土壤中~(137)Cs的化学性质及其分布规律

本文对13 7Cs的土壤化学行为及剖面运移规律进行了论述 ,并阐明了13 7Cs可作为中长期土壤侵蚀作用的有效示踪剂的理论基础     

岩溶区坡面土壤侵蚀特征研究

以重庆南川岩溶区为例,用137C s法研究了岩溶区坡面土壤侵蚀特征。结果表明,坡面上部侵蚀速率较小,平均侵蚀速率为400.8 t/(km2.a),最大侵蚀速率为1 138.4 t/(km2.a);坡面中部侵蚀加剧,平均侵蚀速率2 264.8 t/(km2.a),最大侵蚀速率可达3 760 t/(km2.a);坡面下部侵蚀减弱甚至堆积。土壤表层有机质、表层粘粒及水稳性团聚体含量在坡面上的变化与土壤侵蚀速率具有负相关趋势。     

Carbon stocks and sequestration potentials of agricultural soils in the federal state of Baden‐Württemberg,SW Germany

Soil organic carbon (SOC) inventories are important tools for studying the effects of land‐use and climate change and evaluating climate‐change policies. A detailed inventory of SOC in the agricultural soils of the federal state of Baden‐Württemberg was therefore prepared based on the highest‐resolution geo‐referenced soil, land‐use, and climate data (BÜK200 inventory). In order to estimate the quality of different approaches, C inventories of the region were also prepared based on data from the National Inventory Report (UBA, 2003) and by applying the IPCC (1997) method to the two data sets. Finally, the BÜK200 inventory was used to estimate potentials of no‐tillage agriculture (NT) and peatland restoration to contribute to C sequestration and greenhouse‐gas (GHG)‐emission mitigation since both measures are discussed in this context. Scenario assumptions were change to NT on 40% of the cropland and restoration of 50% of cultivated peatlands within 20 years. On average, grasslands contained 9.5 kg C m^–2 to 0.3 m depth as compared to only 6.0 kg C m^–2 under cropland, indicating strong land‐use effects. The SOC content depended strongly on waterlogging and elevation, thus reflecting reduced C mineralization under aquic moisture regimes and low temperatures. Comparison of the BÜK200 inventory with the approach used for UBA (2003) showed high inconsistencies due to map resolution and SOC contents, whereas the IPCC method led to fairly good agreements. Results on the simulated effects of NT and peatland restoration suggested that 5%–14% of total agricultural GHG emissions could be abated with NT whereas peat restoration appeared to have a minor mitigation potential (0.2%–2.7%) because the total area of cultivated organic soils was too small to have larger impact.     

Comparing the potential effectiveness of conservation planning approaches in central North Carolina, USA

We compared four approaches to conservation site selection to protect forest biodiversity in the Triangle Region of North Carolina, USA. Using biological inventory data and an inventory-based conservation plan as benchmarks, we evaluated the potential effectiveness of a focal species plan and three “simple” plans (large forested patches, close to wetlands and riparian areas, diverse forest types). Effectiveness was measured in three ways: the number of inventory elements captured at least once by the plan (representation), the total number of inventory elements captured (completeness), and the proportion of land in the inventory-based plan included (overlap). We further examined the potential effectiveness of the simple plans by calculating their overlap with land identified by the focal species approach. The simple and focal species plans did not differ markedly in terms of representation, but diverged when completeness and overlap were considered. Although representation rates for all four plans were relatively high, lower rates for completeness and overlap raise concerns about long-term viability. The simple plans did not identify the same lands as the focal species plan, and are thus unlikely to provide appropriate habitat for the focal species. Each approach we tested failed to capture some subset of species and communities, highlighting the importance of explicit conservation targets and consideration of ecological processes. Forced to act quickly and with little data, our findings suggest using initially a set of complementary simple plans, each focused on a different habitat type. This should be considered a stopgap measure, however, while more sophisticated plans are constructed, defining explicit conservation targets and considering ecological processes.     

