REFERENCE COMMUNITY: ADAPTING NATIVE PLANTS TO NORTH AMERICAN GREEN ROOFS

The North American design community typically regards green roofs as inhospitable environments for native plants due to the infrastructure’s characteristic thin soils,low organic matter,temperature fluctuations,and wind exposure.Consequently,green roofs are often planted with an industry-standard palette of non-native Sedum and Phedimus species that are adept at withstanding stress,but lack biodiversity and visual interest,and offer little food or shelter to native birds and insects.Regionally specific reference plant communities that thrive in similarly harsh growing conditions can positively influence green roof design throughout North America,and consequently provide ecosystem services,contribute to habitat conservation,and increase human exposure to the beauty and benefits of native plants.

Native Species Composition and Diversity of Valuable Woody Plants Regeneration during Fallow Period in Kamwatta, Moruca, Guyana

An intelligent method of shifting cultivation to regenerate vegetation after a long fallow period is critical information for restoration strategies. The literature review identified that the assessment of woody plant species on abandoned farmland has never been done before in Kamwatta, Moruca Region 1. In addition, more information should be available in indigenous communities and at the national level, including more documentation of the utilization of natural resources by the Warrau community. This study assessed the valuable woody plant species that grew during the fallow periods. Nine farmlands were randomly selected along a 100 m transect, each with varying fallow periods. In order to collect information on the age of farm abandonment, the researcher employed a mixed-methods approach. First, we found how long each farm had been fallow by administering a semi-structured questionnaire. Then, we conducted a flora survey to gain information on the variety and abundance of valuable plants using the age of farm abandonment as a dependent variable. The data analysis included the number of valuable woody trees with a diameter of >10 cm, seedlings and saplings with a diameter of <10 cm, the location of identified trees, and the uses of identified tree species. Microsoft Excel was used to code and analyze the questionnaire, while QGIS, Shannon’s Index of Diversity, and Simple Linear Regression were used to analyze the inventory data. The results showed that the respondents listed 38 valuable woody species, and 79% occurred in the studied area. The field verification revealed that the dominant family in the area was Mimosaceae. Species abundance increased with fallow up to 10 years before declining in the latter years. Plant diversity and abundance had a weak relationship with the age of abandoned farmlands for woody trees, while the seedlings and saplings showed no relationship.

Native Plants Can Help Conserve Water

这篇文章本来是针对美国读者的,但我们把它引介过来的目的是想让读者对美国的绿化状况有所了解。 Xeriscaping(无水绿化)对我们来说是个陌生的名词(欲探究其构词法的读者可在文中找到答案),可它对于维持生态平衡和节约水资源意义重大。因为about half the water we use in our homes is diverted to the lawn and gardenpatch,反过来,Done right,xeriscaping can cut landscape watering demandanywhere from 20 percent to 80 percent。由于国情不同,以上两句对我们来说不免生隔靴搔痒之感。但文中涉及的花卉栽培技术、选种(原产还是非原产)以及对喜干喜湿植物的判断等都提供了具体的指导,对于喜好侍花弄草的朋友是很有启发的。 生态环境恶化和资源危机业已得到全球人士的共识,美国人从身边绿化着眼,提出“无水绿化”的观点,方法简便易行,又着眼于生态大计,且惠泽子孙,他们这种务实的态度是值得我们学习的。

Prospects and limitations of soil amendment and irrigation techniques for the water-saving public urban greenery and ephemeral weed management in the sandy soils of the United Arab Emirates

