绿化造林工程中人工林不同宽度带状混交造林方法研究

常规的人工林不同宽度带状混交造林方法主要使用不规则块状补植技术进行整地处理,易受林木覆盖度影响,导致造林效果不理想,因此需要设计一种全新的人工绿化造林工程不同宽度带状混交造林方法,即进行苗木选择与精细整地处理,优化混交造林栽植抚育过程,从而完成人工林不同宽度带状混交造林。实例分析结果表明,设计的人工绿化造林工程不同宽度带状混交造林方法在不同带状混交林宽度下的林木生长量、成活率、保存率均较高,证明设计的混交造林方法的造林效果较好,具有可靠性,有一定的应用价值。     

由此绿化“怪圈”说开去

春天,是绿化造林的黄金季节。经过一场数十年未遇的雪灾后,绿化林地惨遭毁坏。今年的绿化造林任务尤为艰巨。然而,我们在大力开展造林绿化的投资与劳作中,须防备一种不良造林绿化“怪圈”影响造林复绿工程。     

应对气候变化的重要措施:碳汇造林

通过植树造林增加"碳汇"是针对气候变化问题的一项重要应对措施,与节能减排相比,具有成本低、易操作、可持续等优点。近年来,世界各国就林业碳汇问题不断达成共识,国际与国内碳汇市场发展迅速。开展碳汇造林不仅有助于我国实现既定的碳减排目标,同时顺应森林生态效益市场化趋势,有望让造林者通过清洁发展机制实现经济收益。为了让读者更全面深入地了解"碳汇造林",本刊特邀请有关专家对森林碳汇的产生背景、作用机制以及在我国开展碳汇造林工作的意义和前景进行分析解读。     

新疆荒漠灌溉条件下造林营林技术探讨

在新疆荒漠地区造林营林成败的关键，在于运用生态学的观点，因地制宜地采用抗旱造林系列配套技术，即改良林地、良种壮苗、适时灌溉和加强抚育等项技术措施，达到造林营林优质高效。     

应用信息量法评价西宁东川丘陵斜坡的稳定性

采用二态变量信息量法,选定西宁市东川北侧丘陵前缘做为评价对象,对斜坡稳定性进行试评价。通过计算评价与实际情况对比检验,其准确率达到８９％,故该法在斜坡稳定性评价中较为实用。     

模糊数学综合评判法在泥石流沟判别与危险度评价中的应用

以西宁市东川北侧北山寺—中庄间泥石流形成的地质环境背景为基础,以流域面积、沟谷长度等11项因素为背景参数,应用模糊数学综合评判法对泥石流沟进行判别与危险程度评价.其计算评价结果表明该方法可行,对监测和整治泥石流具有重要的参考价值.     

干旱区防风固沙林建设与管理的进一步思考

根据干旱区的典型特点,突出"水"的问题,结合已有成果的经验,针对目前新疆防风固沙生态林建设与管理中存在的问题,就造林树种选择、林带结构、造林密度、用水方式等问题,从恢复生态学的理论高度提出一些供参考的想法。     

投资环保 企业增效——南部县绿神丝绸有限责任公司

南部县地处川北，座落在嘉陵江畔，人畜饮用水部分从嘉陵江中取用，县内深丘地貌较多，部分乡镇淡水资源溃乏，因此保护好嘉陵江淡水资源迫在眉睫。在县域经济高速增长的今天，用更多的精力协调好经济的增长与环境保护的关系是整个社会刻不容缓的责任，大力发展环保型循环经济是南部县企业的义务。     

旧案新说 违法or违纪

1995年，X县林业研究所、县林业局、X乡林管站等单位同X乡姚家村、大坡村等签订营造科研林3000亩的协议书。协议书规定：凡属造林山，需砍伐造林时，均由林科所根据规划的需要，先通知各村村委，由村委组织劳力进行砍伐，所伐木材经林科所签字证实后，由县林业局如数拨给木材采伐指标，木材由村委会安排销售，林科所只负责造林。     

光皮桦资源的开发利用与发展前景

光皮桦是一种用途较广的珍贵树种 ,近年来皖南山区对光皮桦资源的需求日益增大。对光皮桦资源的利用现状、经济效益、造林技术及发展前景进行了论述。     

Restoration of Mountain Big Sagebrush Steppe Following Prescribed Burning to Control Western Juniper

