Las funciones ecológicas de los bambúes en la recuperación de servicios ambientales y en la restauración productiva de ecosistemas

Este artículo es una revisión bibliográfica sobre las funciones ecológicas que caracterizan a los bambúes, por las cuales merecen un mayor reconocimiento e inclusión en los programas de restauración ecológica. Los bambúes son un grupo de plantas muy diverso, de amplia distribución geográfica y económicamente importante. Aunque son más reconocidos por los usos comerciales, su potencial de uso en programas de restauración ecológica es prometedor, ya que pueden ser eficientes en la prestación de varios servicios ambientales relacionados con el suelo, el agua y el secuestro de carbono. Su rápido crecimiento, junto con su capacidad para controlar la erosión y mantener el agua a nivel del suelo, así como para proporcionar nutrientes mediante la descomposición de la hojarasca, convierte a los bambúes en un grupo valioso para la recuperación de áreas degradadas y para la restauración productiva de ecosistemas, en particular a través de sistemas agroforestales. Los enfoques agroforestales pueden combinar diferentes especies de bambú con otros cultivos, para satisfacer las necesidades humanas y generar a la vez beneficios para los ecosistemas. De manera similar, los bosques o plantaciones de bambúes, junto con sistemas agroforestales mixtos, pueden actuar como áreas de conexión y corredores biológicos, en paisajes muy fragmentados, proporcionando refugio y alimento para una amplia diversidad de organismos. A pesar de las percepciones de que los bambúes pueden ser invasivos, las pruebas para apoyar esto son limitadas. Recomendamos una evaluación cuidadosa de las características biológicas de las especies de bambúes seleccionadas, antes de su implementación en proyectos de restauración productiva y de recuperación de los servicios ambientales.

This article is a bibliographic review on the ecological functions that distinguish bamboos, for which they deserve greater recognition and inclusion in ecological restoration programs. Bamboos are a highly diverse, geographically widespread and economically important plant group. Although they are more recognized by commercial uses, their potential for use in ecological restoration programs is promising, as they can be effective in delivery of several environmental services related to soil, water and carbon sequestration. Their rapid growth, along with their abilities to control erosion and maintain water at soil level, as well as provide nutrients by litterfall decomposition, make them a valuable group for recovery of degraded areas and in productive restoration of ecosystems, in particular via agroforestry systems. Agroforestry approaches can combine different bamboo species with other crops, to meet human needs while generating benefits for ecosystems. Similarly, bamboo forests or plantations together with mixed agroforestry systems can act as stepping-stones and biological corridors, in very fragmented landscapes by providing shelter and food for a wide diversity of organisms. Despite perceptions that bamboos can be invasive, evidence to support this is limited. We recommend careful evaluation of the biological characteristics of bamboo species selected, prior to deployment in productive restoration projects and for the recovery of environmental services.

Land Degradation Mapping in Singhanhalli-Bogur Micro-watershed in Northern Transition Zone of Karnataka through Remote Sensing and GIS Techniques.

The study was undertaken to identify and map areas affected by various land degradation through remote sensing and GIS techniques. The study revealed that the major process of land degradation is water erosion. Three types of water erosion, namely sheet, rill and gully erosion were prevalent in different land forms. Sheet erosion accounted for 77.2 %, rill erosion 6.7 % and gully erosion 16.2 % of the study area. The lowlands, majority of which area was under agriculture land use, was observed to be sheet eroded with severity ranging from slight to severe which was attributed t o overcutting of vegetation, overgrazing and agricultural activities. Rill erosion was prevalent in undulating midlands under agriculture and open scrub land uses, whereas gully erosion occurred in agriculture and open scrub lands. The moderately degraded lands were observed in all land uses but they were more prominent in agriculture lands on moderate slopes. The severely degraded lands were observed on moderate-to-steep slopes in undulating midlands and uplands. The adoption of soil and water conservation measures was recommended for improve soil productivity and sustaining agricultural production at higher levels. In addition, watershed programmes should be undertaken considering the summarized priority for land treatment.

