Comparison of image and rapid field assessments of riparian zone condition in Australian tropical savannas

Suitable methods for measuring and monitoring the condition of riparian environments are being investigated by government agencies responsible for maintaining these environments in Australia. The objective of this work was to compare two riparian condition assessment approaches, the Tropical Rapid Appraisal of Riparian Condition (TRARC) method developed for rapid on-ground assessment of the environmental condition of savanna riparian zones and an image based riparian condition monitoring scheme. Measurements derived from these two approaches were compared and correlated. The sample representativeness of the TRARC method was evaluated and the cost-effectiveness and suitability for multi-temporal analysis of the two approaches were assessed. Two high spatial resolution multi-spectral QuickBird satellite images captured in 2004 and 2005 and coincident field data covering sections of the Daly River in the Northern Territory, Australia were used in this work. Both field and image data were processed to map indicators of riparian zone condition including percentage canopy cover, organic litter on the ground, canopy continuity, tree clearing, bank stability, and flood damage. Spectral vegetation indices, image segmentation, and supervised classification were used to produce riparian health indicator maps. QuickBird image data were used to examine if the spatial distribution of TRARC transects provided a representative sample of ground based estimates of riparian health indicators. Covering approximately 3% of the study area, the sample mean of the TRARC estimates of individual indicators of riparian zone condition were in most cases within 20% of the global mean derived from the whole imaged riparian area. The cost-effectiveness of the image based approach was compared to that of the ground based TRARC method. Results showed that the TRARC method was more cost-effective at spatial scales from 1 km to 200 km of river in relatively homogeneous riparian zones along rivers with only one channel, while image based assessment becomes more feasible at regional scales (200–2000 km of river). A change detection analysis demonstrated that image data can provide detailed information on gradual change, while the TRARC method is less suited for multi-temporal analysis due to the ranked data format, which inhibits precise detection of change. However, results from both methods were considered to complement each other for single date assessment of riparian zones if used at appropriate spatial scales.     

Temporal development of crown condition of beech and oak as a response variable for integrated evaluations

The evaluation uses the longest available time series for beech and oak defoliation in Germany. The data from Hesse, starting from 1984, show a typical pattern: for the first 12 years, a continuous increase in defoliation was observed ranging from an average value of 14% in 1984 to a peak value of 30%. This was followed by a subsequent decrease in the loss of foliage accompanied by a high variability, until the last monitoring in 2003, where an average value of 25% defoliation was observed. For both tree species, the years of trend reversal were identical. The same pattern was observed in the German federal states: Rhineland-Palatinate, North Rhine-Westphalia, and Bavaria. The year of trend reversal was identical in Hesse and Rhineland-Palatinate. In North Rhine-Westphalia, it occurred 1 year earlier and in Bavaria 3 years earlier. Whereas defoliation trends were clearly demonstrated, tree mortality did not appear on a large scale. The sample trees were grouped into four discrete clusters according to their annual defoliation values from 1984 to 2003. In 1996, the clusters represent 15, 25, 35, and 50% defoliation values. Regarding beech in Hesse, there was no overlap in the defoliation curves observed among the different clusters. These four clusters having different degrees of defoliation over the whole time span of 20 years were used for a further detailed statistical analysis. For discrete variables like crown spacing and—in the case of beech—fruit bearing, mosaic plots were applied in order to visualize relations of low dimensional contingency tables, with defoliation trends being used as the response variable. The data show for beech a very clear relation between defoliation and age, relative crown spacing, stand composition, and fruit bearing. Regarding oak, besides age and relative crown spacing, the years with significant appearance of biotic stress factors—leaf eating insects—show a clear relation to trends of defoliation. The statistical model used in this study—logistic regression—allows applying a multinomial response variable and a number of continuous or categorical explanatory variables. With this approach, an iterative optimized selection of effect variables was used to test the relevance of different variables on the defoliation pattern of the same four clusters mentioned above. For this, the variables were grouped in an iterative process with five steps, starting with a few basic variables of tree and site information, and ending with a total of more than 20 variables in the fifth step. The process selects first the variables which are of significance on the defoliation, and calculates the possible errors in the grouping of the different trees to the four clusters. In this analysis of beech, the basic tree and stand variables: age, relative crown spacing, stand composition and fruit bearing proved to be the most relevant group of parameters, with the other variables explaining the variation of defoliation only to a minor extent. More complex model levels do not change any basic selected variables; however, Cation Exchange Capacity (CEC), C/N-ratio, Al- and Ca-proportion of CEC are additionally selected and give a hint of the relevance of soil conditions. Regarding beech, the errors of the statistical model are lower compared to oak.     

