Sustainable management of a coastal lagoonal system (Ria Formosa, Portugal): An ecological model for extensive aquaculture

The Ria Formosa lies in southern Portugal, extending for about 55 km. It is a true barrier island system, comprising mainland, backbarrier lagoons, inlet deltas, barrier islands, barrier platforms and shoreface. Of the Ria Formosa system, which covers a total area of 163 km², 20 km² are occupied by salinas and aquaculture ponds. The main water reservoir of thesalinas and the extensive aquaculture ponds behave like small lagoons where there are one or more openings to a tidal channel. These small lagoons have the advantage of being easy to study and to model. An ecological model was developed to estimate the potential production of the gilthead seabream in the Ria Formosa, in an extensive aquaculture regime. This model was based on information concerning chemical and physical factors (forcing functions) and secondary production estimates from four sites in the Ria Formosa with different environmental conditions, where extensive aquaculture is practised. Published information on optimal growth parameters of the gilthead was used to build the model, which was based on some assumptions concerning the detrimental effect of an excessive increase of salinity and other environmental factors both on gilthead growth (one state variable) and on prey production (divided into two state variables), which is essentially benthic macrofauna. Reservoirs with low water renewal undergo large environmental fluctuations. The growth of gilthead or other fish can be difficult, not only because of the adverse environmental conditions but also because of the low secondary production. The maximum yield of fish is predicted to be less than 6 g m⁻². In reservoirs where the water exchanges on almost every tide, the maximum yield of gilthead can be in excess of 22–25 g m⁻². Nevertheless, the high productivity of these sites in terms of secondary production of benthos and fish, as well as primary production, can lead to oxygen depletion during the night or at day-break. An attempt to further improve fish production by fertilisation or by adding food could provoke a rapid deterioration of the water quality and endanger all production.     

Evaluation of forest cover change using remote sensing techniques and landscape metrics in Moncayo Natural Park (Spain)

Monitoring the change in land cover in natural places, such as ecotones, has become an important tool for forest management, especially in protected areas. The present work analyses the spatial and temporal changes in forest cover in Moncayo Natural Park (Spain) from 1987 to 2010 using remote sensing techniques, geographical information systems (GIS) and quantitative indices of landscape ecology. Four Landsat images were used to map nine representative land cover categories in this preserved area in both years. The overall classification accuracies in land cover cartographies in 1987 and 2010 were 87.65% and 84.56%, respectively. Landscape metrics obtained at the landscape level show an increase in fragmentation and, as a result, an increase in landscape spatial diversity. Focusing on the class level, the results show a forest expansion of sessile oaks (Quercus petraea) and beech forest (Fagus sylvatica), two important bioclimatic indicators in this natural park, because they are the southernmost locations for these species in Europe. The decrease of mainly introduced pine forest and the transformation of mixed shrub areas into natural forested areas explain the aforementioned increase in fragmentation. These results are in agreement with the strategies for nature conservation designed by forest managers during the period evaluated.     

Morphological features and processes in the central Algarve rocky coast (South Portugal)

Morphological features along the Algarve rocky coast, South Portugal, are identified and described, with an emphasis on shore platforms and notches. The contributions of processes, such as wave attack, chemical weathering and bioerosion, to sculpting the shore platforms are discussed. The preferential localization of shore platforms on sites exposed to waves, and the lack of significant chemical weathering, point to wave erosion as the first-order factor in platform formation, whilst bioerosion/bioprotection, lithology and geological structure determine platform morphological variations. In addition, platforms above the present intertidal zone appear to have a polygenetic evolution, being inherited from former sea-level highstands and currently undergoing chemical weathering. The occurrence of notch features is independent of the degree of exposure to waves, but they mostly occur where the substratum is sand. Hydrostatic pressure appears to be an important factor in the formation of marine caves in the more sheltered sites.     