Public urban greenery greatly contributes to the residential and tourist value of cities in the Gulf Region,but due to the hyper-arid climatic conditions,the cost of irrigation and plant maintenance is very high.Existing strategies to reduce the monetary and ecological costs involve the cultivation of native xerophytic plantations,and/or the use of soil improvers to increase water-and nutrient-holding capacity of the sandy soils.Various soil improvers based on mineral,organic,or synthetic materials have entered the United Arab Emirates(UAE)market in recent years,but there is considerable uncertainty about how they should best be used in combination with ornamental plant stands involving xerophytic native plants.The present study investigated the effect of soil amendment and deep pipe irrigation on perennial ornamental plant stands involving native plants(Tephrosia appolinea(Gel.)Link in combination with Aerva javanica(Burm.f.)Juss.ex Schult.)and native-exotic plants(T.appolinea in combination with Ruelia simplex C.Wright)either or not topsoil and subsoil amendment with bentonite and hydrophobic sand under the irrigation water supply of less than 50%of reference evapotranspiration(ET0).After one year of cultivation,T.appolinea and A.javanica(native vs.native)produced high biomass and exhibited high water use efficiency(WUE)as compared with T.appolinea and R.simplex(native vs.exotic)combination given that no significant differences were found under the soil amendment treatments.All stands thrived under irrigation water supply far below what is usually supplied to exotic ornamental stands in public parks of the Al Ain City,the UAE.However,subsoil amendment in combination with deep pipe irrigation reduced the occurrence of weeds and increased the overall plant rooting depth.Our results suggest that subsoil amendment and irrigation up to 60-80 cm depth can potentially control ephemeral weed infestation,which is a great challenge in various plant production systems of the Gulf Region.The results of the present study suggest that the impact of soil amendment on the WUE of exotic plants is marginal and might not be economically justified.Replacing exotic with native ornamental plant species seems to have a far greater water-saving potential than the amendment of the soil,while weeds can be suppressed in the absence of topsoil moisture.

Application and Analysis of Native Plant in Landscaping

With PVESM point of view, this study analyzed comprehensive functions of native plants, which including natural function, visual function, ecological function, social function and spiritual function, the advantages of native plants in landscaping and the effects of it on human living environment were expounded. Based on analyzing the present situations of native plants in landscaping, the relative improvement measures were put forward.

Reflection on Popular Concepts of Landscape Design

Guided by the values of harmonious coexistence between humans and nature,methods and concepts such as“biodiversity”,“sponge cities”,and“urban agriculture”have become popular.These methods and concepts are indisputable as a value orientation.But if conditional truth is promoted nationwide as unconditional truth,it will inevitably move from one extreme to the other.Starting from specific issues and practical experience,combined with the regional differences in the natural conditions,social customs and climate environment,the four popular viewpoints of“urban agriculture”,“biodiversity”,“local characteristics”,and“sponge cities”are reflected,and their“exclusion”reactions in certain regions are revealed,in order to awaken people’s rational thinking about popular concepts.

Accumulation behavior of heavy metals by Bidens pilosa L.from metallurgical slag:effects on plant physiology and absorption characteristics

Many of the abandoned mining and industrial land in villages and towns are seriously polluted by heavy metals in China,it is necessary for sustainable development to adopt efficient and economical ways to restore the ecology of abandoned mining and industrial land.Pollution level of topsoil contaminated with metallurgical slag from nonferrous metal smelting waste site in Baoding,North China and the heavy metals(HMs)accumulation behavior of Bidens pilosa L.(B.pilosa,native pioneer plant)were studied.Two selected study sites were mainly contaminated by As(270~434 mg/kg),Cd(63~95 mg/kg),Pb(5496~24504 mg/kg)and Zn(4500~21300 mg/kg),which exceed the national standard severely.Investigation of multi-metal accumulation in different parts of B.pilosa indicated that the absorption of toxic metals varied by types,concentration and species of HMs under stress conditions,soil property and plant tissues.The results showed that B.pilosa had excellent ability to accumulate HMs under different HMs stress condition,with the highest accumulation concentration of 85 mg/kg for As,380 mg/kg for Cd,4000 mg/kg for Pb,and 7500 mg/kg for Zn in roots under experimental conditions,respectively.The growth trend of B.pilosa declined with the increase of HMs stress concentration in tested soils.HMs stress led to different degrees of plant toxicity and obstruction of physiological metabolism.Among the plant physiological index,Chla and ChlT decreased 28.0%and 28.1%,37.3%and 35.5%under different stress treatments,respectively.Indicators related to physiological metabolic strength and stress resistance of plant,such as MDA(Malondiadehyde),CAT(catalase),SOD(superoxide dismutase)and SP(soluble protein),all increased with the increase of HMs stress concentration.

