Showing papers in "AMBIO: A Journal of the Human Environment in 2008"
TL;DR: Coastal wetlands function as valuable, selfmaintaining “horizontal levees” for storm protection, and also provide a host of other ecosystem services that vertical levees do not, which is an extremely cost-effective strategy for society.
Abstract: Coastal wetlands reduce the damaging effects of hurricanes on coastal communities. A regression model using 34 major US hurricanes since 1980 with the natural log of damage per unit gross domestic product in the hurricane swath as the dependent variable and the natural logs of wind speed and wetland area in the swath as the independent variables was highly significant and explained 60% of the variation in relative damages. A loss of 1 ha of wetland in the model corresponded to an average USD 33 000 (median ¼ USD 5000) increase in storm damage from specific storms. Using this relationship, and taking into account the annual probability of hits by hurricanes of varying intensities, we mapped the annual value of coastal wetlands by 1km 3 1km pixel and by state. The annual value ranged from USD 250 to USD 51 000 ha � 1 yr � 1 , with a mean of USD 8240 ha � 1 yr � 1 (median ¼ USD 3230 ha � 1 yr � 1 ) significantly larger than previous estimates. Coastal wetlands in the US were estimated to currently provide USD 23.2 billion yr � 1 in storm protection services. Coastal wetlands function as valuable, selfmaintaining ‘‘horizontal levees’’ for storm protection, and also provide a host of other ecosystem services that vertical levees do not. Their restoration and preservation is an extremely cost-effective strategy for society.
679 citations
TL;DR: In order to improve the intercommunication among disciplines, a set of specific requirements that peer reviewed journals should request from all authors is proposed and an advocate for urgent institutional and financial support directed at reinvigorating the formation of scientific collections that integrate taxonomy and ecology is advocated.
Abstract: Why do ecologists seem to underestimate the consequences of using bad taxonomy? Is it because the consequences of doing so have not been yet scrutinized well enough? Is it because these consequences are irrelevant? In this paper I examine and discuss these questions, focusing on the fact that because ecological works provide baseline information for many other biological disciplines, they play a key role in spreading and magnifying the abundance of a variety of conceptual and methodological errors. Although overlooked and underestimated, this cascade-like process originates from trivial taxonomical problems that affect hypotheses and ideas, but it soon shifts into a profound practical problem affecting our knowledge about nature, as well as the ecosystem structure and functioning and the efficiency of human health care programs. In order to improve the intercommunication among disciplines, I propose a set of specific requirements that peer reviewed journals should request from all authors, and I also advocate for urgent institutional and financial support directed at reinvigorating the formation of scientific collections that integrate taxonomy and ecology.
329 citations
TL;DR: This article estimates the changes in parameters of the Tonle Sap flood pulse due to the flow alterations in the Mekong River and the impacts on the flooded area and loss of gallery forest and protected areas were analyzed using geographic information system–based methods.
Abstract: Rapid development in the upper reaches of the Mekong River, in the form of construction of large hydropower dams and reservoirs, large irrigation schemes, and rapid urban development, is putting water resources under stress. Recent studies have concluded that these developments will lead to flow alterations in the Mekong River. These flow alterations would threaten the sensitive ecosystems downstream, particularly Tonle Sap River, Tonle Sap Lake, its floodplain, and its gallery forest and protected areas, by changing the flood-pulse system of the lake. This article estimates the changes in parameters of the Tonle Sap flood pulse due to the aforementioned flow alterations. The impacts on the flooded area and loss of gallery forest and protected areas were analyzed using geographic information system–based methods. Relatively small rises in the dry-season lake water level would permanently inundate disproportionately large areas of floodplain, rendering it inaccessible to floodplain vegetation and eroding the productivity basis of the ecosystem. It is highly important to maintain the natural hydrological pattern of the Mekong River, particularly the dry-season water levels, to preserve Tonle Sap Lake’s ecosystem productivity.
315 citations
TL;DR: There was some variation in the rates of clearing across regions, where most protected areas from North America and Europe showed positive rates of land-cover change, whileprotected areas from Asia had the highest rates ofLand-cover clearing.
