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1.
The maintenance of invertebrate diversity within agricultural environments can enhance a number of agronomically important processes, such as nutrient cycling and biological pest control. However, few Australian studies have been undertaken which specifically address the effects of commercial management regimes on rice field biodiversity. In this study, we compared aquatic macroinvertebrate communities within Australian rice fields cultivated under three commercial management regimes: conventional-aerial (agrochemicals applied, aerially sown), conventional-drill (agrochemicals applied, directly drill-sown) and organic-drill (agrochemical-free, directly drill-sown). These comparisons were undertaken using a combination of community assessment approaches, including morphospecies richness, abundance, diversity and community composition. In general, greater biodiversity existed within macroinvertebrate communities that developed under organic management regimes than under conventional regimes (i.e., higher morphospecies richness and Shannon diversity). Although there were significant differences in several parameters across management regimes early in the rice-growing season, as the growing season progressed the invertebrate communities that developed in the different management regimes became more similar. Only community composition analyses showed significant differences late in the growing season, with functional differences across aquatic faunal assemblages suggested by increased predator abundance in communities sampled from the organic management regime. In order to improve biodiversity within these aquatic environments, management techniques need to be examined individually and the most disruptive processes identified. Alternative management procedures can then be developed that minimise biodiversity loss whilst still delivering required agronomic outcomes.  相似文献   

2.
Much of the literature on common-pool resources has focused on elucidating the social mechanisms and local institutions that lead to the regulation of common-pool resources. There is much less information about how management regimes translate into environmental impacts or how environmental impacts influence the emergence of management decisions. We use quantitative and qualitative methods to investigate the link between forest condition, agricultural change and the emergence of common-pool resource management regimes in two indigenous Kichwa communities in the Ecuadorian Amazon. We show that forest condition is linked to agricultural production and that the perception of common-pool resource scarcity influences the emergence of management regimes. We argue that population pressure, market forces and resource scarcity, which are usually associated with measures of agricultural change can also promote the emergence of common-pool resource management regimes.  相似文献   

3.
Despite being fragmented and highly disturbed habitats, urban turfgrass ecosystems harbor a surprising diversity of arthropods. The suitability of turf as arthropod habitat, however, likely depends on the extent and types of pesticides and fertilizers used. For example, moderate levels of weed cover in low-input lawns may provide alternative food resources. We conducted a 2-yr field study to: 1) characterize the ground beetle (Carabidae) species assemblage in turfgrass, and 2) assess the direct and indirect effects of lawn management on carabid communities. Weed cover and beetle activity were compared among four lawn management programs: 1) consumer/garden center, 2) integrated pest management (IPM), 3) natural organic, and 4) no-input control. Nearly 5,000 carabid beetles across 17 species were collected with the predator Cyclotrachelus sodalis LeConte numerically dominating the trap catch (87% and 45% of individuals in 2005 and 2006, respectively). Populations of C. sodalis underwent a distinct peak in activity during the third week of June, whereas omnivorous and granivorous species tended to occur at far lower levels and were less variable over the season. We found no evidence for direct effects of lawn management on carabid species diversity; however, we detected an indirect effect mediated by variation in weed cover. Seed-feeding species were positively correlated with turf weeds early in 2006, whereas strictly predaceous species were not. Thus, turf management programs that lead to changes in plant species composition (i.e., herbicide regimes) may indirectly shape epigeal arthropod communities more strongly than the direct effects of insecticide use.  相似文献   

4.
Abstract Empirical estimates of the function and resilience of communities under different management regimes can provide valuable information for sustainable natural resource management, but such estimates are scarce to date. We quantified the functional richness and relative resilience of bird communities inhabiting five regions in southeastern Australia that represented different management regimes. First, we show that functional richness and relative resilience were reduced at species-poor sites in all regions. Second, we show that bird communities in agricultural regions had fewer body mass groups and fewer functional groups than expected by chance. This suggests that both the function and the resilience of bird communities in agricultural regions were reduced. The likely mechanisms for the observed loss of function and relative resilience are: (1) the simplification of landscape texture resulting in selective extinction of certain body mass groups; and (2) the selective extinction of certain functional groups that are particularly sensitive to intensive land use. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

