Levels Of Agricultural Intensification Research Articles

Agriculture intensification reduces plant taxonomic and functional diversity across European arable systems

Abstract Agricultural intensification is one of the main drivers of species loss worldwide, but there is still a lack of information about its effect on functional diversity of arable weed communities. Using a large‐scale pan European study including 786 fields within 261 farms from eight countries, we analysed differences in the taxonomic and functional diversity of arable weeds assemblages across different levels of agricultural intensification. We estimated weed species frequency in each field, and collected species' traits (vegetative height, SLA and seed mass) from the TRY plant trait database. With this information, we estimated taxonomic (species richness), functional composition (community weighted means) and functional diversity (functional richness, evenness, divergence and redundancy). We used indicators of agricultural management intensity at the individual field scale (e.g. yield, inputs of nitrogen fertilizer and herbicides, frequency of mechanical weed control practices) and at the landscape scale surrounding the field (i.e. number of crop types, mean field size and proportion of arable land cover within a radius of 500 m from the sampling points). The effects of agricultural intensification on species and functional richness at the field scale were stronger than those of intensification at the landscape scale, and we did not observe evidence of interacting effects between the two scales. Overall, assemblages in more intensified areas had fewer species, a higher prevalence of species with ruderal strategies (low stature, high leaf area, light seeds), and lower functional redundancy. Maintaining the diversity of Europe's arable weed communities requires some simple management interventions, for example, reducing the high intensity of field‐level agricultural management across Europe, which could be complemented by interventions that increase landscape complexity. A free Plain Language Summary can be found within the Supporting Information of this article.

Usage of Agricultural Intensification Practices by Smallholder Farmers in Kenyan Rapidly Developing Dry Areas

Developing countries, Kenya included are mostly affected by food problems and poverty as a result of high dependence on agriculture. In Kenya agriculture contributes to 27.3% of the Gross Domestic Product. Agriculture in Kenya is dominated by smallholder farmers, whose production is hampered by climate variability, declining land sizes and low agricultural technologies. Agricultural intensification is aimed at solving the problem of low agricultural productivity and poverty through increasing farm output per unit land area. Makueni and Nyando Sub-County were considered as hotspots of climate change by CCAFS. A total of 320 households were sampled from the two sub-counties. From the scope farmers were engaged in 16 agricultural intensification practices, some practices were substitutes others complementary so they were highly correlated. Principal Component Analysis (PCA) was then used to group them into clusters called principal components. PCA helped in creating levels of agricultural intensifications. From the results, the number of components (Levels of agricultural intensification) of users was ranging from one to five. That is from low users of strategy 1, partial users of 2, 3 and 4 to full users of 5. The result revealed that 56% of farmers used 5 sets of strategies while 31%, 8%, 3% and 1% of farmers’ used 4, 3, 2 and 1 levels of agricultural intensification practices respectively. The results implied that there was need for smallholder farmers to increase agricultural intensification which leads to improved smallholder farmers livelihood outcomes and helps in building their resilience to harsh climatic conditions. Keywords: Agricultural intensification practices, Kenya, Principal Component Analysis, Smallholder farmer DOI : 10.7176/JESD/10-18-04 Publication date :September 30 th 2019

Plant species, functional assemblages and partitioning of diversity in a Mediterranean agricultural mosaic landscape

Agricultural landscapes represent mosaics of different habitats that can harbour high plant diversity where plant traits and trait syndromes can be used for predicting either plant responses to agricultural intensification or plant functional effects on other organisms. Understanding the spatial components of diversity within an agricultural mosaic can help to select the appropriate spatial scale for conserving species and ecological functions such as the provisioning of resources for pollinators. We hypothesize that trait syndromes aimed at provisioning resources for pollinators are positively related to non-crop habitats and negatively related to increasing agricultural intensification. We sampled plant species in 140 patches distributed among seven habitats (abandoned fields, boundaries, roadverges, and edges and inner alfalfa and cereal fields) that were classified into three levels of agricultural intensification: Low, Medium and High. We examined differences in species and functional assemblages, splitting response and effect traits, across various habitats and levels of agricultural intensification. Species richness and functional diversity of response and effect traits were partitioned along spatial scales. Both species and functional assemblages changed across habitats and with different levels of agricultural intensification. Non-cropped habitats and low levels of agricultural intensification promoted trait syndromes with trait-overdispersion mainly linked to the provisioning of resources for pollinators. The species turnover did not imply a functional turnover. Our study shows that traits are determined by agricultural intensification, and no further details on field position and habitat variability are needed to promote vegetation types with trait syndromes able to support pollinating insects.

