Agroecosystems

Spiders are among the most abundant predators recorded in grain crops in Australia. They are voracious predators, and combined with their high abundance, may play an important role in the reduction of pest populations. The significance of spider assemblages as biological control agents of key pests such as Helicoverpa spp. in Australian agroecosystems is largely unknown. A thorough inventory was made of the spider fauna inhabiting unsprayed soybean fields at Gatton, southeast Queensland. Onehundred-and-two morphospecies from 28 families were collected using vacuum sampling and pitfall traps across two summer seasons (2000-01, 2001-02). No-choice feeding tests in the laboratory, using eggs and larvae of Helicoverpa armigera (Hübner) as prey, were used to ascertain the predatory potential of each spider group. The field-collected spider assemblage ate on average 2.4 (± 0.7 standard error) to 5.0 (± 0.8) eggs per 24 h per spider (10-25% of those available), depending on level of starvation. Clubionidae were the only spiders to readily consume eggs in the laboratory (mean of 18.4 ± 1.5 eggs per starved spider and 8.2 ± 3.9 per non-starved spider after 24 h). Starved spiders consumed 9.4 (± 0.1) first-instar larvae per 24 h per spider (90% of those available). This information was combined with field observations and literature from Australian and overseas studies to assess the potential of spider groups as predators of Helicoverpa spp. Lycosidae, Clubionidae, Oxyopidae, Salticidae and Thomisidae have the capacity to contribute to control of Helicoverpa spp.

The pollination requirements of eggplant (Solanum melongena) were investigated. One variety of eggplant exhibited a significantly reduced seed set in absence of pollinators, and two varieties significantly increased seed numbers when pollen deposition was enhanced. Two solitary bee species, Xylocopa caffra and Macronomia rufipes, were identified as effective pollinators of the crop. The visitation rates of these pollinators to eggplant flowers declined significantly with distance from the wild habitat. The importance of wild plants as alternative forage source for pollinators was assessed by a survey of the flowering plants in different habitats surrounding eggplant fields. While ruderal farm weeds provide much of these resources, the Acacia tortilis riverine forest experienced high visitation rates in one critical period of the dry season. The spatio-temporal foraging behaviour of eggplant pollinators highlights the role of the agricultural matrix in conserving ecosystem services. Interspersion of wild habitats with cultivated land promoted increased pollination services.

The evaluation of agroecosystems sustainability requires to transform complex aspects in another more simple, objectives and generals that allow to detect tendencies at a system level, called indicators. The aim of this paper was to develop a set of indicators to evaluate the sustainability of traditional agroecosystems in Misiones, Argentina. Five farms, dedicates to self-production were analysed. A set of indicators was constructed to evaluate the fulfi lled of Economics, Ecological and Socio-cultural objectives. The indicators were standardized and weighted according to its importance. The use of indicators allowed to detect clear tendencies in general sustainability index and in the ecological, economical and sociocultural dimensions. The ecological sustainability of these agroecosystems was associated to economical and sociocultural aspects. The system were ecologically sound, based on low external inputs, compatible with farmer conscience and provide an adequate diet for the f...

At the Rio+20 Conference (June 2012), the biodiversity conservation agenda was subsumed into broader environmental issues like sustainable development, "green economy," and climate change. This shoehorning of biodiversity issues is concomitant with a trend toward market-based instruments and toward standardized biodiversity assessment and monitoring. This article raises concern that these trends can marginalize important and specific aspects of biodiversity governance, including other policy tools and regionspecific socio-ecological environments. Among other trends, this contributes to the marginalization of agroecosystems as habitat and matrix for biodiversity. Such agroecosystems, however, can have a major impact on conservation outcomes as they comprise a major part of terrestrial lands. If the biodiversity crisis is to be curbed, special attention must be drawn to societies, institutional approaches, and environments that are currently marginalized in conservation policies.

