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Does RGP predict field performance? A debate 总被引：3，自引：0，他引：3
Root Growth Potential (RGP) has become the most commonly used and reported measure of seedling quality. It has also been used to predict field performance after planting, but not everyone agrees that this is an appropriate use. The authors were solicited by the Making the Grade Organizing Committee to engage in a debate on the topic Does Root Growth Potential (RGP) predict Field Performance with D. G. Simpson arguing the affirmative position and G. A. Ritchie the negative. Simpson's key debate points are: (1) RGP predicts actual field performance when trees are dead __ dead trees do not grow, (2) RGP predicts field performance potential when water uptake is dependent on new root growth, and (3) RGP is a practical tool to monitor and improve reforestation system performance. Ritchie, arguing against the proposition, maintains that: (1) the logic which underlies the dependence of Field Performance on rapid root growth after planting is flawed, i.e. root growth immediately following planting rarely occurs because soils during the planting season are generally below the threshold temperature for root growth, and (2) RGP does not provide enough information about the complex of interacting factors which control Field Performance to give reliable, consistent predictions. The authors conclude by proposing a conceptual model which accommodates both positions. 相似文献
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Maria Ivanilda de Aguiar Jamili Silva Fialho Francisco das Chagas Silva de Araújo Mônica Matoso Campanha Teógenes Senna de Oliveira 《Agroforestry Systems》2013,87(3):699-711
In order to ensure the sustainability of agroecosystems, biodiversity must be a priority. Agroforestry, which includes trees, is an example of such diverse systems. We evaluated plant diversity and aboveground biomass production to assess whether areas under fallow following traditional cultivation return to their initial condition. Also, plant diversity and aboveground biomass production were assessed in agroforestry systems (AFS) to determine if these were similar to unmanaged ecosystems. Another objective of the study was to observe the influence of plant diversity on aboveground biomass production in plant communities and also in the population of the dominant species, Cordia oncocalyx. Plant diversity was evaluated by assessing species richness, as well as using Shannon’s (H′) and Pielou’s (J′) indices. Aboveground plant biomass was evaluated in two AFS: agrosilvopastoral (ASP) and silvopastoral (SP), and also in a traditionally managed agricultural system (AG), areas that had been under fallow for six years (F6) and nine years (F9) and an area of unmanaged caatinga (CAT) vegetation. We observed that the ASP system had a lower diversity and number of species, especially tree species. However, it sustained the same total biomass production as CAT and fallow areas. The SP system, despite having lower H′ and J′ indices as well as lower total biomass production, had a similar number of species to CAT and cropped and fallow systems AG, F6 and F9. Plant biomass in F6 and F9 had recovered to productivity levels of unmanaged CAT vegetation; however the diversity indices were not restored to the same level. Plant diversity did not have an effect on the productivity of the agroecosystems. Likewise, annual biomass production by C. oncocalyx is not dependent upon diversity, but it is influenced by the growth stage of individuals. 相似文献
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文章探讨了１，１－二甲基－７－异丙基－１，２，３，４－四氢萘－６－磺酸钠合成的磺化工艺。通过实验室的试验，确定了适宜的工艺条件，１，１－二甲基－７－惜内基－１，２，３，４，－四四氢萘与浓度硫酸的配比为１：１０．５（ｍｏｌ比），反应温度９０±２℃，反应时间２０ｍｉｎ，产品得率达８０．３％。同时测定了产物表面活性性能，可用作表面活性剂。 相似文献
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森林—人工林—可持续发展 总被引：1，自引：0，他引：1
人工林木材成为研究的热点木材是当今世界四大材料(钢铁、水泥、塑料、木材)中惟一可再生的。人工林木材与来自天然林的木材相比优势在于:在实施 SFM(森林可持续经营)后,天然林木材在培育和采伐方面成本都高于人工林,而人工林受SFM 的影响较少,尤其在生物多样性方面;特别是人工林可以选择合适的地点,使林地靠近用户,减少运输成本。人工林木材在 SFM 和资源供应方面的优势表明了 相似文献
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盛夏,骄阳似火,大地流金,都市郁闷而燥热,令人坐卧不宁,寝食难安。天祝三峡这颗镶嵌在高原金盆上的绿宝石,正在向你招手。走进天祝,走进“三峡”,清凉的山风,清脆的鸟鸣,淡淡的花香,悠远嘹亮的牧歌;绿色的山,绿色的树,绿色的草地,绿色的心情……你不陶醉,你不心旷神怡,那已是情 相似文献
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