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Search Results: 1 - 10 of 95 matches for " Agroecosystem "
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Collembolan Density and Diversity in a Forest and an Agroecosystem  [PDF]
D. Paul, A. Nongmaithem, L. K. Jha
Open Journal of Soil Science (OJSS) , 2011, DOI: 10.4236/ojss.2011.12008
Abstract: Collembola, commonly called “springtails” are wingless soft-bodied hexapods that are usually between 1 and 3 millimetres in length and occur in varying habits such as, soil surface and litter, under rocks or the bark of trees. The great majority develop in soil, feeding on fungi, bacteria, algae and decaying plant matter, and along with other soil fauna constitute the decomposer community. The present study examines the diversity, density, and seasonal variation patterns of collembolan fauna under different intensities of disturbance, as evidenced in a forest and an agroecosystem. Results indicate that both densities and diversity of collembola was higher in the forest than in the agroecosystem. Seasonal fluctuation exhibited an increase from spring to summer and autumn and a decrease during winter. The coorelation patterns with different chemo-edaphic factors did not show any specific trend.Indices of diversity and significant correlation values are discussed in light of landuse.
Potential legacy effects of biofuel cropping systems on soil microbial communities in southern Wisconsin, USA  [PDF]
Chao Liang, Gregg R. Sanford, Randall D. Jackson, Teri C. Balser
Agricultural Sciences (AS) , 2011, DOI: 10.4236/as.2011.22019
Abstract: Soil microbial community structure is clearly linked to current plant species composition, but less is known about the legacy effects of plant species and agricultural management practices on soil microbial communities. Using microbial lipid biomarkers, we assessed patterns of com-munity-level diversity and abundance at depths of 0-10 and 10-25 cm from three hay (al-falfa/orchardgrass) and two corn plots in south ern Wisconsin. Principal components analysis of the lipid biomarkers revealed differential composition of the soil microbial communities at the two depths. Despite similar abundance of fungi, bacteria, actinomycete, protozoa, and total microbial lipids in the hay and corn at 0-10 cm, community structure differed with a sig-nificantly higher absolute abundance of arbus-cular mycorrhizal fungi and gram-negative bacteria in the hay plots. No significant micro-bial lipid mass differences were detected be-tween the two management regimes at 10-25 cm, but the proportional dominance of bacterial gram type differed with depth. These results indicate the potential for legacy effects of an-nual and perennial cropping systems manage-ment on microbial community composition and suggests the importance of considering past land-use when initiating long-term agroecolo- gical trials.
Fauna de aranhas (Arachnida, Araneae) em diferentes estágios do cultivo do arroz irrigado em Cachoeirinha, RS, Brasil
Rodrigues, Everton N. L.;Mendon?a Jr., Milton de S.;Ott, Ricardo;
Iheringia. Série Zoologia , 2008, DOI: 10.1590/S0073-47212008000300011
Abstract: the spider diversity associated to a rice field was surveyed along different stages of the culture. the studied area belongs to the esta??o experimental do arroz (eea), instituto rio grandense do arroz (irga), cachoeirinha, state of rio grande do sul, brazil (50o58'21"w; 29o55'30"s). between october 2004 and june 2005, 17 samples were taken, distributed in three periods: before seeding, during the development of the rice plants and after the harvest. samples were done in the morning using sweeping nets (35 cm diameter), 50 sweeps in each of four randomly chosen transects. a total of 918 spiders were sampled, distributed in 14 families, mostly araneidae, anyphaenidae, oxyopidae and tetragnathidae. among the adults, 38 morphospecies were found, the most abundant were alpaida veniliae (keyserling, 1865), tetragnatha nitens (audouin, 1826), ashtabula sp.1 and tetragnatha aff. jaculator, the four together comprising more than 45% of the adult specimens. of the species richness estimators used, chao 1 was closer to the observed richness; 87,4% of the potentially present species were effectively sampled. both abundance and species richness showed an increasing trend, accompanying rice development (and thus increasing habitat complexity), with a stern decrease after harvesting. a constant colonization of the habitat is thus postulated, also given the high number of young spiders found at all times. there were no significant correlations between climatic factors (temperature and rainfall) and neither abundance nor species richness, except a positive one between rainfall and richness. among the functional groups, ambushing hunters dominated, followed by orb-web builders. an analysis of similarity (anosim) found significant differences among the fauna of the three evaluated periods. thus, system disturbance, in the form of rice sowing and harvesting, brutally altering environmental structure, leads to strong spider diversity changes both in terms of species richness and specie
Cultivos Tropicales , 2010,
Abstract: nowadays, floriculture is a productive staple that wins space in the national and international market. the introduction of flowers in urban agricultural systems is a form of diversifying agroecosystems, with the aim of raising the variety of species and yields. the wrong agricultural managements, misapplication of pesticides and fertilizers as well as monoculture have involved an important biodiversity reduction in agroecosystems; however, this way has been proved to protect crops from the attack of pests and diseases. so far, studies referred to the relationships established between crop diversity and pest occurrence have been mainly directed towards edible, medicinal and aromatic species; nevertheless, it is necessary to know the role that flowers play inside the agroecosystem, so that they contribute to its ecological balance and sustainability.
