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At least 19 recordsLinked to original sources
PubMed2003

[Ecological study on small-middle size soil animals in a compound ecosystem of farmland, grassland and woodland in the grassland region of Songnen Plain].

Based on the method of selecting samples in field, the ecological characters of small-middle size soil animals communities were investigated in a compound ecosystem of farmland, grassland and woodland in the grassland region of Songnen Plain. The results showed that the dominant groups were Hypogastruridae, Actinedida, Gamasida and Oribatida; and the common groups were Isotomidae and Jassidae. From the comparison analysis of farmland, grassland and woodland, the diversity of small-middle size soil animals communities was the highest in grassland, and the habitat in grassland was superior to the other two. The number of individuals and groups of small-middle size soil animals was decreased with increasing soil depth, and the surface gathering was obvious. But, the characteristics of vertical distribution in the three subsystems were different. Using the principal component analysis, the correlations between soil environmental factors and small-middle size soil animals communities and those between climate factors and small-middle size soil animals communities were analyzed. The results showed that soil environmental factors were the dominant factors affecting small-middle size soil animals communities.

Animals↗
PubMed2004

[Function of artificial grassland in restoration of degraded natural grassland and its research advance].

This paper analyzed the degradation actuality of natural grassland, its reasons and corresponding restoration ways. Natural restoration is the easiest way, but it is very slow. The establishment of some artificial grassland is the most effective way to lessen the oppressiveness of natural grassland. The research advances on artificial grassland were summarized, and the ways for promoting the sustainable development of pasturing area were suggested. Considering the high productivity, planting forage maize may be an available attempt in Hunshandak Sandland.

Conservation of Natural Resources↗
PubMed2001

Methane fluxes from differentially managed grassland study plots: the important role of CH4 oxidation in grassland with a high potential for CH4 production.

Methane oxidation fluxes were monitored with the closed chamber method in eight treatment plots on a semi-wet grassland site near Giessen, Germany. The management regimes differed in the amount of nitrogen (NH4NO3) fertilizer applied and in the height of the in-ground water table. No inhibition of CH4 oxidation occurred, regardless of the amount of annual N fertilizer applied. Instead, the mean CH4 consumption rates were correlated with the mean soil moisture of the plots. However, the correlation between daily soil water content and corresponding CH4 oxidation rate was always weak. During drought period (late summer) water stress was observed to restrict CH4 oxidation rates. The findings led to the question whether methane production with soil depth might modify the CH4 fluxes measured at the surface. Therefore, two new methods were applied: (1) soil air sampling with silicone probes; and (2) anaerobic incubations of soil cores to test for the methane production potential of the grassland soil. The probe measurements revealed that the CH4 sink capacity of a specific site was related to the vertical length of its CH4 oxidizing column, i.e. the depth of the CH4 producing horizon. Anaerobically incubated soil cores produced large amounts of CH4 comparable with tropical rice paddy soil. Under field conditions, heavy autumnal rain in 1998 led to a dramatic increase of soil CH4 concentrations upto 51 microliters l-1 at a depth of 5 cm. Nevertheless, no CH4 was released when soil surface CH4 fluxes were measured simultaneously. The results thus demonstrate the high CH4 oxidation potential of the thin aerobic topsoil horizon in a non-aquatic ecosystem.

Agriculture↗
PubMed1993

Response of grassland ecosystem to air pollutants: I-Experimental concept and site of the Braunschweig grassland investigation program.

Between 1984 and 1991 in Braunschweig (South-east Lower Saxony, Germany) experiments concerning the influence of chronic stress by air pollutants to a permanent grassland ecosystem were performed, the conceptual background of which is dealt with in this paper. The site itself, the management practices and treatments applied, and the physical climate are described in detail.

Journal Article↗
PubMed2005

Seed bank composition of open and overgrown calcareous grassland soils--a case study from Southern Belgium.