美国的森林动态评价模型及其对中国森林健康评价的启示

应用动态模型评价森林健康状况,预测树木或林分的生长与收获,以及在不同立地条件下采用某些特定的营林技术措施后林分的动态变化,一直是森林健康评价及管理的核心问题.当前在美国应用的两个森林动态评价及决策模型SIMPPLLE和MAGIS主要是用来评价当前林分状况、模拟林分发展以及预测不同经营管理方式下林分未来的动态变化状况,通过分析不同决策下森林植被的收获状况,选择最优化的管理措施以及实施措施的时间及地点制定最优化决策.针对现阶段中国森林健康评价中,以建立评价指标体系进行静态评价、缺乏空间信息数据和森林健康经营动态变化规律模型等问题,提出今后应针对中国实际情况开展切合实际的研究,开发出以促进森林健康经营为目的的动态预测模型和决策模型,提高森林健康的预测能力,完善森林健康经营综合评价技术体系.     

基于WebGIS的森林健康评价与区划专家支持系统的设计与实现

为了解决森林经营单位森林健康状况的评价问题,利用综合因子评价法建立了改进的林分级森林健康评价指标体系,并基于ArcGISServer开发了森林健康评价与区划专家支持系统．以八达岭林场为例进行了森林健康评价与区划．结果表明,该系统可辅助实现森林经营单位健康状况判定、区划、出图、查询和统计等功能,并可以根据已有数据自定义评价指标体系及实时生成评价结果．     

Landscape-scale variation in the structure and biomass of the hill dipterocarp forest of Sumatra: Implications for carbon stock assessments

One of the first steps in estimating the potential for reducing emissions from deforestation and forest degradation (REDD) initiatives is the proper estimation of the carbon components. There are still considerable uncertainties about carbon stocks in tropical rain forest, coming essentially from poor knowledge of the quantity and spatial distribution of forest biomass at the landscape level.     

Demand for non-timber forest products: Surveys of urban consumers and sellers in Switzerland

In recent years, worldwide socioeconomic, ecological, and cultural changes have led to a paradigm shift in forestry and forest management. Some years ago, most forest enterprises exclusively focused on wood production, whereas today, forest management is expected to be multifunctional and economically as well as socially and ecologically sustainable [Harrison, S., Herbohn, J., Niskanen, A., 2002. Non-industrial, smallholder, small-scale and family forestry: what's in a name? Small-scale Forest Economics. Management and Policy 1 (1), 1–11; Schmithuesen, F., 2004. Forest policy developments in changing societies — political trends and challenges to research. Towards the sustainable use of Europe's forests: Forest ecosystems and landscape research: Joensuu: European Forest Institute, Proc., vol. 49, pp. 87–99]. In this context, non-timber forest products (NTFPs) such as forest honey, mushrooms, or berries could gain importance as an additional source of income for the forestry sector. To assess the market potential of NTFPs in Switzerland, two corresponding surveys were conducted. A consumer survey (N = 897) conducted in six cities in Switzerland investigated the purchase of Swiss NTFPs, consumer preferences, and demand potentials. An additional survey of sellers of NTFPs (N = 105) looked at these aspects from a complementary perspective. The results showed that there is a high esteem and considerable demand potential for such products among urban consumers. Food products were mentioned most frequently. Both consumers and sellers considered quality and environmental friendliness the most important attributes of NTFPs. Structural and organizational innovations and considerable marketing efforts and sales promotion would be required to expand the market for Swiss NTFP, however. Our results indicate that certification of the products' origin, environmental performance, and quality could support such efforts and that recreational and ecological forest services have a synergetic potential for the marketing of NTFPs.     

