| 1. |
- Ajal, James, et al.
(författare)
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Functional trait space in cereals and legumes grown in pure and mixed cultures is influenced more by cultivar identity than crop mixing
- 2021
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Ingår i: Perspectives in Plant Ecology, Evolution and Systematics. - : Elsevier BV. - 1433-8319 .- 1618-0437. ; 50
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Tidskriftsartikel (refereegranskat)abstract
- More efficient resource use, especially nitrogen (N) in agricultural fields could considerably reduce the losses and spillover effects on the environment. Cereal-legume mixtures can lead to more efficient uptake of growth-limiting resources, and increase and stabilize yields, due to the variation in functional traits that facilitate partitioning of niche space. Here we identify crop mixtures with functional traits that facilitate optimal N resource use in two selected cereal-legume mixtures by using the multi-dimensional trait space concept. Combinations of pea-barley and faba bean-wheat crops were grown in the field as pure cultures and mixtures in Central Sweden, during two years with contrasting weather. The ecological niche space was defined via the n-dimensional hypervolumes represented by N pool, tiller/branch number, shoot biomass, and grain yield functional traits. Regressions and correlations allowed quantifying the relations between functional traits and plant N pools. Differences in trait space were not a result of crop mixing per se, as similar hypervolumes were found in the pure culture and mixture-grown crops. Instead, the trait space differences depended on the cultivar identities admixed. Furthermore, cereals increased their efficiency for N uptake and therefore benefitted more than the legumes in the mixtures, in terms of accumulated N and grain yields. Tiller and shoot biomass production in cereals was positively correlated to N pool accumulation during the season. Resource acquisition through increased N uptake in the mixture was associated with a reduced overlap in niche-space in the mixtures, and initial seed N pools significantly contributed to within-season N accumulation, shoot and tiller production.
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| 2. |
- Bassiouni, Maoya, et al.
(författare)
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Optimal plant water use strategies explain soil moisture variability
- 2023
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Ingår i: Advances in Water Resources. - : Elsevier BV. - 0309-1708 .- 1872-9657. ; 173
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Tidskriftsartikel (refereegranskat)abstract
- Plant responses to water stress influence water and carbon cycles and can lead to feedbacks on climate yet characterizing these responses at ecosystem levels remains uncertain. Quantifying ecosystem-level water use strategies is complex due to challenges of upscaling plant traits and disentangling confounding environmental factors, ultimately limiting our ability to understand and anticipate global change in ecosystem dynamics and ecohydrological fluxes. We reduce the dimensionality of this problem and quantify plant water use strategies by combining plant traits with soil and climate variables into parameter groups that synthesize key eco-physiological tradeoffs. Using a parsimonious soil water balance framework, we explore variations in plant water uptake capacity, water stress responses, and water use performance via these non-dimensional parameter groups. The group characterizing the synchronization of plant water transport and atmospheric water demand emerges as the primary axis of variation in water use strategies and interacts with the group representing plant hydraulic risk tolerance, especially in arid conditions when plant water transport is limiting. Next, we show that specific plant water use strategies maximize plant water uptake (leading to carbon gain benefits) weighted by risks of water stress (leading to higher costs of water use). A model-data comparison demonstrates that these ecohydrologically optimal parameter groups capture observed soil moisture variability in 40 ecosystems and beyond aridity, rainfall frequency is an important environmental control for plant water use strategies. The emerging parsimonious link between ecohydrological performance and non-dimensional parameters provides a tractable representation of plant water use strategies, relevant to parameterize global models while accounting for ecological and evolutionary constraints on the water cycle.
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| 3. |
- Bassiouni, Maoya, et al.
(författare)
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Parsimony vs predictive and functional performance of three stomatal optimization principles in a big-leaf framework
- 2021
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 231, s. 586–600-
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Tidskriftsartikel (refereegranskat)abstract
- Stomatal optimization models can improve estimates of water and carbon fluxes with relatively low complexity, yet there is no consensus on which formulations are most appropriate for ecosystem-scale applications. We implemented three existing analytical equations for stomatal conductance, based on different water penalty functions, in a big-leaf comparison framework, and determined which optimization principles were most consistent with flux tower observations from different biomes.We used information theory to dissect controls of soil water supply and atmospheric demand on evapotranspiration in wet to dry conditions and to quantify missing or inadequate information in model variants. We ranked stomatal optimization principles based on parameter uncertainty, parsimony, predictive accuracy, and functional accuracy of the interactions between soil moisture, vapor pressure deficit, and evapotranspiration.Performance was high for all model variants. Water penalty functions with explicit representation of plant hydraulics did not substantially improve predictive or functional accuracy of ecosystem-scale evapotranspiration estimates, and parameterizations were more uncertain, despite having physiological underpinnings at the plant level.Stomatal optimization based on water use efficiency thus provided more information about ecosystem-scale evapotranspiration compared to those based on xylem vulnerability and proved more useful in improving ecosystem-scale models with less complexity.