The success of calcareous grassland recreation following abandonment depends to a large extent on the composition of the soil seed bank. We studied the species richness and composition of the seed bank along a chronosequence from well-developed calcareous grassland to scrub and forest vegetation, which had developed on calcareous grassland over the last 225 years. The seed bank density was highest in the calcareous grassland soils (930 seeds/m(2)). However, the seed bank was mainly composed of rather common species of nutrient poor grassland, which were poorly represented in the surface vegetation. There were no significant differences in soil seed bank density and species composition between the calcareous grassland and scrub vegetation that was less than 15 years old, largely because several grassland species had persisted in the scrub vegetation and were therefore able to replenish the soil seed bank. In contrast seed density and species richness declined significantly after 40 years of grassland abandonment. Indeed, forest soils had the lowest seed densities (214 seeds/m(2)) with only a few grassland species represented. This reflects the lack of grassland species in the field layer of the forest, and, therefore, the lack of seed production and seed bank replenishment. It is clear that recreation of calcareous grassland on long abandoned sites cannot rely on germination of target species from the seed bank alone. Even in the calcareous grassland soil, seeds of target species are not abundant as the majority produces transient seeds, which decay rapidly if they do not germinate immediately. Successful grassland recreation on such sites therefore may require seeds of target species to be introduced artificially (e.g. as seed mixtures, green hay, etc.). Alternatively, reinstatement of traditional practices, such as grazing or mowing, will increase the natural dispersal potential of these species, allowing population reestablishment in the long term.

Belgium↗
PubMed2002

[Characteristics of vegetation, soil, and their coupling of degraded grasslands].

This paper presented the characteristics of the vegetation, soil, and their coupling in the gradient of grazing pressure of the degraded alpine grassland in Sunan county and of the typical arid grassland in Huanxian county, Gansu province. The abundance index of species, Simpson index, Shannon-Wiener index, Cody index, nutrient functional diversity index and life type diversity index increased, while the Bray-Curtis index and nitrogen fixation diversity index decreased with the reduced grazing intensity in both types of degraded grassland. With reduced grazing pressure, the contents of total nitrogen, available nitrogen and organic matter in both grasslands and the content of available phosphorus in arid grassland at 0-40 cm soil depth were increased, and that of total phosphorus in alpine grassland was decreased, while phosphorus concentration in arid grassland showed no regular pattern of change. The total and available nitrogen, available phosphorus and the ratio of available phosphorus to total phosphorus and of organic carbon to nitrogen were all higher in alpine grassland than in arid grassland. The grey correlativity of vertical distribution pattern between soil elements and living root biomass was positively related to grazing pressure, while the coupling intensity of soil-herbage subsystem was increased with decreased grazing pressure. There existed a significant correlation between poor soil elements and abundance of poisonous and poor-nutritional plants in both degraded grasslands. The degradation process of grassland resulted not only from the degeneration of vegetation and soil subsystems, but also from the disappearance of coupling between both subsystems and the development of their discordance. The ecological process could be quantified by coupling intensity and discordance intensity. It is concluded that the studied arid grassland was degraded more seriously than alpine grassland.

China↗
PubMed2005

Genetic diversity in perennial ryegrass and white clover among old Dutch grasslands as compared to cultivars and nature reserves.

To support conservation policies for old Dutch grasslands that are still in agricultural use, morphological variation and AFLP-based (amplified fragment length polymorphism-based) genetic diversity was studied in perennial ryegrass and white clover populations and compared with the diversity in reference varieties. In addition, AFLP variation was also studied in grasslands located in nature reserves. From principal component analysis (PCA), it appeared that date of ear emergence in perennial ryegrass and characters related to plant vigour in white clover were the main morphological characters separating the reference varieties from the old Dutch grassland populations, and some of the grassland populations from each other. In both species, intrapopulation variation was lower for the reference varieties. Lower heterogeneity within the reference varieties was also found in the AFLP analysis. All common AFLP's observed in old Dutch grasslands could also be found in the reference varieties and nature reserves. Only a small number of low-frequency alleles found in old Dutch grasslands were absent from the other two groups. However, band frequencies of markers could vary considerably between populations, which may have been caused by selection. Analysis of the AFLP data by PCA distinguished the majority of reference varieties from the old Dutch grasslands, and showed genetic differentiation only between some grasslands. Comparison of old Dutch grasslands with grasslands in nature reserves indicated that basically the same range of genetic variation is covered by the two groups. Our study indicates that the Netherlands harbour a more or less continuous population for major parts of the diversity of perennial ryegrass and white clover. It was concluded that no specific conservation measures are presently needed to maintain genetic diversity of perennial ryegrass and white clover occurring in old Dutch grasslands.

