Diversified crop rotations have been suggested to reduce grain yield losses from the adverse climatic conditions increasingly common under climate change. Nevertheless, the potential for climate change adaptation of different crop rotational diversity (CRD) remains undetermined. We quantified how climatic conditions affect small grain and maize yields under different CRDs in 32 long‐term (10–63 years) field experiments across Europe and North America. Species‐diverse and functionally rich rotations more than compensated yield losses from anomalous warm conditions, long and warm dry spells, as well as from anomalous wet (for small grains) or dry (for maize) conditions. Adding a single functional group or crop species to monocultures counteracted yield losses from substantial changes in climatic conditions. The benefits of a further increase in CRD are comparable with those of improved climatic conditions. For instance, the maize yield benefits of adding three crop species to monocultures under detrimental climatic conditions exceeded the average yield of monocultures by up to 553 kg/ha under non‐detrimental climatic conditions. Increased crop functional richness improved yields under high temperature, irrespective of precipitation. Conversely, yield benefits peaked at between two and four crop species in the rotation, depending on climatic conditions and crop, and declined at higher species diversity. Thus, crop species diversity could be adjusted to maximize yield benefits. Diversifying rotations with functionally distinct crops is an adaptation of cropping systems to global warming and changes in precipitation.

Agricultural field margins are often recommended as a cost-effective and efficient method for wild bee conservation, in response to the threat imposed by global pollinator declines as a result of intensive agricultural practices. In this study we compared margin characteristics and wild bee community structure from sites with landscapes of varying agricultural intensity in order to (i) investigate if field margins are valuable for wild bee conservation in all types of landscapes, and (ii) determine which biotic and abiotic margin characteristics best support wild bee abundance and community richness. Margin surveys and wild bee community sampling, comprising pan traps and observations of foraging activity, were carried out over three years at 27 cereal field margins in Catalonia, Spain. Generalized linear models indicated a strong inverse relationship between surrounding landscape diversity and wild bee abundance. The proportion of Halictidae bees (common generalists) increased with decreasing landscape complexity. Floral richness exhibited a positive association with number of foraging bees and morphospecies richness, and was positively correlated with the proportion of shrubs and trees represented in the margins. It was observed that wider margins held a higher proportion of perennial plants and a lower proportion of Halictidae bees. Our study suggests that field margins are more crucial in intensively farmed areas than in heterogeneous landscapes where foraging resources are more abundant. Maintaining wide margins with high flowering plant richness, comprising perennial and shrub species, best supports a dense and diverse bee community. In more diverse landscapes, conservation efforts focused on maintaining the quality of existing natural patches may be most effective.This work was supported by FEDER (European Regional Development Funds) and the Spanish Ministry of Economy and Competitiveness grants (projects number AGL2012-33736 and AGL2015-64130-R). The Natural Sciences and Engineering Research Council of Canada (NSERC) provided J.M. with a doctoral scholarship.Peer reviewe

Several purported cases of plasticity in plant allocation patterns appear to be the effects of size and allometric growth (“apparent plasticity”). To ask whether there is true plasticity (i.e., a change in the allometric trajectory) in reproductive allocation in Senecio vulgaris L., we grew S. vulgaris plants at high and low levels of water, nutrients, and competition, and analyzed the relationship between vegetative and seed biomass. Plant size was the major determinant of reproductive output, accounting for 83% of the variation in log (seed mass). There were also significant effects of the treatments that were not due to size, accounting for an additional 9% of the variation. The treatments affected the allometric coefficient (intercept), not the allometric exponent (slope) of the relationship, reflecting a small but significant shift in the efficiency of conversion of total plant biomass into reproductive biomass. In a second experiment, we grew S. vulgaris plants at three nutrient levels and allowed all individuals to complete their life cycles. Again, nutrient level had a small but significant effect on the allometric coefficient. Plasticity in reproductive allocation exists, but is very limited. The primary effects of the environment on the reproductive output of S. vulgaris occur via plant size.