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Grassland
Abstract
Grassland vegetation is dominated by grasses, which covers one quarter of earth land, while legumes are the second most important species. Consumption of milk, meat, and eggs has substantially increased in past decades especially in developing countries. To meet the increasing demand of animal-based food, forage and feed production need to be increased simultaneously. Grasslands are the principal source of livestock feed, and management decisions play significant roles on the productivity and sustainability of grasslands. Animal grazing improves pasture productivity and long-term farm profitability. Hay and silage can provide nutrients to grazing animals when forage is limited. Grasslands provide habitat for wildlife and are considered an important source of carbon stored in the vegetation and soil. Grasslands significantly contribute to the climate and ecosystems and ultimately to the sustainability of the world.
... Grasslands, defined as ecosystems in which the dominant vegetation is composed by herbaceous species , are of great ecological value since they provide food for livestock, habitat for wildlife and improve soil quality and productivity Saha & Butler, 2017), storing 10-30 % of global SOM (Eswaran et al., 1993). Management practices such as burning can influence soil C sequestration since they can alter the rates of SOM inputs, its composition and how it is incorporated into the soil . ...
... Grasslands, defined as ecosystems in which the dominant vegetation is composed by herbaceous species (Jones and Donelly, 2004), are of great ecological value since they provide food for livestock, habitat for wildlife and improve soil quality and productivity (Follett and Reed, 2010;Saha and Butler, 2017), storing 10-30% of global SOM (Eswaran et al., 1993). Management practices such as burning can influence soil C sequestration since they can alter the rates of SOM inputs, its composition and how it is incorporated into the soil (Jones and Donelly, 2004;Follett and Reed, 2010). ...
Prescribed burning has been readopted in the last decade in the Central Pyrenees to stop the regression of subalpine grasslands in favour of shrublands, dominated among others by Echinospartum horridum (Vahl) Rothm. Nevertheless, the effect of this practice on soil properties is uncertain. The aim of this work was to analyse the effects of these burnings on topsoil organic matter and biological properties. Soil sampling was carried out in an autumnal prescribed fire in Buisán (NE-Spain, November 2015). Topsoil was sampled at 0–1 cm, 1–2 cm and 2–3 cm depth in triplicate just before (U), ~ 1 h (B0), 6 months (B6) and 12 months (B12) after burning. We analysed soil total organic C (TOC), total nitrogen (TN), microbial biomass C (Cmic), soil respiration (SR) and β-D-glucosidase activity. A maximum temperature of 438 °C was recorded at soil surface while at 1 cm depth only 31 °C were reached. Burning significantly decreased TOC (− 52%), TN (− 44%), Cmic (− 57%), SR (− 72%) and β-D-glucosidase (− 66%) at 0–1 cm depth while SR was also reduced (− 45%) at 1–2 cm depth. In B6 and B12, no significant changes in these properties were observed as compared to B0. It can be concluded that the impact of prescribed burning has been significant and sustained over time, although limited to the first two topsoil centimetres.
The grasslands in the Third Pole of the World (TPW) or Qinghai-Tibetan Plateau take very important positions in the global context. The TPW is the largest distribution area of the global alpine grassland, which is an important gene pool of alpine biological resources. The diverse types of TPW/QTP’s grasslands enrich the worldwide grassland biome in Eurasia and the world. The TPW/QTP’s grasslands cover two critical ecoregions for conserving the best and most representative habitats for alpine biodiversity on the planet. The TPW/QTP’s grassland is also regarded as one of the best carriers and objects of the social-ecological system of pastoralism in the world. In this chapter, an overview of global grasslands and TPW/QTP’s grasslands is synthesized, the importance of TPW/QTP’s grasslands in regional and global settings is emphasized, and the values of TPW/QTP’s grasslands in ecological and socioeconomic dimensions are stressed. We highlight that the sustainability of the TPW/QTP’s grasslands is key to maintaining and promoting their functions and structures.
Red clover (Trifolium pratense L.) is an important perennial forage crop in Europe. Unfortunately, seed production of modern cultivars is often unsatisfactory and breeding progress for higher seed yield is slow. We evaluated whether marker assisted parentage analysis could identify progeny plants with two high seed-yielding parents in a diploid selection trial. Furthermore, we studied if breeding for high seed yield could be speeded up by selecting progeny plants with two high seed-yielding parents, compared to traditional selection on the mother plant only. In this study, 111 genotypes with excellent vegetative traits from a first cycle selection trial were allowed to pollinate each other in isolation. After seed harvest, ten high seed-yielding plants were identified and their seeds were used to grow ten half-sib progeny populations, with 1,121 plants in total. Two multiplex primer sets targeting 18 SSR loci were designed and used to fingerprint parental and progeny plants.
Parentage was reliably determined for 1,083 progeny plants: 135 plants were the result of a cross between two high seed-yielding parents. In a 2-year seed yield trial, the seed yield of these 135 progeny plants was compared to that of a control group of 216 progeny plants from the same ten high seed-yielding mother plants but with no selection on the male contribution, as is current practice. Compared to the control group, progeny plants with two high seed-yielding parents had significantly higher seed yields, 23.0 and 75.9 % higher in 2012 and 2013 respectively, and a significantly higher thousand seed weight, 6.6 and 5.7 % higher in 2012 and 2013 respectively. Seed yield was strongly correlated with flower abundance (r = 0.643) and plant volume (r = 0.593 in 2012 and r = 0.509 in 2013) and negatively correlated with susceptibility to mildew (r = -0.145). We conclude that breeding programs aiming at increasing seed yield in diploid red clover cultivars would strongly benefit from the integration of marker assisted parentage analysis to identify those progeny plants that are the result of a cross between two high seed-yielding plants. This goal cannot be achieved with traditional family selection
where only the seed yield of the mother plant is known.
Grassland covers approximately one-third of the area of the Loess Plateau and plays an important role in the carbon (C) and nitrogen (N) cycles. This study was conducted to estimate the C and N storage of grassland ecosystems under different climates (semi-humid, semi-arid and arid). Results indicated that about 90% of the ecosystem C and N were stored in the soil. Soil organic carbon (SOC) density of grasslands in different climatic zones decreased in the order, semi-humid (53.34 Mg C ha−1) > semi-arid (50.22 Mg C ha−1) > arid (19.13 Mg C ha−1) climatic zone. Also, grassland in the semi-humid climatic zone had the highest belowground biomass C (1.01 Mg C ha−1) and N (0.25 Mg N ha−1) density; whereas grassland in the semi-arid climatic zone had the highest aboveground biomass C (1.06 Mg C ha−1) and N (0.26 Mg N ha−1) density. C and N storage of grassland ecosystem in the arid climatic zone was significantly lower than that in the other two climatic zones (p < 0.05). The vegetation community density, cover, and richness, above- and belowground biomass, and climatic factors significantly influenced the C and N distribution in this region (p < 0.05). The mean annual precipitation emerged as the most important variable for C and N accumulation. Grassland with mean annual precipitation of 350–630 mm might have high C and N sequestration potential. Results of this study provide reliable reference information for predicting C and N dynamics in similar agroecological systems.