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1.
《Plant Ecology & Diversity》2013,6(3-4):503-509
Background: Species persistence, particularly in monocarpic species, depends on the successful recruitment of individuals. An understanding of the factors that limit the recruitment of rare monocarpic plant species is therefore vital for their conservation.

Aims: To identify the factors limiting the recruitment of Rheum nobile, a rare and highly specialised monocarpic giant herb endemic to the high eastern Himalayas.

Methods: Seed sowing (seeds added or not added) and seedling transplanting experiments were conducted in disturbed (vegetation removed) and undisturbed plots in the vicinity of established populations of R. nobile to explore the mechanisms of recruitment limitation. Four levels of photosynthetically active radiation (0, 15, 30 and 50 μmol m?2 s?1) and two sowing positions (beneath and above grass litter or moss layer) were manipulated in the laboratory to determine how ground cover limited seedling emergence.

Results: Seed addition increased seedling recruitment. Disturbance significantly increased seedling emergence and establishment. Seed germination significantly decreased with the reduction of light availability, but 31.7% of all seeds germinated in complete darkness. Seedling emergence was close to zero when seeds were sown on top of a layer of grass litter or moss, but rose to 34.5% when the seeds were sown beneath such layers.

Conclusions: Our results indicate that the recruitment of R. nobile is limited by a combination of seed and microsite availability. Therefore, in order to conserve this species, we suggest adding seeds to suitable sites and implementing soil disturbances in existing populations to create suitable microsites.  相似文献   

2.
The aim of this study is to investigate spirit possession through the lenses of mimesis, permeability, and perspectivity. Recent studies have explored the significance of perspective exchange as reciprocal subjectification. At the same time, the importance of reflexive self‐awareness amid perspective exchange has been noted. Linking studies on perspective exchange with those on spirit possession, this article tries to show an alternative understanding of perspective exchange as the de‐subjectification and generative transformation of self and other. Focusing on the buuta ritual in South India, I examine perspective exchange as the capability for freeing oneself from one's subjectivity enough to let various perspectives come and go through the permeable self. Being permeable and reflexive, the buuta impersonator plays with multiple perspectives to transform both his and others' perspectives to enable all to become ‘real’ humans in relation to the deity.  相似文献   

3.
Background: There is limited understanding about bird dispersal behaviour and seedling distribution of endangered tree species in patchy environments, although these processes are important for plant species persistence.

Aims: We tested how patch features affected bird behaviour and seed dispersal, and thus seedling distribution of the endangered Chinese yew tree (Taxus chinensis).

Methods: In the present study, we combined field data of bird dispersal behaviour and GIS-based information to elucidate the influence of spatial features of habitat patches on bird dispersal behaviour, and the resulting effects on the seedling distribution of the endangered Chinese yew in two patchy habitats.

Results: Our results showed that the only seed source patch could attract eight bird species for dispersal at the two sites. Post-foraging movements of bird dispersers was strongly related to both topography and the relative locations of habitat patches. Yew seedlings aggregated only at the seed source and bamboo recruitment patches, which was affect by both the spatial distribution of recruitment patches and patch use by dispersers.

Conclusions: Our results emphasise that bamboo patches in both patchy environments provide the necessary conditions for germination of yew seeds, and the post-foraging behaviour of dispersers determines seed deposited in these patches. Our study highlights the importance of the dispersal behaviour of frugivorous birds in the successful regeneration and colonisation of yew populations in patchy habitats.  相似文献   

4.
On Lombok island, in the province of West Nusa Tenggara, Indonesia, indigenous medicine and biomedicine coexist. Nevertheless, biomedicine, a product of modernity and the development of the state has been superimposed on village life along with other state institutions such as education. In this paper I analyse the processes involved in Sasak villagers' quest for health. Operating within various and sometimes overlapping social fields and conflicting discourses, villagers utilise both local indigenous practices as well as the Indonesian national health system in their quest. Because local or ordinary knowledge is a rich resource for interpretation, I describe the health quest through the participant individuals: family members, neighbours, doctors and nursing personnel involved. The subjectivity of the individual participants contributes to the intricate unfolding of health seeking quests to expose the various tensions which emerge between tradition (tradisi [I]) and modernity (moderen [I]) and between state and village.  相似文献   

