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1

Effects of the Conversion of a Degraded Alpine Kobresia Meadow on the Organic Carbon and Nitrogen of Soil and Plants

Qiao Y., Duan Z., Li X., Quan X., Liang H.

Polish Journal of Ecology

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2015

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Vol. 63, nr 4

500--511

EN

Three sites with both degraded alpine Kobresia meadow (DM) and adjacent mix-seeded perennial grasses pastures (MSP) in the headwater region of the Yellow River, Qinghai-Tibetan Plateau, were selected to investigate plant and soil organic carbon (SOC), total nitrogen (TN) and their isotope composition. The SOC and TN in the top soil layer to a depth of 10 cm were significantly affected by ploughing and planting mix-seeded perennial grasses. The SOC content in 0–10 cm soil layer of MSPs was 25.6%, 5.5% and 12.9% lower than those of DMs at the I-III sites, respectively, and the rate of OC density loss was 23.8, 14.5 and 18.2%, respectively. The soil TN content in 0–10 cm soil layer of MSPs was 16.6%, 2.2% and 9.4% lower than those of the DMs at three sites, respectively, and the TN density was 15.6, 10.6 and 15.3% lower than those of DMs, respectively. The plant and soil 13C values (-27.03‰, -25.16‰, respectively) suggest that the vegetation of both DMs and MSPs are C3 plant communities. The 15 N value in the soil (>4‰) was significantly greater than in plants (<2‰). No differences of either 13C or 15N abundance between MSPs and DMs at Site I and II, but were found at Site III, indicating that the effects were site specific. The rehabilitation of a degraded Kobresia meadow has a significant influence on the soil properties, SOC and TN. Caution should be taken in site selection before performing conversion.

2

Aerobic Methane Emission from Plant: Comparative Study of Different Communities and Plant Species of Alpine Meadow

Guo X., Du Y., Li J., Liu S., Han D., Li Y., Lin L., Zhang F., Oyang J., Cao G.

Polish Journal of Ecology

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2015

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Vol. 63, nr 2

223--232

EN

This study was aimed at qualifying the methane emission ability of different communities in alpine meadow, and monitoring if the dominant species from these communities could emit methane in a sand culture experiment. Using the static chamber technique and gas chromatography method, two experiments were conducted in the field and in laboratory. First, the methane flux rate was measured in plant communities: natural alpine meadows (NM), Elymus nutans pasture (EP), herbaceous community in shrub (HS), and a Poa fruticosa meadow (PS). A 3-month sand culture experiment was conducted to show the non-microbial methane emission from living plants. Average methane emission rates were estimated to be 16.83 µg m-2 h-1 (range -49.3–107.8), 28.49 µg m-2 h-1 (range -55.0–96.2) and 20.91 µg m-2 h-1 (range -31.9– 145.8) for NM, EP, and PS, respectively. Methane emission rate from EP was significantly higher than from NM during the growing season. The reclaim of grassland would enhance the methane emission in this aera through this one year's measurement, but whether this conclusion suit to the whole Tibet Plateau, it remains further longer time and larger spatial scale experiments to verify it. The result of the sand culture experiment showed that some plant species emitted methane in an aerobic, nonmicrobial environment, most of herbaceous species showed a methane emission characteristic, the methane emission from plant may have a species dependent characteristic.

3

Próba oceny produktywności ekosystemu w warunkach polowych Wielkopolski

Kowalska N., Chojnicki B. H., Józefczyk D., Urbaniak M., Juszczak R., Olejnik J.

Rocznik Ochrona Środowiska

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2013

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Tom 15, cz. 3

2481--2495

EN

The Eddy Covariance technique has been applied for corn field NEE estimation. The Smith, Michaelis-Menten and Misterlich formulas has been used for calculation of net ecosystem exchange (NEE) values between corn canopy and the atmosphere. These approaches have been applied for estimation of temeparture and radiation modification impact on the corn field productivity. The NEE has been evaluated in the first part of this paper and then the relation of NEE runs and elements that influence the NEE values has been summarized. In another part the analysis of NEE under thermal and radiative conditions has been presented. The Michaelis-Menten model has been found as the most distinct one for the measurements of the relationship. This model indicated that the highest NEE value (NEE = 10.0 µmol m-2 s-1) has been found under combination of the low radiation and high temperature conditions. The lowest value of NEE has been estimated under the highest PPFD and lowest Ta amount. The applied models have confirmed relationship between NEE, PPFD and Ta. All three models confirmed the fact that the lowest ecosystem productivity is found under high radiation input. The accumulated NEE values were compared with the real values according to the Smith, Michaelis-Menten and Misterlich equations. The results of the Michaelis-Menten equation and Misterlich were the most similar to the real cumulative NEE values. The theoretical change of thermal (0.5°C increase) and radiation (4% decrease) resulted in tested higher CO2 sequesteration from the atmosphere.

