The missing pieces for better future predictions in subarctic ecosystems: A Torneträsk case study

Arctic and subarctic ecosystems are experiencing substantial changes in hydrology, vegetation, permafrost conditions, and carbon cycling, in response to climatic change and other anthropogenic drivers, and these changes are likely to continue over this century. The total magnitude of these changes results from multiple interactions among these drivers. Field measurements can address the overall responses to different changing drivers, but are less capable of quantifying the interactions among them. Currently, a comprehensive assessment of the drivers of ecosystem changes, and the magnitude of their direct and indirect impacts on subarctic ecosystems, is missing. The Torneträsk area, in the Swedish subarctic, has an unrivalled history of environmental observation over 100 years, and is one of the most studied sites in the Arctic. In this study, we summarize and rank the drivers of ecosystem change in the Torneträsk area, and propose research priorities identified, by expert assessment, to improve predictions of ecosystem changes. The research priorities identified include understanding impacts on ecosystems brought on by altered frequency and intensity of winter warming events, evapotranspiration rates, rainfall, duration of snow cover and lake-ice, changed soil moisture, and droughts. This case study can help us understand the ongoing ecosystem changes occurring in the Torneträsk area, and contribute to improve predictions of future ecosystem changes at a larger scale. This understanding will provide the basis for the future mitigation and adaptation plans needed in a changing climate.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01381-1) contains supplementary material, which is available to authorized users.     

Prenatal and postnatal exposure to diazinon and its effect on spermatogram and pituitary gonadal hormones in male offspring of rats at puberty and adulthood

The objective of this research is to study the possible reproductive adverse effects of diazinon on rat offspring exposed in utero and during lactation. Twenty-four Sprague–Dawley female rats (10–12 week old) were randomly assigned to four groups, each consisting of six rats. Group 1 served as the control and these rats were given normal saline orally. Rats in groups 2, 3, and 4 were administered diazinon, dissolved in saline at 10, 15, 30 mg/ kg^?1 body weight, per oral, once daily, during mating, pregnancy and lactation. The male offsprings were examined at puberty and adulthood for body weight, testis weight, epididymis weight, sperm count, motility and morphology, pituitary-gonadal hormone levels. At 30 mg kg^?1 dose, the male offsprings showed a decrease in testicular weight, sperm count, motility, with an increase in abnormal sperm percentage and a decline in pituitary-gonadal hormones, at puberty. Upon attaining adulthood, there was a decrease in testicular weight, sperm count and motility with an increase in abnormal sperm percentage and a decrease in pituitary hormone level. There was evidence of some adverse reproductive effects on the male offspring at the 15 mg/ kg^?1 dose. Most of the adverse effects were irreversible and were evident at both puberty and adulthood in the offsprings, although a few parameters reverted to the normal growth pattern. Diazinon is a reproductive toxicant for male offsprings if exposed during prenatal and postnatal phases.     

“New” DDT inputs to North America: Atmospheric deposition

Measurement of untransformed (p,p'- and o,p'-) DDT in rain, snow, and peat indicates that input of “new” DDT continues over a large portion of eastern North America. Peat cores obtained from ombrotrophic bogs indicate that current atmospherically derived fluxes are about 10–20% of those which occurred during peak DDT usage (～1960). Since DDT has been banned in North America and considering the magnitude of present fluxes, these residues must result from atmospheric transboundary transport. It is suggested that “new” DDT is being transported from neighboring areas where current use is substantial, Mexico and Central America.     

Reserves, resilience and dynamic landscapes

In a world increasingly modified by human activities, the conservation of biodiversity is essential as insurance to maintain resilient ecosystems and ensure a sustainable flow of ecosystem goods and services to society. However, existing reserves and national parks are unlikely to incorporate the long-term and large-scale dynamics of ecosystems. Hence, conservation strategies have to actively incorporate the large areas of land that are managed for human use. For ecosystems to reorganize after large-scale natural and human-induced disturbances, spatial resilience in the form of ecological memory is a prerequisite. The ecological memory is composed of the species, interactions and structures that make ecosystem reorganization possible, and its components may be found within disturbed patches as well in the surrounding landscape. Present static reserves should be complemented with dynamic reserves, such as ecological fallows and dynamic successional reserves, that are part of ecosystem management mimicking natural disturbance regimes at the landscape level.     

