935 resultados para Restoration of sandbank forest
Resumo:
Small-scale farmers in the Brazilian Amazon collectively hold tenure over more than 12 million ha of permanent forest reserves, as required by the Forest Code. The trade-off between forest conservation and other land uses entails opportunity costs for them and for the country, which have not been sufficiently studied. We assessed the potential income generated by multiple use forest management for farmers and compared it to the income potentially derived from six other agricultural land uses. Income from the forest was from (i) logging, carried out by a logging company in partnership with farmers' associations; and (ii) harvesting the seeds of Carapa guianensis (local name andiroba) for the production of oil. We then compared the income generated by multiple-use forest management with the income from different types of agrarian systems. According to our calculations in this study, the mean annual economic benefits from multiple forest use are the same as the least productive agrarian system, but only 25% of the annual income generated by the most productive system. Although the income generated by logging may be considered low when calculated on an annual basis and compared to incomes generated by agriculture, the one-time payment after logging is significant (US$5,800 to US$33,508) and could be used to implement more intensive and productive cropping systems such as planting black pepper. The income from forest management could also be used to establish permanent fields in deforested areas for highly productive annual crops using conservation agriculture techniques. These techniques are alternatives to the traditional land use based on periodic clearing of the forest. Nevertheless, the shift in current practices towards adoption of more sustainable conservation agriculture techniques will also require the technical and legal support of the State to help small farmers apply these alternatives, which aim to integrate forest management in sustainable agricultural production systems.
Resumo:
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Resumo:
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Resumo:
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Resumo:
Regeneration microsites are characterized by diverse combinations of attributes which assure the best conditions for seed germination and seedling establishment. By understanding these attributes, we can contribute to determining better management methodologies for reestablishing ecological process in sites under restoration. Thus, we sought to characterize and differentiate the micro-site conditions of restoration plantings to indentify likely physical-chemical limitations for the establishment of native tree species in the forest understory. This study was carried out in reforestation plantings with different ages (10, 22 and 55 years). The physical-chemical characterization of the micro-site of regeneration of the study areas was carried out by evaluating the soil compression level, porosity, humidity, organic matter and nutrients content and granulometry, as well as litter dry mass and canopy cover. An increase on the canopy cover and soil porosity, humidity, clay and organic matter content were observed in the oldest restored areas, as well as a decrease in soil compression. Thus, these findings demonstrated that the evaluated microsite properties are in process of restoration. Therefore, microsite conditions for seedling establishment become even more similar to reference ecosystems as restoration planting evolve.
Resumo:
Chaetomys subspinosus is the sole species within the Chaetomyinae subfamily of Caviomorph rodents. This poorly studied porcupine is restricted to the Atlantic Forest in eastern Brazil, where deforestation and habitat fragmentation threaten its survival. Data on the ranging and roosting behavior of C. subspinosus is fairly scarce as it is difficult to observe these behaviors in nature and, consequently, it is very rarely detected during field surveys. We monitored the home ranges of three radio-tagged females over the course of 1 year (2005-2006) and collected data on several aspects of their natural history including movement patterns and the use of diurnal roosts and latrines. The animals were monitored at Parque Estadual Paulo Cesar Vinha, a nature reserve dominated by restinga forests, a subtype of Atlantic Forest occurring on sandy soil. The estimated home range varied little between individuals and was relatively small (mean = 2.14 ha/individual and 1.09 ha/individual using minimum convex polygon and kernel methods, respectively). The animals travelled an average of 147 m/night (range: 21-324 m/night) between two consecutive day roosts. The day roosts were mostly located on vine and liana tangles in the canopy which also aid in connecting the canopy to adjacent trees or the forest floor. Latrines were mostly located near the ground in places heavily protected by spiny bromeliads or by other tangled vegetation. Our data suggests that C. subspinosus has the smallest range among all Neotropical Erethizontids which is likely due to its small size and strictly folivorous diet. Our data also helps explain why C. subspinosus is so difficult to observe in nature: researchers should focus on arboreal masses of tangled vegetation where individuals will normally rest during the day. (C) 2011 Deutsche Gesellschaft fur Saugetierkunde. Published by Elsevier GmbH. All rights reserved.