It is of global concern to adopt measures to mitigate land degradation caused by agricultural production systems. One of the strategies proposed is to replace degraded pastures with agrosilvopastoral systems which integrate three different land-use types: crop production, livestock pasture and forestry plantation (denoted iCLF). However, little is known about the differences between iCLF and other land use types in terms of soil microbial community structure. Distance matrices based on individual soil chemical properties and individual soil microbial variables were correlated by Procrustes analysis and these relationships yielded vectors of residuals depicting these correlations (matches). These vectors were used as univariate response variables in an ANOVA framework in order to investigate how the match sizes (the strength of correlation/covariance) between individual soil chemical properties and individual soil microbial variables vary across land use types (levels: iCLF; degradated pasture; improved pasture; and a native cerrado fragment) and also across sample origin within iCLF (levels: soil samples under more influence of the exotic tree forest stand; soil samples under influence of the pasture; samples within the transition between the forest stand and the pasture). We were able to obtain insights into the fact that the land use distinction can be driven by more than just individual soil chemical and microbial variables. The integration of crop, livestock and forestry promoted a dominance of fungi in this low fertility and low pH environment. P availability and the composite variable exchangeable base cations (Ca þ2 , Mg þ2 , K þ) were the soil properties whose strengths of correlation (match sizes) with individual microbial variables were the most affected by land use type and sampling origin within iCLF. While the strength of the correlation between soil microbial structure variables and P availability was typically land use type dependent, the response of the microbial structure to exchangeable base cations was mainly affected by the sample origin within iCLF. Finally our results point towards the conclusion that increases in the heterogeneity of vegetation within integrated crop, pasture and forestry systems are an important driver of microbial community response to environmental changes, and may be one means by which to increase the sustainability of tropical agroecosystems.

... resources rapidly, leaving very little for weeds and thus reducing the chances of their survival. ... should be revived, and in this pro-cess allelopathy can play an important role, if crops ... out that crop rotation is one of the most powerful techniques of reducing weed seed banks in soil ...

1. Land-use change frequently reduces local species diversity. Species losses will often result in loss of trait diversity, with likely consequences for community functioning. However, the converse need not be generally true: management approaches that succeed in retaining species richness could nevertheless fail to maintain trait diversity. We evaluated this possibility using bee communities in a California agroecosystem. 2. We examined among site patterns in bee species diversity and functional-trait diversity in a landscape composed of a mosaic of semi-natural habitat, organic farms and conventional farms. We sampled bees from all three habitat types and compiled a data base of life-history ('functional') traits for each species. 3. Although species richness was higher on organic farms than conventional farms, functional diversity was lower in both farm types than in natural habitat. Nesting location (below-ground vs. above-ground) was the primary trait contributing to differences in functional diversity between farms and natural habitat, reflecting observed differences in availability of nesting substrates among habitat types. Other traits, including phenology and sociality, were also associated with species' occurrences or dominance in particular site types. These patterns suggest that management practices common to all farms act as environmental filters that cause similarly low functional diversity in their bee communities. 4. Synthesis and applications. Although our results support the value of organic farming in maintaining abundant and species-rich bee communities, components of bee functional diversity are not well supported in farmed landscapes, regardless of farming practice. Maintenance of natural habitat, and/or the addition of natural habitat elements to farms, is therefore important for the retention of functionally diverse bee assemblages in agroecosystems.

La evaluación de la sustentabilidad de agroecosistemas requiere transformar aspectos complejos en otros más claros, objetivos y generales que permitan detectar tendencias a nivel de sistema, denominados indicadores. El objetivo de este trabajo fue el desarrollo y uso de indicadores para evaluar la sustentabilidad de agroecosistemas de pequeños productores en la Provincia de Misiones, Argentina. Se analizaron 5 fi ncas, dedicadas a la producción de autoconsumo. Se construyeron indicadores para evaluar el cumplimiento de objetivos económicos, ecológicos y socioculturales. Los indicadores se estandarizaron y se ponderaron de acuerdo a su importancia. El uso de indicadores permitió observar claras tendencias en la sustentabilidad general y en los aspectos económicos, ecológicos y socioculturales. Se observó una alta interdependencia entre las diferentes dimensiones de la sustentabilidad. El cumplimiento de los objetivos ecológicos estuvo condicionado por aspectos económicos y socioculturales. La producción para autoconsumo resultó ecológica, con baja utilización de insumos externos, compatible culturalmente con la conciencia de los productores y proveyó de una dieta adecuada. Este sistema productivo cumpliría objetivos ecológicos, sociales y culturales pero sólo parcialmente los económicos, por lo que los productores se ven obligados a incluir el cultivo de tabaco que responde a un modelo de alto uso de insumos, a cambio de ciertos benefi cios, como la obra social. Se concluye que el desarrollo de indicadores es adecuado para detectar puntos críticos a la sustentabilidad, establecer sus causas y proponer soluciones a mediano plazo.