5.
Denitrification causes loss of available nitrogen from soil systems, thereby reducing crop productivity and increasing reliance on agrochemicals. The dynamics of denitrification and denitrifying communities are thought to be altered by land management practices, which affect the physicochemical properties of the soil. In this study, we look at the effects of long-term tillage and fertilization regimes on arable soils following 16 years of treatment in a factorial field trial. By studying the bacterial community composition based on 16S rRNA amplicons, absolute bacterial abundance and diversity of denitrification functional genes (nirK, nirS and nosZ), under conditions of minimum/conventional tillage and organic/synthetic mineral fertilizer, we tested how specific land management histories affect the diversity and distribution of both bacteria and denitrification genes. Bacterial and denitrifier communities were largely unaffected by land management history and clustered predominantly by spatial location, indicating that the variability in bacterial community composition in these arable soils is governed by innate environmental differences and Euclidean distance rather than agricultural management intervention.  相似文献   

6.
Indigenous communities commonly face a major impediment in their ongoing efforts to participate effectively in the stewardship and sustainable management of their traditional lands, waters and resources. Externally driven projects and policies can overwhelm communities' abilities to respond, severely impact in their resource base, and significantly eclipse traditional knowledge, practices and values. Such projects and policies can be devastating to small, Indigenous communities struggling to maintain their culture and economic independence in a changing world. While many examples of external impacts on small-scale resource use could be drawn upon for these communities, we illustrate this situation by examining the impact of fisheries management regimes on Indigenous coastal communities in British Columbia, Canada and Aotearoa New Zealand. We characterize the problem and identify key stressors involved. Within the context of Indigenous rights and Indigenous peoples' knowledge, perspectives and experience, we highlight the need to recognize this type of constraint on Indigenous Peoples' resource use and effective participation in resource management.  相似文献   

7.
Resprouting as a life history strategy in woody plant communities   总被引:40,自引:0,他引:40  
Resprouting is an efficient means by which woody plants regain biomass lost during disturbance, but there is a life history trade-off that occurs in all disturbance regimes between investment in the current generation through resprouting vs investment in future generations at the same or more distant sites. The relative allocation to resprouting vs seeding in woody plant communities is dictated by the nature of disturbance regimes. Resprouting is the predominant response to the least severe disturbance regimes, but is also a common response in disturbance regimes of high severity, those that destroy most or all above-ground biomass, and which occur at medium to high frequency. The response to disturbance either by resprouting or seeding is dictated by the site's productivity. We present a comprehensive model for relative allocation to resprouting vs seeding across a range of disturbance regimes. Competition between plants that mostly seed vs those that mostly resprout should accentuate differences in allocation along a gradient of disturbance frequency. However the patchy nature of disturbance in time and space, coupled with gene flow among populations undergoing different disturbance regimes, ensures that it is unlikely that either resprouting or seeding will be the sole response in most plant communities at most disturbance frequencies. Additional influences on resprouting in woody plant communities include changes in allocation during the lifespan of individual plants and phylogenetic constraints that are expressed as biogeographic patterns.  相似文献   

8.
《Journal of phycology》2001,37(Z3):34-34
McVey, J. P. Program Director, National Sea Grant College Program, 1315 East West Highway, Silver Spring, Maryland, 20910, USA The National Oceanic and Atmospheric Administration (NOAA), through its National Marine Fisheries Service (NMFS) and National Sea Grant College Program (NSGCP) has developed a vision for how seafood will be produced in the USA which includes the proper management of natural fisheries, aquaculture and the management and involvement by human coastal communities. The concept of balanced ecosystem management is not only being talked about at national levels but active research programs are being planned and supported. The recent $5 million National Marine Aquaculture Initiative (NMAI) specifically called for proposals that study the “trophic level consequences of marine aquaculture and marine species enhancement”. Recent workshops at the World Aquaculture Society meeting in Orlando and at the regional aquaculture meeting held at Boston on the topic of “Aquaculture and the Environment” have focused on a balanced approach to both aquaculture and fisheries management. All of the workshops focused on the important role of plants in the aquatic community. The basic premise about a balanced ecosystem approach is to incorporate the biological functions of a diverse group of plants and animals into a unified system that maintains the natural interactions of species and allows an ecosystem to function. Models are useful in understanding the energy and nutrient flow within an ecosystem; as are GIS technologies that allow us to map biological and ecological regimes. Macroalgae and phytoplankton both convert nutrients to plant material and transform carbon dioxide to oxygen. In contrast, animals derive much of their nutrition from plants, in one way or another and transform oxygen to carbon dioxide. This presentation will discuss the need to incorporate the use of plants in ecosystem maintenance such that there is balance between the animal, including humans, and plant communities in coastal areas. This will all be related to new NOAA programs and funding opportunities for research support in this area.  相似文献   

