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1.
The intensification of agriculture has led to a loss of biodiversity and subsequently to a decrease in ecosystem services, including regulation of pests by natural enemies. Biological regulation of pests is a complex process affected by both landscape configuration and agricultural practices. Although modeling tools are needed to design innovative integrated pest management strategies that consider tritrophic interactions at the landscape scale, landscape models that consider agricultural practices as levers to enhance biological regulation are lacking. To begin filling this gap, we developed a grid-based lattice model called Mosaic-Pest that simulates the spatio-temporal dynamics of Meligethes aeneus, a major pest of oilseed rape, and its parasitoid, Tersilochus heterocerus through a landscape that changes through time according to agricultural practices. The following agricultural practices were assumed to influence the tritrophic system and were included in the model: crop allocation in time and space, ploughing, and trap crop planting. To test the effect of agricultural practices on biological regulation across landscape configurations, we used a complete factorial design with the variables described below and ran long-term simulations using Mosaic-Pest. The model showed that crop rotation and the use of trap crop greatly affected pollen beetle densities and parasitism rates while ploughing had only a small effect. The use of Mosaic-Pest as a tool to select the combination of agricultural practices that best limit the pest population is discussed. 相似文献
2.
Landscape change is an ongoing process for even the most established landscapes, especially in context to urban intensification and growth. As urbanization increases over the next century, supporting bird species’ populations within urbanizing areas remains an important conservation challenge. Fundamental elements of the biophysical structure of urban environments in which bird species likely respond include tree cover and human infrastructure. We broadly examine how tree cover and urban development structure bird species distributions along the urban-rural gradient across multiple spatial scales. We established a regional sampling design within the Oak Openings Region of northwestern, Ohio, USA, to survey bird species distributions across an extensive urbanization gradient. Through occupancy modeling, we obtained standardized effects of bird species response to local and landscape-scale predictors and found that landscape tree cover influenced the most species, followed by landscape impervious surface, local building density, and local tree cover. We found that responses varied according to habitat affiliation and migratory distance of individual bird species. Distributions of short-distance, edge habitat species located towards the rural end of the gradient were explained primarily by low levels of urbanization and potential vegetative and supplemental resources associated with these areas, while forest species distributions were primarily related to increasing landscape tree cover. Our findings accentuate the importance of scale relative to urbanization and help target where potential actions may arise to benefit bird diversity. Management will likely need to be implemented by municipal governments and agencies to promote tree cover at landscape scale, followed by residential land management education for private landowners. These approaches will be vital in sustaining biodiversity in urbanizing landscapes as urban growth expands over the next century. 相似文献
3.
Kate Sherren Joern Fischer Helena Clayton Jacki Schirmer Stephen Dovers 《Landscape Ecology》2010,25(8):1219-1230
In a context of global agricultural intensification, integrating conservation and agricultural production is a major challenge.
We have tackled the problem using a transdisciplinary research framework. Our work focuses on part of the upper Lachlan River
catchment in southeastern Australia. The region is dominated by livestock grazing, and is part of an internationally recognised
threatened ecoregion because most native woodland vegetation has been cleared. In productive areas, most remnant vegetation
occurs as scattered and isolated paddock trees, which are dying from old age and not regenerating due to agricultural practices.
The policy context and industry trends present additional risks for sparse trees. These declining trees provide many ecosystem
services, including enhanced water infiltration, shade for livestock, aesthetic and cultural values, and habitat for native
species. Our research aims to identify management options and policy settings that enable landscape-scale tree regeneration
while maintaining grazing production. Our findings highlight tensions between the trajectory of tree cover in the region and
stakeholder values. Under status quo management, many scattered and isolated paddock trees will be lost from farms, although
most farmers would like to see them persist. Case studies on selected farms reveal management strategies that may be more
sustainable in terms of tree regeneration and agricultural productivity, such as rotational grazing. In addition to these
applied insights, our work provides a case study illustrating how a transdisciplinary study can be conducted efficiently by
a small team. Our pragmatic approach has successfully combined targeted disciplinary activities with strategic collaborations
and stakeholder engagement, all united by shared landscape, case graziers, and outreach activities. 相似文献
4.