Resumo:
The Brazilian Atlantic forest has been an excellent laboratory for investigations regarding tropical forest ecology and the fragility of tropical ecosystems in face of human disturbances. In this article, we present a synthesis about the spatial distribution of Atlantic forest biodiversity and forest response to human disturbances, as well as the ongoing conservation efforts based on a review of several investigations in this biota. In general, studies have documented an uneven distribution of biodiversity throughout the Atlantic forest region, revealing alarming rates of habitat loss at low altitudes, while protected areas concentrate at higher altitudes. It has been suggested that the remaining forest habitat is moving towards an early-successional systems across human-modified landscapes. Such regressive forest succession increases the threats for several animals and plant groups. Based on these findings, we propose seven guidelines in order to enhance the provision of ecosystem services and the conservation value of human-modified landscapes, reducing the species extinction risk in the Atlantic forest and in other irreplaceable tropical biotas.
Resumo:
Theoretical and empirical studies demonstrate that the total amount of forest and the size and connectivity of fragments have nonlinear effects on species survival. We tested how habitat amount and configuration affect understory bird species richness and abundance. We used mist nets (almost 34,000 net hours) to sample birds in 53 Atlantic Forest fragments in southeastern Brazil. Fragments were distributed among 3 10,800-ha landscapes. The remaining forest in these landscapes was below (10% forest cover), similar to (30%), and above (50%) the theoretical fragmentation threshold (approximately 30%) below which the effects of fragmentation should be intensified. Species-richness estimates were significantly higher (F = 3715, p = 0.00) where 50% of the forest remained, which suggests a species occurrence threshold of 30-50% forest, which is higher than usually occurs (<30%). Relations between forest cover and species richness differed depending on species sensitivity to forest conversion and fragmentation. For less sensitive species, species richness decreased as forest cover increased, whereas for highly sensitive species the opposite occurred. For sensitive species, species richness and the amount of forest cover were positively related, particularly when forest cover was 30-50%. Fragment size and connectivity were related to species richness and abundance in all landscapes, not just below the 30% threshold. Where 10% of the forest remained, fragment size was more related to species richness and abundance than connectivity. However, the relation between connectivity and species richness and abundance was stronger where 30% of the landscape was forested. Where 50% of the landscape was forested, fragment size and connectivity were both related to species richness and abundance. Our results demonstrated a rapid loss of species at relatively high levels of forest cover (30-50%). Highly sensitive species were 3-4 times more common above the 30-50% threshold than below it; however, our results do not support a unique fragmentation threshold.
Resumo:
The Atlantic Forest is an excellent case study for the elevational diversity of birds, and some inventories along elevational gradients have been carried out in Brazil. Since none of these studies explain the patterns of species richness with elevation, we herein review all Brazilian studies on bird elevational diversity, and test a geometric constraint null model that predicts a unimodal species-altitude curve, the Mid-domain Effect (MDE). We searched for bird inventories in the literature and also analysed our own survey data using limited-radius point counts along an 800 m elevational gradient in the state of São Paulo, Brazil. We found 10 investigations of elevational diversity of Atlantic Forest birds and identified five different elevational patterns: monotonic decreasing diversity, constant at low elevations, constant at low elevations but increasing towards the middle, and two undescribed patterns for Atlantic Forest birds, trough-shaped and increasing diversity. The average MDE fit was low (r² = 0.31) and none of the MDE predictions were robust across all gradients. Those studies with good MDE model fits had obvious sampling bias. Although it has been proposed that the MDE may be positively associated with the elevational diversity of birds, it does not fit the Brazilian Atlantic Forest bird elevational diversity.