5.
Coral recruitment describes the addition of new individuals to populations, and it is one of the most fundamental demographic processes contributing to population size. As many coral reefs around the world have experienced large declines in coral cover and abundance, there has been great interest in understanding the factors causing coral recruitment to vary and the conditions under which it can support community resilience. While progress in these areas is being facilitated by technological and scientific advances, one of the best tools to quantify recruitment remains the humble settlement tile, variants of which have been in use for over a century. Here I review the biology and ecology of coral recruits and the recruitment process, largely as resolved through the use of settlement tiles, by: (i) defining how the terms ‘recruit’ and ‘recruitment’ have been used, and explaining why loose terminology has impeded scientific advancement; (ii) describing how coral recruitment is measured and why settlement tiles have value for this purpose; (iii) summarizing previous efforts to review quantitative analyses of coral recruitment; (iv) describing advances from hypothesis-driven studies in determining how refuges, seawater flow, and grazers can modulate coral recruitment; (v) reviewing the biology of small corals (i.e. recruits) to understand better how they respond to environmental conditions; and (vi) updating a quantitative compilation of coral recruitment studies extending from 1974 to present, thus revealing long-term global declines in density of recruits, juxtaposed with apparent resilience to coral bleaching. Finally, I review future directions in the study of coral recruitment, and highlight the need to expand studies to deliver taxonomic resolution, and explain why time series of settlement tile deployments are likely to remain pivotal in quantifying coral recruitment.  相似文献   

6.
Aditya Bharadwaj 《Ethnos》2014,79(1):84-107
Drawing on Foucault's notion of subject formation or subjectification, this article shows how a process of experimental subjectification, a wilful submission and participation in seemingly experimental treatments, produces both empowering and life-affirming experiences as well as a critique of established scientific norms and practices. The article examines processes of experimental subjectification in the narratives of patients pursuing clinical application of human embryonic stem cells in India to treat chronic spinal cord injury and in the narrative of the director of the clinic providing the treatment. The article addresses how the clinic's director and patients from around the globe continue to successfully pursue embryonic stem cell therapies, despite intense media speculation and scientific scrutiny labelling the clinic as a maverick experimental site.  相似文献   

7.
Background: Current understanding of treeline or forest-alpine ecotone (FAE) dynamics does not fully explain past and present FAE patterns and their underlying processes, nor allow prediction of their response to climate change.

Aims: We address the overarching hypothesis that the FAE is a mosaic of distinct landscape units of vegetation and landforms that result in differential responses to climate change. We focus on climate-related, landscape and vegetation characteristics, but also consider the effect of landscape heterogeneity on biogeochemistry and overall resilience of the FAE to climate change.

Results: There are three distinct FAE land units at Niwot Ridge, generated by different interactions of climate with vegetation, landforms and topography. Within these FAEs, a process of self-organisation takes place from organism to patch to landscape scales, and is modulated by positive and negative feedback loops along an elevation gradient. The underlying controls cannot be attributed solely to temperature, but to a combination of interactions along a physical/biotic gradient.

Conclusions: FAE dynamics result from interactions among mechanisms and processes at the microsite, patch and landscape scales: (1) tree persistence; (2) forest patch establishment; (3) drivers of patch forest configurations and (4) resilience, increasing along a gradient of biotic control.  相似文献   

8.
9.
Background: Seedling recruitment following fire is an infrequent yet critical demographic transition for woody plants in Mediterranean ecosystems.

Aims: Here we examine whether post-fire seedling recruitment of three widespread Californian chaparral shrubs is affected by local adaptation within an edaphically and topographically complex landscape.

Methods: We reciprocally transplanted 6-month-old seedlings of Adenostema fasciculatum, Ceanothus cuneatus and Eriodictyon californicum to serpentine and sandstone soils, and cool northerly and warm southerly slopes.