自然保护区、恢复力和动态景观

在这个日益被人类活动所改变的世界里,保护生物多样性对于维持有恢复力的生态系统和确保生态系统产品的可持续流动以及对社会的服务是至关重要的.但是,现有的自然保护区和国家公园不大可能结合生态系统的长期和大尺度的动态.因此,保护策略必须包括大面积的人类利用经营的土地.为了能使生态系统在大规模的自然和人为干扰之后得以重组,以生态存储形式出现的空间恢复力是必备的前提.生态存储包括那些能使生态系统得以重组的物种、相互作用和结构,它的组成部分可能出现在干扰斑块中,也可能出现在周围的景观中.现有的静态自然保护区应该由动态自然保护区加以补充,例如生态休闲地和动态演替保护区,这些都是在景观尺度上模拟自然干扰状况,进行生态系统经营的组成部分.     

Graph theory as a proxy for spatially explicit population models in conservation planning.

Spatially explicit population models (SEPMs) are often considered the best way to predict and manage species distributions in spatially heterogeneous landscapes. However, they are computationally intensive and require extensive knowledge of species' biology and behavior, limiting their application in many cases. An alternative to SEPMs is graph theory, which has minimal data requirements and efficient algorithms. Although only recently introduced to landscape ecology, graph theory is well suited to ecological applications concerned with connectivity or movement. This paper compares the performance of graph theory to a SEPM in selecting important habitat patches for Wood Thrush (Hylocichla mustelina) conservation. We use both models to identify habitat patches that act as population sources and persistent patches and also use graph theory to identify patches that act as stepping stones for dispersal. Correlations of patch rankings were very high between the two models. In addition, graph theory offers the ability to identify patches that are very important to habitat connectivity and thus long-term population persistence across the landscape. We show that graph theory makes very similar predictions in most cases and in other cases offers insight not available from the SEPM, and we conclude that graph theory is a suitable and possibly preferable alternative to SEPMs for species conservation in heterogeneous landscapes.     

我国城市生活垃圾处理行业2006年发展报告

本文介绍了2006年我国城市生活垃圾处理有关标准的政策进展和城市生活垃圾处理设施的建设和运行情况,并对行业发展进行了展望。     

Global change shifts vegetation and plant-parasite interactions in a boreal mire

The aim of this study was to detect vegetation change and to examine trophic interactions in a Sphagnum-dominated mire in response to raised temperature and nitrogen (N) addition. A long-term global-change experiment was established in 1995, with monthly additions of N (30 kg x ha(-1) x yr(-1)) and sulfur (20 kg x ha(-1) x yr(-1)) during the vegetation period. Mean air temperature was raised by 3.6 degrees C with warming chambers. Vegetation responses were negligible for all treatments for the first four years, and no sulfur effect was seen during the course of the experiment. However, after eight years of continuous treatments, the closed Sphagnum carpet was drastically reduced from 100% in 1995 down to 41%, averaged over all N-treated plots. Over the same period, total vascular plant cover (of the graminoid Eriophorum vaginatum and the two dwarf-shrubs Andromeda polifolia and Vaccinium oxycoccos) increased from 24% to an average of 70% in the N plots. Nitrogen addition caused leaf N concentrations to rise in the two dwarf-shrubs, while for E. vaginatum, leaf N remained unchanged, indicating that the graminoid to a larger extent than the dwarf-shrubs allocated supplemented N to growth. Concurrent with foliar N accumulation of the two dwarf-shrubs, we observed increased disease incidences caused by parasitic fungi, with three species out of 16 showing a significant increase. Warming caused a significant decrease in occurrence of three parasitic fungal species. In general, decreased disease incidences were found in temperature treatments for A. polifolia and in plots without N addition for V. oxycoccos. The study demonstrates that both bryophytes and vascular plants at boreal mires, only receiving background levels of nitrogen of about 2 kg x ha(-1) x yr(-1), exhibit a time lag of more than five years in response to nitrogen and temperature rise, emphasizing the need for long-term experiments. Moreover, it shows that trophic interactions are likely to differ markedly in response to climate change and increased N deposition, and that these interactions might play an important role in controlling the change in mire vegetation composition, with implications for both carbon sequestration and methane emission.