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921.
Private domestic gardens contribute substantially to the biodiversity of urban areas and benefit human health and well-being.
We previously reported a study of 267 gardens across five cities in the United Kingdom in which variation in geographical
and climatic factors had little bearing on the richness, diversity and composition of plant species. We therefore hypothesise
that garden management is an important factor in determining garden characteristics. Here, from the same sample of gardens,
we investigate potential associations between the uses to which people put their gardens, the types of management activities
they undertake, and the characteristics of those gardens. Householders (n = 265) completed a questionnaire detailing various aspects of garden use and management activities. The majority of respondents
used their gardens chiefly for relaxation, recreation, and eating. Fewer than one fifth included “gardening” amongst their
garden uses even though all performed some garden management, suggesting that not all management activity resulted from an
interest in gardening. Garden-watering and lawn-mowing were the most prevalent activities and were predictors of other types
of management including weeding, vegetation-cutting, leaf-collection, and dead-heading flowers. A number of these activities
were associated with one another, the richness and composition of plant species, and the number of land uses in gardens. However,
relationships between management activities and the amount of tall vegetation were less consistent, and garden management
appeared to be independent of garden area. More species of amphibians, birds, and mammals were observed in gardens with ponds
and in which efforts were made to attract wildlife, particularly by providing drinking water. This study supports the hypothesis
that garden use and management is associated with garden characteristics. 相似文献
922.
We investigated the type and extent of degradation at three sites on the Agulhas Plain, South Africa: an old field dominated
by the alien grass Pennisetum clandestinum Pers. (kikuyu), an abandoned Eucalyptus plantation, and a natural fynbos community invaded by nitrogen fixing—Australian Acacia species. These forms of degradation are representative of many areas in the region. By identifying the nature and degree
of ecosystem degradation we aimed to determine appropriate strategies for restoration in this biodiversity hotspot. Vegetation
surveys were conducted at degraded sites and carefully selected reference sites. Soil-stored propagule seed banks and macro-
and micro-soil nutrients were determined. Species richness, diversity and native cover under Eucalyptus were extremely low compared to the reference site and alterations of the soil nutrients were the most severe. The cover of
indigenous species under Acacia did not differ significantly from that in reference sites, but species richness was lower under Acacia and soils were considerably enriched. Native species richness was much lower in the kikuyu site, but soil nutrient status
was similar to the reference site. Removal of the alien species alone may be sufficient to re-initiate ecosystem recovery
at the kikuyu site, whereas active restoration is required to restore functioning ecosystems dominated by native species in
the Acacia thicket and the Eucalyptus plantation. To restore native plant communities we suggest burning, mulching with sawdust and sowing of native species. 相似文献
923.
Gabi N. Waite Stéphane J. P. Egot-Lemaire Walter X. Balcavage 《The Environmentalist》2011,31(2):107-113
Over the past decades, strong evidence has accumulated that low-frequency electromagnetic fields (EMFs) can be useful in treating
human pathologies, such as bone fractures, soft tissue illnesses, and pain. Common strategies for the design of commercial
therapeutic devices are to generate EMFs that simulate body endogenous EMFs, or EMFs that resonate with a particular biological
process, such as the natural motions of ions. We recently came across a biologically active commercial EMF signal that seems
to be different. The signal is generated by summing the fundamental frequencies and harmonics of several periodic base signals
which remain proprietary to the company. When first examined in the time domain, the signal resembled electronic noise; however,
when critically analyzed, the signal is not identical with noise. Rather, it is a highly complex waveform exhibiting a very
wide range of values for the time derivative of the magnetic field density (dB/dt) and a beat frequency in the Extremely Low-Frequency
range. In this paper, we speculate on the mechanism of action of this and similar signals. We consider it less likely that
cells, or cell components, act like filters to extract and couple with individual signals that make up the complex EMF signal.
