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"Steppes"
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Sunflower I for Steppe and Dry Steppe Growing Conditions
The dynamics of the productivity of the sunflower hybrid “Baiterek 17” were studied for rainfed conditions of the steppe and dry steppe zones of Kazakhstan for two fertilizer levels (without fertilizers and with the application of a nitrogen-phosphorous fertilizer), two sowing dates, and three seeding rates. The growing season duration varied among zones and was affected by sowing dates. An increase in duration (3–5 days) was observed for the early sowing date and fertilized treatments, regardless of the zone. Increasing the seeding rate for all treatments by sowing date and fertilizer application reduced the duration of the growing season by 3–6 days. The fertilizer application did not affect the formation of seedlings in the study areas. In the dry steppe zone, from 2.5 to 4.8 plants/m[sup.2] were formed before harvesting, with an increase in the number of plants at the high seeding rate (57,000 seeds/ha). In the steppe zone, the same pattern was preserved: from 3.5 to 4.9 plants/m[sup.2] at a seeding rate of 65 thousand seeds/ha. The maximum diameter and weight of the flower head were found for the early sowing date and fertilized treatments at a low seeding rate, with a strong effect on the yield for both the steppe and dry steppe zones in 2022. On average, for both years, the highest yield for the dry steppe zone was obtained for the sowing date of 15 May and at a seeding rate of 57,000 seeds/ha, while for the steppe zone, the highest yield was obtained for the 10 May planting date and at a sowing rate of 65,000 seeds/ha. Improving plant nutrition and increasing the plant density up to a seeding rate of 65,000 seeds/ha for the early sowing dates (10 May) increased the plasticity in the steppe zone. For the dry steppe zone, the plasticity of the hybrid decreased, but the highest plasticity was also obtained for an earlier sowing date (15 May) and at a seeding rate of 57,000 seeds/ha crop. The study shows that the hybrid “Baiterek 17” has a high ecological plasticity under changing environmental conditions and, with an increase in moisture availability, it requires intensive agricultural practices (fertilization, increased seeding rate, and early sowing dates) to obtain a high yield.
Journal Article
Effect of Stocking Rate on Soil-Atmosphere CH.sub.4 Flux during Spring Freeze-Thaw Cycles in a Northern Desert Steppe, China
Methane (CH.sub.4) uptake by steppe soils is affected by a range of specific factors and is a complex process. Increased stocking rate promotes steppe degradation, with unclear consequences for gas exchanges. To assess the effects of grazing management on CH.sub.4 uptake in desert steppes, we investigated soil-atmosphere CH.sub.4 exchange during the winter-spring transition period. The experiment was conducted at twelve grazing plots denoting four treatments defined along a grazing gradient with three replications: non-grazing (0 sheep/ha, NG), light grazing (0.75 sheep/ha, LG), moderate grazing (1.50 sheep/ha, MG) and heavy grazing (2.25 sheep/ha, HG). Using an automatic cavity ring-down spectrophotometer, we measured CH.sub.4 fluxes from March 1 to April 29 in 2010 and March 2 to April 27 in 2011. According to the status of soil freeze-thaw cycles (positive and negative soil temperatures occurred in alternation), the experiment was divided into periods I and II. Results indicate that mean CH.sub.4 uptake in period I (7.51 [micro]g CH.sub.4 -C m.sup.-2 h.sup.-1) was significantly lower than uptake in period II (83.07 [micro]g CH.sub.4 -C m.sup.-2 h.sup.-1). Averaged over 2 years, CH.sub.4 fluxes during the freeze-thaw period were -84.76 [micro]g CH.sub.4 -C m.sup.-2 h.sup.-1 (NG), -88.76 [micro]g CH.sub.4 -C m.sup.-2 h.sup.-1 (LG), -64.77 [micro]g CH.sub.4 -C m.sup.-2 h.sup.-1 (MG) and -28.80 [micro]g CH.sub.4 -C m.sup.-2 h.sup.-1 (HG). CH.sub.4 uptake activity is affected by freeze-thaw cycles and stocking rates. CH.sub.4 uptake is correlated with the moisture content and temperature of soil. MG and HG decreases CH.sub.4 uptake while LG exerts a considerable positive impact on CH.sub.4 uptake during spring freeze-thaw cycles in the northern desert steppe in China.
Journal Article
The edge of two worlds: A new review and synthesis on Eurasian forest-steppes
Aims: Eurasian forest-steppes are among the most complex non-tropical terrestrial ecosystems. Despite their considerable scientific, ecological and economic importance, knowledge of forest-steppes is limited, particularly at the continental scale. Here we provide an overview of Eurasian forest-steppes across the entire zone: (a) we propose an up-to-date definition of forest-steppes, (b) give a short physiogeographic outline, (c) delineate and briefly characterize the main forest-steppe regions, (d) explore forest-steppe biodiversity and conservation status, and (e) outline forest-steppe prospects under predicted climate change. Location: Eurasia (29°–56°N, 16°–139°E). Results and Conclusions: Forest-steppes are natural or near-natural vegetation complexes of arboreal and herbaceous components (typically distributed in a mosaic pattern) in the temperate zone, where the co-existence of forest and grassland is enabled primarily by the semi-humid to semi-arid climate, complemented by complex interactions of biotic and abiotic factors operating at multiple scales. This new definition includes lowland forest–grassland macromosaics (e.g. in Eastern Europe), exposure-related mountain forest-steppes (e.g. in Inner Asia), fine-scale forest-grassland mosaics (e.g. in the Carpathian Basin) and open woodlands (e.g. in the Middle East). Using criteria of flora, physiognomy, relief and climate, nine main forest-steppe regions are identified and characterized. Forest-steppes are not simple two-phase systems, as they show a high level of habitat diversity, with forest and grassland patches of varying types and sizes, connected by a network of differently oriented edges. Species diversity and functional diversity may also be exceptionally high in forest-steppes. Regarding conservation, we conclude that major knowledge gaps exist in determining priorities at the continental, regional, national and local levels, and in identifying clear target states and optimal management strategies. When combined with other threats, climate change may be particularly dangerous to forest-steppe survival, possibly resulting in compositional changes, rearrangement of the landscape mosaic or even the latitudinal or altitudinal shift of forest-steppes.
Journal Article
