草原补奖政策下牧户家庭收入的影响研究——以内蒙古锡林郭勒盟为例

为探究草原补奖政策对牧户家庭收入的影响,本研究基于锡林郭勒盟219户牧民调研数据,运用分位数回归模型,对牧民收入的影响因素和作用程度进行分析。结果显示：草原补奖政策促进牧民增收,尤其是对低收入牧户家庭增收效果显著;草场使用面积、年初家畜数量、劳动力比例、家畜出生率及出售率对牧民收入具有显著正影响,当草场使用面积、年初家畜数量分别增加1公顷、1羊单位,人均总收入分别提高0.02%,0.15%;劳动力比例、家畜出生率及出售率分别提高1%时,人均总收入分别提高0.65%,0.43%,1.83%;各因素对不同收入家庭的收入影响及作用程度具有差异性,即随着收入水平的提高,劳动力比例增收效果趋于加强,而家畜出生率和出售率的增收效果则趋于减弱。因此,建议引导牧民发展畜牧业适度规模经营、加大畜牧业社会化服务体系建设等以提高牧民收入水平。     

Effect of Spirulina fusiformis on cyclophosphamide and mitomycin-C induced genotoxicity and oxidative stress in mice

Spirulina fusiformis was tested for its possible in vivo protective effects against cyclophosphamide (CP) and mitomycin-C (MMC) induced genotoxicity and oxidative stress in mice. Pre-treatment with S. fusiformis (250, 500 and 1000 mg kg(-1), p.o., daily for 5 days) significantly reduced the chromosomal damage and lipid peroxidation with concomitant changes in antioxidants and detoxification systems. All the three tested doses were effective in exerting a protective effect against CP and MMC.     

Annualized diameter and height growth equations for Pacific Northwest plantation-grown Douglas-fir, western hemlock, and red alder

Simulating the influence of intensive management and annual weather fluctuations on tree growth requires a shorter time step than currently employed by most regional growth models. High-quality data sets are available for several plantation species in the Pacific Northwest region of the United States, but the growth periods ranged from 2 to 12 years in length. Measurement periods of varying length complicate efforts to fit growth models because observed growth rates must be interpolated to a common length growth period or those growth periods longer or shorter than the desired model time step must be discarded. A variation of the iterative technique suggested by Cao [Cao, Q.V., 2000. Prediction of annual diameter growth and survival for individual trees from periodic measurements. Forest Sci. 46, 127–131] was applied to estimate annualized diameter and height growth equations for pure plantations of Douglas-fir, western hemlock, and red alder. Using this technique, fits were significantly improved for all three species by embedding a multi-level nonlinear mixed-effects framework (likelihood ratio test: p < 0.0001). The final models were consistent with expected biological behavior of diameter and height growth over tree, stand, and site variables. The random effects showed some correlation with key physiographic variables such as slope and aspect for Douglas-fir and red alder, but these relationships were not observed for western hemlock. Further, the random effects were more correlated with physiographic variables than actual climate or soils information. Long-term simulations (12–16 years) on an independent dataset using these annualized equations showed that the multi-level mixed effects models were more accurate and precise than those fitted without random effects as mean square error (MSE) was reduced by 13 and 21% for diameter and height growth prediction, respectively. The level of prediction error was also smaller than an existing similar growth model with a longer time step (ORGANON v8) as the annualized equations reduced MSE by 17 and 38% for diameter and height growth prediction, respectively. These models will prove to be quite useful for understanding the interaction of weather and silviculture in the Pacific Northwest and refining the precision of future growth model projections.     