Biodiversity↗
PubMed2002

[Perspectives in researches on grassland ecology for the early 21st century in China].

Grassland degeneration is a prominent problem in China. More in-depth studies should be carried out on the key problem--grassland degeneration for Chinese grassland ecologists in the early 21st century. Some hot research fields were restoration ecology, interface ecology, grazing ecology, health diagnoses and evaluation for grasslands. Among them, restoration ecology was the foundation for restoring degenerative grasslands; interface ecology involved with the point of contact for analyzing degenerative grasslands; grazing ecology was the effective way to control degenerative grasslands; diagnoses of grassland health benefited accurately appraising degenerative levels of grasslands; and evaluation for grassland was also considered as an estimation on services and benefits of grassland ecosystems.

China↗
PubMed2004

Effectiveness of voluntary habitat stewardship in conserving grassland: case of operation burrowing owl in Saskatchewan.

There have been no published performance evaluations of nongovernmental, voluntary habitat stewardship programs. The Operation Burrowing Owl (OBO) stewardship program, initiated in 1987, was evaluated for its effectiveness in conservation of grassland habitat during 1986-1993. The 108 OBO sites from 1987 to 88 and 98 randomly selected non-OBO sites that were grassland in 1986 in the Regina-Weyburn, Saskatchewan study area were classified by size and agricultural soil suitability. By 1993, 41 (38%) of the 108 OBO sites had been withdrawn from the program. The 1986 area of grassland was compared with grassland area calculated from digitized 1993 LANDSAT imagery. A correction for satellite inaccuracies was determined. Grassland retention in 1993 was significantly higher at OBO sites (66%) than at random sites (49%), demonstrating that the OBO voluntary program effectively conserved habitat. Also, grassland retention was significantly lower on sites with better agricultural soils, and for sites <12 ha in size. Site type (OBO or random), size and their interaction, followed by agricultural soil suitability, had the greatest effects on grassland retention. During an era of accelerated grassland loss, OBO strongly and positively (statistically significant) affected conservation of grassland sites most at risk: sites <12 ha in size and with good to excellent agricultural soils. This suggests that grassland conservation efforts focus on vulnerable sites (small size and/or good agricultural soils) to provide nesting habitat for burrowing owls. Our study demonstrates that a voluntary stewardship program can significantly increase conservation of habitat.

Agriculture↗
PubMed2000

Estimation of Nitrous Oxide Emissions from US Grasslands.

/ Nitrous oxide (N(2)O) emissions from temperate grasslands are poorly quantified and may be an important part of the atmospheric N(2)O budget. In this study N(2)O emissions were simulated for 1052 grassland sites in the United States using the NGAS model of Parton and others (1996) coupled with an organic matter decomposition model. N(2)O flux was calculated for each site using soil and land use data obtained from the National Resource Inventory (NRI) database and weather data obtained from NASA. The estimates were regionalized based upon temperature and moisture isotherms. Annual N(2)O emissions for each region were based on the grassland area of each region and the mean estimated annual N(2)O flux from NRI grassland sites in the region. The regional fluxes ranged from 0.18 to 1.02 kg N(2)O N/ha/yr with the mean flux for all regions being 0.28 kg N(2)O N/ha/yr. Even though fluxes from the western regions were relatively low, these regions made the largest contribution to total emissions due to their large grassland area. Total US grassland N(2)O emissions were estimated to be about 67 Gg N(2)O N/yr. Emissions from the Great Plains states, which contain the largest expanse of natural grassland in the United States, were estimated to average 0.24 kg N(2)O N/ha/yr. Using the annual flux estimate for the temperate Great Plains, we estimate that temperate grasslands worldwide may potentially produce 0.27 Tg N(2)O N/yr. Even though our estimate for global temperate grassland N(2)O emissions is less than published estimates for other major temperate and tropical biomes, our results indicate that temperate grasslands are a significant part of both United States and global atmospheric N(2)O budgets. This study demonstrates the utility of models for regional N(2)O flux estimation although additional data from carefully designed field studies is needed to further validate model results.