Gully development in the Moldavian Plateau of Romania

Gully erosion has been recognized as an important environmental threat in the Moldavian Plateau of Eastern Romania. The main objective of this study was to define the process-based gully development by providing quantitative information from long-term field measurements in small catchments.Three main areas of monitoring gullies were explored: aerial photographs of flights in 1960 and 1970, classical leveling and repeated survey through a particular close stakes grid after 1980. The Caesium-137 technique has been used effectively in the areas of deposition of gully sediments to obtain reliable information on dating specific levels of sediments and to provide chronological measures of gully development.Most of the discontinuous gullies exhibit both proper gullying, mainly if not exclusively by gully head advance, and aggradation of the gully basin floor. Results indicated that the mean gully head retreat was 0.92 m year^− 1 and the mean areal gully growth was 17.0 m² year^− 1. Both values indicate a slow erosion rate for this area. The average annual regime of gullying is pulsatory, one that is best described by great fluctuations. Conventional measurements on sedimentation over the period 1987–1997 indicate a higher rate of aggradation in the upper half of the gully floor. Information on the Caesium-137 depth profile was used to provide estimates of a mean sedimentation rate of 4.4 cm year^− 1 over the period 1963–1996 and 2.5 cm year^− 1 after 1986 for the short successive discontinuous gullies. A new classification of the discontinuous gullies based on two criteria, respectively, the field patterns and the rate of aggradation within the gully basin floor was established.For continuous gullies, linear gully head retreat, areal gully growth and eroded material rates were quantified for three periods (1961–1970, 1971–1980 and 1981–1990). Results indicate that gully erosion has decreased since 1960. This gullying decline is due to the rainfall distribution, and the increased influence of soil conservation practices. The mean gully head retreat of 12.5 m year^− 1 between 1961–1990 was accompanied by a mean areal gully growth of 366.8 m² year^− 1 and a mean erosion rate of 4168 t year^− 1. As with discontinuous gullies, continuous gullies showed pulsatory development.The critical period for gullying over 1981–1996 covers 4 months from Mid March to Mid July in an area with mean annual precipitation around 500 mm. Another main finding of this 16-year stationary monitoring was that 57% of the total gullying occurred during the cold season, with the remainder during the warm season. Of the total gully growth, 66% results from only four years (1981, 1988, 1991 and 1996), when a greater amount of precipitation fell.     

The immune system of cyprinid fish. Oxytetracycline and the regulation of humoral immunity in carp (Cyprinus carpio)

The antibiotic oxytetracycline (oxyTC) was administered either by mixing with food or by intraperitoneal injections. In oxyTC treated animals decreased serum immunoglobulin levels were found. The primary anti-sheep red blood cell (SRBC) response was measured by enumerating plaque forming cells (PFC). It was observed that the PFC response was depressed by 80–95% in oxyTC treated animals. When an anti-SRBC serum was injected together with SRBC the immunosuppressive effect of oxyTC was absent. A secondary anti-SRBC response was not inhibited by oxyTC. On base of the results a model for antigen presentation and the interaction between macrophages, T- and B-like cells during primary and secondary responses in fish is proposed. In primary responses cellular interaction is needed to develop a proper immune response whereas after a high antigen dose challenge SRBC might behave as a T-independent antigen.     

Drought damage in the park forests of the city of Helsinki

During spring and summer 2003 severe drought-caused damage was observed in the park forests of the city of Helsinki; especially in barren site pine and spruce stands. The objectives of this study were to map and document the extent of the damage through the use of existing geographical information, digital aerial photography and field surveys and to examine the feasibility of assessing drought damage by visual interpretation of digital aerial photography. Our aim was also to assess the reasons for drought damage in Helsinki city park forests using geographic information system (GIS) analyses of existing interpretative and geographical data, i.e. digital aerial photographs, rainfall statistics and the compartmentwise GIS database of the park forest site and soil types.The total amount of area falling into serious damage classes represented approximately 25 ha (the total forested area in Helsinki is about 3700 ha). A majority of these areas were located on rocky sites having low stem volumes. The total proportion of damaged stock volume was estimated as 17 300 m³, which is 3.3% of the total stock volume in the study area. An accuracy assessment showed that visual interpretation of digital aerial photos is an excellent tool for assessing drought damage. The mean estimation error was 0.7 classes, and errors comprising 2 classes were found in all test grids. The overall correct percentage of photointerpretation was 46%, and estimation was unbiased (kappa 0.264). The forest site and soil type together with the tree species on site showed the greatest correlation with drought damage. The drier and more barren the site, the more likely that damage will occur. Roadside forests were in better condition than areas located further off the roads. Hills clearly impacted the condition of the trees through soil type and flow.     