The susceptibility of white spruce seedlings to overwinter injury and their post-injury field responses

Foliar and stem injury was assessed in white spruce (Picea glauca (Moench) Voss) seedlings planted in the spring and in the summer of 1992 and injured during their first overwintering on two sites in the southeastern boreal forest of British Columbia. Freeze-desiccation appears to be the main cause of the injury. Seedlot effect on the injury was significant, while planting time effect was not. Although the seedlot effect may be confounded with stock-type effect, analyses indicated increasing injury with increasing seedling height and declining ground-level diameter. Seedling vigour (height and diameter increments in the previous growing season) was also significantly related to the injury which increased with increasing vigour but the significance of this relationship varied from site to site. Condition of injured seedlings generally declined further during the post-injury growing season. This decline was greater in spring-planted than in summer-planted seedlings. Excavated root systems of container-grown seedlings showed the majority of post-planting root growth originating from the bottom-third of the nursery-container plug, deeper than 10 cm from the soil surface. This is seen as a factor potentially contributing to desiccation injury as the soil in the geographic region often remains frozen at these depths long into spring.     

Uncertainties of mapping aboveground forest carbon due to plot locations using national forest inventory plot and remotely sensed data

Abstract

Forest carbon sinks significantly contribute to mitigation of atmospheric concentrations of carbon dioxide. Thus, estimating forest carbon is becoming important to develop policies for mitigating climate change and trading carbon credits. However, a great challenge is how to quantify uncertainties in estimation of forest carbon. This study investigated uncertainties of mapping aboveground forest carbon due to location errors of sample plots for Lin-An County of China. National forest inventory plot data and Landsat TM images were combined using co-simulation algorithm. The findings show that randomly perturbing plot locations within 10 distance intervals statistically did not result in biased population mean predictions of aboveground forest carbon at a significant level of 0.05, but increased root mean square errors of the maps. The perturbations weakened spatial autocorrelation of aboveground forest carbon and its correlation with spectral variables. The perturbed distances of 800 m or less did not obviously change the spatial distribution of predicted values. However, when the perturbed distances were 1600 m or larger, the correlation coefficients of the predicted values from the perturbed locations with those from the true plot locations statistically did not significantly differ from zero at a level of 0.05 and the spatial distributions became random.     

建立与集体林权制度改革相适应的光泽县森林经营和森林防火新机制

通过分析光泽县集体林权制度改革后的林业现状和问题,探索闽北林区森林经营管理和森林防火新机制,提出新时期森林经营的总体目标是构建巩固林权制度改革成果的五大配套体系(资源培育和管理体系、森林集约化经营和管理体系、林业科技和技术服务体系、森林防火体系、森林病虫害防治体系)。     

四川阿坝辐射松引种长期森林健康风险初步评估

Pinus radiata was introduced to the summer rainfall environments of Sichuan Province, China in the 1990s as a part of an afforestation pmgram for soil and water conservation in the arid and semi-arid river valley area of Aba Prefecture. Within this region a total area of 26 000 ha have been identified through climate matching as suitable and a further 63 000 ha potentially suitable for environmental plantings of P. radiata. The plantations are being established in widely separated small patches on steep and degraded slopes along the dry river valley The newly introduced P. radiata are exposed to two kinds of forest health risks： they may be attacked by （a） indigenous pathogens and pests against which they may not possess any resistance or （b） by inadvertently introduced foreign pests or pathogens. This paper presents a survey of the potential damaging pests and a preliminary assessment of forest health risks facing the P. radiata plantations over a much longer timeframe than the initial phase of introduction and early plantation establishment. An empirical appmach was adopted to evaluate forest health risks by a combination of literature review, examination of historical records of pest and disease outbreaks in the surrounding conifemus forests, field surveys and inspections, specimen collection and identification, and most importantly, expert analysis of the likelihood of attack by specific pests and pathogens and the subsequent impact of such attacks. The assessment identified some specific forest health risks to the long-term success of P. radiata introduction in this area. These risks are closely associated with the indigenous pests and pathogens of the two native pine species, P. tabulaeformis and P. armondii since these pests and pathogens are considered more likely to establish on P. radiata over time. Exotic pests and pathogens are of a quarantine concern at present. Based on the results of assessment, recommendations are pmvided to improve forest vigour and to reduce the forest health risks pos     

