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1.
Urban trees store and sequester large amounts of carbon and are a vital component of natural climate solutions. Despite the well-recognized carbon benefits of urban trees, there is limited effort to examine how spatial distribution of carbon density varies across distinctive social, demographic, and built dimensions of urban landscapes. Moreover, it is unclear whether specific aspects of landscape structure and design could help increase carbon densities in urban trees. Here, we produced a fine-resolution carbon density map of urban trees in New York City (NYC) by integrating high-resolution land cover map, LiDAR-derived tree metrics, i-Tree Eco, and field survey data. We then explored spatial variations of carbon density across the gradients of urban development intensity, social deprivation index, and neighborhood age, and we examined the relationships between carbon density, and fragmentation, aggregation, size, and shape of tree canopy cover. We find that carbon stored in urban trees in NYC is estimated as 1078 Gg, with an average density of 13.8 Mg/ha. This large amount of carbon is unevenly distributed, with carbon densities being highest in Bronx and in open parks and street trees. Furthermore, carbon densities are negatively associated with urban development intensity and the social gradient of deprivation. Regarding the impacts of tree morphology on carbon density, our results show that while the amount of tree cover is the most influential factor in determining carbon density, small-sized forest patches and moderate levels of forest edges are also conductive to increasing carbon densities of urban trees. To incorporate urban forestry into developing innovative, effective, and equitable climate mitigation strategies, planners and decision makers need to identify the optimal spatial configuration of urban forests and invest in tree planting programs in marginalized communities.  相似文献   

2.
An exceptionally rich and colorful literature, drawn in almost equal parts from pure mathematics, from the sciences, and from the technologies, has grown up over the years, which bear in different ways on the topics under discussion. It is the intent of the present paper to survey this far-flung literature, point out some of the commonalities and interrelationships which underlie it, and briefly indicate how it has been and can be applied. To my knowledge, this kind of review has not been attempted before.  相似文献   

3.
A soft paradigm for landscape analysis is presented. This paradigm focuses on the analysis of function first, and then on structure. The objective is to determine which factors are operationally significant, how these factors bring about change, and how they define the spatial characteristics of landscapes.  相似文献   

4.
This paper is based on interviews with fifteen professionals within ecology, forestry and park and landscape architecture. The interviewees are believed to have had a large influence on woodland planning in Sweden between 1950 and 2000. They have won recognition because of their ability to transform theoretical knowledge into practical action. Their work is translating theory into practice and, as such, it may be regarded as art in its deepest sense. During a long period the educational system as well as the dominating research has been concentrating on providing better facts in a search for the best knowledge, high degrees of generality and objectivity. However, this may cause many disadvantages. It has lead to a standardisation and an oversimplification of knowledge and thereby also to an oversimplification of the landscape. This study is based on a humanistic approach, on theory of knowledge, of how facts coming from the world of natural sciences can be encapsulated in daily woodland management.  相似文献   

5.
This paper shows the effects of several variables, which co-cause the Urban Heat Island effect on temperature distribution and outdoor thermal comfort (by using the Predicted Mean Vote, PMV) on dense urban environments. The study was conducted by means of a three-dimensional microclimate model, ENVI-met 3.1, which forecasts the microclimatic changes within urban environments. The effects of building density (% of built area) and canyon effect (building height) on potential temperature, mean radiant temperature, and Predicted Mean Vote distribution are quantified. The influence of several types of green areas (vegetation on the ground and on roofs) on temperature mitigation and on comfort improvements is investigated for different atmospheric conditions and latitudes in a Mediterranean climate. The research quantifies the effects of the variables investigated on temperature distributions and in determining outdoor comfort conditions. Vegetation on the ground and on roofs mitigates summer temperatures, decreases the indoor cooling load demand, and improves outdoor comfort. The results of the study demonstrate that density and height of buildings in a city area influence potential temperature, mean radiant temperature, and Predicted Mean Vote distribution; for most of the cases examined higher density causes higher temperatures and with taller buildings vegetation has higher cooling effects. Considering the cooling effect of vegetation, a difference can be noticed depending on the amount of green areas and vegetation type. The results of this study show also that vegetation is more effective with higher temperatures and lower relative humidity values in mitigating potential temperatures, mean radiant temperatures, and PMV and in decreasing the cooling load demand.  相似文献   

6.
紫苏、香紫苏、东紫苏同为唇形科植物,是一类重要的药材、香料作物,其名称与用途相近,由此产生了同名异种、同种异名现象。现从植物学分类、起源分布、特征特性、开发利用等方面将三者进行比较和区别,以期为该类植物资源的开发利用提供依据。  相似文献   