Evaluación espacial y temporal de la agrobiodiversidad en los sistemas campesinos de la comunidad “Zaragoza” en La Habana
Lores,A; Leyva,A; Tejeda,Tamara;
Cultivos Tropicales , 2008,
Abstract: a specific diagnosis on agricultural crops and their spatial and temporary behavior was conducted in farmer agroecosystems from zaragoza community in san josé de las lajas, during the period between may, 2004 and december, 2006. thus, 15 farms representing 20 % of farmer community systems were selected. data were collected by direct counting and participatory techniques, such as formal surveys and growers’ interviews. inventoried species were taxonomically classified and arranged into groups according to their use and profitable value. a total of 104 plant species were found, distributed in 39 families; 86 of them are managed by farmers and 18 are associated species, mainly weeds. mean values of richness, diversity and similarity were calculated through ecological indexes. specific richness within a range from 5 to 34 species was considered mid to low and a low general diversity index. similarity index showed very low values with an average of 0.41, indicating a great variation of species cultivated in each agroecosystem. predominating crop groups were fruit trees, horticultural and grain crops with 25, 12 and 10 species, respectively.
Interacciónes entre hormigas e insectos en follaje de cafetales de sol y sombra, Cauca-Colombia
Revista Colombiana de Entomología , 2010,
Abstract: the interactions between ants and other insects can directly or indirectly affect coffee plants and their production. the objective of this study was to describe these interactions in four coffee plantations, with and without the presence of shade trees, in the locatión of pescador (caldono), cauca department. at each plantation, 45 coffee bushes were selected, and, on each one, two opposing branches on the productive part were selected. one of the branches was excluded from the path of ants and the other was left free. ants and other insects were identified and the interactions among them were recorded. the observations were done over seven months every two weeks for an estimated time of 5 min at each branch. a total of 119 interactions were observed, involving 31 ant species distributed in seven subfamilies, and 38 morphospecies of other insects distributed in seven orders (blattaria, dermaptera, orthoptera, hemiptera, neuroptera, coleoptera and hymenoptera) and 24 families. the interactions were grouped into three types: mutualism, commensalism and predation. the predominant associations were facultative mutualistic (32%), followed by commensalistic (30%). the ant species involved in the greatest proportión of associations were linepithema neotropicum (32%), brachymyrmex heeri (12%) and wasmannia auropunctata (7%). associations with hemipterans were observed in 53% of the cases, followed by coleopterans in 27%. a greater species richness of insects and number of associations were found in coffee plantations with shade than those without shade. the structural complexity offered by this type of agroecosystem provides more opportunities for the associated fauna.
Ecosystem Services in Differently Used Agroecosystems along a Climatic Gradient in Slovakia  [PDF]
Jarmila Makovníková, Boris Pálka, Milo? ?iráň, Beáta Hou?ková, Radoslava Kanianska, Miriam Kizeková
Open Journal of Ecology (OJE) , 2018, DOI: 10.4236/oje.2018.812037
For analysis and evaluation of potential of agroecosystem (arable land and grassland) services (provisioning, regulating and cultural) in Slovakia we have created a mapping unit combining these input layers: slope topography, soil texture and landuse in four climatic regions. Evaluated potential of agroecosystem services was categorised into five categories (very low, low, medium, high and very high). Our results show that climate has the most significant impact on agroecosystem services. Warm, dry lowland region has a higher potential of provisioning services, regulation of water regime, filtration of pollutants and control of soil erosion in comparison to moderately warm and cold regions. In moderate cold region, more than 90% of the total area of arable land has low potential of water regime regulation and cleaning potential (immobilization of risk elements). In the moderate warm climatic region, there is a high share of categories of low and moderate potential of provisioning services and low and moderate potential of water regime regulation. Majority of the total area of warm climatic region belongs to the categories of moderate to high potential of provisioning services and high potential of regulation of water regime. In this climatic zone low potential categories of risk elements immobilization are present in more than 65% of the arable land total area. On the other hand, in very warm climatic zone, more than 89% of the total area of arable land belongs to the category with a very high cleaning (buffering) potential. Potential of natural conditions for recreation is higher only in moderate cold and moderate warm climatic zones with a higher proportion of area of grassland agroecosystems and protected areas NATURA 2000. Moreover, the methodology developed in this paper is replicable and could be applied by planners in the case that they are proficient in geographical information systems.