Western juniper (Juniperus occidentalis ssp. occidentalis Hook) encroachment into mountain big sagebrush (Artemisia tridentata spp. vaseyana (Rydb.) Beetle) steppe has reduced livestock forage production, increased erosion risk, and degraded sagebrush-associated wildlife habitat. Western juniper has been successfully controlled with partial cutting followed by prescribed burning the next fall, but the herbaceous understory and sagebrush may be slow to recover. We evaluated the effectiveness of seeding perennial herbaceous vegetation and sagebrush at five sites where juniper was controlled by partially cutting and prescribed burning. Treatments tested at each site included an unseeded control, herbaceous seed mix (aerially seeded), and the herbaceous seed mix plus sagebrush seed. In the third year post-treatment, perennial grass cover and density were twice as high in plots receiving the herbaceous seed mix compared to the control plots. Sagebrush cover and density in the sagebrush seeded plots were between 74- and 290-fold and 62- and 155-fold greater than the other treatments. By the third year after treatment, sagebrush cover was as high as 12 % in the sagebrush seeded plots and between 0 % and 0.4 % where it was not seeded. These results indicate that aerial seeding perennial herbaceous vegetation can accelerate the recovery of perennial grasses which likely stabilize the site. Our results also suggest that seeding mountain big sagebrush after prescribed burning encroaching juniper can rapidly recover sagebrush cover and density. In areas where sagebrush habitat is limited, seeding sagebrush after juniper control may increase sagebrush habitat and decrease the risks to sagebrush-associated species.     

The Fate of Priority Areas for Conservation in Protected Areas: A Fine-Scale Markov Chain Approach

Park managers in alpine areas must deal with the increase in forest coverage that has been observed in most European mountain areas, where traditional farming and agricultural practices have been abandoned. The aim of this study is to develop a fine-scale model of a broad area to support the managers of Paneveggio Nature Park (Italy) in conservation planning by focusing on the fate of priority areas for conservation in the next 50–100 years. GIS analyses were performed to assess the afforestation dynamic over time using two historical maps (from 1859 and 1936) and a series of aerial photographs and ortho-photos (taken from 1954 to 2006) covering a time span of 150 years. The results show an increase in the forest surface area of about 35%. Additionally, the forest became progressively more compact and less fragmented, with a consequent loss of ecotones and open habitats that are important for biodiversity. Markov chain-cellular automata models were used to project future changes, evaluating the effects on a habitat scale. Simulations show that some habitats defined as priority by the EU Habitat Directive will be compromised by the forest expansion by 2050 and suffer a consistent loss by 2100. This protocol, applied to other areas, can be used for designing long-term management measures with a focus on habitats where conservation status is at risk.     

Modeling the Potential of the Northern China Forest Shelterbelt in Improving Hydroclimate Conditions1

Abstract: The forest shelterbelt (afforestation) project in northern China is the most significant ecosystem project initiated in China during the past three decades. It aims to improve and conserve the ecological environment in the project areas. The tree belt stands along the southern edge of the sandy lands, nearly paralleling to the Great Wall. This study used a regional climate model to simulate the potential of improving regional hydroclimate conditions resulting from the afforestation project. Two simulations with preafforestation and postafforestation land cover were performed over East Asia from January 1987 to February 1988. The model resolution is 60 km. The differences between the two simulations suggest that the northern China forest shelterbelt project is likely to improve overall hydroclimate conditions by increasing precipitation, relative humidity, and soil moisture, and by reducing prevailing winds and air temperature. The effects are more significant in spring and summer than fall and winter. Changes in many hydrologic properties (e.g., evapotranspiration, soil moisture, and water yield), however, differ between the dry Northeast China and the moist Northeast China. The hydroclimate effects are also found in the surrounding areas, featured by noticeably moister conditions in the area south of the afforestation project. The results imply that the shelterbelt project would reduce water yield in afforested Northwest and North China during spring, but increase water yield in the afforested Northeast China as well as in the southern surrounding area, offset some greenhouse effects, and reduce the severity of dust storms. Possible improvements of this study by using actual afforestation data, modeling with higher resolution, longer integration and more detailed processes, and analyzing the physical mechanisms are discussed.     