Patterns of Diversity and Spatial Variability of β-Defensin Innate Immune Genes in a Declining Wild Population of Tree Swallows

Assessing the genetic variation and distribution of immune genes across heterogeneous environmental conditions in wild species is essential to further our understanding of the role of pathogen pressure and potential resistance or prevalence in hosts. Researchers have recently investigated β-defensin genes in the wild, because their variability suggests that they may play an important role in innate host defense. This study investigated the variation occurring at 6 innate immune genes of the β-defensin family in a declining population of tree swallows (Tachycineta bicolor) in southern Québec, Canada (N = 160). We found that all 6 genes showed synonymous and nonsynonymous single nucleotide polymorphisms (SNPs) within the exon coding for the mature peptide. These results indicated that this group of genes was diverse in tree swallows. Our results suggested a potential interaction of this group of genes with fluctuating pathogen diversity, however, we found no sign of positive or negative selection. We assessed whether or not the distribution of genetic diversity of β-defensin genes in our study population differed between 2 regions that strongly differ in their level of agricultural intensification. Adults are highly philopatric to their breeding sites and their immunological responses differ between these 2 regions. However, we found little evidence that the level and distribution of genetic variability differed between these heterogeneous environmental conditions. Further studies should aim to assess the link between genetic diversity of β-defensin genes and fitness-related traits in wild populations.

Does intensification of the rice cultivation cycle influence anuran diversity in rice fields?

The reduction in the amount of fallow time in rice production has occurred in the last years to increase the grain production and to sustain the global market. Some studies have shown environmental problems with reduced fallow time and it could influence negatively the pond anuran diversity. The present study tested three hypotheses: (1) amphibian richness and abundance will be greater in natural areas than rice fields; (2) rice fields with a fallow period will have greater amphibian richness and abundance than fields without this period; and (3) changes in the species composition between natural ponds and rice fields with and without a fallow period will be determined by community nestedness over the agricultural intensification gradient—natural ponds (no impact), fields with fallow period (medium impact) and fields without fallow period (greatest impact). Anurans were sampled from six rice fields cultivated under different levels of agricultural intensification (three fields with and three fields without a fallow season), and three natural ponds in southern Brazil. Although richness did not vary significantly between fields with and without fallow periods, there was a strong tendency in the results for the anuran community in the fields with fallow to be richer than that in the fields without fallow. Additionally, it is important to emphasize that the species composition of the fields with fallow were richer than the species composition of fields without fallow. Therefore, allowing the land to rest could be an important practice for the amphibian community, and rice farmers should manage some parcels of land in the agricultural matrix with resting practices in order to minimize the negative effects of rice production expansion on aquatic biodiversity in natural wetlands.

Climate adaptation imperatives: global sustainability trends and eco-efficiency metrics in four major crops – canola, cotton, maize, and soybeans

Supplying our world's growing nutrition needs in more sustainable ways has become an urgent global imperative, given the constraints of finite resources and the challenges of accelerating climate change. We present national-level eco-efficiency metrics in several representative production countries during the most recent decade (2000–2010) for four important crops: canola, cotton, maize, and soybeans. The metrics address greenhouse gas emissions and the utilization of land, water, and energy – all calculated per unit of production. We group countries based on their level of agricultural intensification and find that high-intensification countries are achieving the highest and yet still increasing levels of eco-efficiency, with these decadal gains: canola (26%), cotton (23%), maize (17%), and soybeans (18%). By stark contrast, low-intensification countries had no change in eco-efficiency during this same decade. Overall, our results suggest large opportunities for additional improvements in the developing world, and that cumulative resource savings through intensification have been significant. For instance, in the case of irrigated maize, if the high- and medium-intensification production countries had only achieved the same irrigation water-use efficiency as in the low-intensification countries, approximately 4 quadrillion (4×1015) more litres of irrigation water would have been consumed during the period 2000–2010.

Population density and use of grasslands by female Little Bustards during lek attendance, nesting and brood-rearing

The Little Bustard (Tetrax tetrax) is one of Europe’s most threatened birds, and depends mostly on extensive agricultural and pastoral schemes for survival. Due to the female’s secretive behaviour, information concerning female breeding ecology is scarce and restricted to sites with some level of agricultural intensification. Consequently, most advice for improving the habitat for this species is based on male habitat needs alone. The breeding season encompasses three distinct biological phases for females—visiting lekking males, nesting, and brood-rearing—which are likely to result in different habitat requirements. In northern Alentejo (Portugal), we studied how female densities vary during the breeding season and analysed their habitat preferences at different scales during the three phases. Both female and male density varied during the season. Local and regional female densities of 16 and 7.6 females/100 ha, respectively, are among the highest ever recorded for the species. The results of a binary GLM suggest a greater probability for the occurrence of nests in larger grassland fields with a vegetation height under 42 cm. Nests were also located preferentially in the proximity of displaying males. Female micro habitat requirements varied significantly throughout the breeding season. Vegetation heterogeneity in larger grassland fields is likely to play an important role in providing adequate habitat for females throughout the whole breeding season. Large grassland fields should, therefore, constitute a management priority in key breeding sites for the species.

