...Peninsula, Mexico. Nitrogen addition did not affect decomposition rates at the drier sites. However, fertilization at the wettest site increased the decomposition of Gymnopodium litter and decreased the decomposition of Piscidia litter. Water-soluble carbon and lignin, and water-soluble carbon and nitrogen concentrations were the best predictors of decomposition for Gymnopodium and Piscidia litters, respectively. We conclude that the effects of nitrogen addition on decomposition will vary from site to site as a function of mean annual precipitation, inherent soil fertility, and species identity. Resumen Nosotros realizamos en campo un experimento de un año para investigar como la adición de nitrógeno afecta la descomposición de Piscidia piscipula y Gymnopodium floribundum a lo largo de un gradiente de precipitación en la Península de Yucatán, México. La adición de N no afectó las tasas de descomposición en los sitios secos. Sin embargo, la fertilización en el sitio más húmedo aumentó la descomposición de la hojarasca de Gymnopodium, pero disminuyó la descomposición de la hojarasca de Piscidia. Las concentraciones de carbono soluble en agua y lignina, y las de carbono soluble en agua y N fueron los mejores predictores de la descomposición para las hojarascas de Gymnopodium y Piscidia, respectivamente. Concluimos que los efectos de la adición de N en la descomposición variarán de sitio a sitio en función de la precipitación media anual, la inherente fertilidad del suelo, y la identidad de las especies. PUBLICATION ABSTRACT
Atmospheric N deposition is predicted to increase four times over its current status in tropical forests by 2030. Our ability to understand the effects of N enrichment on C and N cycles is being ...challenged by the large heterogeneity of the tropical forest biome. The specific response will depend on the forest's nutrient status; however, few studies of N addition appear to incorporate the nutrient status in tropical forests, possibly due to difficulties in explaining how this status is maintained. We used a meta-analysis to explore the consequences of the N enrichment on C and N cycles in tropical montane and lowland forests. We tracked changes in aboveground and belowground plant C and N and in mineral soil in response to N addition. We found an increasing trend of plant biomass in montane forests, but not in lowland forests, as well as a greater increase in NO emission in montane forest compared with lowland forest. The N2O and NO emission increase in both forest; however, the N2O increase in lowland forest was significantly even at first time N addition. The NO emission increase showed be greater at first term compared with long term N addition. Moreover, the increase in total soil N, ammonium, microbial N, and dissolved N concentration under N enrichment indicates a rich N status of lowland forests. The available evidence of N addition experiments shows that the lowland forest is richer in N than montane forests. Finally, the greater increase in N leaching and N gas emission highlights the importance of study the N deposition effect on the global climate change.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Los habitantes de la comunidad indígena Camaritagua (La Pedrera-Amazonas, Colombia), utilizan 129 especies de plantas medicinales en sus prácticas médicas tradicionales. La mayor representación se ...obtuvo para las familias Araceae, Rubiaceae y Piperaceae, y para los géneros Piper, Protium, y Anthurium. El 80% de las especies encontradas tienen un origen neotropical, así mismo el 16% son cultivadas; ambos datos muestran el bajo nivel de sincretismo cultural que ha experimentado Camaritagua en cuanto al uso de las plantas medicinales. El paisaje que mayor número de especies presenta (65%), es el bosque Sucesional, éste resultado promueve la posibilidad de hacer productivas estas áreas disminuyendo el uso del bosque Primario permitiendo así su conservación. El 46,5% de las especies encontradas en este estudio ya habían sido citadas por otros autores como medicinales, señalando hacia dónde deben conducirse las investigaciones fitoquímicas.
PDF