Predictive theory on how plant diversity promotes herbivore suppression through movement patterns, host associations, and predation promises a potential alternative to pesticide-intensive monoculture crop production. We used meta-analysis on 552 experiments in 45 articles published over the last 10 years to test if plant diversification schemes reduce herbivores and/or increase the natural enemies of herbivores as predicted by associational resistance hypotheses, the enemies hypothesis, and attraction and repellency model applications in agriculture. We found extensive support for these models with intercropping schemes, inclusion of flowering plants, and use of plants that repel herbivores or attract them away from the crop. Overall, herbivore suppression, enemy enhancement, and crop damage suppression effects were significantly stronger on diversified crops than on crops with none or fewer associated plant species. However, a relatively small, but significantly negative, mean effe...

The pollination requirements of eggplant (Solanum melongena) were investigated. One variety of eggplant exhibited a significantly reduced seed set in absence of pollinators, and two varieties significantly increased seed numbers when pollen deposition was enhanced. Two solitary bee species, Xylocopa caffra and Macronomia rufipes, were identified as effective pollinators of the crop. The visitation rates of these pollinators to eggplant flowers declined significantly with distance from the wild habitat. The importance of wild plants as alternative forage source for pollinators was assessed by a survey of the flowering plants in different habitats surrounding eggplant fields. While ruderal farm weeds provide much of these resources, the Acacia tortilis riverine forest experienced high visitation rates in one critical period of the dry season. The spatio-temporal foraging behaviour of eggplant pollinators highlights the role of the agricultural matrix in conserving ecosystem services. Interspersion of wild habitats with cultivated land promoted increased pollination services.

Predictive theory on how plant diversity promotes herbivore suppression through movement patterns, host associations, and predation promises a potential alternative to pesticide-intensive monoculture crop production. We used meta-analysis on 552 experiments in 45 articles published over the last 10 years to test if plant diversification schemes reduce herbivores and/or increase the natural enemies of herbivores as predicted by associational resistance hypotheses, the enemies hypothesis, and attraction and repellency model applications in agriculture. We found extensive support for these models with intercropping schemes, inclusion of flowering plants, and use of plants that repel herbivores or attract them away from the crop. Overall, herbivore suppression, enemy enhancement, and crop damage suppression effects were significantly stronger on diversified crops than on crops with none or fewer associated plant species. However, a relatively small, but significantly negative, mean effect size for crop yield indicated that pest-suppressive diversification schemes interfered with production, in part because of reducing densities of the main crop by replacing it with intercrops or non-crop plants. This first use of meta-analysis to evaluate the effects of diversification schemes, a potentially more powerful tool than tallies of significant positive and negative outcomes (vote-counting), revealed stronger overall effects on all parameters measured compared to previous reviews. Our analysis of the same articles used in a recent review facilitates comparisons of vote-counting and meta-analysis, and shows that pronounced results of the meta-analysis are not well explained by a reduction in articles that met its stricter criteria. Rather, compared to outcome counts, effect sizes were rarely neutral (equal to zero), and a mean effect size value for mixed outcomes could be calculated. Problematic statistical properties of vote-counting were avoided with meta-analysis, thus providing a more precise test of the hypotheses. The unambiguous and encouraging results from this meta-analysis of previous research should motivate ecologists to conduct more mechanistic experiments to improve the odds of designing effective crop diversification schemes for improved pest regulation and enhanced crop yield.

Controversy exists over the impact of soil cultivation on soil macro-arthropods. Inappropriate sampling methodologies and experimental design have been partly responsible for the contradictory findings. In this study emergence trapping was utilized during 1998 from plots ploughed in winter, spring or left undisturbed in fields of wheat stubble or undersown grass leys. In 1999, emergence from winter-ploughed or undisturbed plots in fields of wheat stubble or undersown grass leys was compared, with and without frost protection. The catch was dominated by adult and larval Coleoptera, of which 68 and 77 % were Carabidae in 1998 and 1999 respectively. In 1998 the period of peak emergence of Carabidae, Curculionidae and total Coleoptera were earlier from unploughed compared to ploughed treatments. None of the treatments influenced the time of arthropod emergence in 1999. In 1998 only Curculionidae were affected by ploughing, with more being captured from the winter-ploughed plots. In 1999 the emergence of six carabid species was lower from the ploughed plots, whereas Notiophilus biguttatus (Coleoptera: Carabidae) favoured the ploughed plots. Total Carabidae, other coleopteran adults and larvae and aranean groups were also lower in the ploughed plots. The provision of frost protection had no impact, but temperatures throughout the winter were relatively mild.