有年龄生长模型应用于无年龄情况研究

许多生长模型含有年龄因子。由于一方面年龄测定困难,另一方面在异龄林中林木的年龄意义不大,导致以年龄为自变量的生长模型在应用中遇到困难。针对森林资源连续清查体系中具有大量重复观测样木数据,但无年龄数据的实际情况．探讨将有年龄模型应用于无年龄情况,为将已有的有年龄生长模型用于森林资源连续清查数据的更新和预测做准备。用浙江省丽水市龙泉市的9株马尾松Pinus massoniana解析木数据建立有年龄的胸径生长模型．然后用丽水市森林资源连续清查体系中重复观测的马尾松固定样木数据进行无年龄情况应用研究。分单点估计和双点估计2种方式进行了试验．单点估计是用前期数据估计理论年龄然后估计后期胸径,双点估计是用前2期数据估计理论年龄和生长指数。然后用于后期胸径的估计。结果表明：单点估计和双点估计的精度都比直接用年龄的高．尤其双点估计具有更高的精度和适应性,它完全可以用于森林资源连续清查数据的更新和预测。图2表5参14     

高精度保证下的浙江省森林植被生物量评估

为准确评估浙江省森林植被生物量,以2009年浙江省森林资源连续清查第一手野外调查数据为数据源,以样地为评估基本单元,采用单株生物量模型法(乔木,毛竹Phyllostachys edulis,杂竹,下木和灌木),单位面积生物量模型法(草本)和单位面积生物量法(矮化乔木林、灌木经济林),测算了样地水平的森林植被生物量.在此基础上,运用系统抽样统计方法,将样地水平微观数据转换到全省宏观尺度,评估了全省总体的森林植被生物量,提供了主要评估结果的估计精度和估计区间.结果显示:2009年,浙江省森林植被总生物量为37 010.732×104t.主要森林植被类型中,乔木林群落为29 096.269×104t,竹林群落3 762.964×104t,灌木林群落1 747.953×104t.在P＜0.05的可靠性保证下,森林植被总生物量估计精度为96.64％,估计区间为35 767.171×104～38 254.293×104t;乔木林群落9558％,估计区间为27 810.214×104～30 382324×1 04t;竹林群落89.13％,估计区间为3 353.930×104～4 171.998×104t;灌木林群落90.00％,估计区间为1 573.158×104～1 922.748×104t.可见,采用以上方法测算的浙江省各类森林植被生物量评估结果,均有很高的精度保证和较好可信度.     

基于森林资源二类调查数据的杉木人工林收获表编制

应用旌德县庙首林场198个杉木人工林小班数据,选用3种林分因子生长模型拟合杉木人工林林木生长过程,用非线性麦夸特迭代求解法,确定各模型参数、剩余离差、相关指数等;根据相关指数最大、剩余离差最小原则,确定最佳杉木人工林林分因子最佳生长模型。结果表明,理查德模型拟合效果最好,直径(D)=455.409 9SI0.197 6(1-e-0.000 2 t)0.753 4,树高(H)=8.926 8SI0.370 2(1-e-0.029 4 t)1.103 9,蓄积(M)=98.808 5SI0.306 3(1-e-0.132 3t)4.709 7。根据上述模型编制的杉木人工林经验收获表,可以为庙首林场杉木人工林林分收获预估及森林经营决策提供依据。