After 30 years of economic reform since opening to the outside world in 1978, China's Gross Domestic Product (GDP) has increased by 150% over the past 15 years. The sustainability of such intense economic activity has been questioned from the perspectives of the social, environmental, and economic dimensions of sustainability. In this study, we assessed the spatial and temporal trends in sustainable development in two sensitive agricultural areas of China: Dezhou district, a well-developed region, and Guyuan district, an underdeveloped region. We used the pressure–state–response (PSR) model and a participatory approach that involved local experts to select and evaluate 27 area-specific indicators, then calculated changes in their values from 1985 to 2002. We aggregated these indicators into dimension- and PSR-specific indices to assess the sustainability of development in both regions. There two regions differed greatly in sustainability, but the current status of sustainable development raises concerns in both areas, especially from the perspective of balancing the three dimensions of sustainability. In 2002, Dezhou district performed well economically, with an index value of 0.78 (where 1.0 = sustainable), followed by environmental and social sustainability (both with index values of 0.48). All three indices have increased since 1985 (by 0.17, 0.25, and 0.13, respectively). In Guyuan district, environmental sustainability was highest (with an index value of 0.73), followed by economic and social sustainability (values of 0.55 and 0.37, respectively), but economic sustainability has decreased by 0.04 since 1985, whereas environmental and social sustainability increased by 0.18 and 0.12, respectively. To promote sustainable regional development, development priorities should be determined by considering both the regional and temporal variation in the three sustainability indices. 相似文献
Species-rich semi-natural grasslands have declined drastically in Europe over the last century and occur in modern landscapes as small and isolated fragments. Recreation of these species-rich plant communities and increasing connectivity of remaining grasslands are important goals for nature conservation. Ex-arable fields located adjacent to species-rich grasslands have been suggested as targets for such recreation, but we still lack knowledge about the processes determining colonization from grasslands to ex-arable fields. We examined transects from species-rich semi-natural grasslands to ex-arable fields in a nature reserve located in southeast Sweden, and analysed relationships between observed colonization of ex-arable fields and two characteristics of species: dispersal ability and recruitment ability. Colonization of ex-arable fields was not related to dispersal ability, assessed as adhesive potential to animal coat, wind dispersal potential and seed mass (related to seed production), but was positively related to recruitment ability, assessed by sowing experiment. The same relationships appeared when using a performance index from sowing experiments conducted in the UK. We conclude that recruitment ability is a key factor for colonization of ex-arable fields. In our study, around 50% of semi-natural grassland species were able to colonize adjacent ex-arable field margins spontaneously within a time window of less than 50 years. Seed sowing is however needed to increase the speed of the colonization process, because increasing seed density promotes colonization of species with poor recruitment in ex-arable fields. Actions to increase area and connectivity of species-rich grasslands should consider incorporating ex-arable fields. 相似文献
A spectacular new terrestrial Konzentratlagerst?tte is introduced from the Turpan Basin of Xinjiang, China that probably belongs to the late Middle Jurassic Qigu Formation. It contains a mass accumulation of “xinjiangchelyid” turtles preliminarily identified as Annemys sp. In the zone with the highest turtle concentration, complete and articulated turtle skeletons are tightly packed at a density of up to 36 turtles per square meter. The fossiliferous layer is thickened here and shows an erosional base. This high concentration zone outcrops approximately 10?m in length and shows no decrease in turtle density after exposing 2?m of the layer into the hillside. Adjacent is a more expansive zone of at least 10?m by 30?m. In this region, the fossiliferous layer is evenly thick, and approximately five, fully disarticulated turtles are present per square meter. A conservatively estimated 1,800 turtles may, therefore, have been deposited at this site. It is likely that these aquatic turtles gathered in a retreating water hole in a riverine environment during a drought, much as some aquatic turtles will do today, but perished when the habitat dried up completely. A following catastrophic rainfall event caused a debris flow, possibly channelized in a dry river bed, which transported complete turtles, disarticulated turtles, and mudstone clasts and deposited them after a short distance. This taphonomic model is consistent with previous environmental reconstructions of the Turpan Basin during the late Middle Jurassic in predicting the episodic breakdown of regional monsoonal circulation resulting in a seasonally dry climate with severe episodic droughts. 相似文献
