How Effective is Reduced Tillage–Cover Crop Management in Reducing N2O Fluxes from Arable Crop Soils?

Field management is expected to influence nitrous oxide (N₂O) production from arable cropping systems through effects on soil physics and biology. Measurements of N₂O flux were carried out on a weekly basis from April 2008 to August 2009 for a spring sown barley crop at Oak Park Research Centre, Carlow, Ireland. The soil was a free draining sandy loam typical of the majority of cereal growing land in Ireland. The aims of this study were to investigate the suitability of combining reduced tillage and a mustard cover crop (RT?CCC) to mitigate nitrous oxide emissions from arable soils and to validate the DeNitrification?CDeComposition (DNDC) model version (v. 9.2) for estimating N₂O emissions. In addition, the model was used to simulate N₂O emissions for two sets of future climate scenarios (period 2021?C2060). Field results showed that although the daily emissions were significantly higher for RT?CCC on two occasions (p?<?0.05), no significant effect (p?>?0.05) on the cumulative N₂O flux, compared with the CT treatment, was found. DNDC was validated using N₂O data collected from this study in combination with previously collected data and shown to be suitable for estimating N₂O emissions (r ²?=?0.70), water-filled pore space (WFPS) (r ²?=?0.58) and soil temperature (r ²?=?0.87) from this field. The relative deviations of the simulated to the measured N₂O values with the 140?kg N ha^?1 fertiliser application rate were ?36?% for RT?CCC and ?19?% for CT. Root mean square error values were 0.014 and 0.007?kg N₂O?CN ha^?1 day^?1, respectively, indicating a reasonable fit. Future cumulative N₂O fluxes and total denitrification were predicted to increase under the RT?CCC management for all future climate projections, whilst predictions were inconsistent under the CT. Our study suggests that the use of RT?CCC as an alternative farm management system for spring barley, if the sole objective is to reduce N₂O emissions, may not be successful.     

Spatial α-diversity patterns of diverse insect taxa in Northern China: Lessons for biodiversity conservation

Current approaches in terrestrial biodiversity conservation focus predominantly on plants and vertebrates. While these groups account for less than 4% of the estimated global species richness, it is commonly argued that especially the species richness in higher plants is a suitable indicator of overall biodiversity. We tested this assumption, investigating species richness and equitability patterns in three highly species-rich insect families and their links with the vegetation and other environmental factors. Vegetation surveys were combined with pitfall and light trapping to establish the α-diversity of ground beetles, geometrid moths and arctiid moths on 48 plots at varying altitudes between Beijing and the Inner Mongolian Plateau. Soil pH and nutrient status were also recorded. The α-diversity patterns in the three insect families were non-congruent, and links with phytodiversity were weak. The spatial α-diversity patterns in each of the three insect families were significantly correlated with the species density of individual plant families. These links varied between the three insect taxa and were mostly negative in moths. Furthermore, geometrid moth diversity decreased with increasing elevation and decreasing soil pH. Strongly diverging α-diversity patterns across different insect taxa illustrate that it is impossible to find a simple surrogate representing cross-taxon diversity for these highly diverse groups. Furthermore, phytodiversity and vegetation composition appear to play a limited role in governing insect diversity patterns. These results underline the significant risk that current plant-focused approaches in terrestrial biodiversity conservation are inadequate in addressing the conservation needs of the vast majority of species on earth.     

Opportunity costs: Who really pays for conservation?

Designing conservation areas entails costs that, if considered explicitly, can be minimized while still achieving conservation targets. Here we focus on opportunity costs which measure forgone benefits from alternative land uses. Conservation planning studies often use partial estimates of costs, but the extent to which these result in actual efficiencies has not been demonstrated. Our study partitions land costs into three distinct opportunity costs to smallholder agriculture, soybean agriculture and ranching. We demonstrate that opportunity costs to single stakeholder groups can be inaccurate measures of true opportunity costs and can inadvertently shift conservation costs to affect groups of stakeholders disproportionately. Additionally, we examine how spatial correlations between costs as well as target size affect the performance of opportunity costs to single stakeholder groups as surrogate measures of true opportunity costs. We conclude that planning with opportunity costs to single stakeholder groups can result in cost burdens to other groups that could undermine the long-term success of conservation. Thus, an understanding of the spatial distributions of opportunity costs that are disaggregated to groups of stakeholders is necessary to make informed decisions about priority conservation areas.     

