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31.
Steppe-like dry (semi) natural grasslands are valuable and endangered habitats in central Europe. In the study area (the ?eské st?edoho?í Hills, Czech Republic), they occur in fragments on southern slopes of volcanic hills, often in the vicinity of quarries, which are numerous there. We performed sowing experiments and observed seedling recruitment of six species, typical for the dry grasslands, in 9 basalt quarries located in 3 different climatic regions over 3 yr. The sowing experiments were established in young successional stages, 5–12 yr after quarrying was stopped. The objectives of the experiments were to evaluate: (i) if seedling recruitment and survival of the target species are possible regarding different climatic regions and (ii) what is the influence of weather fluctuations among years on seedling survival. Seedlings of all studied species were able to recruit and survive in the early successional stages at least in some quarries. The species, except one, showed significant differences in recruitment among the climatic regions, with the best recruitment and survival in the driest and warmest region. Seedlings of two species did not recruit in the wettest and coldest region. All species survived in the driest and warmest region, while only one did so in the coldest and wettest region. Different weather conditions in the studied years significantly influenced recruitment of two species. The number of localities (floristic records) of particular species in the regions was the best predictor of species germination and survival. Thus a traditional floristic survey may help to predict success of species in restoration projects. It emerged that artificial sowing can be considered in restoration programs as a way of contributing to restoration of dry grasslands in disused quarries. 相似文献
32.
Moisture Effects on Temperature Sensitivity of CO<Subscript>2</Subscript> Exchange in a Subarctic Heath Ecosystem 总被引:1,自引:1,他引:0
Lotte?IllerisEmail author Torben?R?jle?Christensen Mihael?Mastepanov 《Biogeochemistry》2004,70(3):315-330
Carbon fluxes between natural ecosystems and the atmosphere have received increased attention in recent years due to the impact they have on climate. In order to investigate independently how soil moisture and temperature control carbon fluxes into and out of a dry subarctic dwarf shrub dominated heath, monoliths containing soil and plants were incubated at three different moisture levels and subjected to four different temperature levels between 7 and 20 °C. Ecosystem CO2 exchange was monitored continuously day and night during the 16 to 18 days that each of three experiments lasted. Additionally, the carbon allocation pattern of the plants was investigated by labelling monoliths with 14CO2 followed by harvest of above and below ground plant parts. The results revealed that the three different soil moisture levels caused distinctly differing levels of CO2 fluxes. Also, both carbon fixation calculated as gross ecosystem production (GEP) and carbon release measured as ecosystem respiration (ER) increased with increasing temperatures, with ER increasing faster than GEP. Hence, short term carbon loss from the ecosystem accelerated with raised temperatures. Temperature sensitivity of the ecosystem was dependent on the soil moisture level, shown by differing Q10 values of both GEP and ER at different soil moisture levels. It is therefore highly important to take soil moisture levels into consideration when evaluating responses of ecosystem carbon balance to changes in temperature. The greatest C fixation took place via the two most dominant species of the ecosystem, Vaccinium uliginosum and Empetrum hermaphroditum, with the former being responsible for the different size of C fixation at the three moisture levels. 相似文献
33.
Ogawa K 《Journal of plant research》2002,115(6):449-453
The carbon balance in reproductive organs over the whole reproductive period was estimated for 20 woody species on the basis
of the published data on the final dry weight and CO2 exchange of reproductive organs. The relationship between net respiration and dry weight growth was formulated by a linear
function with a negative y-intercept. From this linear relationship, linear relations of dry weight growth and net respiration to net translocation
were derived. The size dependence of net respiration showed that the net respiration changed from negative to positive as
the final dry weight of the reproductive organ exceeded 0.481 g. The cost for translocation per unit dry weight was much lower
in the species with small reproductive organs (<0.481 g) because of their photosynthetic contribution to the weight growth.
The relation of dry weight growth/net translocation ratio to net translocation was expressed as a hyperbolic function. The
dry weight growth/net translocation ratio remained at 0.650, in the higher range of net translocation, irrespective of woody
species.
Electronic Publication 相似文献
34.
播种季节对玉米生长发育及干物质生产和分配的影响 总被引:11,自引:0,他引:11
1996-1997年,在蒙自坝对春、夏、秋、冬四季玉米的生长发育和干物质生产与分配进行了系统研究,结果表明:1冬玉米生育最长达171天,而夏玉米只有101天。2.春玉米花丝期的生产了较多的干物质,其它的则是花线期后生产的干物质更多,干物质生产量与日照时数和LAI的乘积正相关。3.灌浆期籽粒重占总增重的比例与各季玉米灌浆期≥10℃的积温正相关。4.春玉米籽生产除灌浆期的光合产物外,动用了前期贮存物的11.1%,其他玉米完全依赖于灌浆期的光合产物,并且不同比例光合产物贮存于营养体中。说明其玉米的产量受限于灌浆期的光合产物,其它玉米则受库容小或运输不畅的限制。 相似文献
35.