5.
There is increasing interest in developing criteria to evaluate the environmental implications of intensive agricultural land use. This implies discriminating between nature and man-made effects upon structural and functional attributes of agroecosystems. Adequate indicators of these combined effects should be cost efficient yet compatible with the core of ecological theory on biodiversity, spatial organization and ecosystem stability. We developed resistance-resilience metrics of plant growth to evaluate the intensity of agricultural use in a temperate irrigated basin in southern Argentina. The metrics are based on an analysis of the components of a temporal series of vegetation indices computed at a low resolution from available globally remote sensed reflectance imagery. We related the developed metrics to the properties of the soils and plant canopies observed at field scale and high-resolution imagery of the basin. Soil depth, soil erosion status and land fragmentation account for large fractions of the variance of the distribution of functional groups of the plant canopies and are also correlated with smaller scale attributes of land vegetation cover. Resistance-resilience indicators constitute a cost-efficient and adequate approach to evaluate the degree of intensification of land agricultural use. 相似文献
6.
Proesmans Willem Smagghe Guy Meeus Ivan Bonte Dries Verheyen Kris 《Landscape Ecology》2019,34(5):1033-1044
Landscape Ecology - Bumblebees are important pollinators for agricultural crops and wild plants. However, agricultural intensification and loss of semi-natural habitat may have adverse effects on... 相似文献
7.
Street trees can provide important environmental services to residents living in high-altitude cities. Nevertheless the performance of street trees in this unique environment is largely unknown. This article examines the impact of high-altitude environments on the growth of street trees through a case study in Lhasa, China. The structure, species composition, and health condition of street trees in Lhasa were surveyed using a representative sampling approach. The history of street tree programs and factors that affect the health of street trees was also analyzed. The results showed that there were 24 species and cultivars in 2032 sampled street trees. The street tree population in Lhasa contained a significant number of small trees, which was due to the large-scale planting program initiated in recent years. The street tree population in Lhasa was not very stable due to the uneven age distribution. The health conditions of street trees were affected by climatic factors as well as by management practices. We concluded that unfavorable environmental conditions in high-altitude cities may affect the sustainability of street tree populations to some degree but that human management of the street tree population is a more significant factor. 相似文献
8.
以银杏茎尖及根尖为试材，采用压片法对雌雄株核型及性别早期鉴定进行了深入研究，结果表明，①银杏雌雄株核型一致，唯一差异就是雌株第１０对亚中部着丝粒染色体的长臂上各有一个随体，而雄株这对染色体仅一条染色体具有随体，属异型染色体，即性染色体，如果用ＸＹ表示雄株这一对染色体，则雌株可用ＸＸ表示。因此，雌株核型为２ｎ＝２ｘ＝２４＝２２ＡＣ［４ｍ（２ｓａｔ）＋６ｓｍ＋１２ｓｔ］＋ＸＸ；雄株核型为２ｎ＝２ｘ＝２４＝２２Ａ［Ｃ４ｍ（２ｓａｔ）＋６ｓｍ＋１２ｓ］＋ＸＹ，进一步证实了银杏的性别决定机制属ＸＹ型；②根据ＸＹ性别决定机制，借助胚培技术对７５株银杏实生幼苗进行了性别早期鉴定，雌株为３１珠，占４１．３％，雄株为４４株，占５８．７％ 相似文献
9.
Isolated trees may significantly enhance biodiversity at the landscape level. However, our understanding of their impacts
is still poor, particularly in environments with high soil moisture where research on this topic has been comparatively limited.