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| 4. |
- Berghuijs, Herman, et al.
(författare)
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Calibrating and testing APSIM for wheat-faba bean pure cultures and intercrops across Europe
- 2021
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Ingår i: Field Crops Research. - : Elsevier BV. - 0378-4290 .- 1872-6852. ; 264
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Tidskriftsartikel (refereegranskat)abstract
- Cereal-legume intercropping can increase yields, reduce fertilizer input and improve soil quality compared with pure culture. Designing intercropping systems requires the integration of plant species trait selection with choice of crop configuration and management. Crop growth models can facilitate the understanding and prediction of the interactions between plant traits, crop configuration and management. However, currently no existing crop growth model has been calibrated and tested for cereal-legume intercrops throughout Europea. We calibrated the Agricultural Production Systems sIMulator (APSIM) for pure cultures of wheat and faba bean using data from Dutch field trials, and determined the phenological parameters to simulate pure cultures and intercrops from seven field experiments across Europe. APSIM successfully reproduced aboveground dry matters and, for wheat only, grain yields in pure cultures. In intercrops, APSIM systematically overestimated the aboveground dry matter and grain yield of faba bean and underestimated those of wheat. APSIM was reasonably capable of simulating plant heights in pure cultures, but respectively overestimated and underestimated the height of faba bean and wheat in intercrops. In order to simulate wheat-faba bean intercrops better, APSIM should be improved regarding the calculation of biomass partitioning to grains in faba bean and of height growth in both species.
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| 5. |
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| 6. |
- Berghuijs, Herman, et al.
(författare)
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Identification of species traits enhancing yield in wheat-faba bean intercropping: development and sensitivity analysis of a minimalist mixture model
- 2020
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Ingår i: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 455, s. 203-226
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Tidskriftsartikel (refereegranskat)abstract
- Aim Cereal-legume intercropping can result in yield gains compared to monocrops. We aim to identify the combination of crop traits and management practices that confer a yield advantage in strip intercropping. Methods We developed a novel, parameter-sparse process-based crop growth model (Minimalist Mixture Model, M-3) that can simulate strip intercrops under well-watered but nitrogen limited growth conditions. It was calibrated and validated for spring wheat (Triticum aestivum) and spring faba bean (Vicia faba) grown as monocrops and intercrops, and used to identify the most suitable trait combinations in these intercrops via sensitivity analyses. Results The land equivalent ratio of intercrops was greater than one over a wide range of nitrogen fertilizer levels, but transgressive overyielding, with total yield in the intercrop greater than that of either sole crop, was only obtained at intermediate nitrogen applications. We ranked the local sensitivities of the individual yields of wheat and faba bean of the whole intercrop under various nitrogen input levels to various crop traits. Conclusions The total intercrop yield can be improved by selecting specific traits related to phenology of both species, as well as light use efficiency of faba bean and, under high nitrogen applications, of wheat. Changes in height-related crop traits affected individual yields of species in intercrops but not the total intercrop yield.
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| 7. |
- Bommarco, Riccardo, et al.
(författare)
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Exploiting ecosystem services in agriculture for increased food security
- 2018
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Ingår i: Global Food Security. - : Elsevier BV. - 2211-9124. ; 17, s. 57-63
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Forskningsöversikt (refereegranskat)abstract
- Despite contributing to economy and food security, Ecosystem Services (ES) are still not fully exploited in agriculture. Instead, external inputs have been used to boost yields, while exacting costs on public goods. Ecological intensification capitalizes on ecosystem services to enhance and stabilize production and reduce the need for external inputs, while sparing the environment. Of particular relevance are biodiversity-based ES connected to soil fertility, pest control and pollination. Ecological intensification is applicable in all regions, but for food security purposes, particular attention should be dedicated to implement it as ecological enhancement in regions with wide yield gaps, coinciding with poor food security. Diversified cropping system show promise to create win-win situations. Knowledge on ecology and socio-economy of ES will be needed, and agricultural research and innovation need to heed to resource use efficiency, production stability, minimal environmental impact, buffering of extreme events and adaptation to local conditions.