Are all three components of conservation agriculture necessary for soil conservation in the Sudan Savanna?

ABSTRACT

Conservation agriculture (CA) as recommended by the Food and Agriculture Organization of the United Nations consists of three components: minimum soil disturbance, soil cover, and crop rotation/association. CA was expected to become an effective countermeasure against water erosion in the Sudan Savanna, but it has not been adopted by local smallholder farmers. As markets for grain legumes (including cowpea) have not been developed in the Sudan Savanna, crop rotation/association should be considered impractical for these farmers. Therefore, we examined whether legume intercropping as a crop rotation/association component is necessary for preventing soil erosion in the Sudan Savanna. Three-year field experiments were conducted in runoff plots at Institute of Environment and Agricultural Research Saria station. The four treatments were conventional practice (full tillage, no sorghum residue mulching, and no intercropping), two-component CA (minimum tillage (MT) and sorghum residue mulching without intercropping), and three-component CA with velvet bean (VB) or pigeon pea (PP) intercropping. It was revealed that: (1) MT and sorghum residue mulching (without intercropping) effectively reduced the annual soil loss by 54% mainly due to the improvement of soil permeability by the boring of termites and wolf spiders found under the sorghum stover mulch; (2) intercropping in combination with MT and crop residue mulching had no effect on soil erosion control mainly because: (a) PP did not survive the long dry season; (b) VB did not serve effectively as a cover crop since soil loss was concentrated at the beginning of the rainy season when VB was still too small; (c) unexpectedly, in combination with MT and crop residue mulching, intercropping with VB did not increase mulch biomass, especially sorghum biomass which prompts the boring of termites and wolf spiders. These results demonstrate that the third component of CA, namely legume intercropping, is not always necessary; rather, the two remaining components – minimum soil disturbance and soil cover – are sufficient for soil conservation in the Sudan Savanna. This finding lightens the burden of adopting CA and thus facilitates its future promotion to the smallholder farmers in the Sudan Savanna.     

Do railway edges provide functional connectivity for plant communities in an urban context?

Functional connectivity is essential to maintaining biodiversity in fragmented landscapes but little attention has been given to structures that can provide it in an urban context. Using both the taxonomic and functional diversity of semi-natural grassland plant communities, we assessed the functional connectivity of linear transportation infrastructures in urban landscape. We sampled the vegetation at 71 study sites located along the edges of two railway lines. We hypothesised that if railways favour functional connectivity, then spatially connected communities should be more similar than disconnected communities. Therefore, we compared floristic dissimilarities between site pairs that were either connected or separated by a railway spatial break (overpass or station). As a further approach, we supposed that functional connectivity may attenuate the effect of urbanisation filters on plant communities. Thus we examined whether and how edges’ plant communities were influenced by urbanisation and compared our results to the patterns described in the literature. Functional connectivity was mainly maintained at railway stations, contrary to overpasses, which seemed to interrupt dispersal, demonstrating that railway edges provide connectivity for some but not all functional groups: this was only true for moderately mobile species. Surprisingly, railway edges did not seem to play an additional connective function for invasive species, the presence of which being strongly related to the urbanisation intensity and not influenced by spatial breaks along railways. Our study thus highlights the potential function of railway edges as corridors for common grassland plants. Landscape managers should include railways in green networks to improve connectivity in urban landscapes.     

