Wyniki wyszukiwania

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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

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

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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

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

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 61

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nr 4

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.

4

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

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.

5

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

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.

6

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

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.

Ograniczanie wyników

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

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

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

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)

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

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