Mm Of Annual Precipitation Research Articles

Understandings of Relationships between Agriculture and Biodiversity in Kunisaki GIAHS

1 Characteristics of Kunisaki GIAS and aims of this research Kunisaki GIAHS in the Kunisaki peninsula and Usa area,Oita,Japan,is a system where forestry,agricultural production,and fisheries are sustained by the strong connection between Sawtooth Oak forest,multiple interlinked irriga tion ponds,and Seto Inland Sea(Vafadari 2013a;2013b;Hayashi 2013).This area receive around 1,500 mm of annual precipitation with a

Localización más oriental en Chile de Pilgerodendron uviferum (D. Don) Florin, la conífera más austral del mundo. Antecedentes fitogeográficos

Pilgerodendron uviferum es una conífera que tiene una amplia distribuciónen los bosques de América del Sur (39°-57° S.) con una mayor expansiónen Chile. Se presenta un breve estudio de una pequeña agrupación de este“ciprés de las Guaitecas”, que constituye el lugar de la mayor distribución orientalde esta especie en Chile. El sector se encuentra muy próximo a la formaciónde la estepa patagónica, no más de 10 km, y por consiguiente vive en un hábitatde moderada humedad (alrededor de 1.980 mm anuales de precipitaciones),comparado con la alta humedad bajo la cual normalmente se desarrolla (hastamás de 4000 mm), en las costas de la región de Aisén (44°-49° S.). Esta curiosidadgeobotánica requiere de una protección de la cual aún carece.

Natural Suppression of Rhizoctonia Bare Patch in a Long-Term No-Till Cropping Systems Experiment.

The soilborne fungus Rhizoctonia solani AG-8 is a major concern for farmers who practice no-till in the inland Pacific Northwest of the United States. Bare patches caused by Rhizoctonia spp. first appeared in 1999 during year 3 of a 15-year no-till cropping systems experiment near Ritzville, WA (269 mm of annual precipitation). The extent and pattern of patches were mapped each year from 1999 to 2012 at the 8-ha study site with a backpack-mounted global positioning system equipped with mapping software. Bare patches appeared in winter and spring wheat (SW; Triticum aestivum), spring barley (SB; Hordeum vulgare), yellow mustard (Brassica hirta), and safflower (Carthamus tinctorius). At its peak in years 5 to 7, bare patches occupied as much as 18% of total plot area in continuous annual monoculture SW. The area of bare patches began to decline in year 8 and reached near zero levels by year 11. No measurable patches were present in years 12 to 15. Patch area was significantly greater in continuous SW compared with SW grown in a 2-year rotation with SB. Additionally, the 15-year average grain yield for SW in rotation with SB was significantly greater than for continuous SW. Russian thistle (Salsola tragus), a troublesome broadleaf weed with a fast-growing tap root, was the only plant that grew within patches. This article reports the first direct evidence of natural suppression of Rhizoctonia bare patch with long-term no-till in North America. This suppression also developed in a rotation that contained broadleaf crops (yellow mustard and safflower) in all but 5 years of the study, and the suppression was maintained when safflower was added back to the rotation.

Ecological impacts of fire and postfire restoration in Korea

Fire is a major driving force shaping and maintaining the integrity of various forest ecosystems. In particular, pine forests often depend on fire for sustainability, because fire removes the organic layer of the forest floor to prepare a desirable seedbed and helps eliminate competitors. The majority of Korean forests are dominated by pine species, because pine forests were historically protected for various purposes (e.g., source for building material), and pine species were widely planted in the 1960s and 1970s to restore the barren soil that resulted from the Korean War and excessive natural resource extraction since 1907. Fires, however, have been excluded from the modern Korean landscape for an extended time mainly due to an aggressive fire exclusion policy and low fuel loading to sustain crown fires. Consequently, it is not clearly known how dominant native species (e.g., Pinus densiflora, P. thunbergii, and Quercus mongolica) interact with fire in Korea and how fire influences interspecific competition among them. Naturally, the general public did not consider fire an integral and essential part of forest maintenance in Korea and believed it could only yield harmful results. Moreover, some people even believed that Korean forests could be maintained without fire. For the first time in modern history, Korea experienced a wildland fire [1,000 ha in 1996 (3,762 ha), which was followed by several large fires, including the Eastern Coastal Fire in 2000 that burned 23,794 ha (or approximately 0.4 % of Korea’s total forest) in 9 days. These series of fires concerned the general public for two reasons: (1) people became aware that large-scale fires ([1,000 ha) can occur in Korea, and (2) forest fire can threaten daily life because many people live very close to the forest (two thirds of Korea is forest). Climate change is also believed to increase wildfire intensity and size, and high fuel loading that is a result of a fire exclusion policy exacerbates it. These circumstances emphasize the need to understand fire regime and behavior in Korea. Various studies were also conducted pertaining to fire prevention and prediction and forest restoration and ecology over the last 15 years. Synthesizing and sharing current knowledge regarding fire science in Korea with the community will generate better synergism. This special issue contains five contributions intended to describe the effects of forest fires on forest ecosystems in eastern coastal areas of Korea and provide an overview of restoration projects. The first contribution, by Ahn et al. (2013) provides a review of studies in Korea over the last two decades and compares findings with other such studies worldwide. Their review covers various fire ecology topics (i.e., postfire stand dynamics, soil property, water quality, and fire effects on insects and soil fauna), as well as postfire restoration planning issues (i.e., pine restoration, fuel breaks, and soil erosion). This work summarizes up-to-date fire science studies in Korea and help readers understand the dynamics of fires in Korea. Moreover, it helps researchers identify future study needs. Korea has approximately 1,300 mm of annual precipitation, approximately half of which falls in July and August; forest fires generally occur in April and May. Generally, the forest canopy intercepts more than half of the precipitation, and removal of the forest canopy increases soil erosion owing to increased water volume and S. R. Ryu (&) Department of Renewable Resources, University of Alberta, Edmonton, AB T6G 2H1, Canada e-mail: soung.ryu@ualberta.ca