4

Warming effects on plant growth, soil nutrients, microbial biomass and soil enzymes activities of two alpine meadows in Tibetan Plateau

Li N., Wang G., Gao Y., Wang J.

Polish Journal of Ecology

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2011

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Vol. 59, nr 1

25-32

EN

The aim of this study was to assess initial effects of warming on the plant growth, soil nutrient contents, microbial biomass and enzyme activities of two most widespread ecosystem types: swamp meadow (deep soil, high water content) and alpine meadow (poor soil, low water content), in the hinterland of the Qinghai-Tibet Plateau (altitude 4600.4800 m a.s.l.) The temperature of air and upper soil layer was passively enhanced using open-top chambers (OTCs) (50 cm high with 60 cm at opening and constructed of 6 mm thick translucent synthetic glass) from 2006 to 2008. The use of OTCs clearly raised temperature and decreased soil moisture. In warmed plots, monthly mean air temperature was increased by 2.10[degrees]C and 2.28[degrees]C, soil moisture of 20 cm soil layer was decreased by 2.5% and 3.9% in alpine meadow and swamp meadow, respectively. Plant biomass significantly increased by 31% in alpine meadow and 67% in swamp meadow. Warming also affected soil microbial biomass C and N at both meadows. In swamp meadow, warming caused the decrease of soil organic carbon and total nitrogen in 0-5 cm layer and an increase in 5-20 cm. While in alpine meadow, these soil parameters increased in 0-5 cm layer and decreased in 5-20 cm layer. The effects of warming on enzyme activities differed depending on the enzyme and the meadow ecosystem. In general, enzyme activities were higher in the upper soil layers (0-5 cm) than in the lower soil layers (5-20 cm). The experiment results exhibited that warming improved the soil biochemical and microbiological conditions in high- mountain meadows, at least in the short term.

5

Simulating N2O emission from Kobresia humilis Serg. alpine meadow on Tibetan Plateau with the DNDC model

Du Y., Cui X., Cao G., Zhao X., Yang G.

Polish Journal of Ecology

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2011

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Vol. 59, nr 3

443-453

EN

Field measured N2O emissions in two years were used to parameterize and validate a process-based model, DNDC, for an alpine Kobresia humilis meadow on the Tibetan Plateau in China. Although this model failed to capture the N2O fluxes in some time periods in the spring or autumn, the modeled results showed overall a good performance in terms of simulating the seasonal variation of N2O fluxes and quantifying the annual total emissions. The relative deviation on the annual basis was about 12.4% and -15.9% for the two years, respectively. The modeled data showed that nitrification contributed about 53% of total N2O production, slightly higher than denitrification. The modeled fluxes were sensitive to soil organic content (SOC), pH, and temperature, but less sensitive to variation of precipitation, soil ammonium and nitrate contents. Further modifications for the model were suggested to focus on the process of soil freezing and thawing as well as the crop growth sub-model that would improve the model's performance for quantifying N2O emission from the alpine meadow.

6

Contribution of the vegetation layers in the nitrous oxide emission from alpine Kobresia humilis Serg. meadow ecosystem on the Tibetan Plateau

Du Y., Cao G., Deng Y., Sun G., Cui X.