Micronutrient Concentrations and Environmental Concerns in an Intensively Cultivated Typic Dystrandept in Mount Bambouto, Cameroon

Micronutrient status of top soils (0 - 25 cm) collected from intensively cultivated soils (typic dystrandept) in the Bambouto highland of Cameroon was investigated. Thirty-six soil samples were collected within a 100 m × 100 m grid. 16 of them were analyzed for pH, organic carbon, cation exchange capacity (CEC), Total N (totN), available P, exchangeable K, Ca and Mg, and 36 samples were analyzed for Cu, Mn, Fe and Zn. The status of trace elements was compared with soil critical levels and soil-based risk thresholds, and was declared deficient, sufficient or toxic. The soils were generally, slightly acidic, of high organic and nitrogen status and of adequate concentrations in exchangeable bases and available P. Mean values of Fe, Cu, Mn and Zn were 58.59, 0.52, 29.20 and 4.99 ppm, respectively. Relative to critical levels, 53% and 8% of the soils examined were deficient in Cu and Zn respectively while in all soils, Fe and Mn were above critical levels. The concentrations of the micronutrients investigated (except for Fe in 3% of the soils) were lower than toxic thresholds prescribed by European Economic Community (EEC) and the United States Environmental Protection Agency. Farmers’ current level of agricultural intensification has no threats on micronutrient toxicity. However, because of Cu and Zn deficiency observed in some fields, an analysis of spatial variability is required to guide site specific soil nutrient management. Furthermore, in order to obtain quality produce and protect the environment, a balanced fertilizer recommendation including NPK + Cu + Zn is required for intensively cultivated typic dystrandept soils in the Bambouto highlands.

Mapping and spatial analysis of the soybean agricultural frontier in Mato Grosso, Brazil, using remote sensing data

The main pioneer frontier considered by geographers is the Amazonian pioneer frontier. The occupation of the Brazilian territory has been carried out through successive economic cycles. Currently, the expansion of soybean crops in Amazonia is considered as the last economic cycle involving new migrations to still unexplored areas. Mapping this frontier is necessary in order to better understand its drivers and think about efficient land use policies to struggle its progress. In this paper, we propose an innovative methodology for mapping the agricultural frontier in the Amazonian state of Mato Grosso (Brazil) using satellite data acquired during the 2000–2006 period. We assume that the frontier evolves through successive land-use stages such as wildlands, non-croplands, extensive croplands and intensive croplands areas. The transitions between two stages can then be monitored through land-use change analysis. A particular emphasis is given on three land-use transitions named “deforestation”, “economic” and “intensification sub-frontiers”. In order to adapt this model for the use of remote sensing data, we defined (1) a relevant spatial scale corresponding to an agrarian locality, (2) relevant indices to qualify the land-use types and (3) rules applied on land-use types to define the frontier’s location. Our results highlight the dynamic of the agricultural frontier towards northern areas. We identified four main agricultural regions with different levels of agricultural intensification. We finally discuss these results with respect to governmental policies and economics for a better understanding of the frontier’s dynamic.

Changes in soil organic carbon and climate change – Application of the RothC model in agro-silvo-pastoral Mediterranean systems

Due to the complexity of soil organic carbon (SOC), models have proved very useful in helping to improve our understanding of the soil–plant–atmosphere system. In this study we used the Rothamsted carbon model (RothC), which considers the effect of climate (temperature, rainfall and evaporation), soil texture (clay content) and crop management on the decomposition processes, to predict changes in SOC under different land uses and the different climate that may occur in the future.SOC turnover was evaluated in land uses under different levels of agricultural intensification. The agriculture of the study-area is mainly extensive and markedly agro-silvo-pastoral, and is typical of north-eastern Sardinia (Italy) and similar areas of the Mediterranean basin. The following land uses were considered: vineyards, hay crops, pastures, semi-natural systems (formerly vineyards) and cork oak forests. Since the study-area is characterized by the same soil type (Haplic Endoleptic Cambisols, Dystric) derived from granitic rocks and potential native vegetation (Quercus suber L.), this was considered as the model baseline to study soil organic carbon dynamics. Climate change scenarios for 90yr were generated from the baseline climate with two Global Climate Models: GISS (Goddard Institute of Space Studies, USA), and HadCM3 (Met Office, Hadley Centre, UK), for two of the Intergovernmental Panel on Climate Change (IPCC) emission scenarios (SRES A2 and B2).Land uses at low cropping intensity were more efficient than intensive agricultural systems in terms of SOC storage in the order: hay crop>pasture>cork oak forest>semi-natural systems. Land use change to vineyards decreased the carbon balance significantly between 0.09 and 0.15tCha−1yr−1. However, former vineyards have almost recovered from soil disturbance following the establishment of the vineyards.