We examined understorey vegetation and soil oribatid mite assemblages under live and dead Scots pine trees and in open treeless
areas, all within the same Scottish upland wet heath system, to determine whether isolated live trees affected the understorey
and mite components of the ecosystem, and whether these effects occurred in parallel. We also explored whether these responses
might result from tree-driven reductions in soil moisture content. Live trees reduced soil moisture (relative to wet heath
and beneath dead trees) and appeared to change vegetation from wet heath to dry heath type communities. These effects were
strongly related to tree trunk diameter (tree size). No major effects of dead trees on understorey vegetation or soil moisture
were apparent. Higher mite species abundance and richness were found under live trees than in treeless open heath. Although
mite abundances were lower under dead trees than live trees, richness remained similar, thus different factors seem to be
regulating mite abundance and community composition. These findings indicate that landscape-level biodiversity responses to
environmental change such as habitat fragmentation cannot be predicted from vegetation patterns alone, and that even in heavily
fragmented landscapes comparatively small patches such as isolated individual trees can enhance biodiversity. 相似文献
10.
The impact of agricultural practices on the dynamics of weed invasion in a rural landscape was studied by describing the spatial distribution of Chaerophyllum aureum populations colonising less intensive managed hay meadows. Polyphenol compounds were used as individual markers to identify the structure of C. aureum diversity, in terms of its scale and patterns, within and between fields along the bottom of a Pyrenean valley. The results revealed, firstly, the existence of a dominant `genotype' successfully colonising the entire area, and secondly, the maintenance of high levels of polyphenol diversity within five different populations. This spatial arrangement of `genetic' population diversity was obviously not related to the natural reproduction and dispersal patterns of this species, but to human practices of hay production, the principal effect of which is to mix seeds of different genetic origin and thus accelerate and amplify the colonisation process of adapted `genotypes'. 相似文献
11.
This paper focuses on understanding human impact on landscape. Both ecological and human practices are analysed as interacting
processes. An agent-based model integrating biological and historical knowledge is used to analyse the pattern of Scots Pine
encroachment in a French Mediterranean upland. In the STIPA model, pine trees are autonomous agents and a cellular automaton
simulates land-use. We test the effects of shifting cultivation on tree establishment at the landscape scale. This allows
us to understand how agropastoral practices patterned this area from the 17th to 19th century: simulations show the importance
of shifting cultivation in limiting woodland progression. Fallow duration linked to environmental heterogeneity is a significant
factor for explaining pine dynamics and landscape patterning at the scale of the study region. We put this result in perspective
with current rangeland management policies that often consider grazing as the most relevant tool for open landscape maintenance.
Our results also show the importance of taking into account time-scale effects when linking landscape patterns to agricultural
systems. 相似文献
12.
Vegetation Composition and Succession of Abandoned Farmland: Effects of Ecological,Historical and Spatial Factors 总被引：6，自引：0，他引：6
In North America, as well as in Europe, the mechanization and the modernization of the agricultural activities had strongly
modified the agricultural landscapes. Originating from these transformations of the agricultural environment, abandoned farmlands
remain poorly known environments. A holistic approach, including the analysis of ecological, historical and spatial factors,
is used in order to understand the dynamics of these environments created by agricultural abandonment in southwestern Québec
(Canada). The analysis of 36 abandoned farmlands in the study area reveals the existence of two ecological groups. The first
ecological group is composed by abandoned farmlands originating from pasture and at the moment dominated by a spiny shrub
vegetation. The second ecological group includes past cultivated field at the moment dominated by either hydric herbaceous
and shrub vegetation. Abiotic ecological variables such as slope, surface stoniness, canopy opening and soil pH, as well as
land-use history, and age of the abandoned farmlands, are major factors explaining the current state of abandoned farmlands.
Succession vector analysis reveals a strong differentiation among abandoned farmlands as to their tree species regeneration.
Possible management alternatives, such as reforestation, are proposed in order to integrate those new environments to the
modern agricultural landscape. 相似文献
13.
Tobias Plieninger 《Landscape Ecology》2006,21(1):91-105
Mediterranean agroforestry landscapes, dehesas, experience significant structural changes that affect their ability to support
habitats for a rich biodiversity. The goal of this study is to provide quantitative information on loss, fragmentation, and
alteration of holm oak (Quercus ilex) stands over a 42-year period, based on two sites in the lowlands of Cáceres province, Spain. Aerial photography and orthoimages
from 1956, 1984, and 1998 were processed in a geographic information system (GIS). Important changes in demography and land-use
were rural depopulation, abandonment of traditional agricultural activities, and a sharp increase in livestock stocking levels.