Soil Conservation Measures in Rainfed Olive Orchards in South-Eastern Spain: Impacts of Plant Strips on Soil Water Dynamics

Sloping and mountainous olive production systems are widespread, occupying large parts of the Mediterranean landscape prone to water erosion. Soil erosion, runoff, and soil water content patterns over a three-year period were monitored in erosion plots on a mountainside with rainfed olive （Olea europaea cv. Picual） trees under： 1） non-tillage with barley strips of 4 m width （BS）; 2） non-tillage with native vegetation strips of 4 m width （NVS）; and 3） non-tillage without plant strips （NT）. The erosion plots, located in Lanjaron （Granada, south-eastern Spain）, on a 30% slope, were 192 m2 in area. For assessing soil water dynamics in real-time and near-continuous soil water content measurements, multisensor capacitance probes were installed in the middle of plant strips and beneath the olive tree at five soil depths （10, 20, 30, 50, and 100 cm）. The highest erosion and runoff rates were measured under NT, with a mean of 17.3 Mg ha-1 year-1 and 140.0 mm year-1, respectively, over the entire study period. The BS and NVS with respect to the NT reduced erosion by 71% and 59% and runoff by 95% and 94%, respectively. In general, greater available soil water content was found under BS than NVS and NT, especially beneath the olive tree canopies. These results supported the recommendation of non-tillage with barley strips in order to reduce erosion and to preserve soil water for trees in traditional mountainous olive-producing areas, where orchards cover vast tracts of land.

Cell Viability of Byrsonima intermedia A Juss Calli

Byrsonima intermedia A Juss. is a species with pharmacological properties from the Brazilian Cerrado that shows difficulties related to sexual propagation. Research on cell viability may provide useful information for the selection of cells with embryogenic potential during the callus culture, Within this context, our research is aimed at establishing the cell viability of calli from Byrsonima intermedia leaf segments. The calli went through three subculture phases, of 60 days each, in MS medium with 0.09 M sucrose, 0.6% agar, pH 5.8 and 4.52 laM 2,4-D. The calli were stored in dark conditions and samples were collected every 10 days from each subculture for viability tests with fluorescein 3,6-diacetate （FDA） and 2,3,5-triphenyltetrazolium chloride （TTC）. The staining methods allowed quantifying cell viability in each subculture. The best results from the FDA tests were obtained at 21, 25 and 29 days for the first, second and third subcultures respectively, with 53,86%, 61.88% and 53.73% viable cells. Regarding the TTC test, the largest absorbance values were obtained at 21, 27 and 28 days for the first, second and third subcultures respectively. Fluorescence and spectrophotometry analyses were efficient for determination of cell viability during callus cultivation period.

Characterization of Pro-embryogenic Calli and Somatic Embryogenesis of Byrsonima intermedia A. Juss.

Byrsonima intermedia A. Juss. is a species from the Brazilian Cerrado that produces edible fruits and, in common with other species from the Byrsonima genus, has pharmacological potential. Previous attempts to propagate the species through conventional methods showed difficulties. Thus, the purpose of this work was to characterize pro-embryogenic masses of Byrsonima intermedia callus, aiming for their in vitro propagation through somatic embryogenesis. Leaf segments from in vitro germinated seedlings were employed as explants for callus production. The calli were then subcultured and exposed to dyes to fulfill their embryogenic potential. Digitalizations of the cytological preparations were made in order to measure the area that was stained by both Aceto-Carmine and Evans-Blue, using image tool software. Somatic embryos were induced after treatments with l-naphthaleneacetic acid （NAA）. The percentages of double-colored areas （by Aceto-Carmine and Evans-Blue） were calculated and the data were analyzed by using the Skott-Knott test （P ≤ 0.05） and, the embryogenic callus, as well as the formation of somatic embryos were analyzed by using the Krsuskal-Wallis rank test （P ≤0.05）. The results show that double coloration is effective at identifying cells showing embryogenic potential. Early callus subculture phases show a larger percentage ofembryogenic area （83%） Somatic embryos were induced by using high auxin level.

REENGAGING THE LAND AT THE GEORGE W.BUSH PRESIDENTIAL CENTER

In planning the George W.Bush Presidential Center in Dallas,Texas,former First Lady Laura Bush presented a very clear vision of what the Center should epitomize:“Because George was the first president of the new millennium,I wanted it to be forward and modern.”1 For the president and Mrs.Bush this meant making the building and landscape environmentally responsible,beautiful,and welcoming.In particular,their love of native Texas landscapes was an important framework for transforming the project’s urban site into a park that was sustainable and experientially rich for visitors.Sustainability was addressed from the start with smart planning that privileged contiguous parkland over impermeable surfaces and structures.Simultaneous consideration of every landscape component—-stormwater,plants,soil,topography,and more—netted cohesive natural systems that are better able to succeed with short-term establishment and provide enduring long-term health,the ultimate goals for a sustainable landscape.