Background. Up to 75% of crop species benefit at least to some degree from animal pollination for fruit or seed set and yield. However, basic information on the level of pollinator dependence and pollinator contribution to yield is lacking for many crops. Even less is known about how insect pollination affects crop quality. Given that habitat loss and agricultural intensification are known to decrease pollinator richness and abundance, there is a need to assess the consequences for different components of crop production. Methods. We used pollination exclusion on flowers or inflorescences on a whole plant basis to assess the contribution of insect pollination to crop yield and quality in four flowering crops (spring oilseed rape, field bean, strawberry, and buckwheat) located in four regions of Europe. For each crop, we recorded abundance and species richness of flower visiting insects in ten fields located along a gradient from simple to heterogeneous landscapes. Results. Insect po...

This study aims to characterize the main patterns of landscapetransformation in agroecosystems of the Amanã Sustainable Development Reserve – RDSA. The perceptions of the farmers, forms of use and classification of environments, and their implications for the conservation of local ecosystems were also sureveyed. Different local patterns of environment classification and agroecosystems have been identified, and the main conditioners of transformation of the landscape for the establishment of agricultural systems were detected. Great heterogeneity in those patterns observed was observed, which varied as a function of the settlem ent, of the socio-economic profiles of the agriculturists and those ecosystems where the communities are established. Som e topics related to the roductive systems in a perspective of protected areas were listed for further debate.

Riverside communities in the Tapajós Basin have vast traditional knowledge about uses of local flora. Such traditional knowledge transmitted from generation to generation is threatened by anthropic pressure on such ecosystems in the Amazon. The Juá Environmental Preservation Area (APA Juá) is one such area. The objective of this work was to characterize the traditional knowledge of a women and last group living on APA Juá, Santarém city, Pará state, through an Ethnobotanical study. From interviews with a semi - structured questionnaire, guided visit and herborization of the mentioned plant species, the method was configured, for later treatment of ethnobotanical variables by non - parametric analysis. Thirty - six ethnospecies useful for families were identified, distributed in 23 families and 34 genera. The species with the highest relative frequency of citations were Jurú (C. icaco), Piranga (M. apiranga) and Muruci (B. crassifolia.). Açaí (E. oleracea) was the specie with the highest Value of Use, suggesting the importance of conservation of it for sub existence and reproduction of these families over time. Among the medicinal plants, the boldo (P. barbatus), the lemon grass (L. alba), the guava (P. guajava) and the mint (M. villosa) stand out. Ethnobotanical research demonstrates that it is a good tool for popularizing and valuing traditional knowledge of riverside communities, but it is mainly used as a tool for socioenvironmental denunciation of savannas degradation in the Tapajós Basin.

The adoption of genetically modified crops (GMOs) has led to the need to assess impacts on non-target organisms. For this, the impact of transgenic maize (Zea mays) on beneficial entomofauna was studied. Arthropods were collected in eight lots of conventional and transgenic maize using the techniques of Berlesse, Pitfall, Jama and Yellow traps. The diversity analysis was performed using the method proposed by Jost (2006) through three values q = 0, 1 and 2 and range-abundance curves were constructed. For the formation of the functional groups, a cluster analysis was performed using Ward’s hierarchical chaining method. 6,932 individuals were collected between conventional and transgenic crops, registering 102 taxa discriminated in 6 species, 42 genera and 54 families. The transgenic crop recorded the highest abundance with 51,60% and the conventional one 48,39%. The range-abundance curve does not indicate differences between the crops for the municipalities of Cereté and San Pelayo. The dendrogram showed eight (8) functional groups. When analyzing the true alpha diversity 0D, the eight (8) functional groups were obtained in both locations; The true diversity in conventional culture was 1D = 6,76 and the transgenic 1D = 6,83. For the 2D order it was 6,17 in conventional and 6,21 in transgenic; it can be concluded that in these results no significant differences were observed in relation to the three diversity profiles between conventional and transgenic crops.