Resumo:
Atmospheric CO2 concentration ([CO2]) has increased over the last 250 years, mainly due to human activities. Of total anthropogenic emissions, almost 31% has been sequestered by the terrestrial biosphere. A considerable contribution to this sink comes from temperate and boreal forest ecosystems of the northern hemisphere, which contain a large amount of carbon (C) stored as biomass and soil organic matter. Several potential drivers for this forest C sequestration have been proposed, including increasing atmospheric [CO2], temperature, nitrogen (N) deposition and changes in management practices. However, it is not known which of these drivers are most important. The overall aim of this thesis project was to develop a simple ecosystem model which explicitly incorporates our best understanding of the mechanisms by which these drivers affect forest C storage, and to use this model to investigate the sensitivity of the forest ecosystem to these drivers. I firstly developed a version of the Generic Decomposition and Yield (G’DAY) model to explicitly investigate the mechanisms leading to forest C sequestration following N deposition. Specifically, I modified the G’DAY model to include advances in understanding of C allocation, canopy N uptake, and leaf trait relationships. I also incorporated a simple forest management practice subroutine. Secondly, I investigated the effect of CO2 fertilization on forest productivity with relation to the soil N availability feedback. I modified the model to allow it to simulate short-term responses of deciduous forests to environmental drivers, and applied it to data from a large-scale forest Free-Air CO2 Enrichment (FACE) experiment. Finally, I used the model to investigate the combined effects of recent observed changes in atmospheric [CO2], N deposition, and climate on a European forest stand. The model developed in my thesis project was an effective tool for analysis of effects of environmental drivers on forest ecosystem C storage. Key results from model simulations include: (i) N availability has a major role in forest ecosystem C sequestration; (ii) atmospheric N deposition is an important driver of N availability on short and long time-scales; (iii) rising temperature increases C storage by enhancing soil N availability and (iv) increasing [CO2] significantly affects forest growth and C storage only when N availability is not limiting.
Resumo:
Anthropogene Fragmentierung und Störung von Wäldern beeinflussen ökologische Prozesse. Darüber hinaus werden genetische Drift und Inzucht verstärkt und die Fitness von Populationen beeinträchtigt. Um die Einflüsse von Fragmentierung und Störung auf die Biodiversität und Prozesse in tropischen Wäldern zu ermitteln, habe ich im „Kakamega Forest“, West-Kenia, die Baumart Prunus africana genauer untersucht. Dabei lag der Fokus auf (i) der Frugivorengemeinschaft und Samenausbreitung, (ii) der Kleinsäugergemeinschaft im Kontext der Samenprädation und (iii) der genetische Populationsstruktur von Keimlingen und adulten Bäumen. Der Vergleich von Keimlingen mit adulten Bäumen ermöglicht es, Veränderungen im Genfluss zwischen Generationen festzustellen. Die Ergebnisse zeigten, dass im untersuchten Waldgebiet insgesamt 49 frugivore Arten (Affen und Vögel) vorkommen. Dabei lag die Gesamtartenzahl im zusammenhängenden Wald höher als in den isoliert liegenden Fragmenten. An den Früchten von P. africana konnten insgesamt 36 Arten fressend beobachtet werden. Hier jedoch wurden in Fragmenten eine leicht erhöhte Frugivorenzahl sowie marginal signifikant erhöhte Samenausbreitungsraten nachgewiesen. Der Vergleich von stark gestörten mit weniger gestörten Flächen zeigte eine höhere Gesamtartenzahl sowie eine signifikant höhere Frugivorenzahl in P. africana in stark gestörten Flächen. Entsprechend war die Samenausbreitungsrate in stark gestörten Flächen marginal signifikant erhöht. Diese Ergebnisse deuten darauf hin, dass die quantitative Samenausbreitung in fragmentierten und gestörten Flächen etwas erhöht ist und somit eine gewisse Artenredundanz besteht, die den Verlust einzelner Arten ausgleichen könnte. Prunus africana Samen, die auf dem Boden lagen, wurden hauptsächlich von einer Nagerart (Praomys cf. jacksonii) erbeutet. Dabei war in gestörten Waldbereichen eine tendenziell höhere Prädatoraktivität zu beobachten als in weniger gestörten. Zudem waren einzelne Samen im Gegensatz zu Samengruppen in gestörten Flächen signifikant höherem Prädationsdruck ausgesetzt. Diese Ergebnisse zeigen, dass Fragmentierung sowie anthropogene Störungen auf unterschiedliche Prozesse im Lebenszyklus eines tropischen Baumes gegensätzliche Effekte haben