Soil Erosion Mapping in Singhanhalli-Bogur Microwatershed in Northern Transition Zone of Karnataka Using Universal Soil Loss Equation and Geographic Information Systems.

Soil erosion which occurs at spatially varying rates is a widespread threat to sustainable resource management at watershed scale. Thus estimation of soil loss and identification of critical area for implementation of best management practices is central to a successful soil conservation programme. The present study was conducted to assess soil erosion using USLE and suggests possible intervention strategies to address soil loss in Singhanhalli-Bogur Microwatershed of Dharwad District in northern transition zone of Karnataka. The average annual soil loss was 27 tons ha-1yr-1. About 574 ha of the study area was under slight erosion, 118 ha under moderate erosion and 53 ha under severe erosion. The soil loss under different land uses ranged from 7 tons ha-1yr-1 under forest to 40 tons ha-1yr-1 under agriculture. The soil loss under plantation and open scrub land uses were 8 and 26 tons ha-1yr-1 respectively. Major causes of soil erosion were cultivation without proper soil and water conservation measures in area not suitable for crops, denuded areas without vegetation, cultivated fallow on moderate slopes, degraded forests/pastures on steep slopes and poorly managed forest cover. Appropriate soil conservation and land management techniques for the different soil erosion classes were suggested.

Estimating soil erosion in Natura 2000 areas located on three semi-arid Mediterranean islands.

A major initiative in Europe is the protection of its biodiversity. To accomplish this, specific areas from all countries of the European Union are protected by the establishment of the “Natura 2000” network. One of the major threats to these areas and in general to ecosystems is soil erosion. The objective of this study was to quantitatively estimate surface soil losses for three of these protected areas that are located on semi-arid islands of the Mediterranean. One Natura 2000 area was selected from each of the following islands: Sicily in Italy, Cyprus and Rhodes in Greece. To estimate soil losses, Gerlach troughs were used. These troughs were established on slopes that ranged from 35-40% in four different vegetation types: i) Quercus ilex and Quercus rotundifolia forests, ii) Pinus brutia forests, iii) “Phrygana” shrublands and iv) vineyards. The shrublands had the highest soil losses (270 kg ha-1 yr-1) that were 5-13 times more than the other three vegetation types. Soil losses in these shrublands should be considered a major concern. However, the other vegetation types also had high soil losses (21-50 kg ha-1 yr-1). Conclusively, in order to enhance and conserve the biodiversity of these Natura 2000 areas protective management measures should be taken into consideration to decrease soil losses.

Perda de nutrientes via escoamento superficial no sistema plantio direto sob adubação mineral e orgânica / Nutrient losses by surface runoff in no-till system soil under mineral and organic fertilization

O sistema de plantio direto (SPD) tem contribuído para melhorias nos solos agrícolas, dentre elas o aumento da concentração de nutrientes no solo. No entanto, tem se verificado que este aumento ocorre principalmente na camada superficial do solo, o que contribui para que ocorram perdas de nutrientes através de enxurradas, com danos econômicos e ambientais. Este trabalho avaliou a concentração total dos nutrientes potássio (K), cálcio (Ca), magnésio (Mg) e cobre (Cu) e do K nas formas solúvel e particulado, na enxurrada ocasionada por chuvas simuladas com diferentes intensidades aplicadas sobre solo manejado por cinco anos sob SPD, após aplicação superficial de adubo orgânico ou mineral. Os adubos não afetaram a concentração dos nutrientes estudados, exceto na condição da chuva mais intensa e solo sob adubação orgânica, onde a enxurrada apresentou maior concentração de K solúvel e K total. Independente do tipo de adubo utilizado, a chuva de maior intensidade ocasionou maior concentração de todos os nutrientes e formas estudados, evidenciando os benefícios econômicos e ambientais da adoção de práticas de contenção da enxurrada, mesmo em áreas cultivadas sob SPD.

