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1.
The efficacy of grass carp Ctenopharyngodon idella (Cyprinidae) and weevils Neochetina spp. (Curculionidae) to control the aquatic weed, water hyacinth, is investigated in a square net cage (happas) setting at a farm in Cuddalore District, South India. This novel combination of insects and fish is found to be superior to individual treatments for controlling the weed growth within 110 d. The biomass of the weed, number of plants, percentage of flowered plants and chlorophyll contents were studied. The weed biomass is reduced from 5 kg (day 1) to 0.33 kg (day 110) when exposed to grass carp and weevils. The number of plants is reduced to 0.75 in grass carp and weevil exposed happas, while it is 741.5 in the control. The mean number of leaves per plant is also reduced. In addition, the chlorophyll a and b are significantly reduced in happas exposed to the combination of fish and insects when compared to the other treatments. Based on the results of this study, we consider the combined use of grass carp and weevils to be more efficient and sustainable for managing water hyacinths than the use of these organisms individually.  相似文献   

2.
Chitwan-Annapuma Landscape(CHAL)in central Nepal is known for its rich biodiversity and the landscape is expected to provide corridors for species range shift in response to climate change.Environmental assessments have identified biological invasions and other anthropogenic activities as major threats to the biodiversity in the CHAL.One of the rapidly spreading Invasive Alien Plant species(IAPs)in the CHAL is Parthenium hysterophorus L.,a neotropical invasive weed of global significance.This study aimed to investigate the current and future projected suitable habitat of P.hysterophorus in the CHAL using MaxEnt modelling in three"Representative Concentration Pathways"(RCPs 2.6,4.5 and 8.5)corresponding to different greenhouse gases emissiontrajectories for the year 2050 and 2070.A total of 288species occurrence points,six bioclimatic variablesmean diurnal range,isothermality,annual precipitation,precipitation of driest month,precipitation seasonality,precipitation of driest quarter and two topographic variables(aspect and slope)were selected for MaxEnt modelling.Potential range shift in terms of increase or decline in the suitable habitat areas under the projected scenarios were calculated.Slope and annual precipitation were the most important variables that explained the current distribution of P.hysterophorus.Twenty percent of the total area of CHAL was predicted to be suitable habitat for the growth of P.hysterophorus in the current climatic condition.Highest gain in the suitable habitat of this noxious weed was found under RCP 4.5 scenario in 2050 and 2070.whereas there will be a loss in thesuitable habitat under RCP 8.5 scenario in 2050 and2070.Out of four physiographic regions present in CHAL,three regions-Siwalik,Middle Mountain and High Mountain have suitable habitat for P.hysterophorus under current climatic condition.The mountainous region is likely to be affected more than the Siwalik region by further spread of P.fhysteropfhorus in the future under low(RCP 2.6)to medium(RCP 4.5)emission scenarios.The suitable habitat for this weed is likely to increase in the protected areas of mountain regions(Langtang National Park,Annapurna Conservation Area and Manaslu Conservation Area)in the future.The results have revealed a risk of spreading P.hysterophorus from present localities to non-invaded areas in the current and future climatic condition.Such risk needs to be considered by decision makers and resource managers while planning for effective management of this weed to reduce its ecological and economic impacts in the CHAL.  相似文献   

3.
草地退化杂类草入侵遥感监测方法研究进展   总被引：3，自引：0，他引：3  
近年来,受全球气候变暖及日趋频繁的人类活动的共同影响,我国草地生态系统出现了不同程度的退化,成为草地生态学界的研究热点。本文较系统总结了草地退化、杂类草入侵遥感监测方法的应用进展,指出了常规草地退化遥感监测方法的不足,并展望了今后的发展方向。研究发现草地退化在群落尺度上往往表现为优质牧草种类减少,杂类草种类增加。在草地退化过程中,杂类草侵入,往往导致植被覆盖度增加,因而传统的基于植被覆盖度、生产力和产草量下降的草地退化遥感监测方法,无法反映草地退化在植被种群方面的变化特征,尤其是杂类草入侵的草地退化过程。而目前基于高光谱数据的草地退化杂类草入侵监测方法,结合地面光谱测定和对退化草地物种特征微弱光谱差异的定量分析,能有效识别群落中杂类草种类,并反演出占群落的面积比例、高度和盖度等,可为草地退化监测及其治理提供群落演替过程及其态势的重要指标,为草地退化监测提供新的遥感技术方法。  相似文献   