Potential Impact of Afforestation on Water Yield in the Subalpine Region of Southwestern China1

Abstract: To combat its growing ecological problems, China has implemented a large‐scale Natural Forest Protection Program (NFPP). Under the umbrella of this program, the Sloping Land Conversion Program (SLCP) was established in 1999 to return cultivated land with slopes of 25° or more to perennial vegetation. However, the regional impacts on water resource management that are incurred by afforestation have not been carefully evaluated, especially in the subalpine region of southwestern China. The purpose of the present study was to provide reference values for the SLCP by evaluating the potential impact of afforestation on water yield under different climatic regimes. Accordingly, evapotranspiration (ET) in cropland (CL), shrubland, and general forest was calculated using a modification of Thornthwaite’s method, and in coniferous forest, broad‐leaved forest (BF), and mixed coniferous and broad‐leaved forest (MF) using the Surface Energy Balance Algorithm for Land (SEBAL) model. The results of both approaches showed that afforestation reduces water yield by 9.6‐24.3% depending on the types of conversion and climatic conditions. Water‐yield reduction is greatest (>143.4 mm, or 24.3%) when CL is converted to BF in dry climate conditions. Compared with the other forest types studied, coniferous plantations prevented water‐yield reduction by as much as 9.6% because of their relatively low levels of ET. It is expected that implementation of the SLCP, together with continuing climate change, will further pressure regional water resources. Thus, the effectiveness of afforestation must be evaluated in a broader context while taking into account its positive ecological aspects, such as soil‐erosion control, the preservation of biodiversity, and the significant carbon sequestration provided by forests.     

EFFECTS OF SIMULATED CLOUD SEEDING ON STREAMFLOW OF SELECTED WATERSHEDS IN PENNSYLVANIA1

A mathematical model was developed to simulate the hydrologic behavior of five small watersheds in central Pennsylvania. Continuous hydrographs for the 6-month period, April to September 1964, were simulated. Synthesized rainfall cycles consisting of increasing rainfall by 10, 20, and 30 percent to simulate the effects of cloud seeding were processed through the watershed model to determine the effects on low flow augmentation. Other rainfall cycles used consisted of increasing every third storm by 30 percent and of developing a rainfall cycle by processing daily radiosonde data through a mathematical cumulus cloud model to obtain a prediction of rainfall following seeding. A comparison of actual and predicted hydrographs indicated that simulated cloud seeding resulted in significant monthly and seasonal water yields. In general, the results of the study appear to indicate that on a theoretical basis cloud seeding would be a feasible method of augmenting low stream-flow during the summer months on watersheds in the northern Appalachian region.     

Financing of wasteland afforestation in India

India has vast tracts of wastelands, which have been lying barren for ages. Most such lands are physically suitable for growing trees and thus could be put to socially productive uses. However, although usually economically viable, afforestation requires massive initial investment, generally beyond the means of the landowners. Also, government budgetary allocations do not cover current needs. In this situation, institutional credit is required. The National Bank for Agriculture and Rural Development (NABARD) of India has recognized this need and has devised a number of different schemes to provide refinance facilities to individuals and organisations. Although the number of forestry schemes refinanced by NABARD has increased rapidly in the past, they currently constitute only about 1% of the total number of loans sanctioned, and only about 2% of NABARD's cumulative loan disbursement to date. In fact, since 1992, the share of afforestation schemes has declined. A number of factors have been identified as major constraints, including time-consuming and complicated procedures for accessing land; restrictions on harvesting and selling trees; delays in sanctioning and disbursement of bank credit; non-remunerative prices for tree products; and flawed public policies and programmes. This article argues that unless these constraints are overcome, NABARD will not be able to play an effective role in speeding up development programmes in the forestry sector. It further argues that most of the current constraints on institutional credit for wasteland afforestation can be removed or relaxed. Practical strategies are suggested to mobilize more funds and channel more institutional credit for wasteland afforestation in India.     