Tourism and dependency in Southern Africa: the prospects and planning of tourism in Lesotho

During the 1970s tourism in Lesotho developed rapidly, representing a vital source of foreign exchange to a country where economic options are severely constrained. However, an analysis of the spatial and temporal patterns of tourist movements reveals a serious downswing in fortunes in recent years. The number of arrivals, length of stay and bed occupancy are all declining. An explanation for this is sought in the highly specific nature of Lesotho's tourism and in its dependence upon the South African market and externally controlled corporate strategy within the hotel industry. Despite its considerable scenic attractions, Lesotho in fact relies almost exclusively upon its two casinos to generate tourism. Before gambling was legalized within the borders of South Africa's ‘Bantustans’ these kind of operations were monopolized regionally by Holiday Inns and located on the Republic's periphery. However, in the late 1970s Southern Suns successfully invaded this market through investment within the Bantustans and, as an outcome of this competition, the future planning of both corporations is now to transfer development from the traditional arenas to the Bantustans where profitability is higher. Lesotho's inability to compete with these newer units is clearly demonstrated by the data, particularly in the loss of Witwatersrand punters to Bophuthatswana. Nevertheless, tourism planning in Lesotho is still based upon consolidation of its casino trade. In the light of these and parallel observations in Swaziland this prospectus must be seriously reappraised.     

Detecting multi-scale urban growth patterns and processes in the Algarve region (Southern Portugal)

The importance of urban growth processes and their spatial characteristics has led to a growing interest in monitoring these phenomena. Spatial metrics are widely employed for this purpose, appearing in an increasing number of studies where they are used to characterise growth patterns and their evolution over time. This paper presents an analysis of urban growth patterns using spatial metrics in the Algarve (southern Portugal), an area of considerable urban dynamics associated with tourism. Two datasets were used (CORINE 1:100,000 maps and COS 1:25,000 maps) and two time periods (1990 and 2006–2007) in order to compare the different urban land use patterns detected and their evolution over time. The results show differences in urban land use patterns and associated processes at each scale, with stable land use patterns predominating at the 1:100,000 scale whereas the 1:25,000 scale showed a move towards more dispersed patterns. These results have enabled an assessment of the principal differences in urban growth patterns observed at both scales, and the implications for planning these entail.     

Probabilistic landslide risk analysis considering direct costs in the area north of Lisbon (Portugal)

The purpose of the present study is the analysis of landslide risk for roads and buildings in a small test site (20 km²) in the area north of Lisbon (Portugal). For this purpose, an evaluation is performed integrating into a GIS information obtained from multiple sources: (i) landslide hazard; (ii) elements at risk; and (iii) vulnerability. Landslide hazard is assessed on a probabilistic basis for three different types of slope movement (shallow translational slides, translational slides and rotational slides), based on some assumptions such as: (i) the likelihood of future landslide occurrence can be measured through statistical relationships between past landslide distribution and specified spatial data sets considered as landslide predisposing factors; and (ii) the rainfall combination (amount–duration) responsible for past slope instability within the test site will produce the same effects (i.e. same type of landslides and similar total affected area), each time they occur in the future. When the return period of rainfall triggering events is known, different scenarios can be modelled, each one ascribed to a specific return period. Therefore, landslide hazard is quantitatively assessed on a raster basis, and is expressed as the probability for each pixel (25 m²) to be affected by a future landslide, considering a rainfall triggering scenario with a specific return period. Elements at risk within the test site include 2561 buildings and roads amounting to 169 km. Values attributed to elements at risk were defined considering reconstruction costs, following the guidelines of the Portuguese Insurance Institute. Vulnerability is considered as the degree of loss to a given element resulting from the occurrence of a landslide of a given magnitude. Vulnerability depends not only on structural properties of exposed elements, but also on the type of process, and its magnitude; i.e., vulnerability cannot be defined in absolute terms, but only with respect to a specific process (e.g. vulnerability to shallow translational slides). Therefore, vulnerability was classified for the three landslide groups considered on hazard assessment, taking into account: (i) landslide magnitude (mean depth, volume, velocity); (ii) damage levels produced by past landslide events in the study area; and (iii) literature. Finally, a landslide risk analysis considering direct costs was made in an automatic way crossing the following three layers: (i) Probabilistic hazard map for a landslide type Z, considering a particular rainfall triggering scenario whose return period is known; (ii) Vulnerability map (values from 0 to 1) of the exposed elements to landslide type Z; and (iii) Value map of the exposed elements, considering reconstruction costs.     