Abstract: This paper evaluates the impact of protected areas on land-cover clearing, using a metadata analysis of information on 49 locations from 22 countries. Protected areas had significantly lower rates of clearing in comparison to their surroundings. In addition, protected areas had also significantly lowered rates of clearing within their boundary following initiation of protection. Thus, protected areas do appear to be effective at limiting overall land-cover clearing. There was some variation in the rates of clearing across regions, where most protected areas from North America and Europe showed positive rates of land-cover change, while protected areas from Asia had the highest rates of land-cover clearing. While most protected areas from North America and Europe involved a relatively smaller number of actors, a greater number of actors and drivers of clearing was implicated in protected areas from Asia, Africa, and Latin America, indicating the increased difficulties faced by park management in these regions. In contrast, country income levels and the International Union for the Conservation of Nature and Natural Resources category of protection did not appear to impact the likelihood of land-cover clearing in protected areas.
257 citations
TL;DR: The Amazon is being rapidly transformed by fire, and the most alarming scenarios project a permanent disruption of the El Niño–Southern Oscillation leading to greatly increased drought or destructive synergisms between regional and global climate change in the Amazon.
Abstract: The Amazon is being rapidly transformed by fire. Logging and forest fragmentation sharply elevate fire incidence by increasing forest desiccation and fuel loads, and forests that have experienced a low-intensity surface fire are vulnerable to far more catastrophic fires. Satellites typically detect thermal signatures from 40 000 to 50 000 separate fires in the Amazon each year, and this number could increase as new highways and infrastructure expand across the basin. Many are concerned that large-scale deforestation, by reducing regional evapotranspiration and creating moisture-trapping smoke plumes, will make the basin increasingly vulnerable to fire. The Amazon may also be affected by future global warming and atmospheric changes, although much remains uncertain. Most models suggest the basin will become warmer throughout this century, although there is no consensus about how precipitation will be affected. The most alarming scenarios project a permanent disruption of the El Nino–Southern Oscil...
217 citations
TL;DR: It is argued that a more rational focus of the restoration effort should be the replanting of mangroves in the brackish-water aquaculture pond environments, the original habitat ofMangroves.
Abstract: The effort toward restoring lost mangroves in the Philippines has been commendably immense, specifically during the past two decades. In light of such, it is important to evaluate outcomes and, where appropriate, apply the lessons learned to the current strategies in mangrove forest management. This article synthesizes the results from several research projects assessing the performance of planted mangroves across the country. Overall, there is a widespread tendency to plant mangroves in areas that are not the natural habitat of mangroves, converting mudflats, sandflats, and seagrass meadows into often monospecific Rhizophora mangrove forests. In these nonmangrove areas, the Rhizophora seedlings experienced high mortality. Of the few that survived (often through persistent and redundant replanting), the young Rhizophora individuals planted in these nonmangrove and often low intertidal zones had dismally stunted growth relative to the corresponding growth performance of individuals thriving at the high intertidal position and natural mangrove sites. From this evidence, this article argues that a more rational focus of the restoration effort should be the replanting of mangroves in the brackish-water aquaculture pond environments, the original habitat of mangroves. For such, a number of management options can be explored, the implementation of which will ultimately depend on the political will of local and national governments.
169 citations
TL;DR: This article establishes a theoretical framework for EROI analysis that encompasses the various methodologies extant in the literature and establishes variations of E ROI analysis in two different dimensions based on the costs they include and their handling of nonenergy resources.
Abstract: Numerous technologies have been proposed as partial solutions to our declining fossil energy stocks. There is a significant need for consistent metrics to compare the desirability of different technologies. The ratio of energy produced to energy consumed by an energy production technology—known as the energy return on investment (EROI)—is an important first indicator of the potential benefits to society. However, EROI analysis lacks a consistent framework and has therefore yielded apparently conflicting results. In this article, we establish a theoretical framework for EROI analysis that encompasses the various methodologies extant in the literature. We establish variations of EROI analysis in two different dimensions based on the costs they include and their handling of nonenergy resources. We close by showing the implications of the different measures of EROI upon estimating the desirability of a technology as well as for estimating its ultimate net energy capacity.
159 citations
TL;DR: This article examines cases where development efforts, while successful in some dimensions, have also contributed to create new risks for, especially, the poorest groups.
