• Energy Research

A major challenge in sustainability science is identifying targets that maximize ecosystem benefits to humanity while minimizing the risk of crossing critical system thresholds. One critical threshold is the biomass at which populations become so depleted that their population growth rates become negative—depensation. Here, we evaluate how the value of monitoring information increases as a natural resource spends more time near the critical threshold. This benefit emerges because higher monitoring precision promotes higher yield and a greater capacity to recover from overharvest. We show that precautionary buffers that trigger increased monitoring precision as resource levels decline may offer a way to minimize monitoring costs and maximize profits. In a world of finite resources, improving our understanding of the trade-off between precision in estimates of population status and the costs of mismanagement will benefit stakeholders that shoulder the burden of these economic and social costs.

AbstractElevated carbon-dioxide concentration [eCO2] is a key climate change factor affecting plant growth and yield. Conventionally, crop modeling work has evaluated the effect of climatic parameters on crop growth, without considering CO2. It is conjectured that a novel multimodal ensemble approach may improve the accuracy of modelled responses to eCO2. To demonstrate the applicability of a multimodel ensemble of crop models to simulation of eCO2, APSIM, CropSyst, DSSAT, EPIC and STICS were calibrated to observed data for crop phenology, biomass and yield. Significant variability in simulated biomass production was shown among the models particularly at dryland sites (44%) compared to the irrigated site (22%). Increased yield was observed for all models with the highest average yield at dryland site by EPIC (49%) and lowest under irrigated conditions (17%) by APSIM and CropSyst. For the ensemble, maximum yield was 45% for the dryland site and a minimum 22% at the irrigated site. We concluded from our study that process-based crop models have variability in the simulation of crop response to [eCO2] with greater difference under water-stressed conditions. We recommend the use of ensembles to improve accuracy in modeled responses to [eCO2].

Historical exploitation of the Mediterranean Sea and the absence of rigorous baselines makes it difficult to evaluate the current health of the marine ecosystems and the efficacy of conservation actions at the ecosystem level. Here we establish the first current baseline and gradient of ecosystem structure of nearshore rocky reefs at the Mediterranean scale. We conducted underwater surveys in 14 marine protected areas and 18 open access sites across the Mediterranean, and across a 31-fold range of fish biomass (from 3.8 to 118 g m(-2)). Our data showed remarkable variation in the structure of rocky reef ecosystems. Multivariate analysis showed three alternative community states: (1) large fish biomass and reefs dominated by non-canopy algae, (2) lower fish biomass but abundant native algal canopies and suspension feeders, and (3) low fish biomass and extensive barrens, with areas covered by turf algae. Our results suggest that the healthiest shallow rocky reef ecosystems in the Mediterranean have both large fish and algal biomass. Protection level and primary production were the only variables significantly correlated to community biomass structure. Fish biomass was significantly larger in well-enforced no-take marine reserves, but there were no significant differences between multi-use marine protected areas (which allow some fishing) and open access areas at the regional scale. The gradients reported here represent a trajectory of degradation that can be used to assess the health of any similar habitat in the Mediterranean, and to evaluate the efficacy of marine protected areas.

Crop cultivation in greenhouses under semi-arid climatic conditions is subject to various stresses, in particular during the winter season at night, when the interior air is poorly controlled, leading to prolonged periods of low temperature. The aim is then to evaluate and control the heat exchanges of the enclosure in order to prevent low indoor air temperatures and reduce the thermal load of the greenhouse. The objectives of this study are to investigate the convective and radiative heat exchanges at the cover in order to establish new correlations for the convective heat transfer coefficients in semi arid regions. The climatic parameters were measured inside and outside a closed empty glasshouse without crop, for three different nights during the winter season in the semi-arid land of Algeria. A physical model for analysing the convective heat transfers was implemented, and new correlations were established, parameterised, calibrated and validated thoroughly. A significant difference was observed between the correlations obtained by this study and the models obtained for other greenhouse designs under different climatic conditions. Results show that the convection mode along the inside wall of the cover is free turbulent. Conversely, the convection mode along the outside greenhouse cover remains forced turbulent. A consistent performance of the correlations was observed, both in the calibration and validation stages.

AbstractThe planetary boundary framework constitutes an opportunity for decision makers to define climate policy through the lens of adaptive governance. Here, we use the DICE model to analyze the set of adaptive climate policies that comply with the two planetary boundaries related to climate change: (1) staying below a CO2 concentration of 550 ppm until 2100 and (2) returning to 350 ppm in 2100. Our results enable decision makers to assess the following milestones: (1) a minimum of 33% reduction of CO2 emissions by 2055 in order to stay below 550 ppm by 2100 (this milestone goes up to 46% in the case of delayed policies); and (2) carbon neutrality and the effective implementation of innovative geoengineering technologies (10% negative emissions) before 2060 in order to return to 350 ppm in 2100, under the assumption of getting out of the baseline scenario without delay. Finally, we emphasize the need to use adaptive path-based approach instead of single point target for climate policy design.