können. Eine Extrapolation von einem auf einen anderen Prozess kann somit nicht erfolgen. Die genetische Differenzierung der adulten Baumpopulationen war gering (FST = 0.026). Der Großteil ihrer Variation (~ 97 %) lag innerhalb der Populationen, was intensiven Genfluss in der Vergangenheit widerspiegelt. Die genetische Differenzierung der Keimlinge war etwas erhöht (FST = 0.086) und ~ 91 % ihrer Variation lag innerhalb der Populationen. Im Gegensatz zu den adulten Bäumen konnte ich für Keimlinge ein „Isolation-by-distance“-Muster feststellen. Somit sind erste Hinweise auf begrenzten Genfluss im Keimlingsstadium infolge von Fragmentierung gegeben. Obwohl die Momentaufnahmen im Freiland keine Abnahme in der Frugivorenzahl und Samenausbreitung von P. africana als Folge von Fragmentierung beobachten ließen, weisen die Ergebnisse der genetischen Studie auf einen bereits reduzierten Genaustausch zwischen den Populationen hin. Somit lässt sich feststellen, dass die Faktoren Fragmentierung und Störung genetische Diversität, ökologische Prozesse und Artendiversität in Wäldern jeweils auf unterschiedliche Weise beeinflussen. Um Konsequenzen derartiger Einflüsse folgerichtig abschätzen zu können, sind Studien auf unterschiedlichen Diversitätsebenen unabdingbar.
Resumo:
Atmospheric nitrogen (N) and phosphorus (P) depositions are expected to increase in the tropicsrnas a consequence of increasing human activities in the next decades. Furthermore, a possiblernshortened El Niño Southern Oscillation cycle might come along with more frequent calcium (Ca)rndepositions on the eastern slope of the Ecuadorian Andes originating from Saharan dust. It isrncrucial to understand the response of the old-growth montane forest in Ecuador to increasedrnnutrient deposition to predict the further development of this megadiverse ecosystem.rnI studied experimental additions of N, P, N+P and Ca to the forest and an untreatedrncontrol, all in a fourfold replicated randomized block design. These experiments were conductedrnin the framework of a collaborative research effort, the NUtrient Manipulation EXperimentrn(NUMEX). I collected litter leachate, mineral soil solution (0.15 and 0.30 m depths), throughfallrnand fine litterfall samples and determined N, P and Ca concentrations and fluxes. This approachrnalso allowed me to assess whether N, P and/or Ca are limiting nutrients for forest growth.rnFurthermore, I evaluated the response of fine root biomass, leaf area index, leaf area and specificrnleaf area, tree diameter growth and basal area increment contributed from a cooperating group inrnthe Ca applied and control treatments.rnDuring the observation period of 16 months after the first fertilizer application, less thanrn10, 1 and 5% of the applied N, P and Ca, respectively, leached below the organic layer whichrncontained almost all roots but no significant leaching losses occurred to the deeper mineral soil.rnDeposited N, P and Ca from the atmosphere in dry and wet form were, on balance, retained in therncanopy in the control treatment. Retention of N, P and Ca in the canopy in their respectiverntreatments was reduced resulting in higher concentrations and fluxes of N, P and Ca inrnthroughfall and litterfall. Up to 2.5% of the applied N and 2% of the applied P and Ca werernrecycled to the soil with throughfall. Fluxes of N, P and Ca in throughfall+litterfall were higher inrnthe fertilized treatments than in the control; up to 20, 5 and 25% of the applied N, P and Ca,rnrespectively, were recycled to the soil with throughfall+litterfall.rnIn the Ca-applied plots, fine root biomass decreased significantly. Also the leaf area of thernfour most common tree species tended to decrease and the specific leaf area increasedrnsignificantly in Graffenrieda emarginata Triana, the most common tree species in the study area.rnThese changes are known plant responses to reduced nutrient stress. Reduced aluminium (Al)rntoxicity as an explanation of the Ca effect was unlikely, because of almost complete organocomplexationrnof Al and molar Ca:Al concentration ratios in solution above the toxicity threshold.rnThe results suggest that N, P and Ca co-limit the forest ecosystem functioning in thernnorthern Andean montane forests in line with recent assumptions in which different ecosystemrncompartments and even different phenological stages may show different nutrient limitationsrn(Kaspari et al. 2008). I conclude that (1) the expected elevated N and P deposition will bernretained in the ecosystem, at least in the short term and hence, quality of river water will not bernendangered and (2) increased Ca input will reduce nutrient stress of the forest.