Abstract: Development in the Mekong Delta of Vietnam has been very dynamic in the recent past, and currently it stands at an interesting crossroads. On one hand, agricultural production has developed successfully, and economic growth has been very rapid, but on the other hand, intensifying agriculture and large-scale water-control structures have challenged the environmental sustainability and social equity. The development plans have included a strong belief in the human mastery over the nature and waters of the Mekong Delta. In many cases, water resources planners have underestimated the complexity and integrated nature of the ecology and livelihoods of the Mekong Delta. This article examines cases where development efforts, while successful in some dimensions, have also contributed to create new risks for, especially, the poorest groups. The current situation calls for a more sustainable future route that would require examination of more adaptive measures in relation to the changing water flows of the Mekong River.
148 citations
TL;DR: It is hypothesize that the majority of K. pygmaea mats are human-induced and replace forests, scrub, and taller grasslands and that reinforced settlement of nomads threatens this ecosystem especially in its drier part.
Abstract: This paper provides information about the distribution, structure, and ecology of the world's largest alpine ecosystem, the Kobresia pygmaea pastures in the southeastern Tibetan plateau. The environmental importance of these Cyperaceae mats derives from the extremely firm turf, which protects large surfaces against erosion, including the headwaters of the Huang He, Yangtze, Mekong, Salween, and Brahmaputra. The emphasis of the present article is on the climate-driven evolution and recent dynamics of these mats under the grazing impact of small mammals and livestock. Considering pedological analyses, radiocarbon datings, and results from exclosure experiments, we hypothesize that the majority of K. pygmaea mats are human-induced and replace forests, scrub, and taller grasslands. At present, the carrying capacity is increasingly exceeded, and reinforced settlement of nomads threatens this ecosystem especially in its drier part, where small mammals become strong competitors with livestock and the removal of the turf is irreversible. Examples of rehabilitation measures are given.
140 citations
TL;DR: An assessment of temperature, precipitation, and spring precipitation changes in Mediterranean mountains under different emission scenarios and Atmosphere-Ocean-Coupled General Circulation Models for two periods: 2055 (2040–2069 period) and 2085 (2070–2099).
Abstract: Mediterranean mountain biomes are considered endangered due to climate change that affects directly or indirectly different key features (biodiversity, snow cover, glaciers, run-off processes, and water availability). Here, we provide an assessment of temperature, precipitation, and spring precipitation changes in Mediterranean mountains under different emission scenarios (Special Report on Emission Scenarios) and Atmosphere-Ocean-Coupled General Circulation Models for two periods: 2055 (2040-2069 period) and 2085 (2070-2099). Finally, the future climate trends projected for Mediterranean mountains are compared with those trends projected for non-Mediterranean European mountain ranges. The range of projected warming varies between +1.4 degrees C and 5.1 degrees C for 2055 (+1.6 degrees C and +8.3 degrees C for 2085). Climate models also project a reduction of precipitation, mainly during spring (-17% under Alfi and -4.8% under B1 for 2085). On the contrary, non-Mediterranean European mountains will not experience a reduction of annual and spring precipitation. Implications of predicted climate change for both human and physical features are coupled in an integrated framework to gain a broad perspective on future trends and their consequences.
134 citations
TL;DR: The construction of major dams on the headwaters in China appears to have had little impact on the sediment load, although as further larger dams are commissioned, the Mekong can be expected to decrease.
Abstract: The sediment loads of many of the world's major rivers have changed significantly in recent years due to land-use change, reservoir construction, and other human impacts on their drainage basins. For many rivers, the loads have decreased, whereas for others, they have increased. Such changes can have important implications for both the natural functioning of the system as well as for human exploitation of the river system. This paper considers the evidence for recent changes in the sediment load of the Mekong River. The available data have a number of limitations in terms of both sampling frequency and the period of coverage, but they have been processed to provide a basis for considering the changes in the sediment load of the river over the period extending from the early 1960s to 2002. Although there is evidence of increasing loads at some measuring stations, the overall trends show little evidence of major changes, and the system provides evidence of buffering through storage. As of 2002, the construction of major dams on the headwaters in China appears to have had little impact on the sediment load, although as further larger dams are commissioned, the sediment load of the Mekong can be expected to decrease.
TL;DR: It is found that current sedimentation rates within the lake basin proper are low and have been for several millennia, however, sedimentation at the lake margin and in its floodplain is relatively high, which presents a range of issues for riparian communities.
