基于光能利用效率的防护林模式对比研究

林分的冠层结构不仅影响林分对光合有效辐射的截获率和群落各层次空间植物材料对光能的利用率,而且也可以反映出群落整体潜在的净初级生产力。该文应用winSCANOPY林地冠层分析系统,通过对辽蒙边界几种常见的生态经济型防护林模式冠层结构及光合有效辐射截获率的测定研究,探讨不同防护林模式净初级生产力和潜在的经济价值,从而为优良的生态经济型防护林模式筛选提供理论依据。     

A research agenda to explore the role of conservation agriculture in African smallholder farming systems

Controversy surrounds the promotion of conservation agriculture (CA) in smallholder farming systems in sub-Saharan Africa. The introduction of CA is a profound change in farm management. Benefits in reduced erosion and stabilized crop production may be obtained, but technical performance at field level is but one of the determinants of adoption. For various reasons, all of the CA principles are not always fully implemented by farmers and results not as favourable as expected. As with other approaches to increasing agricultural productivity, the production constraints, farmers’ objectives, and the expected benefits and costs of implementing CA are important aspects that influence adoption. At farm and village levels, trade-offs in the allocation of resources become important in determining how CA may fit into a given farming system. At a regional level, factors such as the market conditions, interactions among stakeholders and other institutional and political dimensions become important. At each level, opportunities or difficulties emerge that enhance or impede development, adaptation and adoption of CA. The ex-ante identification of situations for where CA (and which form of CA) is appropriate demands research from a multi-stakeholder, multi-level, and interdisciplinary perspective. Recommendations are made where research is required to address key knowledge gaps.     

内蒙古大青山国家级自然保护区管理信息系统建设初探

内蒙古大青山国家级自然保护区于2008年成立,随着"3S"技术不断向纵深发展,在当今打造"数字林业"的热潮中,必然要走一条林业数字化、信息化的道路。文章阐述了内蒙古大青山国家级自然保护区管理信息系统建设的必要性,并详细介绍了系统建设的初步构思和技术路线。     

Spatiotemporal dynamic of European beech (Fagus sylvatica L.) in Slovenia, 1970–2005

Based on data acquired from the spatial information system Silva-SI, the majority of the entire forest area in Slovenia (22,220 forest compartments with a total area of 7446 km², classified into eight forest categories) was analysed for changes in the distribution of European beech (Fagus sylvatica L.) in the period 1975–2005 using a binary logistic regression model in terms of selected site, stand and management variables. Additionally, changes in the abundance of beech in forest stands in which beech was present at the beginning and the end of the analysed period were analysed. Beech expanded its area by more than 1200 ha per year on average, i.e. the annual expansion rate amounted to 0.24%. Among the 18 studied variables, three site, four stand and no management variables were included in the binary logistic regression model of beech expansion. Beech expansion was more pronounced at lower altitudes, on sites with steep topography, and on sites with a higher proportion of beech in potential natural vegetation. The probability of beech expansion reduced by a factor of 0.54 when the distance to the nearest compartment with beech increased by 1 km. Among other stand variables, the proportion of early successional phases and the proportion of silver fir (Abies alba Mill.) and Norway spruce (Picea abies (L.) Karst.) also influenced the expansion of beech. During the observed period the growing stock of beech almost doubled, its proportion in total growing stock increasing from 27% to 32%. Significant differences were found in changes of beech proportion in the total growing stock among different forest categories; a decrease in the beech proportion was registered in alpine coniferous forests and thermophilous deciduous forests, while in other forest categories the proportion of beech increased. The recent development of forest stands and their current structure indicate a further expansion of beech and an increase in the proportion of beech in forest stands.     

A concept in adaptive ecosystem management—An engineering perspective

Uncertainty how ecosystems will behave and look like in the future has been increasing. Several concepts, such as sustainable, adaptive, or risk-based management, were proposed to cope with uncertain, incomplete knowledge, and with changing environmental conditions. However, there is a lack of agreement what those concepts mean and how they differ from traditional forest management approaches. The paper aims at (1) exploring general systems theory, control theory, and risk management theory for general principles that may be guiding the future development of ecosystem management, and that (2) developing a concept in adaptive ecosystem management that may act as a shared mental model for both scholars and practitioners.     

Activity Behavior of Horses Housed in Different Open Barn Systems

Housing conditions do not frequently meet the natural needs of horses. German and Swiss studies have shown that merely 16% of horses are kept in group housing systems, but even these vary greatly with different effects on horses’ behavior. The objective of the survey was to determine whether horses show increased activity in barns with various options for movements and functional elements. Free movement stables allow horses to live within a herd, to decide whether to be outside or inside the herd, and to enable them fresh air supply. Data from 25 horses kept in three different open barns (O1–O3) were compared with that from two active barns with functional elements (active barn 1 and active barn 2), for example, automatic feeder, with five horses each. Activity-Lying-Temperature-pedometers fastened to a rear leg of each horse were used to measure activity. Animal data were recorded throughout a test period of 10 days per barn. The results showed a median of 46 to 68 mean daily activity impulses per 10 minutes for horses in stables O1 to O3. In stables active barn 1 to active barn 2, this measure was exceeded considerably with medians of 77 and 151. The activity impulses in the stable systems were significantly different at an error level of α = 0.05. These results support previous studies and show that activity of horses depends on their opportunities for moving. The sectioning of a stable, placement of functional elements, and feeding frequency have considerable effects on the activity level of the horse. It is useful to integrate different functional areas in a group housing system.     