Heterodontosauridae is a morphologically divergent group of dinosaurs that has recently been interpreted as one of the most basal clades of Ornithischia. Heterodontosaurid remains were previously known from the Early Jurassic of southern Africa, but recent discoveries and studies have significantly increased the geographical and temporal range for this clade. Here, we report a new ornithischian dinosaur from the Middle Jurassic Ca?adón Asfalto Formation in central Patagonia, Argentina. This new taxon, Manidens condorensis gen. et sp. nov., includes well-preserved craniomandibular and postcranial remains and represents the only diagnostic ornithischian specimen yet discovered in the Jurassic of South America so far. Derived features of its anatomy indicate that Manidens belongs to Heterodontosauridae, as the sister taxon of Heterodontosaurus and other South African heterodontosaurids. The presence of posterior dentary teeth with high crowns but lacking extensive wear facets in Manidens suggests that this form represents an intermediate stage in the development of the remarkable adaptations to herbivory described for Heterodontosaurus. The dentition of Manidens condorensis also has autapomorphies, such as asymmetrically arranged denticles in posterior teeth and a mesially projected denticle in the posteriormost teeth. At an estimated total length of 60?C75?cm, Manidens furthermore confirms the small size of basal heterodontosaurids. 相似文献
A stand-level optimisation problem formulated to determine a set of efficient thinning regimes satisfying two objectives, i.e. value production for sawlog harvesting and volume production for a pulpwood market, was demonstrated for a Eucalyptus fastigata trial in Kaingaroa Forest, New Zealand. Genetic algorithms were used to estimate the set of efficient thinning regimes (i.e. regimes that occur when it is not possible to increase the achievement of one objective without reducing another) known as a Pareto frontier. Each thinning regime specified a unique combination of initial planting density; frequency, timing and intensity of thinning; final crop number; and rotation length. Specifications for the “best” regime in the Pareto set (i.e. the one that satisfied a balanced trade-off between value and volume production) were similar to those recommended through professional judgment based on pooled long-term field observations from different eucalypt species grown throughout New Zealand. The advantage of Pareto optimality was the ability of not only identifying a unique thinning regime, but equally efficient regimes each providing a different combination of value and volume production. Research on this approach has the potential of being applied to other forest sites, providing there is sufficient re-measurement data to reflect stand growth dynamics. 相似文献
Objective: Older drivers with dementia are an at-risk group for unsafe driving. However, dementia refers to various etiologies and the question is whether dementias of different etiology have similar effects on driving ability.
Methods: The literature on the effects of dementia of various etiologies on driving ability is reviewed. Studies addressing dementia etiologies and driving were identified through PubMed, PsychINFO, and Google Scholar.
Results and Conclusions: Early symptoms and prognoses differ between dementias of different etiology. Therefore, different etiologies may represent different likelihoods with regard to fitness to drive. Moreover, dementia etiologies could indicate the type of driving problems that can be expected to occur. However, there is a great lack of data and knowledge about the effects of almost all etiologies of dementia on driving. One could hypothesize that patients with Alzheimer's disease may well suffer from strategic difficulties such as finding a route, whereas patients with frontotemporal dementia are more inclined to make tactical-level errors because of impaired hazard perception. Patients with other dementia etiologies involving motor symptoms may suffer from problems on the operational level. Still, the effects of various etiologies of dementias on driving have thus far not been studied thoroughly. For the detection of driving difficulties in patients with dementia, structured interviews with patients but also their family members appear crucial. Neuropsychological assessment could support the identification of cognitive impairments. The impact of such impairments on driving could also be investigated in a driving simulator. In a driving simulator, strengths and weaknesses in driving behavior can be observed. With this knowledge, patients can be advised appropriately about their fitness to drive and options for support in driving (e.g., compensation techniques, car adaptations). However, as long as no valid, reliable, and widely accepted test battery is available for the assessment of fitness to drive, costly on-road test rides are inevitable. The development of a fitness-to-drive test battery for patients with dementia could provide an alternative for these on-road test rides, on condition that differences between dementia etiologies are taken into consideration. 相似文献
Environmental and Ecological Statistics - A spatial sampling design determines where sample locations are placed in a study area. To achieve reliable estimates of population characteristics, the... 相似文献