Abstract: It has been claimed that Tonle Sap Lake is rapidly filling with sediment as a result of increasing sediment yields from the catchment. Infilling of the lake basin would have serious implications for the magnitude of flooding in central Cambodia and the Mekong Delta region and threaten the lake's unique ecosystem. In this article, we synthesize the results of radiocarbon dating of sediment cores and hydrodynamic modeling results to provide an empirically based assessment of this issue. We find that current sedimentation rates within the lake basin proper are low and have been for several millennia. However, sedimentation at the lake margin and in its floodplain is relatively high, which presents a range of issues for riparian communities.
TL;DR: The dramatic fall of white-tailed sea eagle reproduction under the influence of DDT and PCBs, and the subsequent rise following their ban, illustrates the usefulness of raptors like sea eagles as sentinels for environmental pollutants.
Abstract: This paper summarizes results from the monitoring of reproduction of white-tailed sea eagle in Sweden 1965– 2006. Since 1989 the eagle population on the Swedish Baltic coast has been included in the National Environment Monitoring Program as an indicator species for potentially harmful chemicals. The percentage of successfully reproducing pairs and nestling brood size decreased in synchrony with rising concentrations of contaminants in the 1950s on into the 1970s. Mean productivity was 1.3 young per pair prior to 1950 and decreased to 0.3 in 1965–1985. Dichlorodiphenyldichloroethene (DDE) in eagle eggs decreased from a range of annual means in 1965–1974 of 600-1200 l gg � 1 (lipid weight) to 60–140 l gg � 1 in 1996–2005. Total polychlorinated biphenyl (PCB) concentrations averaged above 1000 l gg � 1 into the early 1980s and remained in the range of 250–500 l gg � 1 in 1996–2005. Productivity began to improve when concentrations of DDE and PCBs dropped below approximately 300 and 800 l gg � 1 , respectively. Brood size remains below the pre-1950 level in one coastal region, indicating a possible impact from other contaminants. The power to detect significant trends under the program is presented and discussed: if white-tailed sea eagle reproduction had been monitored earlier during the 20th century, the negative impact of dichlorodiphenyltrichloroethane (DDT, source of DDE) would have been signaled as early as the 1950s in the Baltic Sea. The dramatic fall of white-tailed sea eagle reproduction under the influence of DDT and PCBs, and the subsequent rise following their ban, illustrates the usefulness of raptors like sea eagles as sentinels for environmental pollutants.
TL;DR: Examination of potential effects of predicted climate changes on the forage conditions during both summer and winter for semidomesticated reindeer in Sweden finds positive effects in summer ranges include higher plant productivity and a longer growing season, while negative effects include increased insect harassment.
Abstract: This paper examines potential effects of predicted climate changes on the forage conditions during both summer and winter for semidomesticated reindeer in Sweden. Positive effects in summer ranges include higher plant productivity and a longer growing season, while negative effects include increased insect harassment. Forage quality may change in both positive and negative ways. An increase in shrubs and trees in alpine heaths is also likely. A warmer climate means shorter winters, which will have positive effects for the survival of reindeer. However, warmer and wetter weather may also result in increased probabilities of ice-crust formations, which strongly decrease forage availability. A warmer climate with higher forest productivity will also likely reduce lichen availability through competitive interactions. Adaptations to these changes will include maintaining a choice of grazing sites in both summer and winter. However, this capacity may already be severely limited because of other forms of land use.
TL;DR: Investigation of temperature and rainfall as climatic factors affecting dengue incidence in Metro Manila from 1996 to 2005 finds evidence that rainfall is significantly correlated to dengued incidence and no significant correlation between d Dengue incidence and temperature was established.
Abstract: Dengue is a serious public health problem in Metro Manila, Philippines. Increasing dengue incidence has been attributed to climate change; however, contradicting reports show inconclusive relationships between dengue and climatic factors. This study investigates temperature and rainfall as climatic factors affecting dengue incidence in Metro Manila from 1996 to 2005. Monthly dengue incidence and climatic data for Metro Manila were collected over a 10-y period (1996-2005). Climatic factors temperature and rainfall were linked with dengue incidence through regression analysis. A predictive model equation plots dengue incidence (Y) versus rainfall (X), which suggests that rainfall is significantly correlated to dengue incidence (r2 = 0.377, p 0.05). Evidence shows dengue incidence in Metro Manila varies with changing rainfall patterns. Intensified surveillance and control of mosquitoes during periods with high rainfall are recommended.