Тема очень актуальна и является одной из приоритетных в направлении устойчивого развития Азово-Черноморского региона и создания
прибрежно-морского природного широтного коридора национальной экологической сети Украины.
На сегодняшний день биоземледелие и агроландшафтное проектирование являются перспективными направлениями сельскохозяйственной деятельности, которые дадут возможность не только получать экологически чистую сельхозпродукцию в сочетании с развитием рекреации, а в первую очередь сохранят ландшафтное и биологическое разнообразие, а также значительно снизят уровень поступающих загрязняющих веществ в окружающую природную среду.
Основные базовые положения биодинамического (органического) земледелия как системы выращивания продукции, пригодной для детского, лечебного и профилактического питания:
– организация биоземледельческих хозяйств на незагрязненных землях;
– применение беспестицидных технологий выращивания сельхозкультур;
– проведение защиты посевов от сорняков агротехническими мероприятиями (культивацией, полупаром) и посевами пожнивных сидератов, имеющих алелопатическое влияние на сорняки;
– проведение защиты посевов от вредителей и болезней агротехническими, профилактическими и биологическими методами;
– внедрение технического обеспечения почвозащитных технологий биоземледелия с применением широкозахватных тяжелых дисковых
борон и культиваторов, позволяющих возделывать почву не глубже 4–5 см, кольчато-шпоровых катков и зерновых прессовых сеялок или сеялок прямого сева; мульчирование поверхности почв пожнивными остатками...

Il contributo ha ad oggetto il programma mondiale lanciato nel 2002
dalla FAO sui Globally Important Agricultural Heritage Systems (GIAHS) e
si propone di indagare le ragioni della sua rilevanza per il diritto dell’ambiente.
I GIAHS identificano quei «sistemi di uso agricolo della terra e paesaggi, ricchi
di biodiversità significativa a livello globale, che sono il risultato del
coadattamento evolutivo di una data comunità al suo ambiente e alle sue
esigenze e aspirazioni di sviluppo sostenibile». Questa definizione può essere
interpretata alla luce della nozione giuridica di ambiente, inteso come sistema
di relazione tra fattori, nell’ambito della cornice teorico-metodologica
rappresentata dal paradigma dell’agroecologia. I GIAHS sono chiari esempi di
attività antropica connessa alla produzione agricola compatibile con la tutela
giuridica dell’ambiente; dalla combinazione del programma GIAHS con altri
istituti, quali il programma UNESCO e la disciplina sui paesaggi rurali e di
interesse storico, può derivare la preservazione e la valorizzazione delle
diverse vocazioni dei territori e lo sviluppo sostenibile di questi ultimi.
PAROLE-CHIAVE: GIAHS; coadattamento evolutivo tra uomo e
natura; nozione giuridica di ambiente; agrobiodiversità; agroecologia;
sviluppo sostenibile.

This paper focuses on the “Globally Important Agricultural Heritage
Systems” (GIAHS) Program, which was launched by FAO in 2002, and
investigates the reasons of its relevance for the environmental law. GIAHSs
are defined as «remarkable land use systems and landscapes which are rich in
globally significant biological diversity evolving from the co-adaptation of a
community with its environment and its needs and aspirations for sustainable
development». This concept can be interpreted in the light of the legal notion
of environment, understood as a system of relationships between factors,
within the theoretical and methodological framework represented by the
Agroecology paradigm. The GIAHS are examples of anthropic activity related
to agricultural production and compatible with the legal protection of the
environment. The combination of the GIAHS program with other ones such as
the UNESCO program, or and the national register of historical rural
landscapes, may preserve the different vocations of the territories and promote
their sustainable development.

The world increasingly looks to market-based solutions to meet local and global food security needs. This trend is accompanied by a weakening of the public sector. These two trends have an enormous influence on the creation of a modern food system that is harming the health of people and planet. Individually and collectively governments must define and assert their appropriate role in protecting the public interest in food security. This paper questions the increasingly dominant belief that market-based solutions are sufficient for ensuring local and global food security and emphasizes the need for a revitalized public sector.