7.
Assemblages of plants were studied at 14 sites in northern Patagonia corresponding to localities at which we (Monjeau et al. 1997) earlier studied the relationship between small mammal assemblages and landscape classifications. This allowed us to test predictions that both plants and small mammals correspond to the more inclusive hierarchical landscape divisions but that plants track better than small mammals the less inclusive divisions. Species presence or absence of plants at each locality was used in a series of multivariate analyses and compared by correlation analysis with those generated from small mammal species data. Assemblages of both plants and small mammals corresponded to the upper divisions, which are based on climatic and geomorphological features, but small mammal assemblages did not correspond to the lower divisions of the landscape classifications. Three factors are considered as explanations for the observed differences between plants and small mammals: a) small mammal habitat is determined more by plant growth form than by plant species; b) trophic level differences between the two groups; and c) species pool size affects the resolution of microhabitat correspondence. Our data indicate that both plant assemblages and small mammal assemblages respond to climatic and geomorphological features, which is in contrast to the paradigm that mammal assemblages simply follow plant assemblages. We also attempted to reconcile classification systems in Patagonia by proposing a nomenclatural system based on a hierarchical classification. In the system proposed, ecoregion is the lowest division small mammal assemblages can recognize in Patagonia. Finally, we conclude that the hierarchical nature of landscapes based on a holistic view of environments reflects real entities that are not just the perceptions of landscape ecologists.  相似文献   

8.
AIM: To investigate the angiogenesis status,the expression of vascular endothelial growth factor (VEGF),angiopoietin-1 (ANG-1),angiopoietin-2 (ANG-2),thrombospondin-1 (TSP-1) in cholangiocellular carcinoma (CCC) and relationship with tumor angiogenesis,differentiation,invasion and metastasis.METHODS: 33 specimen of surgically resected CCC were investigated.Immunohistochemical staining of CD34,VEGF,ANG-1,ANG-2 and TSP-1 was carried out.RESULTS: The mean MVD was (87.2±52.6)/mm2.VEGF positive expression was found in 75.6% cases;ANG-1 positive expression was observed in 36% cases;ANG-2 positive was detected in 57.6% cases and 45.5% cases exhibited positive TSP-1 expression.VEGF and ANG-2 expressions were found to be associated with significant higher level of MVD (P<0.01 and P<0.05,respectively).TSP-1 expression was found to be associated with significant low level of MVD (P<0.01).Positive TSP-1 expression was also found to be associated with higher level of intrahepatic metastasis (46.7% vs 5.6%,P<0.05).CONCLUSION: Considerable angiogenesis compared to other solid tumors can be observed in CCC.VEGF and ANG-2 might play a proangiogenic role and TSP-1 may play an inhibitory role.Although TSP-1 may increase the intrahepatic metastasis of CCC,neither MVD levels nor the expression of VEGF,ANG-1,or ANG-2 is associated with tumor differentiation,invasion and metastasis.  相似文献   

9.
Wetlands, carbon, and climate change   总被引:3,自引:0,他引:3  
Wetland ecosystems provide an optimum natural environment for the sequestration and long-term storage of carbon dioxide (CO2) from the atmosphere, yet are natural sources of greenhouse gases emissions, especially methane. We illustrate that most wetlands, when carbon sequestration is compared to methane emissions, do not have 25 times more CO2 sequestration than methane emissions; therefore, to many landscape managers and non specialists, most wetlands would be considered by some to be sources of climate warming or net radiative forcing. We show by dynamic modeling of carbon flux results from seven detailed studies by us of temperate and tropical wetlands and from 14 other wetland studies by others that methane emissions become unimportant within 300 years compared to carbon sequestration in wetlands. Within that time frame or less, most wetlands become both net carbon and radiative sinks. Furthermore, we estimate that the world’s wetlands, despite being only about 5–8 % of the terrestrial landscape, may currently be net carbon sinks of about 830 Tg/year of carbon with an average of 118 g-C m?2 year?1 of net carbon retention. Most of that carbon retention occurs in tropical/subtropical wetlands. We demonstrate that almost all wetlands are net radiative sinks when balancing carbon sequestration and methane emissions and conclude that wetlands can be created and restored to provide C sequestration and other ecosystem services without great concern of creating net radiative sources on the climate due to methane emissions.  相似文献   

10.
Systematic investigations on the forcing of tulips, hyacinths, daffodils, Easter lilies and Dutch iris have produced a fairly complete set of scientific principles. In this review, these principles have been classified into a 3-phase concept of forcing. These are: production, programming, and greenhouse. The production phase is defined as all processes which occur during bulb production and it terminates with the harvesting of the bulbs. The programming phase comprises all handling of the bulbs from harvesting until they are placed under greenhouse conditions. The greenhouse phase is the accelerated development of the bulbs until anthesis or marketing of the plants. These phases have been discussed relative to floral and root development and the basic environmental requirements of the bulb species.  相似文献   