Consequently, we favor the possibility that with the signal discussed here cells respond to the very complex signal and that
the biological response can be modified by the presence of a beat in the signal, in this case a low-frequency beat. More generally,
this would suggest the hypothesis that biological processes can be regulated by noise-like signals and that the effects of
a noisy signal can be modified by the presence of signal repetition patterns, such as beats. Given the very small energy that
signals like these can transduce into a biological system, biological effects can be expected only when the molecular processes
involved are poised so that the available energy leads to molecular reactions that achieve the activation state for the reaction. 相似文献
924.
In this article, we introduce China’s major forest types and discuss the historical development of forest management in China,
including actions taken over the last decade toward achieving SMF. Major challenges are identified, and a strategy for SFM
implementation in China is presented. China’s forests consist of a wide variety of types with distinctive distributional patterns
shaped by complex topography and multiple climate regimes. How to manage this wide array of forest resources has challenged
forest managers and policy-makers since the founding of the country. Excessive exploitation of China's forest resources from
the 1950s to the late 1990s contributed to environmental problems and calamities, such as floods, soil erosion, and desertification.
At the start of the new millennium, the Chinese government decided to shift its emphasis from timber production towards the
achievement of sustainable forest management (SFM). With a series of endeavors such as the implementation of the “Six Key
Forestry Projects” and the reform of forest tenure policies, and the adoption of a classification system for China's forests,
a beginning has been made at reversing the trend of environmental degradation that occurred throughout the latter half of
the last century. At the same time, huge challenges remain to be tackled for the development of forestry in China. 相似文献
925.
We demonstrate the use of an expert-assisted spatial model to examine geographic factors influencing the poaching risk of
a rare plant (American ginseng, Panax quinquefolius L.) in Shenandoah National Park, Virginia, USA. Following principles of the analytic hierarchy process (AHP), we identified
a hierarchy of 11 geographic factors deemed important to poaching risk and requested law enforcement personnel of the National
Park Service to rank those factors in a series of pair-wise comparisons. We used those comparisons to determine statistical
weightings of each factor and combined them into a spatial model predicting poaching risk. We tested the model using 69 locations
of previous poaching incidents recorded by law enforcement personnel. These locations occurred more frequently in areas predicted
by the model to have a higher risk of poaching than random locations. The results of our study can be used to evaluate resource
protection strategies and to target law enforcement activities. 相似文献
926.
The maintenance of a timely, reliable and accurate spatial database on current forest ecosystem conditions and changes is
essential to characterize and assess forest resources and support sustainable forest management. Information for such a database
can be obtained only through a continuous forest inventory. The National Forest Continuous Inventory (NFCI) is the first level
of China’s three-tiered inventory system. The NFCI is administered by the State Forestry Administration; data are acquired
by five inventory institutions around the country. Several important components of the database include land type, forest
classification and ageclass/ age-group. The NFCI database in China is constructed based on 5-year inventory periods, resulting
in some of the data not being timely when reports are issued. To address this problem, a forest growth simulation model has
been developed to update the database for years between the periodic inventories. In order to aid in forest plan design and
management, a three-dimensional virtual reality system of forest landscapes for selected units in the database (compartment
or sub-compartment) has also been developed based on Virtual Reality Modeling Language. In addition, a transparent internet
publishing system for a spatial database based on open source WebGIS (UMN Map Server) has been designed and utilized to enhance
public understanding and encourage free participation of interested parties in the development, implementation, and planning
of sustainable forest management. 相似文献
927.
Recently Prévot-Julliard and colleagues presented a concept paper on biological conservation strategies using exotic species
as a case study. They emphasized the difficulty of integrating conservation into a broad picture that accounts for public
perception as well as scientific knowledge. We support this general call for better integration of society in conservation
research, but we believe that the original framework might misguide conservation practices if wrongly interpreted. Our objective
is to complement their paper and correct a few misleading points, by showing that (1) for regions of high endemicity “reservation”
may be the best conservation practice, and does not prevent public participation, (2) aiming for broad societal agreement
is valuable, but in some cases risky, and always complex, and (3) calling a harmful invasive species harmful shouldn’t be
an issue. The Australian context provides us with many cases of the labeling of exotic species as harmful or not, using inputs
from scientists, industry, and the public. Integration of social and scientific points of view can only improve conservation
on the ground if it allows managers to use the ecological, economic and social impacts of exotic species to prioritize conservation
actions in an operative way. 相似文献
928.