Great Himalayan National Park (GHNP), situated in Kullu district of Himachal Pradesh, India, is home to huge diversity of fauna and flora. Having rich bio-cultural traditions the farmer communities residing in buffer zone of GHNP Conservation Area (GHNPCA) have developed multitude of indigenous on-farm techniques (the methods by which inputs are powered) and technologies (the application of knowledge to the production system) for optimal production. Appreciable diversity of agriculture has been maintained through a variety of crop compositions, cropping patterns and crop rotations. Grassroots Institute undertook the mapping and documentation of in situ agrobiodiversity in 2007-10, followed by promotion of on-farm conservation and organic farming practices. Farmers practice polyculture by growing multiple traditional cultivars of millets, pulses, beans, barley, pea, buckwheat, horse gram, maize, wheat, potato and soybean. About 45 traditional cultivars of 15 different crops are being cultivated by the mountain farmers in 2 gram panchayats covering 20 villages in Tirthan Valley of GHNPCA. Results of the study revealed that these traditional cultivars are far superior in characteristics than their counterpart modern or hybrid varieties. However, the old agronomic practices and poor market rates have ever discouraged the farmers to continue growing the traditional cultivars of these crops, and the farmers were forced to adopt hybrid seeds and monoculture. Abundance and sown area of various cultivars also decreased over past three decades. Grassroots Institute addressed the twofold challenge: one, preservation and re-introduction of traditional cultivars in situ coupled with improvement in agronomic methods of farmers for enhancing the yield; and two, linking the organic produce of the traditional crops with innovative post-harvest techniques and better market opportunities. Challenge ahead lies in engaging large number of farmers in cultivation of genetically-superior traditional cultivars, and in value addition, processing and marketing of organic produce of these crops, so that the livelihood of marginal and poor farmers, which is relatively based on bioresources of national park, can be diversified/diverted and the overall goal of biodiversity conservation is fully achieved.

CITATIONS 3 READS 33 6 authors, including: Some of the authors of this publication are also working on these related projects: Biofuel plantations and energy requirements View project Adaptación y mitigación de la agricultura mexicana ante el cambio climático View project Cesáreo Landeros-Sánchez Colegio de Postgraduados Campus Veracruz

This chapter explores this view using economic theory. In doing so, it takes into account the total economic valuation concept. While the granting of commercial property rights is found to be effective for conserving some species, it is predicted to be a complete failure as a means of conserving other species. Furthermore, its potential for success in different regions of the world varies. Here, particular attention is given to the economics of utilization and conservation of non-captive fugitive (or mobile) wildlife.
In considering the extent to which private property rights of landholders in non-captive wildlife can contribute to the conservation of wildlife, the following issues will be investigated in turn: the total economic value of wildlife and its conservation prospects, variations in the patterns of mobility of wild species, basic consequences for conservation of the private appropriation of non-consumptive use rights in wildlife, and similarly, the consequences of consumptive use rights in wildlife on private land. A brief critical discussion of relevant economic articles is followed by a discussion of global rights in wild genetic resources and concluding comments.

The influence of elevated atmospheric CO 2 concentrations ([CO 2 ]) on the decomposition of spring wheat (Triticum aestivum L. cv. Triso) residues remaining in the soil after harvest was simulated in a microcosm incubation experiment in the lab. Undisturbed soil cores with and without visible wheat residues were taken in the third year after establishment from a Mini-free-air carbon dioxide enrichment (FACE) system, in which we used 13 C-depleted CO 2 to determine the contribution of plant-derived carbon to overall carbon mineralization. The Mini-FACE system is located on a Gleyic Cambisol near Hohenheim (Baden-Württemberg, Germany). Carbon dioxide production and leaching of nitrogen and inorganic and organic carbon were measured during 191 days of incubation. Rates of CO 2 production were generally highest in all treatments during the first two weeks of the incubation and this was followed by a steady decrease until day 58. After this day mineralization rates declined only weakly until the end of the incubation. Cumulative carbon mineralization was similar in the two treatments without visible wheat residues, but significantly lower in the elevated (À19.0%) versus ambient [CO 2 ] treatment with visible plant residues (significant [CO 2 ] Â residue interaction; F 1,13 = 7.17; P = 0.019). This result demonstrated reduced decomposition of wheat residues grown under elevated [CO 2 ]. The contribution of plant-derived carbon to soil respiration was highest in the beginning, followed by a steady decrease until the end of the incubation. Irrespective of incubation time, the amount of mineralized, plant-derived carbon was higher in the treatment with visible wheat residues. Leaching of inorganic carbon (DIC) tended to be affected by [CO 2 ] (F 6,8 = 4.50; P = 0.057), with more DIC leached in the elevated [CO 2 ] treatment without (+47.2%) and with visible plant residues (+29.5%) than in the respective ambient CO 2 treatments. The amount of carbon potentially sequestered as DIC in the wheat cropping system was small compared to the effects of elevated [CO 2 ] on the amounts and decomposition of plant residues. Increased input of plant residues and reduced decomposition of plant-derived carbon are discussed as possible mechanisms for enhanced carbon sequestration under elevated atmospheric CO 2 concentration. #