洛宁县退耕还林固碳产氧效应及价值研究

通过对洛宁县退耕还林林分的蓄积量调查,并取得6株平均木用干燥法测得6株平均木的生物量,根据6株平均木蓄积量和生物量建立线性模型,并以此推算洛宁县退耕还林林分总生物量为188万t。用氧气的市场价格来计算所放出的氧气的价值,吸收二氧化碳的价值用碳税率法来计算。以此来计算洛宁县固碳产氧的总价值。固碳产氧价值分别为平均每年8 485.2万元和15 262.9万元。     

A simulation study on the effects of plot size and shape on sampling plant species composition for biodiversity management

Sustainable management of plant diversity in a forest requires adequate information that is often derived from samples. With limited resources, the plot design has to be efficient. Most studies focused on evaluating effects of plot designs on sample estimates of species richness at landscape scale. This study aims at filling a knowledge gap by investigating how plot size and shape affect sample estimates of species composition at a local scale. Two census datasets with distinct forest ecosystems were used. Fifteen combinations of plot size and shape were simulated. Species compositional similarity between two combinations of plot design at a sample point was estimated by Jaccard and Sørensen indices, and their abundance-adjusted counterparts. Similarity in species composition decreased with increasing difference between two plot sizes. Plots with varying shapes were found to have different local species composition but could be similar in the number of observed species, which has not been explicitly reported elsewhere. For less species-rich forests, a 0.025–0.05 ha circular plot is recommended. For species-rich forests, a 0.05–0.1 ha rectangular plot with aspect ratio of at least 1:20 is recommended. The results should be of interest to stakeholders managing small area forests for conservation of plant diversity.     

Development of the IRGA enclosed-chamber system for soil CO<Subscript>2</Subscript> efflux measurement and its application to a spatial variation measurement

A new system was developed for measuring soil CO₂ efflux. The chamber in this system contains a small infrared CO₂ gas analyzer. This system does not need air tubes or pumps for circulating air, so it is expected to offer the advantages of mobility and durability. This system was verified by a comparison with measurements made by using a closed-dynamic-chamber (CDC) system. The spatial variation in the soil CO₂ efflux in a broadleaved deciduous forest was measured using the new system. The soil CO₂ efflux at sampling locations 50–70cm apart varied within a range of 60%–150%. This variation was smaller than the variation due to differences in soil characteristic reflected in different moisture conditions, etc.     

Understorey condition scoring of Ghanaian lowland tropical moist forest during stock survey: a technique for regulating the allowable cut in ecologically and structurally degraded production forest

Understorey condition scoring is a rapid assessment field technique for appraising and delimiting the various stages of ecological and structural decline in fire-degraded, lowland, tropical moist forest. The scoring system is designed to be incorporated into stock survey. It is simple and consistent, with only minimal time and labour requirements. The degree of degradation is assessed from the vegetation structure contained within the first 2 m of the stand's vertical profile and is assigned to one of six categories. Sample plots of 20 m radius are used to distinguish localised, degraded areas from natural forest chablis and a high sampling intensity is employed to enable accurate mapping of the forest condition. Establishing the spatial extent and degree of degradation facilitates a more appropriate determination of the allowable cut at the sub-compartmental level, thereby affording protection to affected areas of forest against further ecological and structural deterioration. In addition, the system can be used for long-term condition monitoring and targeting dry-season fire-control operations.     

退耕还林还草补偿资金的筹集与运作

拓宽补偿资金筹集渠道是退耕还林还草持续发展的客观要求。目前筹资渠道单一(主要是依靠中央财政),远不能满足退耕还林经济补偿的需要。今后需从国家预算、发行特种国债、建立补偿基金、发行生态环保彩票、开征生态环保税、争取国际资金、引导城市工商企业投资、义务认管方式等多方面来筹措资金。在退耕还林还草中,政府操作的效率低下几乎是众所周知的,改由民间操作(如由民间中介组织来运作)也许更具效率。     

Retention of Forest Strips for Bird-life Adjacent to Water and Bogs in Norway: Effect of Different Widths and Habitat Variables

In Fennoscandinan forestry, retention of forest strips as a buffer adjacent to water and bogs has long been recommended, but their biological value is poorly known and practice varies greatly. This study explored the value for breeding birds of retaining buffer strips of different width and structure, after clear-cutting in coniferous forest. The presence of birds during their nesting season was inventoried in 370 strips in south-eastern Norway. The species number per 100 m strip length increased with increasing strip width up to about 30 m width, and then remained constant up to 70–100 m width. Generalist species dominated all width categories. Important habitat factors other than strip width were basal area of spruce, short visibility and tree height. Although 11–20 m wide strips had the highest density of species and individuals per hectare, buffer strips of about 30 m width may be recommended, as narrower strips had fewer species per unit length of edge.     