TL;DR: This work has been supported by China’s Special Fund for Major State Basic Research Project (2007CB714406), Knowledge Innovation Program of the Chinese Academy of Sciences (approved KZCX2-YW-313 and KZcX1-Y-02), foundation of theChinese State Key Laboratory of Remote Sensing Science (KQ060006).
TL;DR: An analysis of the complex relationship between demographic changes and impacts on the natural-resource base confirms that resource exploitation is occurring not only to meet growing domestic needs but also for other vested interests.
Abstract: The Mekong River Basin possesses the region's largest potential water source and related resources, which support ongoing economic development and basin community livelihoods. It is currently witnessing a major demographic transition that is creating both opportunities and challenges. An analysis of the complex relationship between demographic changes and impacts on the natural-resource base confirms that resource exploitation is occurring not only to meet growing domestic needs but also for other vested interests. Population, together with other major drivers, such as institutions, markets, and technology, will have a very strong bearing on the way in which the rich resources of the Mekong River Basin are developed and distributed in the present and future. The Mekong River Basin's rich resources, and the benefits derived from them, are unevenly distributed both in time and geographically. Moreover, since the causes and impacts do not respect political boundaries, the Mekong countries need to jointly develop alternative management strategies to meet projected demands within the sustainable capacity of the Mekong River Basin natural-resource base.
TL;DR: This paper analyzes the emergence of a national “water grid” that would triple the area of irrigated land in Thailand, its governance, and its economic and environmental soundness.
Abstract: Large-scale development of irrigation has long been an attractive option of postwar development, and the Mekong region has been no exception. Thailand has developed approximately four million hectares of irrigated land, and its northeastern region (Isaan)--both the driest and poorest part of the country--has been the target of many water projects. However, "full development" of its potential has been constrained by the lack of storage sites and the difficulty of diverting water from the Mekong River. Several ambitious projects have been discussed during the last 50 y, all of which have been aimed at "greening Isaan." In 2003, the Thai administration launched the idea of a national "water grid" that would triple the area of irrigated land in the country. This paper analyzes the emergence of this megaproject, its governance, and its economic and environmental soundness.
TL;DR: How the PBMS works is described, some of the key scientific and policy drivers for monitoring contaminants in predatory birds are highlighted, and the specific aims, scope, and methods are described.
Abstract: The Predatory Bird Monitoring Scheme (PBMS) is a long term (>40 y), UK-wide, exposure monitoring scheme that determines the concentration of selected pesticides and pollutants in the livers and eggs of predatory birds. This paper describes how the PBMS works, and in particular highlights some of the key scientific and policy drivers for monitoring contaminants in predatory birds and describes the specific aims, scope, and methods of the PBMS. We also present previously unpublished data that illustrates how the PBMS has been used to demonstrate the success of mitigation measures in reversing chemical-mediated impacts; identify and evaluate chemical threats to species of high conservation value; and finally to inform and refine monitoring methodologies. In addition, we discuss how such schemes can also address wider conservation needs.
TL;DR: This paper identifies two general strategies based on the presence or absence of pine seedling adaptations for fire survival and describes management implications of these two strategies.
Abstract: Fire-dependent pine forests in the Caribbean Basin cover extensive areas in the coastal plain of the Caribbean Sea and Gulf of Mexico and on several islands in the Bahamas Archipelago, Cuba, Hispaniola, and the Honduran Bay islands. These forests are high in conservation value but, unfortunately, remain mostly unprotected. Moreover, even though they are fire dependent, the use of fire for forest management often suffers from poor public perception and is prohibited by law in several countries. In this paper, we describe the fundamental links among fire, forest regeneration, and forest persistence in these ecosystems. We identify two general strategies based on the presence or absence of pine seedling adaptations for fire survival and describe management implications of these two strategies. We also introduce conceptual models describing fire, forest structure, and regeneration strategy linkages.
TL;DR: Island conservation in western México provides an effective approach that can be readily applied to other archipelagos where conservation efforts have been limited, and is a result of an operational model with three main components.