9.
Ecologists have long been concerned that contemporary fire regimes of central Australia have poor consequences for some plant species, vegetation communities and the native animals they support. Fire frequency, size and intensity (the ‘fire regime’) have all been implicated in the decline of native biota and in vegetation changes that potentially constitute ecological drift. However, not all perceived declines and changes are quantified or proven. The fire regimes themselves defy quantification and are arguably unknowable. We examine the relationships between fire, vegetation and the physical landscape and consider the adequacy of available knowledge for guiding fire management. Devising targeted ‘fire management regimes’, which take into account vegetation type and management objectives such as pastoral production, conservation and cultural observance, and which actively use fire to achieve those objectives, is a more realistic goal than controlling unquantifiable fire regimes in spatially diverse landscapes.  相似文献   

10.
长期施肥对紫色土农田土壤动物群落的影响   总被引:6,自引:0,他引:6  
土壤动物在陆地生态系统物质循环和能量流动中起着重要作用,直接或间接的参与土壤有机质的分解与矿化;长期施肥对土壤理化性质产生影响的同时,改变了土壤动物群落组成.为查明紫色土长期施肥对土壤动物群落的影响及其响应关系,于2008年的5、7、9和11月分别对紫色土农田无肥对照(CK)、单施氮肥(N)、常规化肥氮磷钾(NPK)、有机肥(OM)、有机肥与化肥氮磷钾混施(OMNPK)、秸秆还田(RSD)和秸秆还田与化肥氮磷钾混施(RSDNPK)等7种长期施肥定位试验地的土壤动物群落进行调查,采用改良的干漏斗和湿漏斗两种方法,共获得土壤动物9454只,隶属7门17纲24目.分析表明,OM和RSDNPK两种施肥方式下土壤动物群落的多样性显著高于CK、N和NPK等3种施肥方式,说明有机物料的长期投入有利于提高土壤动物群落丰富度和多样性.方差分析表明施肥方式对土壤动物主要类群密度的影响差异性极显著(F=42.412,P=0.0001),对土壤动物群落类群影响存在不均衡性.施肥方式主要影响农田土壤动物类群的种群个体数量、线虫动物门个体数量、大蚓类个体数量、甲螨亚目个体数量、密度-类群指数DG及土壤动物群落类群数等六个指标,初步认为这些主要类群因素能够预测长期施肥引起的土壤肥力变化,可能对指示土壤质量的变化具有一定潜力.  相似文献   

11.
Tao  Jiemeng  Liu  Xueduan  Liang  Yili  Niu  Jiaojiao  Xiao  Yunhua  Gu  Yabing  Ma  Liyuan  Meng  Delong  Zhang  Yuguang  Huang  Wenkun  Peng  Deliang  Yin  Huaqun 《Applied microbiology and biotechnology》2017,101(3):1289-1299

The use of green manures in agriculture can provide nutrients, affect soil microbial communities, and be a more sustainable management practice. The activities of soil microbes can effect crop growth, but the extent of this effect on yield remains unclear. We investigated soil bacterial communities and soil properties under four different green manure fertilization regimes (Vicia villosa, common vetch, milk vetch, and radish) and determined the effects of these regimes on maize growth. Milk vetch showed the greatest potential for improving crop productivity and increased maize yield by 31.3 %. This change might be related to changes in soil microbes and soil properties. The entire soil bacterial community and physicochemical properties differed significantly among treatments, and there were significant correlations between soil bacteria, soil properties, and maize yield. In particular, abundance of the phyla Acidobacteria and Verrucomicrobia was positively correlated with maize yield, while Proteobacteria and Chloroflexi were negatively correlated with yield. These data suggest that the variation of maize yield was related to differences in soil bacteria. The results also indicate that soil pH, alkali solution nitrogen, and available potassium were the key environmental factors shaping soil bacterial communities and determining maize yields. Both soil properties and soil microbes might be useful as indicators of soil quality and potential crop yield.