Crop Response to Long‐Term Potassium Application as Affected by Potassium‐Supplying Power of the Selected Soils in Northern China

Potash resources in China are very scarce. It is especially important to correctly evaluate the potential potassium‐supplying power of soils in northern China in order to use soil potassium sufficiently and potash fertilizer properly. Regional differences in crop yield responses to long‐term potassium application in northern China were determined in this study. Twenty‐five representative soil samples from 13 provinces, municipalities, and autonomous regions of major agricultural regions in northern China were collected from the surface layer (0–20 cm) before crop seeding in 1993. A soil potassium‐depletion study was carried out in a pot experiment with successive planting of corn seedlings for 10 harvests in the 25 soils. Since 1993, field trials on wheat and corn response to long‐term potassium application were conducted at the fixed sites of HLJ‐SC (Shuangcheng of Heilongjiang), JL‐LFZ (Liufangzi of Jilin), HB‐XJ (Xinji of Hebei), SX‐LF (Linfen of Shanxi), QH‐NKY (Nongkeyuan of Qinghai), and XJ‐CJ (Changji of Xinjiang). Soil‐available potassium, slowly available potassium, total potassium, main clay minerals, cation exchange capacity, particle size, other available nutrients, and potassium concentration in plants were measured. The results showed that potential potassium‐supplying powers of the 25 tested soils, which were respectively evaluated by the contents of slowly available potassium in soils and the amount of total net potassium uptake in the pot experiment, generally tended to increase from eastern to western regions in northern China. Significant wheat yield responses to long‐term potassium application in the field trials were found since 2000 in the north‐central region but not observed until 2004 in the northwestern region. Significant corn yield responses to long‐term potassium application in the field trials were found starting in soils of the northeastern region, following in soils of the north‐central region, and then in soils of the northwestern region. These were consistent with potential potassium‐supplying power of the soils, which tended to increase from east to west regions.     

Will climate change reduce the efficacy of protected areas for amphibian conservation in Italy?

Amphibians are an important and imperiled component of biodiversity. In this study we analyze the efficacy of Italian reserve network for protecting multiple amphibian species in a climate change scenario, considering both nationally designated areas and Natura 2000 sites. Our approach is based on ensemble niche modeling estimate of potential range shift under two carbon emission scenarios (A1FI and B1) and two dispersal assumptions. The predicted distributions were used to perform gap and irreplaceability analyses. Our findings show that the current Italian reserve network incompletely represents current amphibian diversity and its geographic pattern. The combination of the nationally designated protected areas and the Natura 2000 sites improves current representation of amphibians, but conservation targets based on geographic range extent are achieved for only 40% of species. Under the future scenarios, Natura 2000 sites become a crucial component of the protected areas system. Nonetheless, we predict that climate change decreases for many species the amount of suitable range falling into reserves, regardless of our assumptions about dispersal. We identify some currently unprotected areas that have high irreplaceability scores for species conservation and that maintain their importance under all the future scenarios we considered. We recommend designation of new reserves in these areas to help guarantee long-term amphibian conservation.     

Frugal conservation: What does it take to detect changes in fish populations?

Many conservation projects have to develop practical and feasible ways to detect changes in populations. We compare the ecological information obtained using intensive monitoring of coral-reef fish populations with that which would be procured from less exhaustive sampling. At each of four sites in the Philippines, we surveyed all non-cryptic fish species in eight transects every month for up to 3 years. We first tested for changes across years and seasons in fish density, size and species richness. We then compared these results obtained by using all data to those obtained in simulated protocols that restricted effort in ways that were relevant in practical marine resource management. We demonstrate the potential for reducing time in the water (number of surveys or number of transects) or in the number of species surveyed (proportions of those that were easily identified or locally fished) with little loss of information. Bimonthly surveys detected most of the overall but few of the seasonal trends that were identified with monthly sampling; far fewer trends were detected with less frequent surveying. Similarly, most trends were detected when at least four transects were carried out monthly. Most trends were also detected when all possible easily-identified species or at least 75% of fished species were considered. Indeed, ability to detect overall trends remained high even when only fished species were considered in four transects monthly. We conclude that some selective sampling protocols can be sufficiently sensitive to detect important trends, and that the choice of protocol will depend on the objective of the research or management.     