Abstract: Islands harbor a disproportionate amount of the earth's biodiversity, but a significant portion has been lost due in large part to the impacts of invasive mammals. Fortunately, invasive mammals can be routinely removed from islands, providing a powerful tool to prevent extinctions and restore ecosystems. Given that invasive mammals are still present on more than 80% of the world's major islands groups and remain a premier threat to the earth's biodiversity, it is important to disseminate replicable, scaleable models to eradicate invasive mammals from islands. We report on a successful model from western Mexico during the past decade. A collaborative effort between nongovernmental organizations, academic biologists, Mexican government agencies, and local individuals has resulted in major restoration efforts in three island archipelagos. Forty-two populations of invasive mammals have been eradicated from 26 islands. For a cost of USD 21 615 per colony and USD 49 370 per taxon, 201 seabird colonies ...
TL;DR: In this article, the authors propose several broad fire regimes and provide an analysis of fire ecology for the principal vegetation types in Mexico, highlighting the trend toward integral fire management, which merges prevention and control, community-based fire management and ecological fire management.
Abstract: I propose several broad fire regimes and provide an analysis of fire ecology for the principal vegetation types in Mexico. Forty percent of Mexican ecosystems are fire-dependent (pine forests, several oak forests, grasslands, several shrublands, savannas, palm lands, wet prairies, “popal” and “tular” swamps), 50% are fire-sensitive (tropical rain forests and tropical seasonal forests, tropical cloud forests, mangrove, fir forests, several oak forests, and several shrublands), and the remaining 10% fall into fire-influenced (such as several gallery forests) and fire-independent categories (shrublands in most xeric environments, very high-altitude prairies). I also present an analysis of current fire-management trends, highlighting the trend toward integral fire management, which merges prevention and control, community-based fire management, and ecological fire management.
TL;DR: Several factors such as fragile ecoenvironment, limited natural resources, and backward agricultural economy contribute to the development of karst rocky desertification.
Abstract: The karst mountain region of Southwest China is one of the largest karst geomorphologic distributing areas in the world (1). It is estimated that the karst geomorphology covers about 620 000 km in this region, involving Sichuan province, Hunan province, Hubei province, Guangdong province, and Chongqing municipality, but largely Guizhou province, Guangxi autonomous region, and Yunnan province (Fig. 1). In the extremely fragile karst geological environment, together with the pressure of overpopulation and lagged social economy, local people have to overexploit land for subsistence, leading to serious land degradation in the form of karst rocky desertification. It is a progressive process where soil is seriously or thoroughly eroded and bedrock exposure is widespread. Productive capability of land declines and, finally, a landscape similar to desert appears under human impact on a vulnerable ecogeoenvironment (2). This major type of desertification finally results in extensive exposure of bedrock. The photo shows different kinds of karst rocky desertification in Southwest China. Because karst rocky desertification is seriously constraining local sustainable development, the productivity of agriculture, forestry, and livestock husbandry are threatened. This issue has attracted widespread social attention. In 1994 and 2003 the Division of Geosciences of the Chinese Academy of Sciences put forward suggestions for comprehensive melioration of karst rocky desertification. The central government also coordinated and organized different rehabilitation for antidesertification at different government levels (state, province, and county) and departments (such as agriculture, forestry, and water conservancy departments) (3, 4). Table 1 provides statistical data about karst areas collected by Ministry of Land Resource, PR China, in 2005 (5). It shows that nearly 22.3% of the karst areas have been developed into karst rocky desertification with an annual increasing rate of 2500 km y 1 in the past 10 y. And three karst-concentrating provinces, i.e., Yunnan province, Guizhou province, and Guangxi Zhuang autonomous region, account for 25.3% of the total karst rocky desertification. The situation is being aggravated further, especially in the southern part of Guizhou province and west part of Guangxi Zhuang autonomous region. The causes behind rocky desertification are rather complex. Several factors such as fragile ecoenvironment, limited natural resources, and backward agricultural economy contribute to the development of karst rocky desertification. Although annual precipitation is 1000 mm or so in this region, runoff often leaks and buries deeply because of the leaking characteristic of limestone. Water resources on the land surface are scarce. This results in both barren cultivated land and scattered and low productivity. Vegetation is hard pressed to survive because of the lack of water. In addition, the potable water facilities for people and livestock are insufficient. In karst-concentrating counties of Yunnan province, Guizhou province, and Guangxi Zhuang autonomous