Results: At the age of 2 years, none of the species manifested higher survival or growth on ‘home’ compared with ‘away’ soils or slopes, indicating an absence of local adaptation with respect to seedling recruitment in these environments. Seedlings of all species manifested lower survival and relative growth on serpentine soils regardless of seedling source, as well as a variety of other destination and source effects.

Conclusions: The ability of these three species to recruit in new environments, such as in restoration settings or in response to shifting climates, is unlikely to be impeded by a need for seeds from sources that closely match their edaphic or topographic destination.  相似文献   


10.
Background: Spatial patterns within forests reflect their formative processes. In Kamchatka, the dominant stone birch (Betula ermanii) forest exists in a primeval state. Betula species can reproduce via clonally produced ramets, leading to a clustered distribution of stems, or from seed on open ground, although subsequent mortality may obscure initial establishment patterns.

Methods: Spatial patterns of all trees and regenerating stems in a fully mapped 0.25 ha plot were analysed using the g(r) function and the pattern of trees modelled using a Matérn cluster process. Mark correlation analysis was used to detect patterns in stem sizes.

Results: Clustering of trees at scales up to 3 m occurred, with model parameters indicating a density of 180 clusters ha?1, each containing on average three stems >1 cm diameter at breast height (DBH) within a 1.6 m radius. Stem size compensation was detected, with nearby trees smaller than expected by chance. Regenerating stems were strongly clustered at scales below 3.5 m and from 5–8 m, and were aggregated around small trees (<10 cm DBH) but not large trees (≥10 cm DBH), or in gaps.

Conclusions: These patterns are consistent with clonal reproduction followed by competition as the processes determining spatial structure in old-growth stone birch forests.  相似文献   

11.
目的 通过实证调查采集患者、医务工作者和志愿者对医务社工及志愿者工作的评价,解析医务社工及志愿者在医院服务管理中的作用。方法 采用问卷调查、文献查阅、深度访谈法,调研上海市三家三级甲等公立医院获取第一手资料。结果 调查结果显示,患者、医务人员及医务管理人员高度认可医务社工与志愿者在医院服务管理的作用。结论 医务社工和志愿者在医院服务管理中能发挥独特的作用,可以增进医患沟通,缓解或预防医患矛盾,给患者更多人文关怀和增值服务,一定程度上解决医患之间的诊治经费问题,提升服务品质、降低人力成本,应当得到全社会更多的重视。  相似文献   

12.
ABSTRACT

Background: Tropical sand dunes are ideal systems for understanding drivers of community assembly as dunes are subject to both deterministic and stochastic processes. However, studies that evaluate the factors that mediate plant community assembly in these ecosystems are few.

Aims: We evaluated phylogenetic community structure to elucidate the role of deterministic and stochastic processes in mediating the assembly of plant communities along the north of the Yucatan Peninsula, Mexico.

Methods: We used plastid genetic markers to evaluate phylogenetic relationships in 16 sand-dune communities. To evaluate the role of climate in shaping plant community structure we carried out linear regressions between climatic variables and mean phylogenetic distance. We estimated the Net Relatedness Index and Nearest Taxon Index to identify ecological processes mediating community assembly.

Results: Observed phylogenetic structure was not different from random, suggesting that stochastic processes are the major determinants of community assembly. Climate was slightly correlated with phylogenetic diversity suggesting that abiotic environment plays a minimal role in community assembly.

Conclusions: Random assembly appears to be the primary factor structuring the studied sand dune plant communities. Environmental filters may represent a secondary factor contributing to the observed phylogenetic structure. Thus, both processes may act simultaneously to mediate the assembly of sand-dune plant communities.  相似文献   

13.
Background: The degradation of alpine meadows on the Qinghai-Tibetan Plateau (QTP) has an impact on vegetation recruitment from seedlings and ramets.

Aims: Understanding the relative contribution of recruitment by seedling and ramet in alpine meadows is for the ecological restoration of degraded grasslands on the QTP.