FROM WASTELAND TO PARKLAND:THE MAKING OF CORKTOWN COMMON

INTRODUCTION Density,public health and safety,quality of life,and sustainability are some of the most confounding issucs that major citics face today as they cxpand in population and arca.How do we bring urban populations closer together in the public realm,while still providing space for the individual psyche and also incrcasing the overall sense of positive conncction to the natural world and to cach other?Robust natural landscapes have somctimes been considered a luxury within a functioning city,but morc and morc they are being recognized for the vital role they play in making citics livable.The story of Corktown Common rclatcs how a landscape built of neces-sity was also designed to deliver myriad public bencfts,including enhanced urban ccology and sustainability.

CITY OF HAWTHORNE OCEAN FRIENDLY GARDEN DEMONSTRATION PROJECT

A comprehensive approach to reducing landscape water use was implemented in the Demonstration Garden in the City of Hawthorne.By creating healthy soil,grading to capture and retain rainwater,using California native and climate-appropriate plants,and implementing sustainable maintenance practices,the garden was designed to mimic the natural processes of a mini-watershed.The soil is now able to soak up and retain rainwater,reducing the need for supplemental irrigation and eliminating urban runoff.Habitat and food for wildlife was introduced,and maintenance costs were minimized by reducing green waste and eliminating the need for chemical fertilizers,herbicides,and pesticides.The installation was supplemented by two classes offered free to the public:a three hour introduction to California Friendly Landscaping principles,and a half day hands-on workshop in which participants used their newly-acquired knowledge to plant California natives and install drip irrigation.California native plantings were selected for their long-lasting and colorful blooms to introduce the public to the beauty and diversity of California’s indigenous flora,which has,until recently,been under-represented in garden centers and under-utilized in residential and commercial landscapes.

Soil Respiration and Litter Decomposition Increased Following Perennial Forb Invasion into an Annual Grassland

Exotic plant invasions may alter ecosystem carbon processes, especially when native plants are displaced by plants of a different functional group. Forb invasions into grasslands are common, yet little is known about how they impact carbon cycling. We conducted a field study over 2 years from April 2010 to March 2012 in China to examine changes in soil respiration （Rsoil） following invasion of exotic perennial forb species （Alternanthera philoxeroides or Solidago canadensis） into an annual grassland dominated by a native annual graminoid （Eragrostis pilosa）. Measurements of Rsoil were taken once a week in stands of the native annual graminoid or one of the forb species using static chamber-gas chromatograph method. Aboveground litterfall of each of the three focal species was collected biweekly and litter decomposition rates were measured in a 6-month litterbag experiment. The monthly average and annual cumulative Rsoil increased following invasion by either forb species. The increases in cumulative Rsoil were smaller with invasion of Solidago （36%） than Alternanthera （65%）. Both invasive forbs were associated with higher litter quantity and quality （e.g., C：N ratio） than the native annum graminoid. Compared to the native annual graminoid, the invasive forbs Altevnanthera （155%） and Solidago （361%） produced larger amounts of more rapidly decomposing litter, with the litter decay constant k being 3.8, 2.0 and 1.0 for Alternanthera, Solidago and Eragrostis, respectively. Functional groups of the invasive plants and the native plants they replaced appear to be useful predictors of directions of changes in Rsoil, but the magnitude of changes in Rsoil seems to be sensitive to variations in invader functional traits.

Arbuscular mycorrhizal fungal community assembly in the Brazilian tropical seasonal dry forest

Introduction:Here,we compare the arbuscular mycorrhizal fungal(AMF)community composition in soils from the root zone of the exotic invasive species Prosopis juliflora(EXO soils)and soils from the root zone of the native species Mimosa tenuiflora(NAT soils)from five locations in the Brazilian tropical seasonal dry forest,Paraíba,Brazil,using morphological analyses.Results:AMF community composition in EXO and NAT soils were dissimilar.Available phosphorus,diversity index,spore abundance,and species richness were the main factors differing between the EXO and NAT soils.In general,the most dominant order present in the soils were Glomerales(44.8%)and Gigasporales(41.4%).The most abundant AMF genus in all studied soils was Funneliformis.Conclusions:Differences in AMF community composition were associated with(1)differences in the dominant plant species(P.juliflora vs.M.tenuiflora)and(2)changes in soil chemical factors(soil,pH,total organic carbon,total nitrogen,and available P)in EXO soils.These results contribute to a deeper view of the AMF communities in exotic soils and open new perspectives for ecological processes involving AMF species and exotic plant species in the Brazilian tropical seasonal dry forest.