The no-tillage system, has contributed to improvements in agricultural soils, among them the like increases in nutrient concentrations.of mineral elements in soil. However, it has been found that this increase concentration occurs mainly in the first few centimeters of the superficial top layer and so risks of nutrient losses by runoff, and associated of the soil, which concurs for losses of mineral elements through of runoff, with economic and environmental damages, are high. This study evaluated the total concentration, in runoff, of mineral elements potassium (K), calcium (Ca), magnesium (Mg) and copper (Cu) in total form and the soluble and particulate concentration form of K, in runoff caused to simulated rainfall of different intensitiesy applied over soil under no-till system and submitted to simulated after application of organic or mineral fertilizers in no-till soil. The fertilizers did not affect the concentration of mineral elements studied nutrients in runoff, except in condition of more high intense rainfall and soil under after organic manure application, which promoted runoff with showed the higher highest concentration of soluble and total K. Independent Irrespective of the type of fertilizers utilized type, the rainfall of higher intensity resulted in higher concentrations of all the mineral elements and forms studied, either in total, soluble or particulate form, evidencing the economic and environmental benefices, risks and suggesting that with the adoption of practices for runoff contention of runoff practices must be adopted , even in tilled croplands areas managed under no-till system.

Measurements of the fallout flux of beryllium-7 and its variability in the soil

The aim of this study was to examine the beryllium-7 behavior in the soil. Natural variability of beryllium-7 concentration was calculated to be about 23 percent (relative standard deviation), and the depth distribution could be approximated by an exponential decay in bare soil, with an average penetration depth in the soil about 1 cm. The nuclide was not found below 2 cm depth, which confirmed its utilization to infer the erosion processes as a tracer of soil surface. The maximum beryllium-7 concentration in the analyzed period was about 40 Bq.kg-1.

Berílio-7 é um radionuclídeo cosmogênico, com meia-vida de 53 dias, produzido pelo processo de espalação de átomos de oxigênio e nitrogênio dentro da troposfera e estratosfera. Após sua produção, este é transportado até a superfície terrestre pela deposição úmida e seca. A precipitação seca contribui somente com 3-8 por cento do inventário total. Medidas de berílio-7 no solo podem serem usadas para indicar movimento de solo da camada superficial e este estudo objetiva examinar o comportamento de berílio-7 no solo. Variabilidade natural do inventário de berílio-7 é em torno de 23 por cento (desvio padrão relativo). A distribuição em profundidade de berílio-7 pode ser aproximada por uma função exponencial no solo nu, com uma profundidade média de distribuição no solo em torno de 1 cm. O berílio-7 não foi encontrado abaixo da profundidade de 2 cm para o tipo de solo estudado, o que confirma sua utilização para avaliar processo de erosão superficial como um traçador de solo superficial. A concentração máxima de berílio-7 no período analisado é em torno de 40 Bq.kg-1.

Farming expansion and land degradation in Western Bahia, Brazil / Expansão agrícola e degradação da terra no Oeste da Bahia, Brasil

Land degradation by soil erosion has called attention in tropical developing countries, particularly when natural vegetation is converted to farmland. Thus, the occupation of Brazilian savannas in Western Bahia is a matter of growing environmental concern. There are approximately 10 million hectares affected by this relatively recent land-use dynamics, but little is known about the temporal and spatial distribution of the process. To better understand such transformations, this paper addresses three related topics: land use/land cover (LULC) in 1985 and 2000; LULC dynamics between 1985 and 2000; and risk of land degradation by soil erosion as a function of farming expansion. The study area is located in Northeastern Brazil, between the coordinates 11º S and 46º 30' W and 14º S and 43º 30' W. All classes of natural vegetation cover decreased their areas during the period of study. Savanna (cerrado) lost 21.0 percent of its original area. Modern farming and irrigated areas increased 154.4 and 526.0 percent, respectively. Farming expansion reached 1,675,233 ha. Moderate risk of land degradation by soil erosion increased from 28.0 to 36.8 percent of the landscape mosaic between 1985 and 2000. The spatial and temporal dynamics observed reproduces development and land degradation examples of other savanna lands in Brazil. The integrity of native vegetation cover and the dissemination of soil and water conservation practices should be considered. This research contributes with an understanding of landscape transformations as a baseline for strategic environmental and land-use planning within the region.