Methods: An experiment was conducted to investigate seedling and ramet densities, species composition and their relationships with standing vegetation in plots representative of non-degraded (ND), lightly (LD), moderately (MD) and severely degraded (SD) alpine meadows.

Results: With increasing degradation and the reduction in vegetation cover, the number of seedlings and ramets declined. The proportion of young plants arising from seedlings was low, with the majority of species reproducing clonally. The establishment of seedlings of forbs in SD meadows led to species-rich, forb-dominant vegetation in these areas.

Conclusions: LD and MD meadows appear to be able to be managed by reduced grazing for the restoration of grass- and sedge-dominated pastures. In contrast, restoration of SD meadows will require additional intervention, such as of seeding and weed eradication.  相似文献   

14.
Background: Seedling recruitment is widely recognised to be important in the maintenance of diversity and coexistence of species. It is not clear how local abiotic factors mediated by litter and biotic interactions influence plant species recruitment in alpine grasslands.

Aims: To determine how litter and standing vegetation affected seedling recruitment in plant communities in Tibetan alpine grasslands.

Methods: Seedling recruitment was quantified in response to experimental treatments: (1) removal of standing vegetation and litter; (2) removal of standing vegetation with litter intact; (3) intact standing vegetation and removal of litter and (4) control: intact standing vegetation and litter.

Results: Litter removal increased seedling numbers, while standing vegetation removal had no effect. An interaction between litter and standing vegetation removal marginally increased seedling number. Species richness of seedlings was not related to either litter removal or standing vegetation removal. Species composition of seedling differed significantly between removal of both litter and standing vegetation and control.

Conclusions: Litter and its interaction with standing vegetation has an important role in affecting plant species recruitment in this alpine plant community. In contrast, biotic interactions, such as competition or facilitation from standing vegetation, appear to have only minor effects on recruitment.  相似文献   


15.
《Plant Ecology & Diversity》2013,6(2-3):115-126
Background: Understanding the processes that determine community assembly and their dynamics is a central issue in ecology. The analysis of functional diversity can improve our understanding of these dynamics by identifying community assembly processes.

Aims: We studied the effect of environment–community covariations on both functional diversity and functional structure of xerophytic shrub communities for inferring the community assembly processes shaping this vegetation type.

Methods: Functional diversity was quantified using (1) community-weighted mean of the studied traits, (2) functional groups, defined using Ward’s hierarchical agglomerative clustering method and (3) Rao’s quadratic entropy. Relationships between functional diversity and environmental gradients were identified by Spearman correlations and modelled using generalised additive models.

Results: Variations in community composition and functional diversity correlated with soil nutrient availability and aridity. Increasing nutrient availability resulted in both greater average plant height and higher abundance of plants with green photosynthetic organ colour, whereas the abundance of nanophanerophytes increases with aridity.

Conclusions: The species composition and trait structure of the studied Mediterranean xerophytic shrub communities varies along nutrient and aridity gradients. This supports the importance of environmental filters for the local assembly and dynamics of these inland dune communities.  相似文献   

16.
Background: Recent work has shown little change in the position of the Smith fir treeline on the south-eastern Tibetan Plateau in response to global warming. However, the relationship between tree distribution patterns within the treeline ecotone and low responsiveness is unknown, and additional constraints than climate might be major drivers of these patterns (e.g. microsite availability for regeneration).

Aims: To characterise the spatial patterns of Smith fir alpine treelines and to infer the underlying processes driving their dynamics.

Methods: We investigated spatial patterns of Smith fir trees across two treeline ecotones in the Sygera Mountains, south-eastern Tibetan Plateau. The O(r)-ring statistic was used to analyse the univariate and bivariate spatial point patterns of three size classes (adults, juveniles and seedlings).

Results: Mature trees presented random spatial patterns. Clusters of juveniles and seedlings colonised areas not occupied by mature trees. Seedlings were clustered and established preferentially near juvenile firs, Rhododendron mats and over moss–lichen and organic matter substrates, indicating the importance of microsite availability for successful Smith fir recruitment.

