Wyniki wyszukiwania - Biblioteka Nauki

1

Effects of CO2 fumigation and nitrogen addition on soil respiration in a wetland ecosystem: experimental approach with top open chambers

100%

Wang J. , Fu X. , Wang J. , Zhong H. , Zhang R. , Ni H.

Polish Journal of Ecology

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2018

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tom 66

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nr 2

EN

Soil respiration plays a crucial role in global carbon cycling of terrestrial ecosystems. Changes in atmospheric CO₂ and nitrogen (N) addition across the globe are likely to affect soil respiration. However, the effects of elevated CO₂, and N addition on soil respiration are not fully understood especially in wetland ecosystems. To evaluate the effects of atmospheric CO₂ and N availability on soil respiration, a paired, nested manipulative in situ experiment was performed, using CO₂ fumigation within Open-Top Chambers as the primary factor, and N (as NH₄NO₃) as the secondary factor in a temperate wetland in northeastern China in 2010 and 2011. CO₂ fumigation significantly enhanced soil respiration, according to repeated-measures ANOVA, and the stimulatory effect of CO₂ fumigation on soil respiration was sustained during the whole experimental period regardless of N addition. However, the positive soil respiration effect of N addition alone weakened over time. Moreover, there was a significant interaction between CO₂ fumigation and N addition. Soil temperature explained 50–66% of the variation in soil respiration. Moreover, soil respiration was positively correlated with the root N content and litter decomposition rate. The results suggested that elevated CO₂ concentrations will accelerate soil respiration and ecosystem carbon cycling, thus, limiting soil carbon sequestration, especially when coupled with increasing N deposition.

2

Effects of nitrogen addition on growth and photosynthetic characteristics of Acer truncatum seedlings

84%

Guo X. , Wang R. , Chang R. , Liang X. , Wang C. , Luo Y. , Yuan Y. , Guo W.

Dendrobiology

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2014

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tom 72

EN

Increasing levels of atmospheric nitrogen deposition have greatly affected forest trees. Acer truncatum Bunge has a large distribution in northern China, Korea and Japan and plays an important ecological role in forest ecosystems. We investigated the responses of A. truncatum to a broad range of nitrogen addition regimes with a focus on seedling growth, biomass partitioning, leaf morphology, gas exchange physiology and chlorophyll fluorescence physiology. Moderate nitrogen addition promoted shoot height, stem diameter at ground height, total biomass, size of leaves and chlorophyll fluorescence and gas exchange performance, whereas extreme level of nitrogen addition did not result in such facilitation. Chlorophyll content, pattern of biomass partitioning, ratio of leaf length to width, leaf water content, and specific leaf area did not change among the addition regimes. The critical amount of nitrogen deposition should be defined in the context of a certain time period in a particular region for a certain species at a special developmental stage. The critical amount of N deposition that weakens total biomass facilitation in A. truncatum planted in mixed soil of yellow cinnamon soil and humic soil is approximately 10 g N m−2 y−1 during the first growing season.

3

Allometric partitioning theory versus optimal partitioning theory: the adjustment of biomass allocation and internal C-N balance to shading and nitrogen addition in Fritillaria unibracteata (Liliaceae)

84%

Guo H. , Xu B. , Wu Y. , Shi F. , Wu C. , Wu N.

Polish Journal of Ecology

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2016

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tom 64

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nr 2

EN

Fritillaria unibracteata is a classic perennial alpine herb. In this study, we examined it's responses to shading (SH) and nitrogen addition (NA), as well as its correlation with internal C-N balance to detect how it adjusted to the changes of habitat conditions. Randomized block experiment was carried out in the field in Chuanbeimu Research Station in Songpan County, Sichuan Province, China (32°09′54″N, 103°38′36″E, altitude 3300 m a.s.l.). Two growing seasons after NA and SH, Fritillaria unibracteata's total plant biomass decreased significantly, with the proportion of biomass allocated to aboveground significantly increased. In addition, in this study, under both SH and NA treatments, Fritillaria unibracteata increased its biomass allocation to above-ground, which consisted with optimal partitioning theory. Moreover, Fritillaria unibracteata's biomass allocation was significantly correlated with its internal C-N status, regardless of nitrogen and light condition. We conclude that Fritillaria unibracteata optimizes its biomass allocation between root and shoot by adjusting its internal C-N balance, which would not be changed by the specialized resource storage organ-bulb.

4

Soil respiration in response to a short-term nitrogen addition in an alpine steppe of Northern Tibet

84%

Sun J. , Cheng G. , Fan J.

