Assessing conservation priorities in the Benguela ecosystem, South Africa: analysing predation by seals on threatened seabirds

Cape fur seals (Arctocephalus pusillus pusillus), a protected species, have become abundant in the Benguela ecosystem off the west coast of southern Africa (present population size about 1.5-2 million animals), and are killing substantial numbers of red data book species of seabirds (African penguin Spheniscus demersus, Cape gannet Morus capensis, Cape cormorant Phalacrocorax capensis, bank cormorant P. neglectus and crowned cormorant P. coronatus). The decision has been taken to reduce the impact of seal predation by selectively culling seals which are witnessed killing seabirds. Between 1993 and 2001 a total of 153 seals, which were killing fledgling gannet chicks, were culled.     

Influences of recovery from clear-cut, climate variability, and thinning on the carbon balance of a young ponderosa pine plantation

From 1999 to 2002, the variations in carbon flux due to management practices (shrub removal, thinning) and climate variability were observed in a young ponderosa pine forest originated from clear-cutting and plantation in 1990. These measurements were done at the Blodgett Forest Ameriflux site located in the Sierra Nevada Mountains of California. Thinning in spring 2000 decreased the leaf area index (LAI) by 34% and added 496 g C m⁻² of wood and leaf debris at the soil surface. Total ecosystem respiration was not significantly affected by thinning (1261 g C m⁻² in 1999 and 1273 g C m⁻² in 2000), while canopy photosynthesis decreased by 202 g C m⁻². As a result the ecosystem shifted from a net sink of CO₂ in 1999 (−201 g C m⁻²) to a small net source in 2000 (13 g C m⁻²). Woody and leaf debris resulting from thinning only accounted for maximum 1% and 7% of the total respiration flux, respectively. Thinning did not affect the relative proportion of the different components of respiration to an observable degree. Low soil water availability in summer 2001 and 2002 decreased the proportion of soil respiration to the total respiration. It also imposed limitations on canopy photosynthesis: as a result the ecosystem shifted from a sink to a source of carbon 1 month earlier than in a wetter year (1999). The leaf area index and biomass of the stand increased rapidly after the thinning. The ecosystem was again a sink of carbon in 2001 (−97 g C m⁻²) and 2002 (−172 g C m⁻²). The net carbon uptake outside the traditionally-defined growing season can be important in this ecosystem (NEE = −50 g C m⁻² in 2000), but interannual variations are significant due to differences in winter temperatures.     

我国农田生态系统碳蓄积及其变化特征研究

对我国近20年来农田生态系统C蓄积的时空变化特征进行估算分析结果表明,我国农田生态系统近20年来C蓄积总量持续增大,主要是由于单位面积C密度持续增大。农田C密度高值区主要分布在我国东部地区且多>3t/hm2,低值区主要分布在我国北方农牧交错带地区且普遍<1t/hm2。而科学管理作物残余物是增强农田生态系统C蓄积能力的关键。     

利益相关者对塔里木河下游荒漠河岸林生态系统服务的认知度分析

近50年以来,塔里木河下游生态环境曾因人类不合理开发利用而导致严重退化。自2000至2013年实施的人工生态输水工程对胡杨为主体的荒漠河岸林的恢复及其生态系统服务功能的提高产生了积极影响。通过问卷调查的方法分析了利益相关者对塔里木河下游荒漠河岸林生态系统服务的认知程度。结果表明:88.1%的被调查者对荒漠河岸林生态系统服务有深刻的认识,7.8%的人不清楚;84%的被调查者认为荒漠河岸林在防止沙(荒)漠化方面的效益最高,仅有8.1%被调查者认为提供建筑材料和动物饲料等方面效益最高;被调查者对人工输水后生态环境变化的感知度依次为:灰尘和沙尘暴减弱沙(荒)漠化减少胡杨长势改善胡杨幼树增多河岸林面积增加;被调查者对人工输水的支付意愿有所差异,其中15.1%的人对其态度模糊,7.8%的人不愿意支付,有36%的被调查者愿意支付工资的1%,15.4%的被调查者愿意支付工资的1%,12%的人愿意支付工资的2%,3.8%的人愿意支付工资的3%,7.9%的人愿意支付工资的3%。问卷调查的结果表明,被调查者对塔里木河下游荒漠河岸林生态系统服务的认知度和支持率相当高,体现出生态输水的社会效益显著。     

山东省寿光市湿地生态系统价值评估

依据资源经济学和生态经济学的理论和方法，针对寿光湿地资源的特点，对寿光湿地的主要生态才能价值一直接利用价值和间接利用价值进行了货币化评估，由此得出寿光湿地的主要生态服务功能价值为58.4亿元，其中价值最大的是降解污染物功能，价值量为40．4亿元，其次是物质生产功能、水文调节价值和文化科研价值，分别为6．5亿元、4．2亿元、4．4亿元。最后在此基础上提出了适合寿光湿地可持续发展的保育措施。     

Spatial and temporal patterns of vegetation recovery following sequences of forest fires in a Mediterranean landscape,Mt. Carmel Israel

The Mediterranean ecosystem of Mt. Carmel is subjected to increasing number of forest fires at various extents and severities due to increasing human activities. Accordingly, we tested whether in areas exposed to different fire histories vegetation regeneration is different in north versus south facing slopes, and the potential impact on erosion processes. Using remote sensing techniques we evaluated the Enhanced Vegetation Index (EVI) to monitor vegetation recovery following a single fire and three successive fires, using a series of Landsat images taken between 1985–2002. Following a single fire, vegetation cover reached pre-disturbance values within less than 5 years. Repeated fires caused further reduction of EVI values, especially at south facing slopes (SFS). The effects of three successive fires within 10 years, followed by a three year recovery period, however, are negligible when considering vegetation cover values. This was deduced as north facing slope EVI values returned to pre-disturbance conditions at the end of the 3 years and SFS EVI values to 80% of the pre-disturbance conditions. Our results indicate that Mediterranean eco-geomorphic systems are quite resilient, showing quick response, at least in terms of return to pre-disturbance states of vegetation cover, and hence of soil erosion rates. This is true not only in response to a disturbance caused by a single fire, but also for repetitive fire incidents.     

