土壤含水量与N2O产生途径研究

土壤含水量变化对N₂O产生和排放影响的研究表明,不同含水量情况下,N₂O排放也不相同。特别是用乙炔抑制技术证明了在播种前后,气候干燥而土壤含水量较低的情况下,N₂O产生主要来自于硝化过程;降雨后,土壤含水量较高时,N₂O主要是通过反硝化过程产生;而在农田中等含水量情况下,土壤微生物的硝化和反硝化作用产生的N₂O大约各占一半。指出旱作农田N₂O产生途径主要取决于土壤水分的控制和调节。

Energy Redundancy in Ecosystems and the Second Low of Thormodynamics.

. The energy in ecosystems is redundant. Not only the energy within a trophic level is redundant,but the energy flowing among the different levels is redundant. Ecosystems are a redundant system consisted of continuous multi-sources of energy. As soon as energy redundancy in one trophic level is not able to sustain the downward trophic level, the energy flow will stop. Energy redundancy limits the number of trophic levels.At the same time, energy redundancy within the trophic level and between trophic levels maintains normal energy flow and stability of trophic structure in ecosystems. Researches indicated that, in terms of explanation of diminishing energy at trophic levels, the concept of energy redundancy is better than the second low of thermodynamics ,for the former is more ecological meaningful.