Function Of Management Practices Research Articles

The application of a plant community model to evaluate adaptation strategies for alleviating climate change impacts on grassland productivity, biodiversity and forage quality

Grasslands are environments characterized by an elevated biodiversity in plant species, which dynamically evolves over time as a function of management practices, soil properties, and climate conditions. Climate change can locally affect grassland growth and floristic composition and, in turn, the quality and quantity of provided ecosystem services. We show how the use of the plant community model CoSMo allows to explicitly account for the dynamics of floristic composition as response to environmental variables. This, in turn, allows quantifying climate change impacts on grasslands growth and composition and evaluating alternative strategies to improve adaptation in the mid-term. As a case study, we focused on mountain areas in the northern Apennines (Italy), where temporary alfalfa (Medicago sativa L.)-dominated grasslands are sown for the production of Parmesan cheese. Five sites and four alternative climate scenarios (RCP4.5 and RCP8.5 projections as provided by the HadGEM2 and GISS general circulation models) were considered, to explore a wide range of agro-environmental conditions. Results showed that the observed dynamics of floristic composition and biomass accumulation were successfully simulated, with a mean absolute error lower than 10% for floristic composition and less than 1 t ha−1 for total biomass. Climate change impacts were globally negative, with a clear decrease of forage production as compared to the baseline (from -3.6% to -14.3% according to the climate scenario). The biodiversity of the plant community also declined (12.5% average decrease in the inverse Simpson index) due to the increase in alfalfa dominance. The latter, however, led to preserve the forage crude protein content (+0.9% on average). Guidelines for optimizing grassland productivity and forage protein under future climate were defined, mainly focused on reducing the alfalfa field duration, sowing grass-legume mixtures, and delaying the last cut of the season. These practices can be easily adopted under operational farming conditions to support the adaptation of temporary grasslands to climate change. According to our knowledge, this is one of the first study of climate change impact that uses a plant community model to explicitly considers phytocoenosis dynamics, biodiversity, and their effect on forage production (quantity and quality). Considering the role of grasslands as providers of key ecosystem services ‒ especially in marginal areas ‒ we believe that our modelling approach can support the identification of effective adaptation strategies to address future climate challenges.

Reduced herbicide use does not increase crop yield loss if it is compensated by alternative preventive and curative measures

Abstract Herbicide use must be reduced because of environmental and health issues. This raises the question of whether weeds and the resulting crop yield loss will increase. Previous studies analysing relationships between herbicide use intensity, weeds and yield loss suffer from methodological shortcomings in terms of weed flora and farm diversity as well as temporal scales. Here, we collected data on 272 arable cropping systems from one Spanish and six French regions, from farm surveys, the Biovigilance-Flore network, expert opinion, cropping system trials, crop advisors and scientists. Each system was simulated over 27 years and with 10 weather repetitions consisting of 28 randomly chosen weather years, using the virtual-field model F lor S ys . This process-based model simulates multi-species weed floras and crop canopies as a function of cropping systems and pedoclimate at a daily time-step over the years. Four series of simulations were run, 1) starting with a typical regional weed flora, 2) eliminating all herbicides without any other change in management practices. The two series were run again, but without an initial weed seed bank. Comparing series 1 and 2 to respectively 3 and 4 led to calculating a crop yield loss due to weeds in series 1 and 2. Comparing series 1 and 2 quantified the herbicide impact on weeds, crop production and yield loss. The simulations showed that (1) crop yield loss increased with increasing weed biomass, and that the weed/crop biomass ratio at crop flowering was the best indicator of the year’s yield loss, (2) herbicide use intensity was not correlated to either weed variables or yield loss, because herbicide use intensity greatly depended on other management practices; e.g., it decreased with increasing frequency and interannual variation of mechanical weeding and superficial tillage, (3) weed biomass and yield loss increased when herbicides were eliminated without any other change in management practices, (4) effects were more visible at the multi-annual than the annual scales. The systems the most sensitive to herbicide suppression were characterized by monotonous rotations with short crop cover, high herbicide use, no plough or winter ploughing and frequent rolling operations. Finally, a decision tree predicting yield loss as a function of management practices was proposed to support farmers and crop advisors when designing innovative cropping systems reconciling low herbicide use and low yield loss.

Mediating mutualisms: farm management practices and evolutionary changes in symbiont co‐operation

1 Root symbionts (rhizobia and arbuscular mycorrhizae) are often assumed to increase agricultural productivity consistently. However, rhizobial and mycorrhizal strains vary in effectiveness, resulting in symbiotic associations that range from parasitic to mutualistic. 2 The extent to which different farming practices mediate evolutionary changes along this continuum of symbiont effectiveness is rarely discussed. However, evolutionary theory suggests that (i) fertilizer use will favour parasitism unless host-plants impose sanctions against less-effective mutualists; (ii) tillage will have contrasting effects because it decreases within-plant symbiont relatedness but also decreases the risk that mutualism will benefit future competitors; (iii) crop rotation can act as a selective agent against dominating symbiont genotypes; and (iv) rhizobial inoculation adds beneficial strains to the soil but may increase the frequency of mixed nodules that allow parasitic strains to escape host sanctions. 3 However, the existing empirical data are inadequate to test our predictions thoroughly. Changes in species composition have been documented as a result of management practices, but evolutionary changes in symbiont effectiveness are difficult to detect. Therefore, a major aim of this study was to stimulate research that will assesses directly changes in symbiotic effectiveness as a function of management practices.

ENTENSITY OF FAMILY DISAGREEMENT OVER FINANCES AND ASSOCIATED FACTORS*

Results from survey research using regression techniques indicate that disagreement over family finances for men was a function of management practices (negative), years married (negative), and wife's employment, with those who had part‐time employed wives reporting more disagreement than those with non‐employed wives. Disagreement over family finances for women was a function of frequency of communication (negative), perceived future financial security (negative), and wife's employment, with full‐time employed wives reporting less disagreement over finances than non‐employed wives. Since the stress and reduced maximization of resources implied by the high percentage of families reporting intense disagreement over finances ultimately affect their well‐being, it is imperative that the skills of financial management and communication be developed through counselling and education.