region, the cultivated land per capita is only 0.06 ha. Furthermore, sloping cultivated land accounts for 70% of the total, of which 20% has a slope more than 258. More than 50% of the cultivated land has medium or low productivity. The average yield of grain is only about 2265 kg ha , much lower than the national average (9285 kg ha ). Disasters such as drought and flood are frequent in this region. Cultivated land in karst mountainous regions is mainly located in basins and valleys. In dry seasons or years with low precipitation, cultivated land often suffers from drought because of surface runoff leakage. The drought cultivated land in the middle Guangxi Zhuang autonomous region, for example, reaches about 51 530 000 ha in 2002, all being the medium or low productivity farmland. In rain seasons or years with high precipitation, however, because of water saturation the karst basin and valley are often flooded, usually lasting for a few days, but sometimes as long as several months. Frequent disasters cause enormous losses of topsoil and economic losses leading to poverty. Under the pressure of population growth, local people have to destroy forests and reclaim mountain lands in order to make a living. They also tend to cultivate steeper lands, which leads to soil erosion and rocky desertification. In this way, the localities fall into a so-called poverty, population, and land-degradation
TL;DR: A combined ecological-hydrodynamic model is presented for the production potential of the Tonle Sap ecosystem and its likely response to hydrological changes.
Abstract: Tonle Sap Lake is a large and complex data-deficient ecosystem in the Mekong River Basin. Highly valuable in biodiversity and natural livelihoods capital, it is susceptible to degradation when the flood pulse that drives its productivity is altered as a result of hydropower and irrigation development on the Mekong River. To date, there are no tools to assess the consequences of such flood pulse alterations, leaving the Tonle Sap underrated in water-resources use and planning. A combined ecological-hydrodynamic model is presented for the production potential of the Tonle Sap ecosystem and its likely response to hydrological changes.
TL;DR: Investigation of the linkage between the trend of forest decline and changes in the social, economic, and political pattern in the Awassa watershed over a 100-year perspective indicates that the forest area declined from about 40% at the turn of the 19th century to less than 3% in the year 2000.
Abstract: Forest decline in Ethiopia is highlighted by several authors but there is no consensus on its causes and consequences. The objective of this study is to investigate, from sociopolitical and geographical perspectives, the linkage between the trend of forest decline and changes in the social, economic, and political pattern in the Awassa watershed over a 100-year perspective. Field observations, satellite image and map analyses, interviews, and literature studies were employed, and natural indicators were analyzed. The findings indicate that the forest area declined from about 40% at the turn of the 19th century to less than 3% in the year 2000. Forest decline in the study area during the elected time period is the result of the combination of biophysical and social conditions. Important causes are geographic properties, sociopolitical changes, population growth, unstable land tenure principles, agricultural development, and the improvement of transport capacity. The main conclusions are as follows: Already in the early 20th century forest decline was in progress and forests were attributed an insignificant economic classification. Large areas of forest were cut down during periods of political transition when as a result of the political vacuum, interest in the protection of resources including forests was lacking. Long-term planning efforts to manage forests were obstructed by uncertainty resulting from land tenure principle change during each political period. The sparse area of forest land that remains is becoming increasingly attractive as potential land for arable agriculture because of improved road access between the study area and distant markets.
TL;DR: In this article, the changes during recent decades of several eutrophication-related variables in the open sea areas surrounding Finland (wintertime nutrient concentrations, wintertime nutrient ratios, and summer time chlorophyll α concentrations at the surface) were reported.
Abstract: Eutrophication is an ongoing process in most parts of the Baltic Sea. This article reports on the changes during recent decades of several eutrophication-related variables in the open sea areas surrounding Finland (wintertime nutrient concentrations, wintertime nutrient ratios, and summer time chlorophyll α concentrations at the surface). The sum of nitrate- and nitrite-nitrogen ([NO3+NO2]-N) was observed to increase nearly fourfold in the Northern Baltic Proper and the Gulf of Finland and almost double in the Bothnian Sea from the 1960s until the 1980s or 1990s. The increase was followed by a decrease, which was modest in the two former subregions. Phosphate-phosphorus (PO4-P) concentrations followed a similar pattern in the Northern Baltic Proper (threefold increase and subsequent slight decrease) and Bothnian Sea (30% increase and subsequent decrease), but increased throughout the study in the Gulf of Finland, with the present concentration being threefold to the measurements made in the early...