Fencing for conservation: Restriction of evolutionary potential or a riposte to threatening processes?

Fencing for conservation is an acknowledgement that we are failing to successfully coexist with and, ultimately, conserve biodiversity. Fences arose during the Neolithic revolution to demarcate resource-rich areas (food sources) and exclude threats (intruders). Fencing for conservation can be viewed as fulfilling a similar function. The aims of this paper were to identify when fencing can and is used to conserve biodiversity; highlight the costs and benefits of fencing for conservation; and make recommendations to ensure appropriate use of fencing for conservation in the future. The IUCN identifies ten major threatening processes and the impacts of eight of these can be mitigated via the use of fencing, however avoiding human-animal conflict and reducing the impact of introduced predators are the two most common uses. Fences implemented to achieve a conservation benefit are not necessarily physical barriers, but can also include ‘metaphorical’ fences of sound, smoke and smell, or even actual islands. Fences provide defined units for managers and separate biodiversity from threatening processes including human persecution, invasive species and disease. Conversely, they are costly to build and maintain; they have ecological costs through blocking migration routes, restriction of biodiversity range use which may result in overabundance, inbreeding and isolation; restriction of evolutionary potential; management; amenity and ethical costs. Despite these problems, fencing for conservation is likely to become increasingly utilized as biodiversity becomes increasingly threatened and methods of ameliorating threats lag behind. In the long-term, fences may ultimately prove to be as much a threat to biodiversity as the threats they are meant to exclude, and a new research agenda should arise to ensure that conservation fences do not remain a permanent part of the landscape.     

Economic valuation and conservation: Do people vote for better preservation of Shadegan International Wetland?

Shadegan International Wetland (SIW) is a unique natural ecosystem with great national and international significance, designated under Ramsar Convention. Located in southern part of Iran, this wetland serves many functions. Among them the rich biodiversity, ecological, hydrological, and economic functions are the most important. Despite the great opportunities for sustainable development of this wetland, it is currently under serious threats from a diverse range of non-sustainable activities. Underestimating SIW’s non-market values in development decisions is a major reason for the conversion and excessive depletion of its resources. The aim of this study was therefore to estimate the economic benefit of SIW as a very useful instrument to reflect the values of this unique ecosystem to society members. A choice experiment (CE) survey was undertaken to estimate the value of different nonmarket attributes of SIW. In addition to the overall model, users and nonusers preferences were also estimated. Random parameter logit (RPL) model was employed to derive the marginal value of the respondents for different attributes of the nonmarket values of SIW. Results indicated the respondents’ positive preferences towards better conservation of SIW.     

Mechanical soil conservation with contour ridges: Cure for,or cause of,rill erosion?

Based on the results of an erosion damage assessment in Southern Zimbabwe, where mechanical conservation work has been carried out since the 1940s, this paper describes the impact of mechanical conservation systems on processes leading to rill erosion. In a study of a catchment area, it was found that influxes of water from roads and waterways as well as contour ridges that were originally designed to control rill erosion had a major role in the formation of rills. Existing rills and depressions which cause water concentration, siltation of contour drains and overflowing of contour ridges were the main factors leading to excessive rill erosion. The study showed that particularly during a highly erosive year like 1992/93, the damage due to rill erosion can be excessive, causing an abrupt degradation. It is concluded that the present conservation system is insufficient to control rill erosion effectively and is often the cause of this erosion. Effective control of rill erosion is a pre-condition for optimal implementation of land management systems such as conservation tillage. Therefore, an integrated approach to land husbandry must be developed jointly with farmers and promoted in order to improve crop production and sustainable management of natural resources. This should consider improved mechanical conservation as well as agronomic and biological soil and water conservation techniques.     

Selenium in agriculture: a nutrient or contaminant for crops?