A field experiment was conducted during 1993–1995 to study the effect of industrial effluent on the initial growth of Azadirachta indica A. Juss. (Neem) in arid region. The effluent released from textile industry had high pH, EC, SAR and RSC. Various treatments were: irrigation with effluent only (W1), effluent mixed with canal water at 1:1 ratio (W2), gypsum‐treated effluent (W3), gypsum‐treated soil (W4) and wood ash‐treated soil (W5). W5 was the best treatment where neem attained 218 cm height, 118 cm crown diameter and 11.2 cm collar circumference at 28 months of age; followed by W1 treatment, where trees were on an average 186 cm tall and had 104 cm crown diameter and 9.4 cm collar circumference. Growth of the seedlings was the poorest in W2treatment. Increase in biomass accumulation over W2 treatment (1.89 kg tree−1) was 3.6 fold in W5, 2.1 fold in W1, 2.0 fold in W4 and 1.4 fold in W3 treatments. Though effluent application increased soil organic matter, electrical conductivity and in some cases pH also, but gypsum‐ and wood ash‐ treated soil ameliorated the pH by 0.25 units in comparison to the initial data. These results suggest that industrial wastewater can be effectively used to boost up establishment and growth of Neem (Azadirachta indica) in arid zone. Addition of wood ash improves the rate of growth. Irrigation with industrial effluent caused slight increase in electrical conductivity and decline in the soil pH. Santrauka Eksperimentas vyko 1993–1995 m. siekiant ištirti pramoninių nuotekų poveikį Azadirachta indica A. Juss. (Neem) sodinukų augimo pradžiai sausringuose regionuose. Tekstilės pramonės išleidžiamų nuotekų didelės pH rodiklio reikšmės, elektrinis laidumas, natrio adsorbcijos santykis ir natrio karbonato liekana. Tiriant taikyti įvairūs dirvožemio apdorojimo būdai: drėkinta tik nuotekomis (W1 ), nuotekos maišytos su kanalo vandeniu santykiu 1:1 (W2 ), nuotekos veiktos gipsu (W3 ), į dirvožemį dėta gipso (W4 ) ir dirvožemis tręštas medienos pelenais (W5 ). Efektyviausias buvo W5 apdorojimo būdas. 28 mėnesių augalai siekė 218 cm aukštį, jų vainiko skersmuo buvo 118 cm, žiedo perimetras – 11,2 cm. Stebint W1 apdorojimo tipą, medžiai buvo vidutiniškai 186 cm aukščio, vainikas – 104 cm skersmens, žiedai 9,4 cm perimetro. Blogiausiai sodinukai augo apdorojant W2 būdu. Nors naudojant nuotekas dirvožemio organinių medžiagų kiekis, elektrinis savitasis laidumas ir kai kuriais atvejais pH reikšmė padidėjo, tačiau gipsu ir medienos pelenais apdorotame dirvožemyje pH padidėjo per 0,25 vienetus, palyginti su pirminiais duomenimis. Šie rezultatai rodo, kad pramoninės nuotekos gali būti efektyviai naudojamos Neem (Azadirachta indica) želdinti ir auginti sausose teritorijose. Medienos pelenai pagerino augimo spartą. Drėkinimas pramoninėmis nuotekomis lėmė nežymų elektrinio savitojo laidumo augimą ir dirvožemio pH sumažėjimą. Резюме Экспериментальное поле возделывалось в 1993–1995 гг. с целью изучить воздействие промышленных стоков на начало роста Azadirachta indica A. Juss. (Neem) в засушливых районах. В стоках от производства текстиля высоко значение pH, электропроводимость, соотношение адсорбции натрия и остаток карбоната натрия. Применялись разные способы обработки почвы: орошение только стоками (W1 ); смесью стоков с водой из канала в соотношении 1:1 (W2 ); стоками, обработанными гипсом (W3 ); обработка почвы гипсом (W4 ) и удобрение древесной золой (W5 ). Наиболее эффективным способом оказалась обработка древесной золой. Высота растений в возрасте 28 месяцев составляла 218 см, венчик в поперечнике – 118 см, цветок – 11,2 см. После обработки почвы по типу W1 растения достигали 186 см в высоту, венчик в поперечнике – 104 см, цветок – 9,4 см. Наименее эффективным для растений способом оказалась обработка почвы по типу W2 . Несмотря на то, что при применении стоков количество органических веществ в почве, электропроводимость и в некоторых случаях значение pH увеличилось, однако при обработке почвы гипсом и древесной золой pH увеличилось более чем на 0,25 единиц по сравнению с начальными данными. Эти результаты показали, что промышленные стоки могут эффективно применяться для озеленения и выращивания Neem (Azadirachta indica) на засушливых территориях. Древесная зола ускоряла рост растений. Орошение промышленными стоками способствовало незначительному увеличению электропроводимости и уменьшению в почве pH.