  相似文献   

12.
David A. Tierney 《Plant Ecology》2018,219(12):1503-1518
Anthropogenic alteration of fire regimes is implicated in the extinction or decline of species across the globe. Active management of fire regimes using specified guidelines can help sustain diversity and counter this loss. However, some species occur across multiple communities with differing fire regime requirements or may exploit the dynamics of associated ecotones. These complexities are not easily understood via a simple consideration of life history traits or unravelled by a simple experimental framework. Population modelling, however, may provide valuable insights in these instances, but to date this remains unexplored. A population model based on detailed demographic, habitat and fire regime data was developed for the species Prostanthera askania. The species occurs across rainforest/eucalypt forest ecotones subject to long-term alteration, fragmentation and invasion by exotic species. Modelling revealed that current recommended fire guidelines will not sustain this species under these novel conditions. Fire regimes that minimised extinction risk in some scenarios had double or five times the fire frequencies of recommended regimes. Managing fire was also more important in specific habitat (gully habitat rather than on slopes or ridges). Currently applied management actions for Prostanthera askania do not include any fire management and the regimes that apply to most habitat in which the species occurs (no fire or fire at up to 50-year intervals in gully habitat) is not optimal for the species. Management will be substantially more effective if specific fire treatments revealed by this study are employed (e.g. fire intervals of 20–30 years in gully habitat). The study demonstrates that a conceptualisation and consideration of communities as both temporally and spatially dynamic can substantially contribute to better fire management outcomes. The approach used herein can be readily adapted and applied to a plethora of species via a range of software packages and codes.  相似文献   

13.
Cape ivy (Delairea odorata) is a highly invasive climbing perennial vine that is primarily distributed in coastal communities of California and Oregon, with patchy infestations in some inland riparian areas. In this study, we evaluated light as a potential environmental limitation to the spread of Cape ivy into inland regions of the western United States. Cape ivy was collected from four locations representing the north to south range. Plants were grown for 9 to 11 weeks in full sunlight and under two shade regimes (20 and 6% of full sunlight). The experiment was conducted twice at two temperature regimes. Results show some within- and among-population variability, with the southernmost San Diego County population having the highest biomass under the warmer growing conditions and the three northern populations responding most favorably in the cooler growing conditions. Despite the minor differences within and between populations, Cape ivy grew very poorly in full sunlight in both experiments. Although plants growing under 6% light grew better than those in full sunlight, they were far less robust compared to plants growing at 20% light. Our results indicate that while Cape ivy will not persist in areas with prolonged high intensity sunlight, characterized by much of the interior regions of California and Oregon, it is expected to invade and spread in areas with reduced light, including coastal regions frequently exposed to fog or cloudy conditions, or sub-canopy layers of riparian forests or woodlands. These communities should be the target areas for early detection and rapid response programs to prevent further Cape ivy invasion.  相似文献   

14.
The composition and structure of bacterial communities were examined in soil subjected to a range of diverse agricultural land management and crop production practices. Length heterogeneity polymerase chain reaction (LH-PCR) of bacterial DNA extracted from soil was used to generate amplicon profiles that were analyzed with univariate and multivariate statistical methods. Five land management programs were initiated in July 2000: conventional, organic, continuous removal of vegetation (disk fallow), undisturbed (weed fallow), and bahiagrass pasture (Paspalum notatum var Argentine). Similar levels in the diversity of bacterial 16S rDNA amplicons were detected in soil samples collected from organically and conventionally managed plots 3 and 4 years after initiation of land management programs, whereas significantly lower levels of diversity were observed in samples collected from bahiagrass pasture. Differences in diversity were attributed to effects on how the relative abundance of individual amplicons were distributed (evenness) and not on the total numbers of bacterial 16S rDNA amplicons detected (richness). Similar levels of diversity were detected among all land management programs in soil samples collected after successive years of tomato (Lycopersicon esculentum) cultivation. A different trend was observed after a multivariate examination of the similarities in genetic composition among soil bacterial communities. After 3 years of land management, similarities in genetic composition of soil bacterial communities were observed in plots where disturbance was minimized (bahiagrass and weed fallow). The genetic compositions in plots managed organically were similar to each other and distinct from bacterial communities in other land management programs. After successive years of tomato cultivation and damage from two major hurricanes, only the composition of soil bacterial communities within organically managed plots continued to maintain a high degree of similarity to each other and remain distinct from other bacterial communities. This study reveals the effects of agricultural land management practices on soil bacterial community composition and diversity in a large-scale, long-term replicated study where the effect of soil type on community attributes was removed.  相似文献   

15.
Since the 1970s the Brazilian Amazon has received over 1 million migrant farm households from other regions of the country, many of whom were attracted to government-sponsored frontier settlement programs that offered free tropical forest land. As a result, pressures on tropical forests have intensified along several settlement corridors throughout the region. Despite their importance as agents of landscape change, surprisingly little is known about the land use practices of these farmers. This paper briefly reviews the research literature on smallholder land use patterns in Amazonia, describes the recent history of one important agricultural land settlement program in the western Brazilian Amazon state of Rondônia, and, based on 240 household surveys conducted in three separate settlement locations in the state, highlights key differences in land use patterns among the rural population. Typologies of farming systems are presented on the basis of cluster analysis of land use data and ANOVA tests. The findings indicate considerable complexity and heterogeneity in smallholder farming systems. Spatial variations in farming system types may be due to geographic differences in soil regimes, the social histories of specific communities, and site-specific responses to exogenous variables.  相似文献   