Evaluating Terrestrial Carbon Sequestration Options for Virginia

Changes in forest and agricultural land management practices have the potential to increase carbon (C) storage by terrestrial systems, thus offsetting C emissions to the atmosphere from energy production. This study assesses that potential for three terrestrial management practices within the state of Virginia, USA: afforestation of marginal agricultural lands; afforestation of riparian agricultural lands; and changing tillage practices for row crops; each was evaluated on a statewide basis and for seven regions within the state. Lands eligible for each practice were identified, and the C storage potential of each practice on those lands was estimated through a modeling procedure that utilized land-resource characteristics represented in Geographic Information System databases. Marginal agricultural lands’ afforestation was found to have the greatest potential (1.4 Tg C yr⁻¹, on average, over the first 20 years) if applied on all eligible lands, followed by riparian afforestation (0.2 Tg C yr⁻¹ over 20 years) and tillage conversion (0.1 Tg C yr⁻¹ over 14 years). The regions with the largest potentials are the Ridge and Valley of western Virginia (due to extensive areas of steep, shallow soils) and in the Mid-Atlantic Coastal Plain in eastern Virginia (wet soils). Although widespread and rapid implementation of the three modeled practices could be expected to offset only about 3.4% of Virginia’s energy-related CO₂ emissions over the following 20 years (equivalent to about 8.5% of a Kyoto Treaty–based target), they could contribute to achievement of C-management goals if implemented along with other mitigation measures.     

Changes in Soil Particulate Organic Matter, Microbial Biomass, and Activity Following Afforestation of Marginal Agricultural Lands in a Semi-Arid Area of Northeast China

Afforestation of agricultural lands has been one of the major land use changes in China in recent decades. To better understand the effect of such land use change on soil quality, we investigated selected soil physical, chemical and microbial properties (0–15 cm depth) in marginal agricultural land and a chronosequence of poplar (Populus euramericana cv. ‘N3016’) plantations (5-, 10-, 15- and 20-years old) in a semi-arid area of Northeast China. Soil bulk density significantly declined after conversion of agricultural lands to poplar plantations. Soil total organic carbon (TOC) and nitrogen (TN) concentrations, microbial biomass C (MBC) and potential N mineralization rate (PNM) decreased initially following afforestation of agricultural lands, and then increased with stand development. However, soil metabolic quotient (qCO₂) exhibited a reverse trend. In addition, soil particulate organic matter C (POM-C) and N (POM-N) concentrations showed no significant changes in the first 10 years following afforestation, and then increased with stand age. These findings demonstrated that soil quality declined initially following afforestation of agricultural lands in semi-arid regions, and then recovered with stand development. Following 15 years of afforestation, many soil quality parameters recovered to the values found in agricultural land. We propose that change in soil quality with stand age should be considered in determining optimum rotation length of plantations and best management practices for afforestation programs.     

A bioeconomic model of afforestation in Southern Ontario: Integration of fiber,carbon and municipal biosolids values

This study explores the economic attractiveness of afforestation as a strategy for the joint production of fibre, carbon storage and biosolids (treated municipal sewage sludge) disposal for municipalities in Southern and Central Ontario, Canada. We use a spatial, stochastic model, the Canadian Forest Service Afforestation Feasibility Model (CFS-AFM), to simulate a range of spatial biosolids application scenarios in hybrid poplar afforestation projects. Results suggest that such joint afforestation strategies could be financially attractive. Significant cost savings can be expected through decreases in transportation distances and avoided waste disposal fees. Sensitivity analysis is used to examine the effects of variations in critical model parameters on net present values. Our findings indicate that waste disposal savings from application of biosolids on hybrid poplar plantations combined with incentives for landowners to sequester carbon can easily compete with agricultural land rental values in some regions of Ontario. Social acceptance of this kind of activity, however, may be an impediment to adoption.     

油气田站场水环境治理与绿化设计应用

长庆油气区大部分地处失陷性黄土地区,其区域特性、降雨特点及地面集流方式易产生水土流失、滑坡、泥石流等自然灾害。通过采用道路型雨水收集和分类区别处理技术对站场设计优化,将站场雨水、废水收集回收利用从而减少外排,既减少排水引起的自然灾害和后期维护费用,又可满足站场绿化用水,节约水资源。经过设计应用初步形成了适应于长庆油气区实际的站场水环境治理与绿化设计模式,为后期新建油气田的治理提供新思路和方法。