Journal Article↗
PubMed2006

Landscape composition and habitat area affects butterfly species richness in semi-natural grasslands.

During the last 50 years, the distribution and abundance of many European butterfly species associated with semi-natural grasslands have declined. This may be the result of deteriorating habitat quality, but habitat loss, resulting in decreasing area and increasing isolation of remaining habitat, is also predicted to result in reduced species richness. To investigate the effects of habitat loss on species richness, we surveyed butterflies in semi-natural grasslands of similar quality and structure, but situated in landscapes of different habitat composition. Using spatially explicit habitat data, we selected one large (6-10 ha) and one small (0.5-2 ha) grassland site (pasture) in each of 24 non-overlapping 28.2 km(2) landscapes belonging to three categories differing in the proportion of the area that consisted of semi-natural grasslands. After controlling for local habitat quality, species richness was higher in grassland sites situated in landscapes consisting of a high proportion of grasslands. Species richness was also higher in larger grassland sites, and this effect was more pronounced for sedentary than for mobile species. However, the number of species for a given area did not differ between large and small grasslands. There was also a significant relationship between butterfly species richness and habitat quality in the form of vegetation height and abundance of flowers. In contrast, butterfly density was not related to landscape composition or grassland size. When species respond differently to habitat area or landscape composition this leads to effects on community structure, and nestedness analysis showed that depauperate communities were subsets of richer ones. Both grassland area and landscape composition may have contributed to this pattern, implying that small habitat fragments and landscapes with low proportions of habitat are both likely to mainly contain common generalist species. Based on these results, conservation efforts should aim at preserving landscapes with high proportions of the focal habitat.

Animals↗
PubMed2004

[Features of grassland resources and their classified management in Alatai region of Xinjiang].

Grassland degradation, an important problem in grassland management, has affected the sustainable development of animal husbandry in Alatai region of Xinjiang. Based on the analysis of the community features, ecological service value and multiple functions, and main function of grassland types in the regional development, the classified management for grassland was designed. The results showed that Alatai grassland could be divided into three sectors, i.e., ecological function region, economic function region and mixed function region. The ecological function region made up 164.66 x 10(4) hm2 or 16.73% of total Alatai grassland, and the grassland types included alpine meadow, alpine rangeland, swamp, mountain desert steppe, mountain steppe desert and part of plain desert. For the ecological function region, the main management strategy was to prohibit grazing and cropping. The economic function region of 116.33 x 10(4) hm2 accounted for 11.82% of the total Alatai grassland, the grassland types included mountain meadow, flat meadow and meadow steppe, and the main management strategy to enhance the productivity was agricultural measures, such as fertilization and irrigation. The mixed function region which included mountain steppe, plain desert steppe and most part of plain desert was 703.21 x 10(4) hm2 or 71.45% of total Alatai grassland, and the main management strategy was rotational grazing.

Animal Husbandry↗
PubMed2000

Amino acids as a nitrogen source in temperate upland grasslands: the use of dual labelled ((13)C, (15)N) glycine to test for direct uptake by dominant grasses.