11.
研究了不施肥处理,氮磷钾配施和增施硼肥对青花菜养分吸收分配及产量和品质的影响。结果表明,现蕾期至花球膨大期,青花菜对氮、磷、钾的吸收量最大,整个生长期对钾的吸收最多,氮次之,磷最少。氮磷钾主要分配在叶片中,现蕾后逐渐向花球转移,从现蕾到采收时,叶片中氮、磷、钾分配率分别降低了19.6%、10%和9.0%,花球中氮磷钾分配率分别提高了23.1%、15.9%和11.1%。不施氮、磷、钾肥显著降低了花球产量、维生素C含量和成品率,增施硼肥处理的花球成品率较氮磷钾肥处理提高了4.8%,不施氮肥和钾硫肥(K2SO4)显著降低了花球中的硫代葡萄糖苷含量。相关性分析表明,青花菜产量与植株内氮、钾积累量显著正相关,成品率与植株内磷营养显著正相关。  相似文献   

12.
The concept of urban wilderness feels like a paradox since natural and urban environments have long been viewed as antithetical. Today, however, wilderness is high on the urban agenda as a response to different challenges: biodiversity and human experiences of nature are being lost in increasingly dense cities, while at the same time a plethora of wild areas are developing in cities that are undergoing post-industrial transformation. Yet there is confusion around the definitions and the anticipated functions of urban wilderness and how humans can be incorporated therein. A unifying framework is proposed here that envisions urban wilderness as a social-ecological system; three major components are identified and linked: (i) the supply of wilderness areas along gradients of naturalness and ecological novelty, leading to a differentiation of ancient vs. novel wilderness, and the identification of wilderness components within cultural ecosystems; (ii) the demand for wilderness in urban societies, which differs among sociocultural groups as a function of underlying values and experiences; (iii) the access to urban wilderness, which can be improved both in terms of providing opportunities for encountering urban wilderness (e.g., by conserving, rewilding wilderness areas) and enhancing the orientation of urban people towards wilderness (e.g., through information, environmental education, citizen science). Evidence from urban wilderness projects in Europe demonstrates that multi-targeted approaches to conserving and managing existing novel urban ecosystems offer manifold opportunities to combine biodiversity conservation and wilderness experience in cities.  相似文献   

13.
Growing a resilient landscape depends heavily on finding an appropriate match between the scales of demands on ecosystems by human societies and the scales at which ecosystems are capable of meeting these demands. While the dynamics of environmental change and ecosystem service provision form the basis of many landscape ecology studies, enhancing landscape resilience is, in many ways, a problem of establishing relevant institutions that act at appropriate scales to modify and moderate demand for ecosystem services and the resulting exploitation of ecosystems. It is also of central importance for landscape sustainability that institutions are flexible enough to adapt to changes in the external environment. The model provided by natural ecosystems suggests that it is only by encouraging and testing a diversity of approaches that we will be able to build landscapes that are resilient to future change. We advocate an approach to landscape planning that involves growing learning institutions on the one hand, and on the other, developing solutions to current problems through deliberate experimentation coupled with social learning processes.  相似文献   

14.
绿地养护的原则及方法和途径   总被引:1,自引:0,他引:1  
绿地养护是绿化得以存续、发展的根本保证,应遵循及时、适度和系统5条原则,采用现场观测法、理论指导法和经验操作法;从灌溉(排涝)、有害生物防治、施肥、整形修剪、清除杂草和垃圾、更新补植、维护设施、协调及创新9个途径开展工作.  相似文献   

15.
Alternate bearing, the occurrence of high yield ‘on’ year followed by low yield ‘off’ year, is striking in pistachio (Pistacia vera L.). Floral buds of pistachio are formed a year before bloom, but abscise during the years with heavy crop (‘on’ year). Abscission of floral buds is due to competition between growing seeds on 1-year-old shoots and developing buds on current season growth. We studied the effects of chemical fruit thinning on alternate bearing and nut characteristics in a commercial orchard of ‘Owhadi’ pistachio cultivar during 2003–2004 in Rafsanjan, Iran. In both years, ethephon (100 and 200 mg l−1), naphthaleneacetic acid (NAA) (125 and 250 mg l−1) and urea (2.5 and 5%) were applied to the branch units of each individual ‘on’-year trees. The results showed that ethephon at both concentrations significantly increased fruit thinning and floral bud retention for the subsequent year. Other treatments also increased fruit thinning and floral bud retention but were inferior to ethephon.  相似文献   

