蔬菜残株的化学组成分析

应用常规化学分析方法系统地测定了辣椒、番茄、黄瓜、茄子、结球甘蓝和芹菜6种主栽蔬菜采后残株的化学组成。结果表明,蔬菜残株各器官含水量为73.77 %~91.91 %;以烘干基计算,大量元素（N、P、K）含量为31.7～85.7 g•kg^-1,中、微量元素（Ca、Mg、Fe、B、Zn）含量为16.2～87.1 g•kg^-1,有机质含量为428.4～674.3 g•kg^-1,其中主要是纤维素和木质素,C/N为7.0～21.3。     

Estimating the biomass and carbon pool of stump systems at a national scale

Countries that are signatories to the UNFCCC and its supplementary Kyoto Protocol are obliged to report changes in carbon pools. These should include the pool of carbon held in tree stumps and roots but, to date, few countries have been able to report this or separate it from the dead-wood pool. The aim of this study was to develop a general system for estimating and monitoring changes in stump system carbon using data from a traditional National Forest Inventory. The system was derived using data based on measurements of carbon (biomass) in inventoried permanent sample plots representing all relevant classes of land-use. With this design it was possible to trace matched carbon at the level of individual trees or stumps back to land-use prior to the 1990 baseline year. Between 1990 and 2003 in Sweden, the average annual net sink of stump systems was estimated to amount to 6.7 Mt CO₂ equiv. year⁻¹ – comparable to the reported net sink in 2008 of about 15 Mt CO₂ equiv. year⁻¹ from the whole Land Use, Land-Use Change and Forestry sector, which excluded any carbon in stump systems. In 2003 the carbon stock of stumps and roots was estimated at 495 Mt CO₂ equiv.; approximately five times that of the dead-wood pool as defined in Sweden, i.e. dead wood that mainly consists of boles. The Intergovernmental Panel on Climate Change requests that reported carbon should be matched to land-use and traced back to the 1990 base year; however, the present study confirms expectations that most carbon in stumps and roots is found on Forest land. The minimum requirements for estimating the carbon pool in stump systems at a national scale using the proposed methodology are that there should be: (i) a consistent time-series of harvest data, usually estimated as merchantable volume; (ii) conversion factors from merchantable volume to stump system biomass at death; and (iii) a representative decomposition model.     

人工林白桦伐根腐朽程度对林隙内土壤温度的影响

通过对不同腐朽程度人工林白桦(Betula platyphylla)伐根林隙内土壤温度的测定,研究了伐根对林隙土壤温度的影响.结果表明:林隙土壤表面温度呈现不同的变异情况,但与伐根无关;有伐根林隙随伐根腐朽程度的加剧,土壤表面下10cm处温度差异性增加;未腐朽和初步腐朽伐根林隙土壤表面下10cm处温度变化趋势--伐根处温度较低,周围温度较高,温度变化梯度最大值发生在伐根南、北侧;严重腐朽伐根林隙伐根处土壤表面下10cm温度较高,且伐根周围温度变化梯度最大.     

In vitro propagation of Acacia sinuata (Lour.) Merr. via cotyledonary nodes

Acacia sinuata is a valuable multipurpose tree in Southern India. The tree is over exploited, but its regeneration rate in natural habitat is low. Therefore, it is important to study if it can be regenerated through in vitro micro-propagation. Cotyledonary node and shoot-tip explants excised from 15 day-old in vitro grown seedlings were used to initiate cultures. Maximum number of shoots was induced from cotyledonary node explants on Murashige and Skoog's (MS) medium containing6.66 µM 6-benzylamino purine (BAP) and 4.65µM kinetin (Kn). Subculturing was done in the fresh medium of same composition. The number of shoots formed was comparatively greater in the first subculture. Maximum shoot elongation was achieved (5.5 cm)when subcultured on MS medium supplemented with 1.75 µMgibberellic acid (GA₃). In vitro regenerated shoots produced roots when transferred to half strength MS medium supplemented with 7.36 µM indolebutyric acid (IBA). From each cotyledonarynode 30 shoots were obtained within 90 days after two subcultures. The success rate of establishing the rooted plantlets in the field was 55%.This revised version was published online in November 2005 with corrections to the Cover Date.     

Assessing carbon balance trade-offs between bioenergy and carbon sequestration of stumps at varying time scales and harvest intensities

Mitigating climate change and securing a supply of energy may be achieved, in part, by substituting fossil fuels with bioenergy from stumps and roots. However, the use of stumps would result in a reduction of the carbon pool and thus, from a greenhouse gas emission perspective, there is a trade-off between using stumps for bioenergy and retaining them in the carbon pool associated with dead organic matter. The objective of this study was to show whether, from a carbon balance perspective and over the short and long-terms, stumps are more important as a source of energy that replaces fossil fuels, or as a carbon sink.