4.
毒草型退化草地具有群落演替特点,通过高光谱遥感技术反演毒杂草分布与退化草地群落结构能对该类退化草地进行有效监测,而光谱特征分析是毒杂草与优良牧草遥感识别的基础。本文选取了三江源区毒草型退化草地的8种典型毒杂草和4种优良牧草的地面实测高光谱数据作为研究样本,经过SG平滑、包络线去除、导数变换和光谱参量化对毒杂草种和优良牧草种的光谱特征进行了分析,并通过马氏距离法提取其特征识别波段。结果表明：① 8种典型毒杂草和4种优良牧草的 “近红外峰值”差异较大,其中鹅绒萎陵菜的“近红外峰值”达到60.07%,而最小者早熟禾仅为17.53%;② 经包络线去除处理后,植被光谱曲线中吸收谷和反射峰光谱差异更加明显,且可减少环境背景对植被光谱的影响,如沼泽草甸的鹅绒委陵菜和驴蹄草,其“绿峰幅值”分别为6.46%和6.89%,经处理后其“绿峰指数”分别为0.2866和0.3671,而在2种环境下生长的同一草种（狼毒草1和狼毒草2）的峰谷特征差异不明显;③ 基于马氏距离法提取的毒杂草与优良牧草的敏感识别波段主要分布在680~750 nm和900~1000 nm波长范围内,以醉马草与矮嵩草为例,其基于反射率的敏感识别波段为713.1~737.1 nm和934.6~965.6 nm。该研究可为利用高光谱遥感进行大面积毒杂草草种识别和植被群落生长监测提供重要科学依据,对于三江源区毒杂草的监测防治和畜牧业的可持续发展具有重要意义。  相似文献   

5.
特呈岛陆地成年乔木资源的研究   总被引：2，自引：0，他引：2  
对特呈岛陆地成年乔木资源进行调查与分析,结果表明,特呈岛陆地的成年乔木:第一类(胸径≥20cm)共1584株,隶属26科41属51个树种,优势树种突出,其中百株以上的树种有4种;第二类(胸径≥20cm与树高≥6m)共1445株,其中大乔木1株、中乔木368株、乔木1076株;第三类(树龄≥80a)30株,其中有古树3种共23株及古树后续资源7株,有胸径≥100cm的大树14株;第四类有二级国家重点保护野生树种樟树32株。建议调整古树后续资源规定标准为树龄≥50a,以加强成年乔木保护。  相似文献   

6.
Understanding of the habitat range of threatened Himalayan medicinal plants which are declining in their abundance due to high anthropogenic disturbances is essential for developing conservation strategies and agrotechnologies for cultivation. In this communication, we have discussed the habitat range of two alpine medicinal plants, Aconitum naviculare （Bruehl） Stapf and Neopicrorhiza scrophulariiflora （Pennel） Hong in a trans-Himalayan dry valley of central Nepal, Manang district. They are the most prioritized medicinal plants of the study area in terms of ethnomedicinal uses. A. naviculare occurs on warm and dry south facing slopes between 4090-4650 m asl along with sclerophyllous and thorny alpine scrubs, while N. scrophulariiflora is exclusively found on cool and moist north facing slope between 4000 and 4400 m asl where adequate water is available from snow melt to create a suitable habitat for this wetland dependent species. The soil in rooting zone of the two plants differs significantly in organic carbon （OC）, organic matter （OM）, total nitrogen （N） and carbon to nitrogen （C/N） ratio. Due to cool and moist condition of N. scrophulariiflora habitat, accumulation of soil OC is higher, but soil N content is lower probably due to slow release from litter, higher leaching loss and greater retention in perennial live biomass of the plant. The C/N ratio of soil is more suitable in A. navuculare habitat than that of N scrophulariiflora for N supply. Warm and sunny site with N rich soil can be suitable for cultivation ofA. naviculare, while moist and cool site with organic soil for N. scrophulariiflora. The populations of both the plants are fragmented and small. Due to collection by human and trampling damage by livestock, the population of A. naviculare was found absent in open areas in five of the six sampling sites and it was confined only within the bushes of alpine scrubs. For N. serophulariiflora, high probability of complete receding of small glaeiers may be a new threat in future to its habitat. The information about habitat conditions, together with the information from other areas, ean be useful to identify potential habitats and plan for cultivation or domestication of the two medieinal plants.  相似文献   