Selenium (Se) is an essential nutrient for animals, humans, and microorganisms, but its role in the plants needs further exploration. It is considered beneficial at low levels, but is toxic at higher levels, and there is a fine boundary between these concentrations. Generally, Se levels less than 1 mg kg^?1 have been found to be beneficial for the plants while higher levels cause toxicity in most of the agricultural crops. At low concentrations, Se can act as a plant growth regulator, antioxidant, anti-senescent, abiotic stress modulator, and defensive molecule against pathogens in plants. At higher concentrations, plants show various toxic symptoms, which include stunting of growth, chlorosis, withering, and drying of leaves, decreased protein synthesis premature and even death of the plant. The roles of selenium as enhancer and inhibitor of plant growth in various agricultural crops are discussed here with recent updates. Biofortification of some crops with Se using agronomic and genetic approaches is being explored to cultivate them in the regions having Se-deficiency in foods. Strategies of phytoremediation of Se in hyperaccumulators and transgenic plants overexpressing enzyme/proteins to increase Se tolerance are also described.     

How does grazing intensity affect different vegetation types in arid Succulent Karoo, South Africa? Implications for conservation management

The Knersvlakte in the Succulent Karoo Biome (South Africa) is known for its high plant diversity and endemism. In the course of establishing a conservation area there, we assessed baseline data for future management. We investigated the effects of grazing on the vegetation in terms of species diversity and composition as well as reproduction of selected species. Data were sampled on four adjacent farms, which were ungrazed, moderately or intensively grazed by sheep and goats. The data were collected in 27 quartz and 24 non-quartz plots, representing two major habitat types of the region. Within each of the 1000-m² plots, 100 subplots of 400 cm² size were sampled. ANOVAs revealed that species richness and abundance of endemic species on quartz fields decreased with grazing. Abundance of annuals did not increase significantly due to grazing. Fidelity analyses indicated that species composition differed between grazing intensities and that the ungrazed and moderately grazed plots both contained unique locally endemic habitat specialists. Reproduction of two endemic dwarf shrubs Drosanthemumschoenlandianum and Argyrodermafissum (both Aizoaceae) increased under moderate grazing, which in the case of D.schoenlandianum was interpreted as an effect of grazing. We attribute the low number of seedlings and annuals on the moderately grazed farm to lower seasonal rainfall on these plots. From a conservation perspective, no or moderate grazing appear to be necessary to preserve plant diversity and vegetation patterns, and their underlying processes.     

The Cuban homegarden ‘conuco’: a perspective environment for evolution and in situ conservation of plant genetic resources

Summary Cuban homegardens are called conucos. On the basis of new case studies additional information is provided about these conucos, their history, composition and importance. They and other gardens of similar type are characterized as suitable environment for in situ conservation and for the continuation of evolutionary processes.     

Different cultures,different values: The role of cultural variation in public’s WTP for marine species conservation

Understanding the cultural variation in public preference for marine species is a necessary pre-requisite if conservation objectives are to include societal preferences in addition to scientific considerations. We report the results of a contingent study undertaken at three case-study sites: Azores islands (Portugal), Gulf of Gdansk (Poland) and Isles of Scilly (UK). The study considered species richness of five specific marine taxa (mammals, birds, fish, invertebrates and algae) as proxies of marine biodiversity and the aim of analysis was to estimate from a multi-site perspective public’s willingness to pay (WTP) to avoid increased levels of species loss (reduction of species richness) for different marine taxa. Results, based on 1502 face-to-face interviews, showed that income, education and environmental awareness of the respondents were significant predictors of WTP for marine species conservation. Results also indicated that respondents in each of the European locations had different preferences for marine taxa. In the Azores, although mammals and fish were valued highly, small differences occurred in the WTP among different taxa. Respondents in the Isles of Scilly put a relatively low value on fish while algae and marine mammals were highly valued. In Gdansk, respondents defined a clear order of preference for marine mammals > fish > birds > invertebrates and algae. These findings suggested that cultural differences may be important drivers of valuation and undermines the commonly held premise that charismatic/likeable taxa consistently have a disproportionately strong influence on WTP for biodiversity conservation. We conclude that conservation policy must take account of cultural diversity alongside biological diversity.     