16.
Climate change, human population growth, the energy crisis, and food insecurity negatively drive livelihoods in developing countries. The trend seems to be severe in arid and semi-arid areas where some livelihood strategies are naturally constrained. Tree planting is one of the mitigation and adaptation approaches applied to climate variability and change for sustainable development in sub-Saharan Africa. The current study assessed the status, determinants, and challenges of tree planting in Nkuhungu, Msalato, and Hombolo villages in the Dodoma district, Tanzania. A household questionnaire survey (HQS) was used to collect data from 213 household respondents. In-depth interviews and focus group discussions were used to supplement data from HQS. Results indicate that tree planting is practiced at household and institutional levels during the wet season and was promoted after the government shifted from Dar es Salaam to Dodoma. Approximately 5111 planted trees were recorded in the study villages, with an average of 24 ± 5 trees planted per household. Fruit and shade trees are widely planted in residential areas, and privately owned nurseries and the Tanzania Forest Services Agency (TFS) are the major sources of seedlings. Level of education (+), type of employment (-), seedling price (-), water availability (+), and the importance of the tree (+) were found to influence the number of trees planted by household respondents. The main challenges of tree planting are inadequate land size, water scarcity, high pricing of seedlings, lack of improved seeds, and insufficient extension services. Knowledge on tree planting determinants would be instrumental in strengthening the current governmental strategies for greening Dodoma. The study suggests increasing water sources such as boreholes and digging wells/ponds for watering trees; improvement of extension services; and provisioning of affordable improved and adaptive seeds to semi-arid areas.  相似文献   

17.
AIM: To detect the treatment of K562 leukemia cells with bortezomib altering the expression of genes fas, bcl-2, bcl2l12, bim, bax, caspase-9 and caspase-3.METHODS: MTT assay was used to detect the inhibition of proliferation. Apoptosis was detected by Annexin-V staining and mitochondrial transmembrane potential (Δψm). RT-PCR was used to analyze the mRNA expressions of fas, bcl-2, bcl2l12, bim, bax, caspase-3 and caspase-9.RESULTS: Bortezomib caused a time- and dose-dependent inhibition of cell proliferation and IC50 of 24 h and 48 h were 161.41 nmol/L and 96.33 nmol/L, respectively. At the concentration of 104 nmol/L, bortezomib induced apoptosis in a time-dependent manner, including increasing annexin-V positivity and decreasing the Δψm. RT-PCR showed that bortezomib up-regulated the mRNA expression of fas, bcl2l12, caspase-9 and caspase-3, but mRNA expressions of bcl-2, bim and bax did not changed obviously.CONCLUSION: Bortezomib inhibits the proliferation of K562 and induces apoptosis, in which fas, bcl2l12, caspase-9 or caspase-3 gene is one of the main genes taking part in.  相似文献   

18.
The effect of night temperature on short day (SD) floral induction has been studied in three June-bearing strawberry cultivars of different geographic origin and compared with yield performance in the cool Nordic environment. At the optimum day temperature of 18 °C, the SD flowering response of the cultivars ‘Florence’ and ‘Korona’ increased significantly with increasing night temperature from 9 to 18 °C, while an optimum was reached at 15 °C in the cultivar ‘Frida’ that is selected under cool-environment conditions in Norway. Also, while saturated flowering response was obtained with 3 weeks of SD treatment at all temperatures in ‘Frida’, several plants of ‘Florence’ and ‘Korona’ failed to initiate flowers at 9 °C night temperature even with 5 weeks of SD. The effect of extended SD period was particularly pronounced in ‘Florence’. The slow SD floral induction response of ‘Florence’ was associated with a 2 week delay of anthesis in subsequent long day (LD) conditions at 21 °C. Yield performance of the same cultivars during 2 years under field conditions at Nes Hedmark and in North Norway also demonstrated that the yield potential of ‘Florence’ was not realized under the climatic conditions prevailing at these locations. In both years the yields varied significantly among the cultivars, ‘Frida’ having the highest yields followed by ‘Korona’, with ‘Florence’ far below. It is concluded that, in the Nordic environment, autumn (September) night temperatures are obviously sub-optimal for yield performance of some June-bearing strawberry cultivars, and that this effect is mediated by autumn temperature effects on flower initiation responses.  相似文献   

19.
Global scale modeling is reviewed with respect to global circulation models, biosphere-atmosphere models, and climate-biosphere models. These different models focus on short to long time scale interactions between atmospheric and surface systems. Remote sensing is shown to play a central role in acquisition of data for these models, and an experiment, termed FIFE, is described, which is the first attempt to take simultaneous land surface observations of meteorological and biophysical parameters at sufficient resolution to test hypotheses linking the vegetated surface and circulation within the lower atmosphere.  相似文献   

20.
通过对湖南省湘潭市岚园路街道现状进行调查,分析研究岚园路街道的特色与现存问题,提出设计目标、对策及策略。即在街道整体景观整治、提质与提升中,贯彻生态、文化和商业的融合这一理念。在尊重街道地域特色的前提下,延续文脉,注重生态的和谐、商机的培育,对重点景观节点进行深入设计,营造新的街道视觉形象,从而提升街道素质。  相似文献   

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