7.
The influence of vegetation and sediment on flow characteristics in open channels cannot be neglected. To study the flow variability under the effects of the instream natural vegetation and sediment supply, experiments were conducted with varied water and sediment supply in a movable bed of a river prototype. The instantaneous three-dimensional velocities near two types of vegetation patches (the shrub and the weed) and along the centerline of the main channel with vegetation belts were measured using a 3-D side-looking acoustic Doppler velocimetry. The experimental results show that both the instream vegetation and sediment supply strongly affect the flow and turbulence characteristics. In the case of vegetation patches, both the shrub and weed have a considerable influence on the distribution of the streamwise velocity and turbulence intensity of their surrounding water. The streamwise velocity distribution followed as J-shape and linear shape around the weed and shrub under different experimental conditions. The turbulence intensity was large at the top of the weed and shrub; the shrub had its greatest influence on the downstream water flow. In the case of vegetation belts, the streamwise velocity along the centerline of the main channel exhibited an S-shape, J-shape and linear shape at different locations under varied water, vegetation structures and riverbed configurations. The turbulence intensity along the centerline of the main channel ranged from 0.0 to 0.1. The upstream turbulence intensity was affected considerably by a sediment supply, while the downstream turbulence intensity changed with the varied vegetation characteristics and riverbed topography. The second flow coefficient M-value increased longitudinally and was almost positive along the centerline of the main channel, implying that the rotational direction of the secondary current cell was clockwise.  相似文献   

8.
The Lipovtsy flora originates mostly from the synonymous Formation exposed at the coal quarries in the Razdolnaya( Suifun) River Basin in Heilongjiang Province( China) and Primorye Region( Russia). The thorough study of this flora has revealed its high diversity and abundance. One of the most prominent groups in the Lipovtsy flora is the ferns. Next in diversity are conifers( Miroviaceae,Taxodiaceae,Podozamitaceae,Taxaceae,Cephalotaxaceae). It was revealed the remarkable quantity of bennettitalean remains( 24 taxa). The main peculiarity of this flora is the appearance of first angiosperms( pollen,dispersed cuticle,leaves). The fine preservation of the cuticles from the coals allows us to research the taxonomical composition of peat-forming plants and clear main components of the swamp plant communities. These plants supplied the material for the accumulation of resinite coals on the territory of Razdolnaya River Basin were conifers Miroviaceae,taxodialeans,bennettites,as well as gleicheniaceous and cyatheaceous ferns.  相似文献   

9.
An ethnobotanical study was conducted in East Hararghe, Ethiopia to identify and investigate the use of various plants by the traditional healers and communities engaged in domestic, pesticide and medicinal use. A total of 78 species were observed to be used by the local inhabitants in the region for the treatments of various ailments. Out of these, herbs constitute 49% followed by trees(36%) and shrubs only 15%. However, most frequently used plant parts were leaf and aerial parts(20) followed by seed(13), fruit(12), other parts(10), rhizome(7) and bark(1). Most of the plants were found to be used for medicinal, aromatic and food flavouring(spices, condiments) purposes. Out of 78 species recorded in the present study, 11 were reported to cure stomachache, seven for cold, cough and respiratory problem, six for diarrhoea and five species were found capable of curing fever. Fabaceae was the largest family contributing to medicinal plant use with seven species followed by Solanaceae, Myrtaceae,(5 spp.), and Zingiberaceae, Asteraceae, Liliaceae(4 spp. each). Some of the important plants utilized for taking care of variety of ailments are Azadirachta indica, Brassica nigra, Balanites aegyptiaca, Maytenus ovatus, Rosmarinus officinalis and Trigonella foenum graecum. Most of these medicinal and aromatic plants(MAPs) play a significant role in the household economy and were observed to be very popular among the people. Unpopular plants were left out of the study. This study provides useful and basic information on usage of different plants for conducting further studies aimed at conservation and documentation of traditional medicine system and economic welfare of rural peoples of the East Hararghe, Ethiopia. It also revealed that indigenous practices contributed to sustainable management of plants.  相似文献   