Feeding habits of sympatric species of small mammals in agroecosystems of central Argentina were analysed using micro-histological analysis of stomach contents. All small mammal species were omnivores, but species changed their diets in relation to the habitat disturbance level. Calomys species showed more dietary overlap in greatly and moderately disturbed habitats than in less disturbed habitats. Calomys species and Akodon dolores behaved in opposite ways. The high degree of dietary overlap among Calomys species was explained by the chance disturbance hypothesis, and their low degree of dietary overlap by classical resource partitioning. The high dietary overlap between Calomys species and A. dolores was explained via the generalization-specialization hypothesis.

The effects of weather on population fluctuation patterns of the South American muroid Calomys venustus were studied. Box-Jenkins data series analysis and anova were used to describe the relationship between climatic variables and population. No relation was found between maximum temperatures or precipitation and the C. venustus population. Temperatures below 4°C appear to affect populations of the overwintered cohort after a time lag of 5 months.

We studied the potential for native birds to control insect pests on farms. We assessed habitat factors correlated with diversity, distribution, and insect-foraging activity of native birds on farms in north-central Florida and then characterized common bird species that consumed insect biomass in crops as "functional insectivores" (birds most likely to contribute to pest control). Analyses of point-count survey data

Ladakh traditional farming system has been included on the F.A.O. list of possible "Globally Important Agricultural Heritage Systems", worthy of being preserved and conserved. The paper describes and assesses cultivation practices in a typical familymanaged farm, located in central Ladakh, analysing how natural resources are exploited, conserved and recycled. Emergy evaluation, an environmental accounting methodology, has been applied to evaluate and compare five staple crop productions: barley, wheat, pea, mustard, and fodder alfalfa. Unit Emergy Values of products (UEV, emergy per unit product, a measure of the environmental production cost) are calculated, taking into account the inputs to production such as water from glaciers, soil fertility, human and animal labour, and more. Results show that the traditional agricultural practices in Ladakh, completely supported by renewable flows, are efficient in the use of local resources. In fact, the UEVs of agroproducts are similar to those of analogous products of conventional agriculture (e.g. 5.27E+05 and 6.64E+05 semj/J for barley and wheat in Ladakh, respectively; 7.37E+05 semj/J for corn in USA), though the inputs of Ladakh agriculture are strongly limited in type and quantity. At the same time, local farmers can create, maintain and rebuild soil functions whose UEV is 1.62E+07 semj/J.

Conservation biological control in agroecosystems requires a landscape management perspective, because most arthropod species experience their habitat at spatial scales beyond the plot level, and there is spillover of natural enemies across the crop-noncrop interface. The species pool in the surrounding landscape and the distance of crop from natural habitat are important for the conservation of enemy diversity and, in particular, the conservation of poorly-dispersing and specialized enemies. Hence, structurally complex landscapes with high habitat connectivity may enhance the probability of pest regulation. In contrast, generalist and highly vagile enemies may even profit from the high primary productivity of crops at a landscape scale and their abundance may partly compensate for losses in enemy diversity. Conservation biological control also needs a multitrophic perspective. For example, entomopathogenic fungi, plant pathogens and endophytes as well as below-and above-ground microorganisms are known to influence pest-enemy interactions in ways that vary across spatiotemporal scales. Enemy distribution in agricultural landscapes is determined by beta diversity among patches. The diversity needed for conservation biological control may occur where patch heterogeneity at larger spatial scales is high. However, enemy communities in managed systems are more similar across space and time than those in natural systems, emphasizing the importance of natural habitat for a spillover of diverse enemies. According to the insurance hypothesis, species richness can buffer against spatiotemporal disturbances, thereby insuring functioning in changing environments. Seemingly redundant enemy species may become important under global change. Complex landscapes characterized by highly connected crop-noncrop mosaics may be best for long-term conservation biological control and sustainable crop production, but experimental evidence for detailed recommendations to design the composition and configuration of agricultural landscapes that maintain a diversity of generalist and specialist natural enemies is still needed.