Impact of systems modelling on agronomic research and adoption of new practices in smallholder agriculture

An analysis of the impact of simulation modelling in three diverse crop-livestock improvement projects in Agricultural Research for Development(AR4D) reveals benefits across a range of aspects including identification of objectives, design and implementation of experimental programs, effectiveness of participatory research with smallholder farmers, implementation of system change and scaling-out of results.In planning change, farmers must consider complex interactions within both biophysical and socioeconomic aspects of their crop and animal production activities.For this, whole-farm models that include household models of food, workload and financial requirements have the most utility and impact.The analysis also proposes improvements in design and implementation of AR4 D projects to improve the utility of simulation modelling for securing positive agronomic and livestock outcomes and lasting legacies.     

Soil carbon sequestration under long-term rice-based cropping systems of purple soil in Southwest China

Carbon sequestration in agricultural soils is a complex process controlled by farming practices, climate and some other environment factors. Since purple soils are unique in China and used as the main cropland in Sichuan Basin of China, it is of great importance to study and understand the impacts of different fertilizer amendments on soil organic carbon(SOC) changes with time. A research was carried out to investigate the relationship between soil carbon sequestration and organic carbon input as affected by different fertilizer treatments at two long-term rice-based cropping system experiments set up in early 1980 s. Each experiment consisted of six identical treatments, including(1) no fertilizer(CK),(2) nitrogen and phosphorus fertilizers(NP),(3) nitrogen, phosphorus and potassium fertilizers(NPK),(4) fresh pig manure(M),(5) nitrogen and phosphorus fertilizers plus manure(MNP), and(6) nitrogen, phosphorus and potassium fertilizers plus manure(MNPK). The results showed that annual harvestable carbon biomass was the highest in the treatment of MNPK, followed by MNP and NPK, then M and NP, and the lowest in CK. Most of fertilizer treatments resulted in a significant gain in SOC ranging from 6.48 to 2 9.13% compared with the CK, and raised soil carbon sequestration rate to 0.10–0.53 t ha–1 yr-1. Especially, addition of manure on the basis of mineral fertilizers was very conducive to SOC maintenance in this soil. SOC content and soil carbon sequestration rate under balanced fertilizer treatments(NPK and MNPK) in the calcareous purple soil(Suining) were higher than that in the acid purple soil(Leshan). But carbon conversion rate at Leshan was 11.00%, almost 1.5 times of that(7.80%) at Suining. Significant linear correlations between soil carbon sequestration and carbon input were observed at both sites, signifying that the purple soil was not carbon-saturated and still had considerable potential to se questrate more carbon.     

Understanding fisheries credit systems: potentials and pitfalls of managing catch efficiency

Following implementation in a range of other resource sectors, a number of credit‐like systems have been proposed for fisheries. But confusion exists over what constitutes these nascent ‘fisheries credit’ systems and how they operate. Based on a review of credit systems in other sectors, this study fills this gap by defining how credit systems function and what credits add to prevailing fisheries management. In doing so, we distinguish ‘mitigation’ and ‘behavioural’ fishery credits. Mitigation credits require resource users to compensate for unsustainable catches of target species, by‐catch species or damaging practices on the marine environment by investing in conservation in a biologically equivalent habitat or resource. Behavioural credit systems incentivize fishers to gradually change their fishing behaviour to more sustainable fishing methods by rewarding them with, for instance, extra fishing effort to compensate for less efficient but more sustainable fishing methods. The choice of credit system largely depends on the characteristics of specific fisheries and the management goals agreed upon by managers, scientists and the fishing industry. The study concludes that fisheries credit systems are different but complimentary to other forms of management by focusing on ‘catchability’ or gear efficiency in addition to effort or catch quota, affecting overall economic efficiency by setting specific goals as to how fish are caught. Credit systems therefore incentivize specific management interventions that can directly improve stock sustainability, conserve habitat and endangered species, or decrease by‐catch.     

林草间作系统土壤微生物及其活性研究

试验对6年龄桉树人工林间作禾本科及豆科牧草后的土壤微生物进行研究,结果表明：间作牧草可显著提高林地土壤微生物的生物量、呼吸强度、硝化作用强度及纤维素分解作用强度,且均随着土层深度的加深而降低;其中以间作热研6号珊状臂形草、热研2号柱花草、GC1581柱花草和Mineirao柱花草的土壤微生物生物量最高;热研15号刚果臂形草、热研6号珊状臂形草、杂交臂形草、热研10号柱花草、Mineirao和GC1581的呼吸强度高于CK;热研11号黑籽雀稗、热研10号柱花草、GC1581和热研2号柱花草的硝化作用强度强于CK;热研9号坚尼草、杂交臂形草和热研6号珊状臂形草、热研10号柱花草和热研2号柱花草的土壤纤维素分解作用强度较强。