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tom 61

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nr 4

EN

Northern Tibet has a vital role in global ecological security. This study determined the effect of environmental factors on the soil respiration of an alpine steppe. Short-term nitrogen addition (2 g N m⁻² yr⁻¹) was performed in an alpine steppe in Northern Tibet in June, 2011. Soil respiration was observed during the growing season of 2011 using LI-8100. The results were as follows. First, soil respiration had clear seasonal patterns, and significant differences existed between the control (CK) and nitrogen addition (ND) treatments (P = 0.004). Second, soil respiration was more sensitive to soil temperature (R² = 0.988, ND; R² = 0.05, CK) than soil moisture (R² = 0.0003, ND; R² = 0.038, CK), and the relationship between soil temperature and soil respiration in ND treatment was more significant than that in CK. Third, the relationships between soil chemical properties and root biomass in CK were greater than that in ND plots, especially the relationship of root biomass with the available nitrogen and nitrate nitrogen. These results indicated that differences among geographical conditions resulted in different phenomena of gas emissions, immature soil, and extremely short plant growing time, which may all be remarkably influenced in an alpine steppe.

5

Soil respiration in response to a short-term nitrogen addition in an alpine steppe of Northern Tibet

84%

Sun J. , Cheng G. , Fan J.

Polish Journal of Ecology

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2013

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tom Vol. 61, nr 4

655--663

EN

Northern Tibet has a vital role in global ecological security. This study determined the effect of environmental factors on the soil respiration of an alpine steppe. Short-term nitrogen addition (2 g N m-2 yr-1) was performed in an alpine steppe in Northern Tibet in June, 2011. Soil respiration was observed during the growing season of 2011 using LI-8100. The results were as follows. First, soil respiration had clear seasonal patterns, and significant differences existed between the control (CK) and nitrogen addition (ND) treatments (P = 0.004). Second, soil respiration was more sensitive to soil temperature (R2 = 0.988, ND; R2 = 0.05, CK) than soil moisture (R2 = 0.0003, ND; R2 = 0.038, CK), and the relationship between soil temperature and soil respiration in ND treatment was more significant than that in CK. Third, the relationships between soil chemical properties and root biomass in CK were greater than that in ND plots, especially the relationship of root biomass with the available nitrogen and nitrate nitrogen. These results indicated that differences among geographical conditions resulted in different phenomena of gas emissions, immature soil, and extremely short plant growing time, which may all be remarkably influenced in an alpine steppe.

6

Effects of global risks – nitrogen additions on growth and competitive relations among invasive and native congeneric species – Bidens frondosa

67%

Pan Y. , Tang S. , Wei C. , Li X.

Polish Journal of Ecology

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2016

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tom 64

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nr 4

EN

Human activity has greatly increased the amount of biologically available nitrogen entering the natural environment. Addition of N can affect growth of and competitive interactions between native and invasive plants, thus increasing or decreasing the risk of invasion by alien species. Bidens frondosa is an invasive weed native to North America that recently has begun to spread in China. The influence of soil nutrient content on B. frondosa invasion has not yet been reported. In a common garden experiment, we compared the growth and competitive effects between B. frondosa and its co-occurring native congeners — B. tripartita and B. biternata — under three N levels (0 g m⁻², 1 g m⁻², 5 g m⁻²) to assess whether increased levels of N modifies risk of B. frondosa invasion. Our results showed that while N additions increased both the growth and competitive advantage of B. frondosa as compared with that of the native congener species, results are particularly pronounced under high N levels. While growth responses to N addition varied little among invasive populations under high N levels, the competitive effect of B. frondosa did vary among populations and was significantly greater than that of the congeners. Anthropogenic N additions are likely to increase risks of B. frondosa invasions. Thus, management efforts should focus on the reduction of N input to ecosystems to mitigate invasions by B. frondosa.

7

Losses of organic matter and nitrogen during composting of municipal solid wastes

67%

Drozd J. , Licznar M. , Licznar S. E. , Walenczak K.

Polish Journal of Soil Science

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2008

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tom 41

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nr 2

127-138

EN

The authors analysed the level of losses of organic matter and nitrogen during five months of composting of municipal solid wastes (MSW) with the addition of nitrogen in the form of urea. The object of the research was raw compost from MSW, pre-treated using MUT–DANO technology. The compost, with 0.5 kg H₂O kg⁻¹ of dry mass moisture content, was composted for a period of 5 months as follows: A – on a pile, B – in a perforated plastic container of total capacity of approximately 1000 l, C – in a plastic container of total capacity of approximately 1000 l with the addition of 2.5 g N kg⁻¹ of dry mass, D – in a plastic container of total capacity of approximately 1000 l with the addition of 5.0 g N kg⁻¹ of dry mass. The results show that losses of organic matter ranged from 64 to 66% and losses of its water-soluble forms from 93 to 95%. Addition of urea to the compost contributed to high losses of total nitrogen (40-45%), especially of its water-soluble forms (96-98%), and decreased compost fertility. Composting of MSW on the pile, with a C/N ratio of approximately 30, limited the loss of nitrogen and enriched the compost in nitrogen and its water-soluble forms.