Forest certification is a mechanism involving the regulation of trade of forest products in order to protect forest resources
and improve forest management. Although China had a late start in adopting this process, the country has made good progress
in recent years. As of July 31, 2009, 17 forest management enterprises and more than one million hectares of forests in China
have been certified by the Forest Stewardship Council (FSC). Several major factors affect forest certification in China. The
first set is institutional in nature. Forest management in China is based on centralized national plans and therefore lacks
flexibility. A second factor is public awareness. The importance and value of forest certification are not widely understood
and thus consumers do not make informed choices regarding certified forest products. The third major factor is the cost of
certification. Together these factors have constrained the development of China’s forest certification efforts. However, the
process does have great potential. According to preliminary calculations, if 50% of China’s commercial forests were certified,
the economic cost of forest certification would range from US$0.66–86.63 million while the economic benefits for the forestry
business sector could exceed US$0.66–86.63 million while the economic benefits for the forestry
business sector could exceed US150 million. With continuing progress in forest management practices and the development of
international trade in forest products, it becomes important to improve the forest certification process in China. This can
be achieved by improving the forest management system, constructing and perfecting market access mechanisms for certificated
forest products, and increasing public awareness of environmental protection, forest certification, and their interrelationship. 相似文献
929.
The management of wild mushroom is interdisciplinary in nature, whereby the biophysical considerations have to be incorporated
into the context of a wide range of social, economic and political concerns. However, to date, little documentation exists
illustrating an interdisciplinary approach to management of wild mushrooms. Moreover, the empirical case studies necessary
for developing applicable and practical methods are even more rare. This paper adopted an interdisciplinary approach combining
participatory methods to improve the habitat management of Thelephora ganbajun, an endemic and one of the most economically valuable mushroom species in Southwest China. The paper documents an empirical
case of how an interdisciplinary approach facilitated the development of a scientific basis for policy and management practice,
and built the local capacity to create, adopt and sustain the new rules and techniques of mushroom management. With this integrative
perspective, a sustainable management strategy was developed, which was found not only technically feasible for farmers, but
also acceptable to the government from an ecological and policy-related perspective. More importantly, this approach has greatly
contributed to raising the income of farmers. The paper highlights how the integration of biophysical and socioeconomic factors
and different knowledge systems provided a holistic perspective to problem diagnosis and resolution, which helped to cope
with conventional scientific dilemmas. Finally, it concludes that the success of this interdisciplinary approach is significant
in the context of policy decentralization and reform for incorporating indigenous knowledge and local participation in forest
management. 相似文献
930.
Biodiversity goals are becoming increasingly important in stream restoration. Typical models of stream restoration are based
on the assumption that if habitat is restored then species will return and ecological processes will re-establish. However,
a range of constraints at different scales can affect restoration success. Much of the research in stream restoration ecology
has focused on habitat constraints, namely the in-stream and riparian conditions required to restore biota. Dispersal constraints
are also integral to determining the timescales, trajectory and potential endpoints of a restored ecosystem. Dispersal is
both a means of organism recolonization of restored sites and a vital ecological process that maintains viable populations.
We review knowledge of dispersal pathways and explore the factors influencing stream invertebrate dispersal. From empirical
and modeling studies of restoration in warm-temperate zones of New Zealand, we make predictions about the timescales of stream
ecological restoration under differing levels of dispersal constraints. This process of constraints identification and timescale
prediction is proposed as a practical step for resource managers to prioritize and appropriately monitor restoration sites
and highlights that in some instances, natural recolonization and achievement of biodiversity goals may not occur. 相似文献