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| 8. |
- Breinl, Korbinian, et al.
(författare)
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Can weather generation capture precipitation patterns across different climates, spatial scales and under data scarcity?
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Stochastic weather generators can generate very long time series of weather patterns, which are indispensable in earth sciences, ecology and climate research. Yet, both their potential and limitations remain largely unclear because past research has typically focused on eclectic case studies at small spatial scales in temperate climates. In addition, stochastic multi-site algorithms are usually not publicly available, making the reproducibility of results difficult. To overcome these limitations, we investigated the performance of the reduced-complexity multi-site precipitation generator TripleM across three different climatic regions in the United States. By resampling observations, we investigated for the first time the performance of a multi-site precipitation generator as a function of the extent of the gauge network and the network density. The definition of the role of the network density provides new insights into the applicability in data-poor contexts. The performance was assessed using nine different statistical metrics with main focus on the inter-annual variability of precipitation and the lengths of dry and wet spells. Among our study regions, our results indicate a more accurate performance in wet temperate climates compared to drier climates. Performance deficits are more marked at larger spatial scales due to the increasing heterogeneity of climatic conditions.
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| 9. |
- Breinl, Korbinian, et al.
(författare)
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Extreme dry and wet spells face changes in their duration and timing
- 2020
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Ingår i: Environmental Research Letters. - : IOP Publishing. - 1748-9326. ; 15:7
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Tidskriftsartikel (refereegranskat)abstract
- Dry spells are sequences of days without precipitation. They can have negative implications for societies, including water security and agriculture. For example, changes in their duration and within-year timing can pose a threat to food production and wildfire risk. Conversely, wet spells are sequences of days with precipitation above a certain threshold, and changes in their duration and within-year timing can impact agriculture, flooding or the prevalence of water-related vector-borne diseases. Here we assess changes in the duration and within-year timing of extreme dry and wet spells over 60 years (1958-2017) using a consistent global land surface precipitation dataset of 5093 rain gauge locations. The dataset allowed for detailed spatial analyses of the United States, Europe and Australia. While many locations exhibit statistically significant changes in the duration of extreme dry and wet spells, the changes in the within-year timing are less often significant. Our results show consistencies with observations and projections from state-of-the-art climate and water resources research. In addition, we provide new insights regarding trends in the timing of extreme dry and wet spells, an aspect being equally important for possible future implications of extremes in a changing climate, which has not yet received the same level of attention and is characterized by larger uncertainty.
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| 10. |
- Daouti, Eirini Lamprini, et al.
(författare)
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Seed predation is key to preventing population growth of the weed Alopecurus myosuroides
- 2022
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 59, s. 471-482
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Tidskriftsartikel (refereegranskat)abstract
- Seed predation can reduce the abundance and spread of unwanted vegetation in agricultural and other semi-natural ecosystems. However, knowledge of how variations in seed predation rates affect plant species population dynamics is needed for decision making and knowledge-based ecosystem management. We developed a stage-classified stochastic matrix population model for Alopecurus myosuroides Huds. (blackgrass), an annual plant species thriving as a weed in temperate agroecosystems of Western and Northern Europe. The model was parameterised using empirical demographic data from long-term experiments in Swedish winter wheat fields, including information on post-dispersal seed losses by vertebrate and invertebrate seed predators. For agroecosystems with highly effective weed control measures (e.g. chemical and mechanical weed control), model simulations showed that seed losses via seed predation need to reach at least 78% at peak seed shedding to suppress population growth of A. myosuroides. The field experiment showed that vertebrates were most important for seed predation in July, at peak seed shedding. In August, after crop harvest, invertebrates were responsible for almost all seed predation. The model indicated that weed seed predation was much more important for weed regulation when it occurred before crop harvest in July. Vertebrates most strongly reduced population growth of A. myosuroides, although both vertebrates and invertebrates were needed to prevent it entirely. Synthesis and applications. We showed that weed seed predation by vertebrate and invertebrate seed predators is key for reducing the population growth of winter annual weeds like A. myosuroides in intensively managed agroecosystems. Therefore, protection of weed seed predators is essential for making management of unwanted vegetation less dependent on chemical and mechanical measures.
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