环京津贫困地区退耕还林后期成果维护建议

依据环京津贫困地区31个县的退耕实施情况调查,对退耕过程中存在问题和危机进行了总结和分析,调查表明:复耕意识的存在严重威胁着退耕成果的巩固和退耕二期工程的进一步深入。建议在退耕工程已取得生态成效的基础上,必须将退耕成果的巩固和解决农民生计问题相结合,并站在退耕成果的巩固和退耕农户生计改善角度,提出了相应的建议和措施。     

Response of Ocotea bullata,Curtisia dentata and Rapanea melanophloeos to medicinal bark stripping in the southern Cape,South Africa: implications for sustainable use

Tree bark is commonly used for traditional medicine in southern Africa and further afield. Increasing demand and commercialisation have resulted in the overexploitation of many species, posing a major challenge to forest managers to develop mechanisms for sustainable resource use. An experimental bark harvesting research project was initiated in the southern Cape, South Africa, to inform best practices for bark harvesting based on tree response to bark stripping. The species selected for the study, Ocotea bullata, Curtisia dentata and Rapanea melanophloeos, are much sought after and well represented in southern Cape forests. The treatment entailed removing vertical strips of bark, 1 m in length and of different strip widths, covering the full range of tree size classes ≥10 cm DBH. The treatments were applied during two seasons, winter and summer. Evaluations were done every six months to assess tree response to bark stripping in terms of bark regrowth through phellogen edge and sheet development, and susceptibility to insect and fungal damage. The results show a differential response of tree species in terms of phellogen edge and sheet growth, as well as susceptibility to fungal and insect attack. Rapanea melanophloeos was the most vulnerable to fungal and insect damage and displayed little bark regrowth following wounding. Curtisia dentata showed best bark regrowth through sheet development. Only O. bullata, though, showed adequate bark regrowth (through edge development) to allow for sustainable strip harvesting. Bark regrowth is influenced by season of stripping, although this is difficult to define considering the wide range of environmental and other factors affecting tree response to bark removal. Smaller trees are more vulnerable to bark stripping, especially with a wide strip, with poorer bark regrowth than bigger trees.     

Persistence of soil and foliar azadirachtin treatments to control sweetpotato whitefly Bemisia tabaci Gennadius (Homoptera: Aleyrodidae) on tomatoes under controlled (laboratory) and field (netted greenhouse) conditions in the humid tropics

Persistence of neem-based products against sweetpotato whitefly Bemisia tabaci Gennadius (Homoptera: Aleyrodidae) was tested in air conditioned rearing rooms and tropical netted greenhouses (GHs). Two commercial neem products, NeemAzal^®-T/S (1% azadirachtin) and NeemAzal^®-U (17% azadirachtin), were used. Foliar application, under room conditions at dose-rates of 7 and 10 ml NeemAzal^®-T/S, induced an immature mortality of 32 and 44%, respectively, whereas 7 days post-application, under GH conditions, mortality rates declined to 5 and 7%, respectively. This result indicated rapid dissipation of the active ingredients. However, systemic application by soil drenching resulted in more stable effects under both laboratory and GH conditions. After soil drenching with solutions of 3.0 g NeemAzal^®-U until 7-day, immature mortality declined from 88% for the first day to almost half (45%) by day-7 in the GH, and from 90% on first day to 64% by day-7 under laboratory condition. Similar response trends for B. tabaci were obtained for other parameters such as adult colonisation, egg deposition, and egg hatch. The loss of efficiency of the neem products was clearly related to dose-rate, methods of application, and environment (temperature and UV). Soil application is therefore, a convenient approach to achieve high efficiency and persistence with neem products under the conditions in tropical GH environments for whitefly management.