A degradação da terra por erosão do solo tem chamado atenção em países em desenvolvimento, particularmente quando a vegetação nativa é convertida em área agrícola. Portanto, a ocupação do cerrado no Oeste da Bahia é um tema de crescente preocupação ambiental. Existem aproximadamente 10 milhões de hectares afetados por esta recente dinâmica de uso da terra, mas pouco se sabe sobre a distribuição temporal e espacial do processo. Para melhor entender estas transformações, este trabalho aborda três tópicos relacionados: uso e cobertura da terra em 1985 e 2000; dinâmica do uso e cobertura entre 1985 e 2000; e risco de degradação da terra por erosão de solo como função da expansão de áreas agrícolas. A área de estudo localiza-se no Nordeste brasileiro, entre as coordenadas 11º S e 46º 30' O e 14º S e 43º 30' O. Todas as classes de vegetação nativa diminuíram suas áreas durante o período de estudo. O cerrado perdeu 21,0 por cento de sua área original. A agricultura moderna e as áreas irrigadas aumentaram 154,4 e 526,0 por cento, respectivamente. A expansão de áreas agrícolas alcançou 1.675.233 ha. O risco moderado de degradação da terra por erosão de solo aumentou de 28,0 para 36,8 por cento do mosaico de paisagem entre 1985 e 2000. A dinâmica espacial e temporal observada reproduz exemplos de desenvolvimento e degradação da terra de outras áreas de cerrado no Brasil. A integridade da cobertura vegetal nativa e a disseminação de práticas de conservação de solo e água deveriam ser consideradas. Esta pesquisa contribui para um entendimento das transformações da paisagem como uma base para o planejamento ambiental estratégico e do uso das terras na região.

Erosividade e características da chuva correlacionadas com perdas de solo em Alagoinha - PB / Erosivity, rain characteristics and soil losses at Alagoinha, state of Paraíba, Brazil

Visando estabelecer o parâmetro da chuva quemelhor expresse a sua capacidade potencial de causar erosão, foram estudadas, para o período de 1981 a 1989, correlações lineares simples entre 13 características da chuva e as perdas de solo provocadas por erosão hídrica em solo classificado como Terra Roxa Estruturada localizada na Estação Experimental de Alagoinha, Paraíba, pertencente a Empresa Estadual de Pesquisa Agropecuária da Paraíba. As características da chuva testadas como estimadores da erosividade foram: quantidade de chuva;energia cinética total; segmentos de chuva com energia cinética igual ou superior a 25 mm/h; intensidades máximas de chuva em 5, 10, 15, 30 e 60 minutos; produto da energia cinética total pelas intensidades máximas em 5, 10, 15, 30 e 60 minutos. As correlações obtidas indicam que a característica da chuva produto da energia cinética total pela intensidade máxima em 15 minutos é a que melhor se correlaciona com as perdas de solo na região em estudo; entretanto, não houve diferença significativa entre as características produto da energia cinética total pela intensidade máxima em 15 minutos e produto da energia cinética total pela intensidade máxima em 30 minutos. O valor médio anual para a precipitação em Alagoinha - PB no período de 1981 a 1989 foi de 3423 MJ.mm/ha.h.

The objective of this study was to establish a rain parameter that can be used to express the potential capability of the rain to cause soil erosion. Datafrom 1981 to 1989 were used in simple linear corre letions among 13 rain characteristics and soil tosses using individual erosive rains in an Alfisol soil of Alagoinha Experimental Station of "Empresa Estadual de Pesquisa Agropecuária", State of Paraíba, Brazil. The rain characteristics tested were: total precipitation; total kinetic energy; kinetic energy higher than 25 milimeters ; rain intensity at 5, 10, 15, 30 and 60 minutes; product between kinetic energy and rain intensity at 5, 10, 15, 30 and 60 minutes. The corre lations obtained among rain characteristics and soil tosses, indicated that the rain characteristic energy-intensity in 15 minutes is better correlated to soil losses. However, there was no difference between energy-intensity in 15 minutes and energy-intensity in 30 minutes characteristics. The médium year value of the erosivity (EI30) obtained for Alagoinha during the studied period was 3.423 MJ.mm/ha, h.