The increasing demands of food and biofuel have promoted cropland expansion and nitrogen (N) fertilizer enrichment in the United States over the past century. However, the role of such long-term ...human activities in influencing the spatiotemporal patterns of ammonia (NH.sub.3) emission remains poorly understood. Based on an empirical model and time-series gridded datasets including temperature, soil properties, N fertilizer management, and cropland distribution history, we have quantified monthly fertilizer-induced NH.sub.3 emission across the contiguous US from 1900 to 2015. Our results show that N-fertilizer-induced NH.sub.3 emission in the US has increased from <50 Gg N yr.sup.-1 before the 1960s to 641 Gg N yr.sup.-1 in 2015, for which corn and spring wheat are the dominant contributors. Meanwhile, urea-based fertilizers gradually grew to the largest NH.sub.3 emitter and accounted for 78 % of the total increase during 1960-2015. The factorial contribution analysis indicates that the rising N fertilizer use rate dominated the NH.sub.3 emission increase since 1960, whereas the impacts of temperature, cropland distribution and rotation, and N fertilizer type varied among regions and over periods. Geospatial analysis reveals that the hot spots of NH.sub.3 emissions have shifted from the central US to the Northern Great Plains from 1960 to 2015. The increasing NH.sub.3 emissions in the Northern Great Plains have been found to closely correlate to the elevated NH4+ deposition in this region over the last 3 decades. This study shows that April, May, and June account for the majority of NH.sub.3 emission in a year. Interestingly, the peak emission month has shifted from May to April since the 1960s. Our results imply that the northwestward corn and spring wheat expansion and growing urea-based fertilizer uses have dramatically altered the spatial pattern and temporal dynamics of NH.sub.3 emission, impacting air pollution and public health in the US.
Agricultural land abandonment is a common land-use change, making the accurate mapping of both location and timing when agricultural land abandonment occurred important to understand its ...environmental and social outcomes. However, it is challenging to distinguish agricultural abandonment from transitional classes such as fallow land at high spatial resolutions due to the complexity of change process. To date, no robust approach exists to detect when agricultural land abandonment occurred based on 30-m Landsat images. Our goal here was to develop a new approach to detect the extent and the exact timing of agricultural land abandonment using spatial and temporal segments derived from Landsat time series. We tested our approach for one Landsat footprint in the Caucasus, covering parts of Russia and Georgia, where agricultural land abandonment is widespread. First, we generated agricultural land image objects from multi-date Landsat imagery using a multi-resolution segmentation approach. Second, we estimated the probability for each object that agricultural land was used each year based on Landsat temporal-spectral metrics and a random forest model. Third, we applied temporal segmentation of the resulting agricultural land probability time series to identify change classes and detect when abandonment occurred. We found that our approach was able to accurately separate agricultural abandonment from active agricultural lands, fallow land, and re-cultivation. Our spatial and temporal segmentation approach captured the changes at the object level well (overall mapping accuracy = 97 ± 1%), and performed substantially better than pixel-level change detection (overall accuracy = 82 ± 3%). We found strong spatial and temporal variations in agricultural land abandonment rates in our study area, likely a consequence of regional wars after the collapse of the Soviet Union. In summary, the combination of spatial and temporal segmentation approaches of time-series is a robust method to track agricultural land abandonment and may be relevant for other land-use changes as well.
•We mapped agricultural land abandonment using dense Landsat time series.•The combined spatial and temporal segmentation captures the timing of abandonment well.•We found strong spatial and temporal variation in land abandonment in the Caucasus.•Our mapping approach is applicable to other regions and land cover classes too.
Species interaction networks, which play an important role in determining pathogen transmission and spread in ecological communities, can shift in response to agricultural landscape simplification. ...However, we know surprisingly little about how landscape simplification‐driven changes in network structure impact epidemiological patterns. Here, we combine mathematical modelling and data from eleven bipartite plant‐pollinator networks observed along a landscape simplification gradient to elucidate how changes in network structure shape disease dynamics. Our empirical data show that landscape simplification reduces pathogen prevalence in bee communities via increased diet breadth of the dominant species. Furthermore, our empirical data and theoretical model indicate that increased connectance reduces the likelihood of a disease outbreak and decreases variance in prevalence among bee species in the community, resulting in a dilution effect. Because infectious diseases are implicated in pollinator declines worldwide, a better understanding of how land use change impacts species interactions is therefore critical for conserving pollinator health.