It is becoming increasingly apparent that soil amino acids are a principal source of nitrogen (N) for certain plants, and especially those of N-limited environments. This study of temperate upland grasslands used glycine-2-(13)C-(15)N and ((15)NH4)(2)SO(4) labelling techniques to test the hypothesis that plant species which dominate 'unimproved' semi-natural grasslands (Festuca-Agrostis-Galium) are able to utilise amino acid N for growth, whereas those plants which dominate 'improved' grasslands (Lolium-Cynosurus), that receive regular applications of inorganic fertiliser, use inorganic N forms as their main N source. Data from field experiments confirmed that 'free' amino acids were more abundant in 'unimproved' than 'improved' grassland and that glycine was the dominant amino acid type (up to 42% of total). Secondly, the injection of representative amounts of glycine-2-(13)C-(15)N (4.76 and 42.86 mM) into intact soil cores from the two grassland types provided evidence of direct uptake of glycine by plants, with both (15)N and (13)C being detected in plant material of both grasslands. Finally, a microcosm experiment demonstrated no preferential uptake of amino acid N by the grasses which dominate the grassland types, namely Holcus lanatus, Festuca rubra, Agrostis capillaris from the 'unimproved' grassland, and Lolium perenne from the 'improved' grassland. Again, both (13)C and (15)N were detected in all grass species suggesting uptake of intact glycine by these plants.

Amino Acids↗
PubMed2006

Drought effects on above- and belowground production of a grazed temperate grassland ecosystem.

The effect of climatic variation on terrestrial aboveground productivity (ANPP) has been well studied. However, little is known about how variable climate, including drought, may influence belowground productivity (BNPP), which constitutes most of the annual primary production of grasslands. The objectives of this study were to (1) examine how a 3-year period of declining moisture, which began as climatically wet to average across Yellowstone National Park (YNP) and ended in drought, affected ANPP and BNPP in grasslands of YNP and (2) how herds of grazing ungulates, which were shown previously to stimulate grassland shoot and root growth in YNP, may have interacted with climatic conditions to influence grassland production. ANPP and 0-20 cm BNPP, representing the bulk of the root dynamics, were measured in grazed and ungrazed (fenced) grassland at nine sites ranging widely in elevation, soil conditions and plant production during the 3-year study. Results revealed that 0-20 cm BNPP was strongly influenced by drought (P = 0.0005) and declined from 1999 to 2001 among ungrazed and grazed grasslands by 39 and 49%, respectively. The greater reduction in 0-20 cm BNPP among grazed grasslands was due, in part, to a decline (P = 0.07) in the stimulatory effect of grazing, i.e., the ratio g BNPP stimulated: g shoot consumed. In contrast, ANPP was unaffected by drought in either type of grassland. Thus, the effect of this drought in YNP was a large reduction in BNPP, which was a function of (1) a direct negative influence of increased moisture stress on root growth and (2) a weak interaction between drought and herbivory that led to a decline in the positive feedback from grazers to BNPP. These findings highlight the need to better understand factors that control root growth and to study the effects of climatic variation on grasslands within an ecosystem framework to include potentially important climate-consumer interactions.

Animals↗
PubMed2006

A comparison of landscapes occupied by increasing and decreasing populations of grassland birds.

For several decades, many grassland bird species have been declining in abundance throughout the Midwest and Great Plains regions of the United States, possibly due to loss of natural grassland habitat and increasing urbanization. I used 20 years of data from the North American Breeding Bird Survey to identify increasing, decreasing, and stable populations of 36 grassland-nesting bird species. I characterized the immediate landscape (circle with radius = 30 km) surrounding each population based on data from the National Resources Inventory. For each landscape, I calculated the proportion of eight different land-cover types: restored grassland, rangeland, cultivated cropland, pasture, noncultivated cropland, forest, urban land, and water. Using a null model, I compared landscape composition of increasing, decreasing, and stable populations. As predicted on the basis of the habitat preferences of grassland birds, increasing populations inhabited landscapes that contained significantly more restored grassland and rangeland but significantly less forest land and urban land than landscapes inhabited by decreasing populations. There was no significant difference in the proportion of cropland within the landscapes of increasing and decreasing populations, although cropland composed a large proportion (>30%) of many landscapes. In contrast, restored grassland typically composed a very small proportion (<3.5%) of total land cover, yet it was significantly more common in the landscapes of increasing than decreasing populations. These results suggest that grassland birds may benefit from government initiatives, such as the Conservation Reserve Program, that promote the restoration of grassland at a landscape scale.