Polish Journal of Ecology

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2010

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Vol. 58, nr 1

115-124

EN

Nitrous oxide (N[2]O) was one of the major atmospheric greenhouse gases. Its budget was poorly understood in alpine meadow, a dominant vegetation type on the Tibetan Plateau. To characterize a Kobresia humilis meadow on the plateau, N[2]O emission rates were monitored from June 2003 to June 2006 in the study area located at 3280 m a.s.l. Nine plots with 1 m x 1 m each were divided into three treatments, i.e. intact herbaceous community (HCK), removal of aboveground plant biomass (CBK), and removal of both above and belowground plant biomass (BSK), to estimate contribution of plants, r hizosphere and bulk soil to the total N[2]O emission. N[2]O emission from plant aboveground biomass was calculated by flux difference between HCK and CBK, denoted as F[(HCK-CBK)], from rhizosphere by F[(CBK-BSK)], and from bulk soil was the flux in BSK treatment. Static chambers (height 50 cm, area 0.5 x 0.5 m2 )were used for gas collection. N[2]O emission rate was significantly correlated with soil temperature at 5 cm depth in both HCK and BSK (P <0.001). Both treatments demonstrated a seasonal peak rate in growing season and minimum rate in dormancy period. The mean emission rates in the three years were 39.7[plus or minus]2.9 and 30.6[plus or minus]2.5 [mu]g m[^-2] h[^-1] in HCK and BSK, respectively, with the former significantly higher than the latter (P <0.05). In CBK, however, the emission rate did not show consistent correlation with soil temperature, especially in growing season. Its three-year mean emission rate was 36.2[plus or minus]3.3 [mu]g m[^-2] h[^-1]. In the K. humilis meadow, bulk soil contributed much more than plants and rhizosphere. The mean emission rate was 3.5[plus or minus]2.9, 5.7[plus or minus]3.8, and 30.6[plus or minus]2.5 [mu]g m[^-2] h[^-1] (P <0.001) from plants, rhizosphere and bulk soil, and these accounted for 9, 14 and 77%, separately. Our results implied that N[2]O emission rate decreased little with grazing as indicated by the difference between HCK and CBK in K. humilis meadow (P <0.05). N2O emission from alpine meadow could not be ignored in addressing regional greenhouse gases budget on the Tibetan Plateau, considering the vast area and much higher radiative forcing of N[2]O.

7

Yak (Bos grunniens L.) grazing effects on vegetation of alpine meadow with Potentilla fruticosa L. (Rosaceae) shrub in Qinghai-Tibet Plateau

Qiao Y., Wang Q., Wang W.

Polish Journal of Ecology

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2009

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Vol. 57, nr 4

769-777

EN

Grazing can change plant community composition and structure, which may alter the functions of the shrub meadow ecosystem. Grazing effects on Potentilla fruticosa shrub community in the headwater region of the Yellow River, which is in core area of the Qinghai-Tibet Plateau, are studied to provide adequate protection decision-making. We investigated continuous grazing and seasonal enclosure effects on P. fruticosa shrub communities. Three sites of P. fruticosa shrub comprising both continuous grazing and seasonal enclosure treatments were selected. The size of each fenced plot of P. fruticosa shrub was about 3000 m2, the stocking rate was about 5 heads per 100 m2 in continuous grazing treatment. Three samplings were made in each growing season of 2003 and 2004. Cover of vegetation, plant species composition and vegetation height were investigated in seven 1 x 1 m quadrates in each treatment. Above-ground biomass was measured in five 0.5 x 0.5 m quadrates. Shrub, forb, graminoid and sedge plant materials were clipped at ground level and oven-dried at 85[degrees] C to a constant mass. Plant composition was affected by long term continuous grazing and changes were caused by forb species shifting. No apparent difference in species richness between the grazed and ungrazed communities over the growing months were found but the Shannon's diversity indices of the grazed communities in June and July were higher than that of the ungrazed but lower in the late August and September. Live vegetation cover was reduced by 6.7%, 7.3% and 11.5%, respectively, owing to grazing in July, August and September, but not in June (P> 0.05). Forbs took up more than 50% cover of the vegetation in both grazed and ungrazed treatments. Relative cover of sedges and forbs in ungrazed treatment decreased in July, August and September, while that of graminoids increased more than 70% in the same period. Live vegetation height was reduced by 27% (2004) and 23% (2003) in late August and early September, but not in early growing season. Grazing reduced total above-ground biomass by 35%, 37% and 36% in July, August and early September, respectively, and the reduction was mainly in forb biomass. Continuous grazing affects plant composition and species diversity. The quantitative characteristics of P. fruticosa communities were influenced by grazing over growing months, but the effects were offset by non-growing season grazing.

8

The effect of habitat on methane emission from an alpine wetland

Chen H., Wu N., Gao Y., Yao S., Wang Y., Tian J., Sun G., Yuan X.