Effects of habitat deterioration on population dynamics and extinction risk of an endangered, long‐lived perennial herb (Scorzonera humilis)

Summary Habitat deterioration has resulted in the extinction of many local populations of plants. However, in long‐lived plants there may be a time lag between habitat deterioration and a decline in population size, although some vital rates may be immediately affected. We studied the dynamics and viability of populations of the endangered, long‐lived perennial Scorzonera humilis to different levels of agricultural intensification in five populations over a period of 4 years at the genet level and for 3 years at the rosette (ramet) level. Asymptotic growth rates varied little between years and the observed stage structure was very similar to the stable stage structure. Mortality of adult genets of S. humilis was low and their life expectancy was several decades. By contrast, turnover of ramets was high and their life expectancy was less than 4 years. Calculations based on mean transition matrices indicated that populations at nutrient‐poor sites would grow (λ > 1), whereas those at nutrient‐rich sites would continuously decline (λ < 1) if conditions stayed the same. Life‐table response experiment analysis revealed that the lower growth rate of nutrient‐rich populations was primarily due to a lower survival of large plants, but also due to lower establishment and growth of new plants. Stochastic simulations indicated that the extinction risk for medium‐sized populations at nutrient‐poor sites is very low, whereas the long‐term survival even of large extant populations at nutrient‐rich sites is unlikely unless favourable conditions for the establishment of young plants are restored. Fertilization did not influence survival, but an additional cutting early in the season significantly reduced survival of S. humilis. Stochastic simulations indicated that a combination of fertilizing and early cutting drives populations quickly to extinction and that the long‐term survival of late‐cut, NPK‐fertilized populations is also unlikely. The results suggest that in long‐lived plants, population size may not be a suitable predictor of long‐term viability of populations because of time delays in their response to habitat deterioration. A detailed demographic analysis may therefore be necessary to assess realistically the conservation status of long‐lived perennials.

The benefits of extensive agriculture to birds: the case of the little bustard

Summary The little bustard Tetrax tetrax is among many birds thought to be declining because of agricultural intensification in western Europe. In contrast with the situation elsewhere, bustard numbers have greatly increased during the last 50 years in the Crau, southern France, as agriculture has been developing. We wished to ascertain which features of agricultural development might have supported this population increase. Using data on habitat‐specific densities obtained by surveys of the Crau in 1998 and 1999, we assessed how breeding male little bustards used habitats representing various levels of agricultural intensification. We also documented historical changes in bustard numbers and agricultural trends in the Crau, comparing them with present patterns of habitat use, to determine how changes in farmed landscapes may have driven population trends. Male bustards used natural steppe and extensive agricultural habitats (fallow, grazed crops, legume crops), whereas more intensive agricultural habitats (hay‐meadows, grain crops) were little used. Mean densities on extensive agricultural habitats were always high, but densities on steppe varied with landscape composition: densities were low where steppe was dominant in the landscape, but high where steppe and extensive agriculture were mixed. Available literature showed that little bustards settled in the Crau around 1950, after 40% of the original steppe had been converted into arable land. We estimate a current population of 473–539 breeding males. Only 17% of the original steppe remains, but extensive agricultural habitats still represent 30% of arable land. Both historical data and present habitat use suggest that little bustard population trends in the Crau are driven by the development of extensive agriculture. Extensive agricultural habitats may provide little bustards with resources unavailable or scarce in natural steppe. Severe declines in little bustard numbers observed elsewhere could be reversed within a few decades by restoring extensive agricultural habitats. The potential impact of current European agricultural policies is discussed, with special reference to agri‐environmental measures and set‐aside policy. This work provides an example of an avian species that benefits from cultivated landscapes, providing that they are extensive rather than intensive. We propose a simple conceptual model to illustrate how little bustards, and possibly grassland birds in general, might respond where natural habitats are modified along orthogonal axes representing cultivation and agricultural intensification.