Soil fertility evolution and landscape dynamics in a Mediterranean area: a case study in the Sant Llorenç Natural Park (Barcelona, NE Spain)

The cartography of land covers was used to study fertility and soil evolution in a mountainous Mediterranean area during the anthropocene period ( Crutzen P J 2002 Geology of mankind Nature 415 23). The aim was to determine changes in fertility as agricultural lands were abandoned in the 14 000 hectare area that constitutes Sant Llorenç del Munt Natural Park in a pre-coastal Catalan mountain range (north-eastern Iberian Peninsula). The analysis of land covers using vegetation maps, orthorectified images and aerial photography has allowed us to differentiate six vegetation groups: holm-oak wood, pine grove, oak wood, scrub, active agricultural fields and abandoned agricultural fields. The anthropic covers over the past 100 years were subdivided into five categories: active fields and those abandoned over four time periods. Study variables include field shape (concave, convex, flat), orientation (north, south) and slope (ranging from 12º to 24º). The parameters used for the physical-chemical soil analysis included organic material, phosphorous and potassium; fertility was classified based on groups, types and classes. The results indicate that even when the visual appearance of certain landscapes is similar, the edaphic characteristics may be very different. Changes induced by human disturbance share this phenomenon. Therefore, land management should be considered globally, taking into account vegetation, soils and water as interdependent factors, since it is their interaction that produces landscape and most affects its evolution over time.     

广州鳄鱼公园野生动物旅游中的生命权力运作

自然的社会建构是近年来欧美地理学界重新审视人与自然关系的重要理论思潮之一。本文从自然的社会建构视角出发,以福柯“生命权力”的概念为理论工具,通过参与式观察、半结构化访谈和文本分析的方法,深入分析野生动物旅游活动中人与动物互动过程及其权力关系的运作,并展示在此过程中景区、野生动物、政府和NGO等组建的行动者网络。研究发现：① 通过标准化、高科技的管治与保育措施,景区中动物种群的性别、健康与数量等方面得以最大程度的调控,并由此形成了与旅游市场相适应的“生命政治”运作模式;② 景区已经能够熟练地规训野生动物参与各项旅游活动,并在此基础上巧妙地操控游客想要亲近并征服野生动物的双重渴望;③ 不同行动者在协商与制衡中组建的行动者网络,实质上为人对野生动物生命权力的施展提供了合法性与道德性的框架,使其更加紧密地嵌入到社会文化情境之中。研究丰富了野生动物旅游研究的相关理论成果,为人文地理学分析自然与社会的关系提供了新的思考和尝试。     

旅游活动对黄石寨景区步道的影响评估

作为旅游景区基础设施的步道,高频率旅游利用会对其产生一定程度的影响。选取张家界森林公园的黄石寨景区为研究对象,运用"既成事实调查法",设置30个样点,选取了若干特征与指标来评估步道的受影响情况。结果显示,景区的步道扩展率为13.5%,步道冲蚀发生率为73.3%,步道损毁有14处,步道边缘的土壤性状和植被状况也发生了改变,这说明旅游活动对黄石寨景区步道产生了负面影响。而且山顶环寨游道受到旅游活动的影响最大,上山游道次之,下山游道最小,这与旅游利用强度密切相关。     

The origin of the Pedra Furada sandstone tubular structures (South of Lisbon, Portugal)

The Pedra Furada is a 12 m wide, 18 m high outcrop feature showing hundreds of ferruginised sandy tubes and looking in part like a giant organ. In this paper the origin of the tubes is explained on the basis of geochemical, petrographic and microscopic (optical and electronic) analytical data. The tubes are considered to represent vertical escape channels for overpressured water, exhibiting inward decreasing grain size due to water velocity gradients inside the escape channels. The ferruginisation is due to iron oxides associated with colloidal/clayey fine sediments and to goethite formed from solution. The overpressure of water may be due to seismically fluidised beds below the Pedra Furada outcrop or to artesian water ascent. In both cases, fault rupturing may have played a major role in the focussing of the ascending flow.     

Management of the old field vegetation in the Namaqua National Park, South Africa: conflicting demands of conservation and tourism

Springtime mass displays of wild flowers are especially prominent on old fields and other disturbed sites in Namaqualand, an arid region in the north–western part of South Africa. This springtime floral spectacle draws thousands of tourists annually. However, there is a potential conflict between biodiversity conservation and the mass flowering that is a valuable source of income to the region. To develop a management plan for the old field vegetation in the Namaqua National Park, the questions of whether to disturb or not, how often to disturb and what type of disturbance should be applied are of vital importance. The aim of this paper is to report on experimental work to determine the impact of disturbance on mass flowering displays and biodiversity. Results show that although species diversity increased with time since last cultivation, the mass effect of the flowering display diminished. The loss of the mass effect appears to be primarily caused by the increased abundance of a short–lived perennial species ( Leysera gnaphalodes ) that suppressed the flowering display of the prominent annual species. To maintain mass displays as a tourist attraction, regular disturbance by tilling therefore seems essential. Initially, a four–year rotational tilling programme is proposed to produce a mosaic of fields of different ages to ensure that there will always be some old fields producing a spectacular and uncluttered display. Frequency of disturbance should thereafter be determined by an adaptive management policy. If the management of the old field vegetation is seen in the context of conserving total landscape ecodiversity, this includes conserving cultural bio–landscapes and their intrinsic values. Viewed in this context, human–induced disturbance in the small area set aside for mass displays in the Namaqua National Park (less than 0.05% of the park) becomes justified.     