Developing programs to monitor ecosystem health and effectiveness of management practices on Lakes States National Forests, USA

Assessing accomplishment of management objectives related to ecosystem health requires monitoring key indicators, including ecological processes and components of biological diversity. For these purposes, a monitoring plan was developed on the Chequamegon National Forest. It was refined by use of public workshops and technical consultation, and later adjusted based on practicality and additional inventory needs. To date, monitoring has focused on plants and birds, including long-term baseline monitoring in both managed forest and more natural areas. Monitoring is done at both the national forest and the ranger district levels, a forest subunit, the latter usually focusing on specific projects rather than forestwide ecosystem health concerns. Examples from the Laurentian ranger district of the Superior National Forest are provided. Future assessments will require qualitative, quantitative and spatial analyses of community, ecosystem, habitat and population trends and patterns, and management effects. An institutionalized program that focuses on key ecosystem components at various scales, and that involves concerned publics and many partners, will be necessary to provide feedback to refine forest management.     

Species diversity and seasonal abundance of Collembola in turfgrass ecosystems of North America

In North America, lawns are the most widely used plantings in urban areas. However, despite the ubiquity and ecological roles of turfgrass soil arthropods, many aspects of their composition and diversity have been neglected. We investigated assemblages of Collembola and their seasonal fluctuations in a newly established lawn and a 10-year old lawn located in Québec City, Canada. Collembola were sampled every month from May to October in 2003 and 2004 by extracting individuals from soil cores using a modified Berlese funnel. A total of 21 species representing 17 genera and nine families were identified. Four species are new records for the province of Quebec: Brachystomella parvula, Mesaphorura simplex, Isotomodes productus, and Sphaeridia pumilis. Turfgrass supports mainly three cosmopolitan species from the Isotomidae family, which represent 73.5% of all Collembola collected during the survey: Parisotoma notabilis, Isotoma viridis, and Cryptopygus thermophilus. Collembola were twice more abundant at the newly established site, but there were minor differences in species diversity between sites and years. No clear patterns of seasonal relative abundance were observed for the whole Collembola populations, as well as for the three dominant species. Turfgrass ecosystem provides a suitable habitat for epedaphic and hemiedaphic Collembola, such as the Isotomidae, most likely because turfgrass mowing and natural leaf, stem and root replacement produces large amounts of decaying organic matter.     

Impact of subterranean fungus-growing termites (Isoptera, Macrotermitiane) on chosen soil properties in a West African savanna

Fungus-growing termites (Isoptera, Macrotermitinae) play an important role in tropical ecosystems in modifying soil physical properties. Most of the literature regarding the impact of termites on soil properties refers to termite epigeous mounds. In spite of their abundance and activity in African savannas, few studies deal with the properties of underground nest structures (fungus-comb chambers) built by subterranean Macrotermitinae termites. We tested whether these termites significantly modify the soil physico-chemical properties within their nests in a humid tropical savanna and whether these effects are different for two termite species with differing building behaviour. Termite-worked soil material was collected from fungus-comb chamber walls of two widespread species: Ancistrotermes cavithorax, which builds diffuse and ephemeral nests and Odontotermes nr pauperans, which most often builds concentrated and permanent nests for a comparatively much longer period of time. Neither species influenced soil pH but both significantly modified soil texture and C-N content in their nest structures. A strong impact on clay-particle size was also detected but no significant differences in clay mineralogy. Thus Odontotermes has a greater effect on soil properties, that could be explained by its building behaviour and the concentration in space of its nest units. Therefore, spatial pattern and life-span of fungus-comb chambers should be an important parameter to be considered in the functional role of subterranean Macrotermitinae termites in the savanna.     

Termite mounds in relation to the surrounding soils in the forest and derived savanna zones of southeastern Nigeria

Some physical and chemical properties of the two common termite mounds in southeastern Nigeria, Macrotermes (MM) and Cubitermes (CM) mounds, were compared and their relationships with the surrounding top and subsoils investigated. Percentage sand, silt, pH, calcium, magnesium, potassium, sodium, iron, and organic carbon were higher and clay and penetrometer resistance lower in the CM than the MM. Sand, silt, organic carbon, and calcium decreased and clay increased from the forest to the derived savanna in the CM, but no clear trend was shown with the other properties in both the CM and the MM. Most of the nutrients were higher in the CM than in the adjacent top or subsoil but the reverse was the case with the MM. More nutrients are associated with the inorganic fractions of the soil than with the organic carbon in the mounds and the soils surrounding them. The Ca:Mg ratio in the mounds and the top and subsoils adjacent to them was low for most crops but the K:Mg ratio was mostly adequate. Because of these differences in properties and sizes of the mounds, different management strategies are recommended for them and the soils around them.