These were related to intensification and extensification of land-uses determined by national and EU agricultural policies.
Results of the land cover analysis indicated that dehesas suffered an annual 0.27% and 0.04% decrease in cover in the two
sites. From 1984 loss rate had markedly accelerated (0.83% and 0.30%). Most dehesas were lost by shrub encroachment or conversion
to open grassland. Fragmentation through roads increased by 28% and 45%, while rural buildings decreased by 17% and 50% from
1956 to 1998. Mean tree density decreased from 1956 to 1984, but a recovery was found since 1984. Significant factors determining
stand densities in most time points were altitude (related with different land-uses and geological substrates), ownership,
and proximity to villages. This suggests that stand structure is controlled both by human interventions and ecological settings.
The findings support the view that opposite trends of land abandonment and intensification of land-uses arise in most northern
Mediterranean countries as an effect of the EU Common Agricultural Policy. 相似文献
14.
Renaturing urban environments is a transformative pathway for urban sustainability that can be leveraged for collaborative research and planning to reverse long trends of ecosystem degradation. People-nature connections need to be reinforced to enable the successful uptake and upscale of urban renaturing practices. Improving people’s understanding, perception, and emotions towards nature is therefore key. In this paper, we discuss how human knowledge and values of nature can be enabled through urban renaturing. Besides, we discuss the required transitions in urban planning processes to support urban renaturing practices. 相似文献
15.
Agri-environmental schemes and the European agricultural landscapes: the role of indicators as valuing tools for evaluation 总被引：8，自引：0，他引：8
In Europe most conservation values, from biodiversity to scenic sites, are integral parts of agricultural landscapes. When these landscapes change as a result of agricultural policies, natural values – species, habitats, landscapes – are usually affected. Until recently however, these values have not been part of agricultural policies. The impacts of such new policies are difficult to evaluate because landscapes are complex and diverse, and the effects of policy are rarely immediate or causal.This paper evaluates the potential effects of Agri-environmental Regulation EC 2078/92 on European agricultural landscapes through the use of agri-environmental indicators (AEIs) on policy effects. After discussing the general framework of the evaluation methodology through the use of AEIs, we distinguish two types of agri-environmental policy (AEP) effects: policy performances and policy outcomes. The impediments to direct measurement of policy outcomes are stated. The potential for measuring policy performances are checked in two case study areas, one in Spain and one in Denmark, characterized by extensive agricultural land-uses and by the dual process of intensification/abandonment that is threatening their natural values. Both study areas are currently targeted by agri-environmental schemes under Reg. 2078/92. The realisability or availability of suitable statistical data to construct and report each AEI is stated for both types of effects. A problem of scale and content is found in most of the available statistics for assessing policy outcomes and the need for data at farm level is concluded to be indispensable if policy performances are to be measured. Effects of policy performance are measured for key selected AEIs in each study area on the basis of the results of a field survey based on questionnaires of participating and non-participating farmers in the AEP schemes. The main effects may be catalogued as improvement effects or protection effects since they represent a change in participant over non-participant farmers' decisions. Finally, the importance of this type of policy evaluation approach is discussed in the light of the likely future development of AEP in the European Union. 相似文献
16.
The frequency and intensity of heat stress events globally have increased over the past 20 years. Climatic modeling predicts that this trend will continue throughout the 21st century, with the global land area experiencing heat waves doubling by 2020 and quadrupling by 2040. Due to the reflective nature of buildings and infrastructure, heat temperatures tend to be higher within urban landscapes than outlying rural areas. Heat stress influences processes from the molecular level to whole-tree biology. At the leaf level, photosynthesis is reduced, photo-oxidative stress increases, premature leaf abscission occurs, and the growth of leaves decreases. Growth decreases at the whole tree level, and biomass allocation between roots, shoots, leaves, and branches is altered. When drought and heat stress are combined, detrimental effects are considerably enhanced and, without irrigation, can quickly lead to tree death. There have been few studies regarding the heat tolerance of urban tree species. However, there is evidence of genetic variation in heat tolerance between and within species within forestry, which could be essential to exploit for urban trees. Understanding the mechanisms of tree physiological, biochemical, and molecular responses to extreme heat events is also necessary for understanding how urban tree species will be affected by climate change. 相似文献
17.