TL;DR: Excepting DDT and DDE, most organochlorine-based pesticides in raptors from Spain have diminished over the last 2 decades, which could in part explain problems in the reproductive success of raptors in Spain.
Abstract: Initial studies on the pressure from environmental contaminants on raptor populations in Spain date back to the 1980s, and they have been carried out from a range of viewpoints using a range of sentinel raptor species. However, there is no national monitoring scheme, and therefore the research carried out has been sporadic both spatially and temporally. The exposure to metals has not varied over time, except in the case of lead, whose concentration in eggs and tissues has diminished. In general, the concentrations of metals detected in raptor samples from Spain are generally low and not sufficient to produce toxic effects. Excepting DDT and DDE, most organochlorine-based pesticides in raptors from Spain have diminished over the last 2 decades. The concentrations of DDE found in the eggs of various species could in part explain problems in the reproductive success of raptors in Spain.
TL;DR: The results point toward a substantial increase (30% or more) in nitrogen deposition over western Norway as a consequence of increasing precipitation but more moderate changes for other areas, mainly due to changes in climate.
Abstract: A high-resolution chemical transport model, driven by meteorology representing current and future climate, was used to investigate the effects of possible future changes in climate on nitrogen deposition in northwestern Europe. The model system was able to resolve the climatology of precipitation and chemical properties observed in northern Europe during the 1980s, albeit with some underestimation of the temporal and spatial variability of meteorological parameters and chemical components. The results point toward a substantial increase (30% or more) in nitrogen deposition over western Norway as a consequence of increasing precipitation but more moderate changes for other areas. Deposition of oxidized nitrogen will increase more than the deposition of reduced nitrogen. Over Sweden, oxidized nitrogen will increase only marginally and reduced nitrogen will decrease, although annual precipitation is expected to increase here as well. This is probably because more reduced nitrogen will be removed further west in Scandinavia because of the strong increase in precipitation along the Norwegian coast. The total deposition of oxidized nitrogen over Norway is expected to increase from 96 Gg N y(-1) during the current climate to 107 Gg N y(-1) by 2100 due only to changes in climate. The corresponding values for Sweden are more modest, from 137 Gg N y(-1) to 139 Gg N y(-1).
TL;DR: Interpretation by skilled guides can indeed reduce visitor impacts in protected areas, especially if role modeling is combined with verbal appeals.
Abstract: Minimal-impact interpretation is widely used to reduce the ecological impacts of visitors to protected areas. We tested whether verbal appeals and/or role-model demonstrations of minimal-impact behavior by a trained guide reduced noise, litter, and trampling impacts on hiking trails in a subtropical rainforest. Interpretation did reduce impacts significantly. Different interpretive techniques were more effective for different impacts. The experimental groups were mature, well-educated professionals; interpretation may differ in effectiveness for different visitors. Interpretation by skilled guides can indeed reduce visitor impacts in protected areas, especially if role modeling is combined with verbal appeals.
TL;DR: A comprehensive model, labeled as the environmental protection process (EPP) framework, is introduced that can be used to analyze and teach why there are environmental problems, what are their characteristics, and in which ways they can be mitigated.
Abstract: The purpose of this article is to review interdisciplinary systemic frameworks of environmental protection and evaluate their use as tools, educational policymaking and education. We analyze the pressures-state-responses (PSR) framework of the Organization for Economic Cooperation and Development, the drivers-pressures-state-impact-response (DPSIR) framework developed in the European Environment Agency and a later environmental political dynamics framework developed by Schroll and Staerdahl. We then continue the discussion by introducing a comprehensive model, labeled as the environmental protection process (EPP) framework that can be used to analyze and teach why there are environmental problems, what are their characteristics, and in which ways they can be mitigated. The EPP model is used for classifying measures of coping with environmental problems. Finally, a submodel of individual and societal factors affecting human action is formed. Environmental issues of transport are used as an illustrative example. We hope to contribute a relevant way to outline a wide interdisciplinary picture of environmental problems and solutions.