16.
Question: Can GIS and GPS technology be used to quantify the hydrological regime of different plant communities on turloughs (groundwater dependent calcareous wetlands)? Location: Skealoghan turlough, County Mayo, Ireland. Methods: Plant communities were mapped and digitised with GIS software and a digital elevation model of the site was constructed from differential GPS data. Together with records of water level fluctuations on the site from May 2001 to May 2004, these data were used to calculate hydrological variables for each plant community. Hierarchical cluster analysis was used to identify groups of plant communities with similar hydrological regimes. Results: 15 plant communities were mapped at Skea loghan, with the Cirsio‐Molinietum and Ranunculo‐Potentilletum anserinae being the dominant phytosociological associations. Skealoghan is subject to large temporal and spatial variation in its hydrological regime and fluctuations in water level are intrinsically linked to rainfall. The spatial variation in flooding can be linked to the vegetation zones. Conclusions: GIS and DGPS technology can be used to quantify the hydrological regime of different plant communities on turloughs. Since the hydrological regime is a major environmental factor controlling the vegetation composition of the site, the maintenance of natural flooding regimes is a vital component for the conservation and management of the diverse vegetation mosaic at Skealoghan turlough.  相似文献   

17.
18.
Maintaining biodiversity is central to maintaining ecosystem functionality of wetlands. Hydrology has the strongest influence on wetland biodiversity, second to which agriculture is the most influential factor. This study investigates the influence of hydrology and farming practices on the abundance, species richness and composition of dipteran communities on temperate Atlantic floodplain hay meadows. Insects were sampled by sweep-net across twenty-four vegetation zones for which hydrological variables were calculated by combining river level data with fine-scale topographical data. Plant communities were surveyed using relevés and land owners were interviewed to gather data on current and past management regimes. A total of twenty-two sciomyzid species were recorded; over one-third of the Irish fauna. Flood depth and duration were found to have the strongest influence on sciomyzids, syrphids and plants. Sciomyzid species richness and total abundance were both positively correlated with hydroperiod and flood depth while both plants and syrphids responded negatively to increases. The difference in response highlights the need to assess more than one taxonomic group, when assessing the impact of changing environmental variables on biodiversity. Whereas vegetation structure drives changes in sciomyzid indicator species, plant species richness and composition, past management regimes and current nutrient inputs do not appear to influence these species. Thus, while the maintenance of the hydrological heterogeneity and the diversity of mowing regimes is important in maintaining biodiversity, variation in nutrient inputs and previous management (at least within the range here investigated) is likely to be of lesser importance for Syrphidae and Sciomyzidae.  相似文献   

19.
20.
The diversity of soil microbial communities can be key to the capacity of soils tosuppress soil-borne plant diseases. As agricultural practice, as well as directedagronomical measures, are known to be able to affect soil microbial diversity, it isplausible that the soil microflora can be geared towards a greater suppressivity ofsoil-borne diseases as a result of the selection of suitable soil management regimes.In the context of a programme aimed at investigating the microbial diversity of soilsunder different agricultural regimes, including permanent grassland versus arableland under agricultural rotation, we assessed how soil microbial diversity is affectedin relation to the suppression of the soil-borne potato pathogen Rhizoctoniasolani AG3. The diversity in the microbial communities over about a growingseason was described by using cultivation-based – plating on different media – and cultivation-independent – soil DNA-based PCR followed by denaturing gradient gel electrophoresis (DGGE) community fingerprinting – methods. The results showed great diversity in the soil microbiota at both the culturable and cultivation-independent detection levels. Using cultivation methods, various differences between treatments with respect to sizes of bacterial and fungal populations were detected, with highest population sizes generally found in rhizospheres. In addition, the evenness of eco-physiologically differing bacterial types was higher in grassland than in arable land under rotation. At the cultivation-independent level, clear differences in the diversities of several microbial groups between permanent grassland and arable land under rotation were apparent. Bio-assays that assessed the growth of R. solani AG3 hyphae through soil indicated a greater growth suppression in grassland than in arable land soils. Similarly, an experiment performed in the glasshouse showed clear differences in both microbial diversities and suppressiveness of R. solani growth in soil, depending on the presence of either maizeor oats as the crop. The significance of these findings for designing soil managementstrategies is discussed.  相似文献   

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