How pristine are tropical forests? An ecological perspective on the pre-Columbian human footprint in Amazonia and implications for contemporary conservation

Archeologists, paleoecologists and anthropologists argue that ecologists need to give greater consideration to the pre-historical influence of humans in shaping the current structure and composition of tropical forests. We examine these arguments within the context of Amazonia, and assess the extent to which (i) the concepts of “pristine forests” and “cultural parklands” are mutually exclusive, (ii) the aggregated distribution of some plants necessarily indicates enrichment planting, (iii) pre-Columbian human disturbance has increased forest biodiversity, (iv) pre-Columbian indigenous practices were always sustainable, and (v) if indeed, the ecological impacts of pre-Columbian peoples are relevant for modern biodiversity conservation. Overall, we reject the notion that “the pristine myth has been thoroughly debunked” by archeological evidence, and suggest that the environmental impacts of historical peoples occurred along gradients, with high-impacts in settlements and patches of Amazonian Dark Earth (ADE), lesser impacts where occasional enrichment planting took place in forests surrounding agricultural plots, and a very low influence (in terms of light hunting pressure and other types of resource extraction) across vast areas of Amazonia that may always have been far from permanent settlements and navigable rivers. We suggest that the spatial distribution of pre-Columbian finds is given more attention, and urge caution before case studies are extrapolated to the entire Basin. Above all, we feel that debates over “naturalness” and environmental impacts of pre-Columbian humans are of limited relevance to present and future biodiversity conservation, and can detract from the major challenges facing Amazonia and other tropical forest regions today.     

Soil Biological Fertility: Foundation for the Next Revolution in Agriculture?

Feeding the world’s population in 40 years will require improved efficiency in the use of plant nutrients and enhancement of soil resources. Over the past 60 years, agricultural production has rapidly increased; however, continued degradation of soil may limit further increases. Improving the soil through enhanced soil biological activity has been proposed as a method of increasing the capacity of the soil to produce crops. Ongoing evaluations of one soil biological fertilizer with a patented process to convert and complex manure into stable finished products (AgroBiotic fertilizers) have been conducted in research plots and producer fields and have shown positive effects on grain yield and potato production. These effects are larger in soils with limited biological activity, suggesting that adding this unique AgroBiotic fertilizer helps restore the biological nutrient cycling in the soil. New developments and innovations that improve nutrient availability and the efficacy of soil biological fertilizers have the potential to help restore degraded soils and improve their production efficiency and capacity to feed the world’s population.     

The Brazilian Atlantic Forest: How much is left, and how is the remaining forest distributed? Implications for conservation

The neotropical Atlantic Forest supports one of the highest degrees of species richness and rates of endemism on the planet, but has also undergone a huge forest loss. However, there exists no broad-scale information about the spatial distribution of its remnants that could guide conservation actions, especially when systematic biodiversity data are not available. In this context, our objectives were to quantify how much of the forest still remains, and analyze its spatial distribution. We considered the entire Brazilian Atlantic Forest, and eight sub-regions, defined according to species distribution. The results revealed a serious situation: more than 80% of the fragments are <50 ha, almost half the remaining forest is <100 m from its edges, the average distance between fragments is large (1440 m), and nature reserves protect only 9% of the remaining forest and 1% of the original forest. On the other hand, our estimates of existing Atlantic Forest cover were higher than previous ones (7-8%), ranging from 11.4% to 16%. The differences among estimates are mainly related to our inclusion of intermediate secondary forests and small fragments (<100 ha), which correspond to approximately 32-40% of what remains. We suggest some guidelines for conservation: (i) large mature forest fragments should be a conservation priority; (ii) smaller fragments can be managed in order to maintain functionally linked mosaics; (iii) the matrix surrounding fragments should be managed so as to minimize edge effects and improve connectivity; and (iv) restoration actions should be taken, particularly in certain key areas. The clear differences in the amount remaining and its spatial distribution within each sub-region must be considered when planning for biodiversity conservation.