We combined mathematical modeling and data from eleven plant‐pollinator networks observed along a landscape simplification gradient to elucidate how changes in network structure shape disease dynamics. Our empirical data show that landscape simplification reduces pathogen prevalence in bee communities via increased diet breadth of the dominant species. Furthermore, our empirical data and theoretical model indicate that increased connectance reduces the likelihood of a disease outbreak and decreases variance in prevalence among bee species in the community, resulting in a dilution effect.
Approach/Methodology/Design: The publication uses data from the Registers of Prices and Values of Real Estate maintained by individual county offices. Additionally, the number of transactions as well ...as the unit price of agricultural land were obtained from reports of the Agricultural Property Agency as well as the National Agricultural Support Centre.
The common ragweed (Ambrosia artemisiifolia Linnaeus 1800) is an exceptionally invasive species. The information on true bugs occurring on ragweed plants is limited in the invasion region. The ...objective of this study was to determine the species composition of Heteroptera associated with A. artemisiifolia, to assess their vectoring potential based on a literature review, and to compare species similarity in the surveyed fields. Field surveys were conducted in 2020–2021 at 10 sites in southern Slovakia. Sweeping and visual observations were conducted in field margins, weedy agricultural fields, and mowed meadows infested with A. artemisiifolia. In the study, food specialization, the abundance of individual species, and their assignment to families were precisely determined. The Jaccard similarity index was used to evaluate similarities in species composition among the sites studied. A total of 2496 true bugs were recorded, representing 47 species of Heteroptera from 12 families. The most common phytophagous species were Nysius ericae ericae (Schilling, 1829) (Pentatomomorpha, Lygaeidae), Adelphocoris lineolatus (Goeze, 1778), Lygus rugulipennis (Poppius, 1911), Lygus pratensis (Linnaeus, 1758) (Cimicomorpha, Miridae), and a zoophagous species Nabis (Dolichonabis) limbatus (Dahlbom, 1851) (Cimicomorpha, Nabidae). The species similarities in pair-wise combined localities were low, with a dominance of highly migratory and polyphagous species able to traverse the field from the adjacent landscape. A. artemisiifolia is a known host for plant viruses and phytoplasmas, and several Heteroptera species are carriers of these plant pathogens. Halyomorpha halys was the only detected vector of phytoplasmas, and its abundance on A. artemisiifolia was extremely low.
One of the most common annual overwintering weeds in various crops worldwide is silky bent grass (Aspera spica-venti (L.) Beauv). The aim of this study was to investigate the selected morphological ...characteristics and chemical composition of A. spica-venti from different cultivation fields in Poland, depending on the macronutrient content of the soil. The average pH values of the soil samples, and the average concentration of nitrogen (N) and phosphorus (P) in the samples were statistically different between study sites. In turn, the concentration of potassium (K) was at the same statistical level. The average values of N, P and K concentrations in the straw of A. spica-venti (% dry matter) in particular study sites were not statistically different. The mean values of the examined morphological features of A. spica-venti did not differ statistically between the individual test sites. Overall, there was no significant impact of the habitat on the chemical composition and morphology of the A. spica-venti occurring naturally in arable fields. However, an increase in soil abundance in some macronutrients (mainly K) may positively affect the morphology of this weed as opposed to an increase in nitrogen concentration in the soil, and an increase soil pH. The lack of significant influence of soil conditions and location of APESV sites on the morphology and chemical composition of the weed indicates that it has high plasticity and is able to thrive under varying habitat conditions.
Abstract
Soil phosphorus (P) loss from agricultural systems will limit food and feed production in the future. Here, we combine spatially distributed global soil erosion estimates (only considering ...sheet and rill erosion by water) with spatially distributed global P content for cropland soils to assess global soil P loss. The world’s soils are currently being depleted in P in spite of high chemical fertilizer input. Africa (not being able to afford the high costs of chemical fertilizer) as well as South America (due to non-efficient organic P management) and Eastern Europe (for a combination of the two previous reasons) have the highest P depletion rates. In a future world, with an assumed absolute shortage of mineral P fertilizer, agricultural soils worldwide will be depleted by between 4–19 kg ha
−1
yr
−1
, with average losses of P due to erosion by water contributing over 50% of total P losses.
Portugal's farmland bird crisis requires action Silva, João P; Gameiro, João; Valerio, Francesco ...
Science (American Association for the Advancement of Science),
01/2024, Volume:
383, Issue:
6679
Journal Article
PDF