Resumo:
This thesis tends to study the origins and developments of the restoration in Iran from its very first moments till the Islamic revolution of 1978. The thesis is its first study of its kind. While almost all recent occidental ideologies regarding the thematic of restoration and conservation of historic monuments are translated and published in Iran, very little efforts have been done regarding the study of the origins of the formation of restoration in the country. The diversity of Iranian contexts, multiplicity of the intervening factors and other factors characterized a different background for the raise and developments of restoration in the country; in the thesis the influencing and characterizing factors in the formation and development of restoration in Iran will be defined and studied in detail with relative examples; due to the complexity of the Iranian context and in order to consider all influencing and characterizing factors the thesis, parallel to have formation and development of restoration, as the main scope of the research, the developments influencing factors will be confronted with necessary flashbacks to the main theme, when and where necessary. A great care will be given to the period of the activity of the restoration experts of IsMEO which is thesis will be called as the period of the introduction of the modern principles of restoration into Iranian context; the fundamental ideologies, practical and theoretical principles of IsMEO will be identified and studied in details; important case of studies of the restoration of IsMEO will be analyzed in details and the innovative aspect of the presence of Italian experts of IsMEO will be revealed.
Resumo:
Silvicultural treatments represent disturbances to forest ecosystems often resulting in transient increases in net nitrification and leaching of nitrate and base cations from the soil. Response of soil carbon (C) is more complex, decreasing from enhanced soil respiration and increasing from enhanced postharvest inputs of detritus. Because nitrogen (N) saturation can have similar effects on cation mobility, timber harvesting in N-saturated forests may contribute to a decline in both soil C and base cation fertility, decreasing tree growth. Although studies have addressed effects of either forest harvesting or N saturation separately, few data exist on their combined effects. Our study examined the responses of soil C and N to several commercially used silvicultural treatments within the Fernow Experimental Forest, West Virginia, USA, a site with N-saturated soils. Soil analyses included soil organic matter (SOM), C, N, C/N ratios, pH, and net nitrification. We hypothesized the following gradient of disturbance intensity among silvicultural practices (from most to least intense): even-age with intensive harvesting (EA-I), even-age with extensive harvesting, even-age with commercial harvesting, diameter limit, and single-tree harvesting (ST). We anticipated that effects on soil C and N would be greatest for EA-I and least with ST. Tree species exhibited a response to the gradient of disturbance intensity, with early successional species more predominant in high-intensity treatments and late successional species more predominant in low-intensity treatments. Results for soil variables, however, generally did not support our predictions, with few significant differences among treatments and between treatments and their paired controls for any of the measured soil variables. Multiple regression indicated that the best predictors for net nitrification among samples were SOM (positive relationship) and pH (negative relationship). This finding confirms the challenge of sustainable management of N-saturated forests.
Resumo:
We used active remote sensing technology to characterize forest structure in a northern temperate forest on a landscape- and local-level in the Upper Peninsula of Michigan. Specifically, we used a form of active remote sensing called light detection and ranging (e.g., LiDAR) to aid in the depiction of current forest structural stages and total canopy gap area estimation. On a landscape-level, LiDAR data are shown not only to be a useful tool in characterizing forest structure, in both coniferous and deciduous forest cover types, but also as an effective basis for data-driven surrogates for classification of forest structure. On a local-level, LiDAR data are shown to be a benchmark reference point to evaluate field-based canopy gap area estimations, due to the highly accurate nature of such remotely sensed data. The application of LiDAR remote sensed data can help facilitate current and future sustainable forest management.