Biodiversity is associated with indicators of soil ecosystem functions over a landscape gradient of agricultural intensification 总被引：1，自引：1，他引：0
Steven W. Culman Anna Young-Mathews Allan D. Hollander Howard Ferris Sara Sánchez-Moreno Anthony T. O’Geen Louise E. Jackson 《Landscape Ecology》2010,25(9):1333-1348
Agricultural intensification has led to dramatic losses in biodiversity over the past several decades. Many studies have shown
the effects of intensification on vegetation or soil communities at field or local scales. However, the functional significance
of biodiversity may only appear at larger spatial and temporal scales, due to exchanges among local ecosystems throughout
a landscape. To examine how patterns of biodiversity loss are reflected at larger spatial scales, plant and soil biodiversity
and associated indicators of ecosystem functions were assessed in riparian areas over a 150 km2 agricultural landscape in the Sacramento Valley of California. Publicly-available GIS data were first used to classify and
select sites over the range of soils, topography and plant community types. Representative sites from the landscape were sampled
for soil physiochemical properties, as well as microbial, nematode, and plant communities. Higher agricultural intensification,
based on field and landscape indices, was negatively correlated with richness and diversity of plant and soil taxa, and was
related to indicators of ecosystem functions, such as increased soil nitrate and phosphorus loading, decreased riparian health
ratings, and lower soil carbon, soil microbial biomass and soil food web structure. Both field- and landscape-scale factors
played important roles in the measured losses. The study area was composed of a wide array of soils, vegetation, and land
management, indicating that the observed trends transcended site-specific conditions. 相似文献
18.
19.
为了解赣南地区蔬菜产业现状,根据项目的需要,通过实地走访、发放问卷等形式对赣南地区的蔬菜经营主体进行调研,对赣南蔬菜产业生产规模、布局、生产经营情况、品牌建设、农业技术应用情况、经济效益等方面进行调研。结果表明:赣南蔬菜种植面积和产量呈稳步上升趋势;蔬菜产业布局合理,形成了三大供应区;蔬菜种植户的文化水平普遍不高;种植大户较少,蔬菜产业集约化程度低;现代化农业信息技术含量低、应用面积小;品牌建设相对落后,经济效益受不确定因素影响大。同时对蔬菜生产中存在的问题及应对措施进行了分析,以期对蔬菜产业的发展提供参考依据。 相似文献
20.
James C. Beasley Zachary H. Olson Guha Dharmarajan Timothy S. EaganII Olin E. RhodesJr. 《Landscape Ecology》2011,26(7):937-950
Human land-use practices have dramatically altered the composition and configuration of native habitats throughout many ecosystems.
Within heterogeneous landscapes generalist predators often thrive, causing cascading effects on local biological communities,
yet there are few data to suggest how attributes of fragmentation influence local population dynamics of these species. We
monitored 25 raccoon (Procyon lotor) populations from 2004 to 2009 in a fragmented agricultural landscape to evaluate the influence of local and landscape habitat
attributes on spatial and temporal variation in demography. Our results indicate that agricultural ecosystems support increased
densities of raccoons relative to many other rural landscapes, but that spatial and temporal variation in demography exists
that is driven by non-agricultural habitat attributes rather than the availability of crops. At the landscape scale, both
density and population stability were positively associated with the size and contiguity of forest patches, while at the local
scale density was positively correlated with plant diversity and the density of tree cavities. In addition, populations occupying
forest patches with greater levels of plant diversity and stable water resources exhibited less temporal variability than
populations with limited plant species complexity or water availability. The proportion of populations comprised of females
was most strongly influenced by the availability of tree cavities and soft mast. Despite the abundance of mesopredators in
heterogeneous landscapes, our results indicate that all patches do not contribute equally to the regional abundance and persistence
of these species. Thus, a clear understanding of how landscape attributes contribute to variation in demography is critical
to the optimization of management strategies. 相似文献