A Methodology for daylight optimisation of high-rise buildings in the dense urban district using overhang length and glazing type variables with surrogate modelling

Urbanization and population growth lead to the construction of higher buildings in the 21st century. This causes an increment on energy consumption as the amount of constructed floor areas is rising steadily. Integrating daylight performance in building design supports reducing the energy consumption and satisfying occupants' comfort. This study presents a methodology to optimise the daylight performance of a high-rise building located in a dense urban district. The purpose is to deal with optimisation problems by dividing the high-rise building into five zones from the ground level to the sky level, to achieve better daylight performance. Therefore, the study covers five optimization problems. Overhang length and glazing type are considered to optimise spatial Daylight Autonomy (sDA) and Annual Sunlight Exposure (ASE). A total of 500 samples in each zone are collected to develop surrogate models. A self-adaptive differential evolution algorithm is used to obtain near-optimal results for each zone. The developed surrogate models can estimate the metrics with minimum 98.25% R2 which is calculated from neural network prediction and Diva simulations. In the case study, the proposed methodology improves daylight performance of the high-rise building, decreasing ASE by approx. 27.6% and increasing the sDA values by around 88.2% in the dense urban district. - Published under licence by IOP Publishing Ltd.We would like to thank Cemre Cubukcuoglu for the collaborative work while implementing the optimisation algorithm. M. Fatih Tasgetiren, who is partially supported by the National Natural Science Foundation of China (Grant No. 51435009), acknowledges the HUST project in Wuhan.Scopu

Leaf litter decomposition in temperate deciduous forest stands with a decreasing fraction of beech (Fagus sylvatica)

We hypothesised that the decomposition rates of leaf litter will increase along a gradient of decreasing fraction of the European beech (Fagus sylvatica) and increasing tree species diversity in the generally beech-dominated Central European temperate deciduous forests due to an increase in litter quality. We studied the decomposition of leaf litter including its lignin fraction in monospecific (pure beech) stands and in stands with up to five tree genera (Acer spp., Carpinus betulus, Fagus sylvatica, Fraxinus excelsior, Tilia spp.) using a litterbag approach. Litter and lignin decomposition was more rapid in stand-representative litter from multispecific stands than in litter from pure beech stands. Except for beech litter, the decomposition rates of species-specific tree litter did not differ significantly among the stand types, but were most rapid in Fraxinus excelsior and slowest in beech in an interspecific comparison. Pairwise comparisons of the decomposition of beech litter with litter of the other tree species (except for Acerplatanoides) revealed a “home field advantage” of up to 20% (more rapid litter decomposition in stands with a high fraction of its own species than in stands with a different tree species composition). Decomposition of stand-representative litter mixtures displayed additive characteristics, not significantly more rapid than predicted by the decomposition of litter from the individual tree species. Leaf litter decomposition rates were positively correlated with the initial N and Ca concentrations of the litter, and negatively with the initial C:N, C:P and lignin:N ratios. The results support our hypothesis that the overall decomposition rates are mainly influenced by the chemical composition of the individual litter species. Thus, the fraction of individual tree species in the species composition seems to be more important for the litter decomposition rates than tree species diversity itself

Cutting improves the productivity of lucerne-rich stands used in the revegetation of degraded arable land in a semi-arid environment

Understanding the relationships between vegetative and environmental variables is important for revegetation and ecosystem management on the Loess Plateau, China. Lucerne (Medicago sativa L.) has been widely used in the region to improve revegetation, soil and water conservation, and to enhance livestock production. However, there is little information on how environmental factors influence long-term succession in lucerne-rich vegetation. Our objective was to identify the main environmental variables controlling the succession process in lucerne-rich vegetation such that native species are not suppressed after sowing on the Loess Plateau. Vegetation and soil surveys were performed in 31 lucerne fields (three lucerne fields without any management from 2003-2013 and 28 fields containing 11-year-old lucerne with one cutting each year). Time after planting was the most important factor affecting plant species succession. Cutting significantly affected revegetation characteristics, such as aboveground biomass, plant density and diversity. Soil moisture content, soil organic carbon, soil available phosphorus and slope aspect were key environmental factors affecting plant species composition and aboveground biomass, density and diversity. Long-term cutting can cause self-thinning in lucerne, maintain the stability of lucerne production and slow its degradation. For effective management of lucerne fields, phosphate fertilizer should be applied and cutting performed

Litter quality and its response to water level drawdown in boreal peatlands at plant species and community level

Changes in the structure of plant communities may have much more impact on ecosystem carbon (C) cycling than any phenotypic responses to environmental changes. We studied these impacts via the response of plant litter quality, at the level of species and community, to persistent water-level (WL) drawdown in peatlands. We studied three sites with different nutrient regimes, and water-level manipulations at two time scales. The parameters used to characterize litter quality included extractable substances, cellulose, holocellulose, composition of hemicellulose (neutral sugars, uronic acids), Klason lignin, CuO oxidation phenolic products, and concentrations of C and several nutrients. The litters formed four chemically distinct groups: non-graminoid foliar litters, graminoids, mosses and woody litters. Direct effects of WL drawdown on litter quality at the species level were overruled by indirect effects via changes in litter type composition. The pristine conditions were characterized by Sphagnum moss and graminoid litters. Short-term (years) responses of the litter inputs to WL drawdown were small. In longterm (decades), total litter inputs increased, due to increased tree litter inputs. Simultaneously, the litter type composition and its chemical quality at the community level greatly changed. The changes that we documented will strongly affect soil properties and C cycle of peatlands.Peer reviewe

Effect of tree age on chemical compounds of ancient Anatolian black pine (Pinus nigra subsp. pallasiana) needles in Northwest Turkey

Plant primary and secondary metabolites are chemical compounds synthesized for essential functions, such as growth and development (primary metabolites), and specific functions, such as pollinator attraction or defense against herbivory (secondary metabolites). Their concentrations in plants are genetically determined, but are also affected by environmental factors. Among these factors, plant age has been reported to influence plant chemical compounds under similar environmental conditions. We aimed to investigate the chemical compounds of ancient Anatolian black pine (Pinus nigra subsp. pallasiana) needles from trees of different ages. Needles of over 500-, 200-, 100-, 50-, and 25-year-old black pine trees growing under similar environmental conditions were sampled and analyzed for photosynthetic pigments (chlorophyll a, chlorophyll b and carotenoids), proline, total soluble protein, glucose, sucrose, total soluble sugar, peroxidation level (MDA-malondialdehyde), hydrogen peroxide (H2O2) and antioxidants such as ascorbate peroxidase (APX), catalase (CAT) and superoxide dismutase (SOD) activities. Significant differences for chemical composition associated with age were found. In general, results showed that over 500-year-old Anatolian black pine had the highest proline, total soluble protein, H2O2, sucrose, total soluble carbohydrates, APX, CAT and SOD concentrations, whereas they had the lowest chlorophyll a, total chlorophyll, total carotenoid and glucose concentrations. However, 200-year-old trees had the highest glucose, but the lowest chlorophyll b, proline, H2O2 and total soluble carbohydrates. 50- and 25-year-old trees together showed the highest chlorophyll a and b, total chlorophyll, total carotenoid and MDA, but lowest total soluble protein and sucrose. In conclusion, these results provide valuable insight into the chemical composition of Anatolian black pine needles in relation to their age, and can be used for complementing studies on tree growth-defence relationships