森林内雾水的水文和化学效应研究现状

从森林对雾水的截留量、雾水对森林分布的影响及雾水的水文和化学效应方面 ,阐述国外在该领域的研究动态和取得的成果 ,以期推动我国在该领域的研究工作。国外的大量研究表明 ,雾水对于植物的生长、分布具有重要的生态意义 ,是森林生态系统水分平衡、养分循环不可忽视的输入项 ,其生态效应是多方面的。因而 ,进一步深入研究森林内雾水的水文和化学效应是必要的     

毒蘑菇菌株及毒素粗提液对樟子松枯梢病菌生长的影响

厚环鹅膏、鹅膏菌、珊瑚菌、白霜杯伞、冠状柄环菇、细鳞环柄菇、鳞柄白鹅膏、绒白乳菇、毒蝇鹅膏9个毒蘑菇菌株及毒素粗提液对樟子松枯梢病原菌菌丝生长影响的研究结果表明:除厚环鹅膏和鹅膏菌外,其他7个菌株对病原菌生长均有一定的抑制作用;鳞柄白鹅膏和细鳞环柄菇相对抑制效果最好,分别为10.80和10.40。除毒蝇鹅膏外,其他8个菌株的毒素粗提液对病原菌菌丝生长均有一定的抑制作用,珊瑚菌和绒白乳菇毒素粗提液的抑菌效果最好,抑菌率分别达到63.89%和58.89%。     

黄河小浪底库区不同人工林水土保持效益研究

采用空间代替时间的方法,通过对黄河小浪底库区不同人工林水土保持效益浅要分析,结果表明:最大吸水率为刺槐>侧柏>20多年生栓皮栎>40多年生栓皮栎,凋落物储量和最大持水量均为20多年生栓皮栎>40多年生栓皮栎>侧柏>刺槐;土壤渗透性能和贮水性能变化较为复杂,侧柏林地的渗透性和贮水性能较其它林地好些,刺槐林地上下层之间变化最大。     

北美浆果树种在中国西部地区引种效果及应用前景

中国西部地区水资源贫乏，生态环境极其脆弱，适合生长的造林树种十分稀少，为此近10a来引进了许多北美生态经济型灌木类浆果树种，以满足生态环境恢复和建设的需要。引种试验结果表明，多数树种适合在中国西部地区栽培，发展前景十分广阔，应尽快大面积推广。同时也指出了易出现的问题、解决方法及发展建议。     

Economic evaluation of financial and non-financial costs and benefits in agroforestry development and the value of sustainability

Financial appraisal of agroforestry is not different in kind from appraisals applied to pure forestry. Existing techniques for valuing non-market effects may also be applied. Effects on hydrological and carbon fluxes might be less favourable than those of pure forests. In the confusing field of biodiversity valuation too, only limited and specific claims can be made for agroforestry. Amenity valuation techniques developed for trees and woodlands encounter additional problems of interpretation in an agroforestry context. Agroforestry may offer a quantifiable value in short-term sustainability, and might meet recent economic definitions of long-term sustainable development, without encountering the full dangers to future generations embodied in conversion of natural to human capital.     

Avoiding edge effects in agroforestry experiments; the use of neighbour-balanced designs and guard areas

A number of different types of edge effects on experimental plots are defined, and it is shown that they are frequently important in agroforestry experiments. Methods of eliminating edge effects, either at the design or the analysis stage, are described. Computer simulations, based on uniformity data, are used to investigate the efficacy of neighbour-balanced designs, with and without neighbour terms, for reducing the problem of neighbour effects between different treatments. It is concluded that, while neighbour-balanced designs may be useful in certain situations or in combination with other methods, it is preferable to eliminate edge effects by using adequate guard rows. Recommendations are therefore made concerning the correct use of guard areas in agroforestry experimentation.     

梨麦间作系统水分效应与土地利用效应的研究

对黄淮海平原农区宽带距多行带梨麦间作系统水分效应、产量效应与土地利用效应进行了研究。结果表明：小麦拔节一乳熟期间，间作系统内小麦日蒸腾耗水比单作麦田低21．6％；距梨树0．0～7．0m，为土壤水分的降低区，7．0～25．0m为土壤水分提高区，间作系统总体上使麦田0～200cm土壤贮水量提高11．81％；间作系统内小麦水分利用率比单作麦田约高8．7％；间作系统小麦单产量比单作麦田高6．6％，土地当量值可达1．19。就水分效应和土地利用效应而言，在黄淮海平原农区发展这种宽带距多行带梨麦间作模式具有一定的可行性。