10.
The developmental activities, particularly the construction of hydroelectric projects are causing a great loss of biodiversity in the Indian Himalayan Region. The Himachal Pradesh, a part of IHR is well known for the development of hydroelectric projects. The Parbati H.E. Project is amongst the major projects of the State. The different stages of the project are all causing loss of biodiversity of the area. Stage III of the Parbati H.E. Project is a run of the river scheme on the Sainj River downstream of Power House of Parbati H.E. Project Stage II. The project shall utilize regulated discharge of Parbati H.E. Project Stage II and inflow of River Sainj for power generation, and has been contemplated as a peaking station operating in tandem with Stage II. The present study has been undertaken to see the impact of hydroelectric project on the biodiversity, particularly on medicinal plants. A total of 104 species of medicinal plants, belonging to different life forms, i.e., trees (23 spp.), shrubs (22 spp.), herbs (57 spp.) and ferns (2 spp.) were recorded. The species have been analyzed and studied for their distribution, classification, altitudinal zones, part (s) used, indigenous uses, nativity, endemism and rarity. DDifferent parts of these species, such as whole plants, roots (including rhizomes and tubers), leaves, flowers, fruits, seeds, stems, barks, spikes, nuts and insect galls are used by the inhabitants for curing various diseases and ailments. 30 species are native to the Himalayan region, 9 species native to the Himalayan region and adjacent countries also and 65 species are non-natives. 9 species are near endemics. Considering the whole Himalaya as a biogeographic unit (sensu lato), the near endemics are endemic to the Himalaya. Among these species, Zanthoxylum armatum is categorized as Endangered and Valeriana wallichii as Vulnerable. Hedychium spicatum, Rhus javanica, Berberis lycium, Thalictrum foliolossum, Salvia lanata, Rubia cordifolia and Bergenia ligulata may be considered as threatened species due to their over exploitation for trade. 90 species are propagated by seeds, 8 species by seeds and rhizomes/roots/tubers, 4 species by seeds and cuttings, and 2 species by sori. A management plan for the cultivation and conservation of the medicinal plants in the dam submergence area, and the commercially viable medicinal plants with high value in the catchment area is suggested.  相似文献   

11.
People’s livelihood in several Himalayan regions largely depends on collection, use, and trade of medicinal plants. Traditional use is generally not a problem, but commercial gathering of selected species to meet increasing national and international demand can result in over-exploitation. Sustainable management of medicinal plants requires a clear understanding of the respective roles, responsibilities and viewpoints of the various stakeholders involved. Through personal interviews and group discussions, this study aimed at investigating the views of two stakeholder groups on use, trade and conservation of medicinal plants in the Rasuwa district of Nepal. Local people and district and national organizations agreed that medicinal plants are collected for a combination of commercial and personal uses. Perceptions on market availability differed significantly: 100 % of the respondents from district and national organizations saw markets as easily available, against only 36 % for local people. This could explain why medicinal plants were perceived by local people to contribute less to income generation than to livelihood improvement. Different viewpoints were also expressed concerning the status of medicinal plants in the district: 81 % of the respondents from district and national organizations considered that medicinal plants were threatened, compared to only 28 % for local people. Despite this disparity, both stakeholder groups agreed upon potential threats to medicinal plants: over-harvesting; habitat loss due to land-use change and deforestation; and over-grazing by livestock. Several challenges were identified regarding sustainable management of medicinal plants, such as ambiguous policies; lack of resources, information and infrastructures; habitat degradation; and over-exploitation. Despite these challenges, respondents agreed that the medicinal plants sector offers huge opportunities in the Rasuwa district, given resource availability, community awareness and motivation, and the priority given to the sector by governments and other agencies. Proper collaboration, communication and coordination among stakeholders are needed to grab these opportunities.  相似文献   