Agriculture↗
PubMed2004

[Effect of grazing on grassland under protective plantation in the ecotone between agriculture and animal husbandry or Songnen plain].

Based on the current special position that grassland under protective plantation is one of the most important grazing spaces of the ecotone between agriculture and animal husbandry in Songnen plain, an experiment was conducted to investigate the effect of grazing on grassland under protective plantation. The results showed that no-grazing grassland in the grassland under protective plantation was seriously degenerated, but light and moderate grazing could stimulate the growth of grass and the product and quality of grassland. The index of grassland quality (IGQ) of no-grazing grassland was the lowest (15.51), attributing to serious degradation, while that of light grazing grassland was the highest (86.41), and the IGQ was decreased with increasing grazing intensity. Therefore, in order to stimulate the grass growth of the grassland, fully utilize the leaves of poplar, and increase the available forage resources, light and moderate grazing intensity should be advocated, but no-grazing and extreme grazing should be avoided.

Animal Husbandry↗
PubMed2006

A preliminary survey of the arbuscular mycorrhizal status of grassland plants in southern Tibet.

We report for the first time the arbuscular mycorrhizal (AM) status of native plant species and AM fungal diversity in the grasslands of southern Tibet. A total of 51 soil samples were collected from the rhizospheres of the dominant plant species, and AM fungal structures were observed in 18 (82%) of 22 plant species examined. Vesicles and aseptate hyphae were the structures most frequently observed in the plant roots. After trap culture for 5 months, 25 AM fungal taxa were identified in the soil samples collected, of which nine belonged to Glomus, ten to Acaulospora, one to Entrophospora and five to Scutellospora. The frequency of occurrence of different genera and species varied greatly. Glomus was the dominant genus, and the most frequent and abundant species was Glomus mosseae. Over the whole sampling area, spore density in the rhizosphere soil of different host plant species ranged from 2 to 66 per 20 g air-dried soil. Overall AM fungal species richness was 2.10 and species diversity was 2.35. AM fungal diversity was also compared among the four different land use types (farmland and normal, disturbed and highly disturbed montane scrub grassland). Spore densities in the farmland and normal grassland were much higher than in the grasslands that had been degraded to varying degrees. The species richness in normal grassland was the highest of the four land use types examined. Species diversity varied from 1.99 to 0.94 and was highest in normal grassland, intermediate in degraded grassland and farmland, and lowest in the highly disturbed grassland.

Biodiversity↗
PubMed1987

Selenium contamination of the Grasslands, a major California waterfowl area.

In a recent study at Kesterson Reservoir in California, selenium was shown to cause mortality and deformities in embryos of aquatic birds. The present study was conducted to determine if selenium or other contaminants in agricultural drainwater used for marsh management were likely to cause similar adverse effects in the nearby Grasslands area. Selenium concentrations were elevated (greater than 15 ppm, dry-weight) in livers of some birds of all species collected from the Grasslands. Mean selenium concentrations in all species sampled in the South Grasslands were significantly higher (P less than 0.05) than those from the "control site", the Volta Wildlife Area. Mean selenium levels in black-necked stilts (Himantopus mexicanus) from the South Grasslands (35.6 ppm) were similar (P greater than 0.05) to levels in stilts from Kesterson (46.4 ppm), but means for American avocets (Recurvirostra americana) from the South Grasslands (67.3 ppm) were higher (P less than 0.05) than those from Kesterson (28.4 ppm). Bird eggs and fish from the Grasslands also contained elevated levels of selenium. Concentrations of eight heavy metals in fish generally reflected those patterns previously found in water entering the study areas. Of the organochlorines detected in fish, only DDE occurred at concentrations potentially harmful to birds (6.1 and 3.0 ppm, wet weight, at two South Grassland sites). The effect on avian health or reproduction of the other contaminants, singly or in combination, could not be determined. However, selenium levels were apparently sufficiently elevated in 1984 to have caused adverse effects on avian reproduction in the South Grasslands.

Animals↗