In agriculture, sustainability can be linked to ecological resilience. In view of present or imminent environmental changes in agricultural landscapes, the diversity of species and genotypes, particularly of potential beneficials and alternative prey, may become of increasing importance. However, the available methods and empirical data concerning species diversity of above-ground insects in agricultural landscapes do not yet allow comprehensive evaluation. Standardized inventory methods must be used more rigorously and over longer time periods to detect significant differences in space and in time. Indicator groups for biodiversity estimates must be defined.

Trombiculid mites are known to parasitize a variety of amphibian species; however, few comparisons of mite parasitism among sites have been made. Here, Hannemania sp. parasitism in frogs (Leptodactylus chaquensis) inhabiting agroecosystems from mideastern Argentina was described. A total of 40 adult frogs (22 females and 18 males) were analyzed to detect ectoparasite Hannemania spp. larvae. Prevalence and mean abundance of Hannemania sp. were consistently higher in frogs from the agroecosystems (rice and soybean fields) than from two reference sites. Leptodactylus chaquensis might be considered an important host species of Hannemania sp., particularly in agricultural areas.

In this study, we investigated the influence of environmental variables (predictor variables) on the species richness, species diversity, functional diversity, and functional redundancy (response variables) of stream fish assemblages in an agroecosystem that harbor a gradient of degradation. We hypothesized that, despite presenting high richness or diversity in some occasions, fish communities will be more functionally redundant with stream degradation. Species richness, species diversity, and functional redundancy were predicted by the percentage of grass on the banks, which is a characteristic that indicates degraded conditions, whereas the percentage of coarse substrate in the stream bottom was an important predictor of all response variables and indicates more preserved conditions. Despite being more numerous and diverse, the groups of species living in streams with an abundance of grass on the banks perform similar functions in the ecosystem. We found that riparian and watershe...

Agricultural expansion and intensification recently occurring in Argentina, particularly in the Pampas region, has resulted in important changes in the agricultural landscape. Consequently, biotic populations may have experienced changes on abundance and distribution. In this work, we analyzed the relationship between changes in the density of four bird species (Eared Dove, Monk Parakeet, Fork-tailed Flycatcher and White-browed Blackbird) and environmental variables associated to climate, vegetation cover and productivity for the 2003-2011 period in Central Argentina. The study area consisted of three agricultural sub-regions (predominantly agricultural, agricultural-rangeland and agricultural-forested rangeland). Bird populations were sampled yearly in 48 30-point routes located on secondary roads. Points were separated by 1 km and sampled for 3 minutes, using distance sampling. Density was estimated using three models (uniform, halfnormal and hazard rate) and two adjustment terms (cosine and polynomial), and the half-normal model with a cosine adjustment was selected for all species, using AIC. We then estimated the species-specific detection probability function combining all years, and bird density for each route and year by stratifying per year and post-stratifying per route. In mixed linear models, the fixed effects were year (i.e., temporal trend) and environmental variables describing climatic, primary productivity and land cover variation. The random effects were “observer”, “route” and “sampling period”. We also constructed models with a temporal autocorrelation structure and heterogeneity of variances. Using AIC and Akaike weights, models most selected were those with random effects and year-specific heteroscedascity. Mean density for Eared Dove was 11 ind/ha, almost three times higher than the second most abundant species, the Fork-tailed Flycatcher (4 ind/ha). Eared Dove and Monk Parakeet density increased significantly in all areas, while the density of the White-browed Blackbird decreased. The density of the Fork-tailed Flycatcher generally increased, but varied between areas. Although the relationships between bird density and environmental variables depended on the species, plant vigor and proportion of land use (annual crops, annual pastures, perennial pastures, plowed fields, fallow fields and forest) were significantly associated to changes in the density of all species. Based on these results, environmental changes occurring in the region have favored increases in some species and decreases in others. Recognizing these individual differences will be fundamental in establishing more precise and systematic baselines for biodiversity management and conservation at regional scales.