12.
Re-vegetation plays a fundamental role for erosion control and plant recovery in lands affected by gully erosion. Bioengineered practices facilitate the gullies rehabilitation. Objectives of the research were: 1) Identify taxonomically the pioneer vegetation on each gully section; 2) Characterize vegetation distribution preferences and 3) Assess structural/functional traits to recognize erosion control key species. Bioengineering was applied in a watershed belonging to Sierra Madre del Sur, at Oaxaca, Mexico, on eight gullies, with local support and minimal investment. "La Mixteca" is a poor ecological and socio-economic region, comparable to other regions of the world. The Initial Floristic Composition(IFC) inventory is the baseline of the successional process. The transect method was used to determine the colonization of species. Cover abundance of registered species was estimated using the semi-quantitative scale of Braun-Blanquet. This procedure was repeated in five different positions(floor, hillslopes and tops), in the cross section of the gully. Throughcorrespondence analysis and clustering, the distribution of species was analyzed. Adequate responses were obtained in soil retention(quantity) and plant cover(existence and diversity); as measurable indicators of the bioengeneering works efficiency. Occupation of soil by native species from the Tropical Deciduous Forest was favored using live barriers. We detected species guilds with spatial distribution preferences in the gullies cross section. Plant cover characterization includes: native colonizer species, herbaceous, shrubby and trees of the forest community bordering the gully area, with cover abundance and structural/functional traits, useful to protect degraded areas. This spatial occupation process of plants responds to a secondary succession in gullies, where the proposed IFC model is correctly represented through bioengineering. Natural establishment of plants was successful by traits of species such as extensive root system and sexual/vegetative reproduction.  相似文献   

13.
Vegetation in high altitude areas normally exhibits the strongest response to global warming. We investigated the tundra vegetation on the Changbai Mountains and revealed the similarities and differences between the north and the southwest slopes of the Changbai Mountains in response to global warming. Our results were as follows: 1) The average temperatures in the growing season have increased from 1981 to 2015, the climate tendency rate was 0.38℃/10 yr, and there was no obvious change in precipitation observed. 2) The tundra vegetation of the Changbai Mountains has changed significantly over the last 30 years. Specifically, herbaceous plants have invaded into the tundra zone, and the proportion of herbaceous plants was larger than that of shrubs. Shrub tundra was transforming into shrub-grass tundra. 3) The tundra vegetation in the north and southwest slopes of the Changbai Mountains responded differently to global warming. The southwest slope showed a significantly higher degree of invasion from herbaceous plants and exhibited greater vegetation change than the north slope. 4) The species diversity of plant communities on the tundra zone of the north slope changed unimodally with altitude, while that on the tundra zone of the southwest slope decreased monotonously with altitude. Differences in the degree of invasion from herbaceous plants resulted in differences in species diversity patterns between the north and southwest slopes. Differences in local microclimate, plant community successional stage and soil fertility resulted in differential responses of tundra vegetation to global warming.  相似文献   

14.
The Middle Jurassic Hangfanggou Formation is well exposed in Shangsanjiao and Xiasanjiao villages area,Baimashi town of Huludao,western Liaoning,China.Recently,abundant fossil plants were collected from the Hangfanggou Formation.One new species,Anomozamites sanjiaocunensis sp.nov.(Bennettitales),is described in this study.This is the first report of the genus Anomozamites from the Haifanggou Formation based upon the leaf morphology and epidermal structures.The discovery of the new species extends significantly the stratigraphic and geographic distribution of Anomozamites in the Middle Jurassic.It also shows that Anomozamites was a common member of Bennettitales once lived in the Middle Jurassic warm temperate region.The new species also improves the knowledge on understanding the leaf morphology,epidermal features and the diversity of Anomozamites during the Middle Jurassic.The epidermal characters of the new species and its associated plants reveal that the plants grew in a warm and moderately humid environment in the warm temperate zone.The presence of some deciduous plants,such as ginkgoaleans,czekanowskialeans and conifers,indicate the climate with seasonal fluctuations in temperature.  相似文献   