36.
Effects of enhanced ultraviolet-B radiation on plant nutrients and decomposition of spring wheat under field conditions 总被引:17,自引:0,他引:17
Spring wheat (Triticum aestivum) was grown in the field under ambient and supplemental levels of ultraviolet-B (UV-B, 280–315 nm) radiation to determine the potential for alteration in plant nutrients, decomposition, leaf quality and dry matter yield. Supplemental UV-B radiation simulating a 12, 20 and 25% stratospheric ozone depletion significantly decreased dry matter yield, but had no significant impact on harvest index. UV-B radiation resulted in an increase of the concentrations of N and K in all plant parts; changes of the concentrations of P, Mg, Fe and Zn varied in a tissue-dependent manner, as the decrease of P in leaves and stems, and its increase in spikes and grains. The mass of N, P, K, Mg, Fe and Zn in various plant parts and whole plant was generally decreased except leaf N mass was increased by enhanced UV-B radiation. Enhanced UV-B radiation decreased the concentrations of soluble carbohydrates in leaves and increased that of holocellulose and soluble proteins. After 60 and 100 days of decomposition of leaves and stems in the field, enhanced UV-B radiation stimulated the loss of organic C. As a consequence, the nutrient content of soils might be less diminished under enhanced UV-B radiation. 相似文献
37.
Sweet flag (Acorus calamus L.) and yellow flag (Iris pseudacorus L.) have been used increasingly in constructed wetlands (CWs) for treatment of eutrophic wastewater. In order to properly match plant species with the type of wastewater being treated, it is important to know the performance of plant species under different NO3−/NH4+ ratios. We investigated dry matter (DW) production and N content of A. calamus and I. pseudacorus under five NO3−/NH4+ ratios (100/0, 75/25, 50/50, 25/75, and 0/100) in a hydroponic system. Results showed that the two species exhibited different preferences for NO3− and NH4+. Total DW, shoot DW, and N content were greater with NO3−/NH4+ ratios of 50/50 and 75/25 than otherwise for A. calamus, but these parameters were only higher under the sole NO3− treatment in I. pseudacorus. We conclude that A. calamus could be best used for treating wastewater in constructed wetlands with NO3−/NH4+ ratios between 50/50 and 75/25, while I. pseudacorus for treating wastewater with NO3− only to achieve the highest biomass production and efficiency in the removal of N. 相似文献
38.
In this work we assessed spatial and temporal variation of leaf pigment content of Clusia hilariana, a dominant CAM tree on the sandy coastal plains of SE Brazil. Chlorophyll a + b concentration, chlorophyll a/b ratio, and total carotenoid concentration were measured three times during the wet season. Chlorophyll a + b and total carotenoids decreased while the chlorophyll a/b ratio increased after a series of dry spells. We discuss our results in the context of Clusia literature, and argue that leaf-level pigmentation changes are an important source of phenotypic flexibility during acclimation
to fluctuating light levels and groundwater availability. 相似文献
39.
Estimates of biomass are essential for studies modeling the structure, animal growth, production, and energy flow in ecosystems.
The relationships between dry weight and carapace width of two varunid crab species in two different populations were examined.
Distribution of the length-weight plots did not show remarkable differences between species, sexes, and populations. Our results
suggest that length-weight relationships, regardless of sex or population or including multiple species, are valid for estimation
of dry weight. 相似文献
40.
Dry flowable formulations of Bacillus subtilis strain T429 with fungicidal activity against the rice blast fungus Magnaporthe grisea were synthesized by spray drying. Inert ingredients including wetting agents, dispersants, disintegrants, and adhesives that show good biocompatibility with B. subtilis T429 were obtained. The formulations were optimized by a four-factor and three-level orthogonal experiment. The optimal contents of the wetting agent AEO-5, dispersant NNO, disintegrant (NH4)2SO4, and adhesive CMC-Na were 1%, 9%, 5%, and 1% respectively, the filler kaolinite supplemented to 100%. The mixture was suspended in the fermentation broth of T429 at a ratio of 20% (m/v). After being ground in a ball mill for 3 h, the suspension was spray-dried, and the dry flowable formulations were obtained. The formulation showed good physical characteristics, such as high dispersibility and viability. After 12 months of storage at room temperature, it revealed long shelf life and high viability. Field tests in rice crops illustrated that dry flowable formulations at 50 and 75 g/667 m2 concentrations were as effective as a commercial fungicide in controlling rice blast, control efficiency up to 77.6% and 78.5%, respectively. No significant differences in disease control efficiency were observed between the formulations and the chemical pesticide tricyclazole (79.5%). Overall, a new shelf-stable and effective dry flowable formulation of the biocontrol agent B. subtilis T429 was obtained by spray drying to control rice blast. 相似文献