Conclusions: Local factors such as microsite availability may play a major role in driving recent Smith fir treeline patterns and determine the lack of significant warming-induced upward shifts of these ecotones.  相似文献   

17.
Contemporary justice-making processes often focus on reconciliation or legal retribution, but not on the complexity of victimhood beyond individual subjectivity or refusals of state propositions for social repair. In Colombia, where drug cartels and state-sponsored violence had terrorized the population for over fifty years, it was not forgiveness and acceptance that punctuated the turn of the twenty-first century, but the refusal to reconcile with the state's duplicity regarding the disappearance and death of thousands. This essay illustrates how irreconciliation as an affective sentiment is taking shape in Colombia through forms of reattribution that take the form of victim visibilizations. In analysing the strategic use of victim visibilizations as a refusal of state accountability, their expansion of the notion of victimhood, and their politics of irreconciliation, I show how even with the state's remorse-driven discourses, the public's understanding that political, judicial, and social accountability was not possible and pushed them to chart new strategies for disclosure and healing.  相似文献   

18.
In 2014, Islamist jihadist groups overran a Lebanese border town and besieged it for four days, spreading terror across the town and the country as a whole. In response, the Lebanese army launched a violent counterattack on these groups with the aid of Hizbullah in what became known as the Battle of Arsal. Declaring the area a security zone, the army restricted mobility and placed Lebanese citizens and Syrian refugees under military confinement. While the battle ended with a government-declared victory that celebrated the ‘reclamation of state sovereignty’, these events disrupted social life in unprecedented ways. This article focuses on the phenomenological experience of sovereignty and the price paid for the desire for this state. I explore the ruptures people experienced in their existence (their right to life, subsistence, and movement under indiscriminate shelling) and existentiality (their reflections on their human existence in time, place, and relationship to others in a social world that is no longer recognizable). I argue for a concept of existential displacement that focuses on the experience of citizens as well as refugees for a broader understanding of the ruptures and dispossessions taking place in conflict.  相似文献   

19.
《Anthrozo?s》2013,26(2):279-294
ABSTRACT

This paper examines the variations in dog owners' attitudes toward, treatment of, and interactions with, animals. Based on 28 in-depth interviews with dog owners from a county in the Midwestern United States, I demonstrate that pets are an important part of many people's lives, often providing companionship, entertainment, and meaningful interactions; however, there are notable, distinct variations in how people relate to them. Pet owners typically exhibit one of three orientations toward pets: “dominionistic,” “humanistic,” or “protectionistic.” The dominionistic have relatively low regard for their pets, valuing them primarily for the uses they provide, such as protection. Those employing the humanistic orientation elevate their pets to the status of surrogate humans and value their pets primarily for the affective benefits they enjoy from their close attachments. The protectionistic have high regard for both pets and animals more generally. They view pets as valuable companions and as creatures with their own interests. This typology offers insights for understanding the source and variety of the often ambiguous and contradictory relations between people and pets. I argue that individual characteristics and experiences impact how people understand and relate to animals, in large part, because they represent exposure to different cultural messages. I suggest that these orientations represent three sets of distinct cultural logics, each with distinct histories and contemporary sources.  相似文献   

20.
Developing organisms require nutrients to support cell division vital for growth and development. An adaptation to stress, used by many organisms, is to reversibly enter an arrested state by reducing energy-requiring processes, such as development and cell division. This “wait it out” approach to survive stress until the environment is conductive for growth and development is used by many metazoans. Much is known about the molecular regulation of cell division, metazoan development and responses to environmental stress. However, how these biological processes intersect is less understood. Here, we review studies conducted in Caenorhabditis elegans that investigate how stresses such as oxygen deprivation (hypoxia and anoxia), exogenous chemicals or starvation affect cellular processes in the embryo, larvae or adult germline. Using C. elegans to identify how stress signals biological arrest can help in our understanding of evolutionary pressures as well as human health-related issues.  相似文献   

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