PL

Oznaczono straty materii organicznej i azotu podczas 5-cio miesięcznego kompostowania odpadów miejskich z dodatkiem azotu w postaci mocznika. Komposty surowe opuszczające linię technologiczną kompostowni MUT-DANO kompostowano przy uwilgotnieniu 0.5 kg·H₂O kg⁻¹ s.m.w następujących wariantach: A – na pryźmie, B – w pojemniku ażurowym o pojemności około 1000 l, C – w pojemniku ażurowym o pojemności około 1000 l z dodatkiem 2.5 g N·kg⁻¹ s.m., D – w pojemniku ażurowym o pojemności 1000 l z dodatkiem 5.0 g·N kg⁻¹ s.m. Stwierdzono, że wielkość strat materii organicznej w badanych wariantach wahała się w granicach 64-66%, a form wodnorozpuszczalnych 93-95%. Dodatek mocznika do kompostów przyczyniał się do wysokich strat azotu całkowitego (40-45%), a zwłaszcza form wodnorozpuszczalnych (96-98%) i obniżenia ich wartości nawozowych. Kompostowanie odpadów miejskich przy stosunku C/N≈30 na pryźmie, najbardziej ograniczało straty azotu i sprzyjało powstawaniu kompostów bardziej zasobnych w azot o wysokiej zawartości jego form wodnorozpuszczalnych.

8

The effect of starting orientations and initial morphology on texture formation in duplex steel SAF 2205

67%

Ryś J. , Witkowska M.

Archives of Metallurgy and Materials

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2009

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tom Vol. 54, iss. 3

789-803

EN

The present investigations concern the rolling texture formation and changes in morphology of two-phase structure in cold-rolled mid-alloy duplex stainless steel SAF 2205 with addition of nitrogen. The preliminary thermo-mechanical treatment included hot-rolling with subsequent solution annealing at the temperature 1150C. Afterwards the steel was cold-rolled within the wide range of reductions by applying two different variants, with rolling directions perpendicular and parallel to the direction of hot-deformation. Texture analysis indicates that austenite shows tendency to develop the textures similar to those in one-phase austenitic steels regardless of the applied cold-rolling variant and the final rolling textures of ferrite significantly differ from the typical textures of ferritic steels. Formation of the texture close to the {110}<112> alloy-type texture was observed in austenite and the orientation changes proceeded gradually over a wide range of reductions, especially for the cold-rolling variant perpendicular to the direction of hot-deformation. On the other hand the major component of the ferrite starting texture, i.e. the rotated cubic orientation {001}<110> and the character of texture spread, which is different for both rolling variants, remained essentially unchanged up to high deformations. It is concluded that the starting orientations of both constituent phases after the preliminary treatment and the band-like morphology of the ferrite-austenite structure considerably influence formation of the cold-rolling textures in the examined duplex type steel.

PL

Prezentowane badania dotyczą rozwoju tekstur walcowania i zmian morfologii struktury dwufazowej w walcowanej na zimno średnio-stopowej nierdzewnej stali duplex w gatunku SAF 2205 z dodatkiem azotu. Wstępna obróbka cieplno-mechaniczna obejmowała walcowanie na gorąco oraz wyżarzanie i przesycanie z temperatury 1150C. Stal poddano następnie walcowaniu na zimno w szerokim zakresie deformacji, stosując dwa różne warianty z kierunkami walcowania prostopadłym i równoległym do kierunku odkształcenia na gorąco. Analiza tekstur wskazuje, że niezależnie od zastosowanego wariantu walcowania na zimno austenit wykazuje tendencje do tworzenia tekstur odpowiadających tym w jednofazowych stalach austenitycznych natomiast końcowe tekstury walcowania ferrytu różnią się istotnie od typowych tekstur stali ferrytycznych. W austenicie obserwuje się rozwój tekstur zbliżonych do tekstury typu stopu {110}<112>, a w przypadku wariantu walcowania na zimno prostopadle do kierunku odkształcenia na gorąco zmiany orientacji zachodza stopniowo w szerokim zakresie odkształceń. Z kolei główna składowa tekstury początkowej ferrytu, tzn. orientacja skręcona sześcienna {001}<110> jak również charakter rozmycia tekstury ferrytu, odmienny dla obu wariantów walcowania, pozostają zasadniczo nie zmienione do wysokich odkształceń. Należy stwierdzić, że orientacje początkowe obu faz po obróbce wstępnej oraz pasmowa morfologia ferrytu i austenitu wywierają istotny wpływ na tworzenie się tekstur odkształcenia podczas walcowania na zimno badanej stali typu duplex.