Effect of vegetation with different evolution degree on soil organic matter in a semi-arid environment (Cabo de Gata-Níjar Natural Park, SE Spain)

The organic matter of the surface horizons of soils developed below scrub vegetation in a Mediterranean semi-arid area of great environmental interest (Cabo de Gata-Níjar Natural Park, SE Spain) has been studied. The study mainly concentrates on examining the influence of two vegetation types, one evolved (according to its successional stage), and the other clearly degraded as a result of prior removal of vegetation. In spite of the homogeneity in the results obtained from the analysis of the organic matter from the soils studied, a relationship may be established between vegetation biotype and characteristics and evolution of the soil organic matter. The evolved vegetation results in the presence in the soil of a somewhat more evolved and stable organic matter (demonstrated by certain chemical and microbiological aspects), resulting in a greater degree of humification, thus favouring the protection of the soil and the ecosystem as a whole. Hence, the presence of degraded vegetation might lead to soil degradation, something that is unsustainable in semi-arid areas that are particularly fragile in nature.     

The creation of a spatial data infrastructure in management of regions (exemplified by Irkutsk oblast)

We examine the currently central issues related to developing the regional component of a spatial data infrastructure. We identify the primary goals and basic principles embedded in the establishment of a spatial data infrastructure; the baseline spatial objects are outlined.     

Resource utilization and regional planning information systems (RURPIS) in Botswana

Abstract

Problems with data organization for increasingly complex resource utilization and regional programmes have encouraged Botswana to turn to a geographical information systems approach. A major project to carry this out, based in the Department of Environmental Science, University of Botswana, is outlined in this paper. The paper documents the design of the programme and lists its modules and variables. It also reports on important considerations that have been taken into account in evaluating the programme's data sets and gives results from an illustrative pilot project that has been undertaken.     

夹金山脉大熊猫栖息地自然遗产的国家公园管理模式

大熊猫栖息地是全球关注的生态系统和价值最突出的自然遗产之一。夹金山脉既是重要的大熊猫栖息地,又是独特的风景区域,“四川大熊猫栖息地———卧龙.四姑娘山.夹金山脉”世界自然遗产已获得了联合国教科文组织第30届世界遗产委员会的提名。目前的以省级为主的多个风景名胜区与自然保护区分别管理,已不能满足保护其突出的遗产价值的要求。作者提出从国家层面上,规划夹金山脉大熊猫栖息地国家公园统一整体管理该项遗产,以增强有效管理能力。然后讨论了夹金山脉在生物多样性保护上的重要性与风景资源价值,论证了国家公园的管理模式,并从国际上关于国家公园的界定、中国国家公园的法律依据、国家公园管理世界自然遗产,分析了国家公园管理大熊猫栖息地自然遗产的可行性。     

呼伦贝尔-阿尔山旅游区旅游资源空间结构研究

运用最近邻比率Rn、β指数、γ指数、紧密度指数、平均径路长定量研究呼伦贝尔-阿尔山旅游区的旅游资源空间分布形态以及空间网络结构的连接性和通达性,分析得出,目前该旅游区的旅游资源集聚性强(Rn＝0.03),适合区域旅游活动的开展,但由于β＝1.5,γ＝0.58,平均径路长为2.57,表明旅游交通网络连接性和通达性较差,说明该旅游区的旅游资源空间联系较弱,加强旅游区旅游交通网络体系建设,提高旅游交通网络结构的连接性和通达性水平,是该旅游区急需解决的一个重要问题.由于旅游区紧密度指数C＝0.81,则表明较紧凑的区域形态为改善旅游交通网络结构的性能提供了较好的基础.研究表明,最近邻比率Rn、β指数、γ指数、紧密度指数和平均径路长等5种分析技术是研究区域旅游资源空间结构较为合理的指标.