Avalia??o rápida da diversidade de formigas em sistemas de uso do solo no sul da Bahia
Braga, Danielle L;Louzada, Júlio N C;Zanetti, Ronald;Delabie, Jacques;
Neotropical Entomology , 2010, DOI: 10.1590/S1519-566X2010000400002
Abstract: we aimed to compare the soil ant diversity in different land use systems from atlantic forest area, in southern bahia state, brazil. the ants were sampled in 16 sites: two primary forest sites (un-logged forest); three young secondary forests (<8 years old); three intermediate secondary forests (8-20 years old); three old secondary forests (>20 years old); three eucalyptus grandis plantations (3-7 years old), and two introduced pastures. each site was sampled in three sampling points 15 m apart, and distant over 50 m from the site edge. in each sampling point we gathered the litter from a 1 m2 and extracted the ants with winkler extractors during 48h. we found 103 ant species from 29 genera and eight subfamilies. the five richest genera were pheidole (19 species), solenopsis (8), apterostigma (10), hypoponera (7) e paratrechina (5). the highest ant richness density was found in the primary forest (7.4 species/sample; s = 37; n = 5); followed by the old secondary forest (5.33 species/sample; s = 48; n = 9); young secondary forest (5.25 species/sample; s = 42, n = 8); eucalyptus plantation (4.22 species/sample; s = 38, n = 9), intermediate secondary forest (3.5 species/sample; s = 35, n = 10, and introduced pasture (2.67 species/sample; s = 16, n = 6). the ecosystems with higher structural complexity showed the highest ant richness density by sample. therefore, in the atlantic forest region, the eucalyptus plantation is a better alternative of land use to conserve the ant biodiversity than pastures, and quite similar to native secondary forests in ant community characteristics.
Fluctuación poblacional, plantas huéspedes, distribución y clave para la identificación de Platypodinae (Coleoptera: Curculionidae) asociados al agroecosistema cacao en Tabasco, México
Acta zoológica mexicana , 2011,
Abstract: the ambrosia beetle dynamic population, hosts and distribution were studied in the cacao agroecosystem in tabasco, mexico during 2007. the insects were collected in four localities with ethanol and light traps and by direct collecting in their host plants. five species were collected with teloplatypus excisus (chapuis) being the most abundant with a total of 346 specimens. t. excisus and tesserocerus dewalquei chapuis are new records for tabasco. spondias mombin is recorded as a new host to platyscapulus pulchellus (chapuis) and t. excisus. the most efficient method of captured was the ethanol trap where which 459 specimens captured. the populational dinamic of the species through the year of study stayed in low levels in most of the towns studied, with exception of teapa where market populational pick was seen in may and july through use the ethanol traps and in its hosts; and in the months of july and november with the light traps.
Intera??o de fragmentos florestais com agroecossistemas adjacentes de café e pastagem: respostas das comunidades de formigas (Hymenoptera, Formicidae)
Dias, Nívia S.;Zanetti, Ronald;Santos, M?nica S.;Louzada, Júlio;Delabie, Jacques;
Iheringia. Série Zoologia , 2008, DOI: 10.1590/S0073-47212008000100017
Abstract: the responses of the ant community to environmental change, from forest fragment to agroecosystems (coffee or pasture) were evaluated in the south of the state of minas gerais, brazil. in this paper we analized the interactions between forest and the two most typical agroecosystem from southest brazil: sun-growing coffee plantation and introduced pasture. we sampled the ant community from five of each agroecosystems, inside the adjacent forest fragment, and on the edge between them. in each site we removed the litter from fifteen 1m2 plots and extracted the ants using a winkler extractor. a total of 165 ant species, distributed in 48 genera and 10 subfamilies were recorded. the coffee plantation presented the lowest abundance and estimated species richness. the causes of the changes observed among the areas are discussed.
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