15.
Located in southwestern China, Jiuzhaigou National Park is one of the most popular tourism destinations in China, famous for its unique aquatic ecosystems and beautiful forests. However, plants in the park may be at high ozone risk as a result of the intensive use of diesel tour buses in the park. In addition, Jiuzhaigou is close to a region with relatively high regional anthropogenic NO x emissions. During the growing season, also the peak season of tourism, we measured ozone concentration at two sites within the Park and these were: Jiuzhaigou Bureau (JB) and Long Lake (LL). The results indicate that ozone concentrations were not high enough to cause foliar injury during the monitoring period, although the risk of ozone to plants was higher in spring than in summer and autumn. Diurnal ozone cycles at JB and LL displayed significantly higher ozone concentrations in the daytime than in the nighttime, suggesting photochemical production of ozone during the day and ozone deposition during the night as a result of the nocturnal boundary layer. In parallel with the seasonal change of background surface ozone in the Northern Hemisphere, maximum daily 8-h average ozone concentration (MDA8) and daily ozone concentration decreased from spring to autumn at the two sites. This temporal variation in Jiuzhaigou was most likely associated with the downward mixing of ozone-rich air from the free troposphere, because all the high-ozone events (MDA8 > 70.0 ppb) were observed in spring and ozone-rich air from the free troposphere was the dominant cause. In summary, our data suggest that ozone concentrations in Jiuzhaigou were more affected by the regional-scale of background pattern in air quality and meteorological conditions than by local tourist activities.  相似文献   

16.
This study aimed to compare the distribution patterns and trends of plant parts used among different groups of medicinal plants, geographical regions,and between medicinal plants and all vascular plants.We used the published sources for elevation records of 2,331 medicinal plant species to interpolate presence between minimum and maximum elevations and estimated medicinal plant richness for each 100-m elevational band. Monte Carlo simulations were used to test whether differences in elevational distribution between different groups of medicinal plants were significant. Total number of medicinal plants as well as different groups showed unimodal relationship with elevation. The elevational distributions of medicinal plants significantly differ between regions and between medicinal plant groups.When comparing the richness of all medicinal plants to all vascular plants,Monte Carlo simulations indicated that the numbers of medicinal plants are higher than expected at low elevations.The highest richness of medicinal plants at low elevation could be possibly due to favorable environmental factors such as high temperature, rainfall,sunlight or due to higher density of human population and thus higher pressure on use of any plants in lower elevations.  相似文献   

17.
Himalayan rangelands, the crucial but by and large the neglected ecosystems, are an integral part of mountain farming systems. The present investigation is based on the extensive survey and collection of mid-altitude range plants from Almora and Champawat districts of Kumaun division in the Uttarakhand Himalaya in India, from September 2003 to June 2007. The rangelands studied were oak types, chirpine types, grass types and mixed ones. Some 300 species of grasses, other herbaceous plants, trees and shrubs were found in the mid-altitude rangelands. A sizeable number of species belonged to the family of Poaceae. The grass-dominated rangelands especially harboured a variety of grass species of good fodder value. The diversity of fodder plants is a proportion of the enormous biodiversity occurring in the parts of the Himalaya. A panorama of the biodiversity emerged in this study, which is of both intangible value and direct value for the livestock- and rangeland- dependent mountain communities, suggests a very high scope of the utilization of this natural and uncultivated biodiversity for supporting livestock- based livelihoods of the region. This biodiversity also has enormous bearing on the cultivated area of the region.  相似文献   