Polish Journal of Ecology

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2009

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Vol. 57, nr 2

377-381

EN

Alpine wetland is a source for methane (CH[4]), an important greenhouse gas, but little is known about how this habitat influences the emission. To understand this wetland habitats were selected at the altitude of 3430 m a.s.l. (in National Wetland Nature Reserve of Zoige, Quingle - Tibetan Plateau) and the methane flux was measured with static chambers in three different sites, including hollows with Carex muliensis Hand - Mazz. and Eleocharis valleculosa Ohwi f. setosa (Ohwi) Kitagawa., grass hummocks composed of Kobresia tibetica Maxim, Cremanthodium pleurocaule R. D. Good, Potentilla bifurca L. and Pedicularis sp. We have found that in alpine wetland these habitats significantly affect CH[4] emissions in the onset (April, 2006) and peak (August, 2005) stages of growing season. Hollows covered with Carex muliensis and Eleocharis valleculosa had higher values of emission than grass hummocks built by several grass species. Slight difference of CH[4] emission was found between two kinds of hollows with Carex muliensis and Eleocharis valleculosa. These results were consistent with the change of water table, which was found best correlated with CH4 emissions (r[^2] = 0.43, P <0.01) in the peak stage of growing season. Directly measured shoot biomass and plant heights were best related to CH[4] emissions (r[^2] = 0.59, P <0.01). However, in the onset stage of growing season, variation of CH[4] emission may not be simply ascribed to changes in water table and vegetation structure.

9

Relationship between seed size and plant abundance in an alpine meadow of the Qinghai-Tibetan Plateau

Liu B., Luo Y.

Polish Journal of Ecology

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2009

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Vol. 57, nr 3

573-579

EN

Theoretical and field studies on seed size and plant abundance relationship have been conducted in various communities. However, inconsistent patterns have emerged from these studies, and still little is known about alpine meadows. Here we identified four models and their predictions: the seed size/number trade-off model (SSNTM), the succession model (SM), the spatial competition model (SCM), and the triangle model (TM), in order to assess the relationship between seed size and abundance in alpine meadows, and to elucidate underlying mechanisms. The study site was situated on the eastern Qinghai-Tibetan Plateau at 3500 m above sea level. From 1999 through 2001, two indices of plant abundance (aboveground biomass and density) were simultaneously measured in 45 quadrates (0.25 m[^2]). Data for 101 plant species (mostly Cyperaceae, Poaceae, Asteraceae, Ranunculaceae and forbs) showed that seed size is like log normal distributed, and it slightly skewed in smaller-sized seeds. The SSNTM, the TM, the SM and the SCM models were not supported in this alpine meadow, and the relationship between seed size and abundance was always positive (although in some samples, the relationship was not significant). The positive correlation between seed size and abundance observed for some grassland communities was also demonstrated in the alpine meadow. It suggests that seed size depends on the plant growth form, but the biomass-density relationship is inconsistent with previous studies. This suggests that the measure of abundance used in these studies is not the only reason for inconsistency of seed size.

10

Effect of burrowing activity of root vole (Microtus oeconomus Pallas) on plant diversity in alpine meadow

Sun P., Zhao X., Zhu W., Xu S.

Polish Journal of Ecology

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2005

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Vol. 53, nr 4

597-602

EN

Herbivory and burrowing activity of mammals may influence the species composition and diversity of plant communities. The effect of corridors and holes systems constructed by root vole (Microtus oeconomus Pallas) on the plant species diversity was studied in the habitat of high - mountain meadow (3250 m a.s.l in Qinghai-Tibet Plateau, China). By using grid method, these disturbances were studied on 16 plots (100 cm x 100 cm) distributed in 4 transects in studied area, in August 2000 and 2001.The disturbance intensity index, D, was calculated as the percent of the ground surface disturbed by voles in the study area. Plant species were identified and counted on the same plots. In total 46 plant species were identified - 39% of this number was considered as sensitive to the vole disturbances as their occurrence and/or abundance decreased along the disturbance intensity. Generally, a significantly negative correlation (r = - 0.911, P < 0.01) between vole aboveground disturbances and plant species diversity (H') was found. The results suggest that root vole ground disturbances, especially in the form of actively utilized holes and corridors have significantly negative influence on plant species diversity in high-mountain grassland habitat.