18.
Understanding the impact of rock bareness on the transpiration in karst plants is essential to karst rocky desertification control and sustainable management of plantation in karst area.This study focused on the variations in sap flow of Zenia insignis caused by different rock bareness rate,and the impact of climate factors,soil water content(SWC)and leaf area index(LAI) on transpiration in karst plants,by continuously measuring sap flux densities (Fcd)of 12 sample trees using thermal dissipation probes and monitoring micrometeorology and SwC on a typical karst hill in north Guangdong of China during the year of 2016.Results show that:(1)the maximum hourly sap flux density occurred at11:00-14:00 and the peak daily sap flux density occurred in September.(2)Sap flow density of Zenia insignis increased with rock bareness rate at all hourly,daily and monthly scales,with the sequence of extremely severeseveremoderatemild rock bareness.(3)The transpiration of Zenia insi.gnis is controlled by different factors at different temporalscales.At hourly scale,transpiration was highly(n=144,R~20.72)correlated to Solar radiation(Rs),Air temperature(Ta),relative humidity(RH),and water vapor pressure deficit(VPD).At daily scale,transpiration was greatly(n=366,R20.31)affected by Solar radiation(Rs),Air temperature(Ta),and water vapor pressure deficit (VPD).While at monthly scale,transpiration was mainly(n=12,R~2=0.85)controlled by LAI.Our study proved that Zenia insi.gnis has a good physiecological adaption to fragile karst environment,and Zenia insignis plantation has long-term sustainability even in extremely rocky landscapes.The results may provide scientific basis for plantation management and ecological restoration in karst area.  相似文献   

19.
Integrated multi-trophic aquaculture (IMTA) has been proposed as a concept that combines the cultivation of fed aquaculture species (e.g., finfish/shrimp) with extractive aquaculture species (e.g., shellfish/seaweed). In seaweed-based integrated aquaculture, seaweeds have the capacity to reduce the environmental impact of nitrogen-rich effluents on coastal ecosystems. Thus, selection of optimal species for such aquaculture is of great importance. The present study aimed to develop a seaweed species-selection index for selecting suitable species in seaweed-based integrated aquaculture system. The index was synthesized using available literature-based information, reference data, and physiological seaweed experiments to identify and prioritize the desired species. Undaria pinnatifida, Porphyra yezoensis and Ulva compressa scored the highest according to a seaweed-based integrated aquaculture suitability index (SASI). Seaweed species with the highest scores were adjudged to fit the integrated aquaculture systems. Despite the application of this model limited by local aquaculture environment, it is considered to be a useful tool for selecting seaweed species in IMTA.  相似文献   

20.
《山地科学学报》2020,17(2):423-434
Intercropping, as an overyielding system, can decrease soil erosion on sloping land through the presence of dense canopy covers. However, the structure mechanism in canopy is still unclear. We conducted a two-year field experiment on runoff plots, exploring whether the interaction between vegetation layers reduce soil erosion in maize and potato intercropping systems. The maize, potato, and weed layers in the intercropping system were removed by a single layer, two layers and three layers, respectively(total of 8 treatments including all layers removed as the control). Then, throughfall, runoff and sediment were measured at the plot and row scale on a weekly basis. Based on the difference between each treatment and the control, we calculated and found a relative reduction of runoff and sediment by any combination of the two vegetation layers greater than the sum of each single layer. In 2016 and 2017, the highest relative reduction of runoff reached 15.65% and 46.73%, respectively. Sediment loss decreased by 33.96% and 42.77%, respectively. Moreover, runoffand sediment reduced by the combination of all vegetation layers(no layers removed) was also larger than the sum of that by each single layer. In 2016 and 2017, the highest relative reduction of runoff reached 7.32% and 3.48%, respectively. So, there were synergistic effects among multi-level(two or three layers) vegetation layers in terms of decreasing soil erosion on sloping land. Maize redistributes more throughfall at the maize intra-specific row and the maize and potato inter-specific, which is favorable for the synergistic effect of reducing soil erosion. This finding shows an important mechanism of maize and potato intercropping for soil and water conservation, and may promote the application of diverse cropping systems for sustainable agriculture in mountainous areas.  相似文献   

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