Simulación del crecimiento de maíces precoces en condiciones de secano.

En el presente trabajo se plantea eluso de modelos de simulación para asistir la selección de materialesde ciclo precoz adaptados a dichos ambientes. Duranteel verano de 1997 en el Campo Experimental Bajío (CEBAJ)se realizó un análisis de crecimiento en 99 colectasprecoces de maíz. Con dicha información se calibraron loscoeficientes genéticos requeridos para utilizar el modelo CERES-MAIZE. Apartir de los valores de emergencia a floración(P1) y floración a madurez (P5) se identificaron ocho gruposdentro de las 99 colectas. Con estos resultados, aunados a lautilización de datos históricos de clima y características específicas del suelo, es posible simular el rendimiento potencialde las colectas para cualquier ambiente. A manera de ejemplo:los coeficientes genéticos de colectas representativas de cadauno de los ocho grupos identificados, se usaron para simularsu rendimiento potencial en la región del norte de Guanajuato,donde se registra una precipitación anual de 300 a 600 mm yel maíz se siembra bajo condiciones de temporal (secano). Larutina utilizada fue Seasonal del DSSAT V.3.1. Se emplearondatos climáticos históricos de 11 años. En dicho ambiente elrendimiento de la colecta 36 fue el más alto, tanto en condicionesde temporal, como sin restricción de humedad, mientrasque en el CEBAJ el rendimiento de esta colecta había sido unode los más bajos. El presente trabajo permitió corroborar la utilidadde los modelos de simulación, para identificar la adaptación específica de genotipos a un ambiente determinado.

Seasonal diet of the burrowing owl Athene cunicularia Molina, 1782 (Strigidae) in a hyperarid ecosystem of the Atacama desert in northern Chile

Located in the Atacama desert of northern Chile, Pampa del Tamarugal is a hyperarid ecosystem characterized by extreme arid conditions (<0.7 mm of annual precipitation) and relatively scarce vegetation, dominated by arboreal species of Prosopis tamarugo. These unfavorable environmental conditions can affect the quantity and diversity of prey available for carnivores, making Pampa del Tamarugal an interesting environmental scenario for the study of the trophic ecology of raptors. Our analyses of the seasonal diet of the burrowing owl Athene cunicularia (Molina, 1782) indicate that insects and scorpions were the most common prey (58.3% and 27.5%, respectively). However, the rodent Phyllotis darwini was the most important prey in biomass (49.5%). Significant differences were observed in diverse trophic statisticians between summer and winter seasons. Unlike similar studies carried out in arid areas of South America and North America, we observe that the diet of the burrowing owl in Pampa del Tamarugal shows a higher trophic niche breadth and trophic diversity, but a lower species-prey richness.

Stand Establishment and Persistence of Perennial Cool-Season Grasses in the Intermountain West and the Central and Northern Great Plains

The choice of plant materials is an important component of revegetation following disturbance. To determine the utility and effectiveness of various perennial grass species for revegetation on varied landscapes, a meta analysis was used to evaluate the stand establishment and persistence of 18 perennial cool-season grass species in 34 field studies in the Intermountain and Great Plains regions of the United States under monoculture conditions. Combined across the 34 studies, stand establishment values ranged from 79% to 43% and stand persistence values ranged from 70% to 0%. Intermediate wheatgrass (Thinopyrum intermedium [Host] Barkworth & D. R. Dewey), tall wheatgrass (Thinopyrum ponticum [Podp.] Z.-W. Liu & R.-C. Wang), crested wheatgrass (Agropyron spp.), Siberian wheatgrass (Agropyron fragile [Roth] P. Candargy), and meadow brome (Bromus riparius Rehmann) possessed the highest stand establishment (≥ 69%). There were no significant differences among the 12 species with the largest stand persistence values. Basin wildrye (Leymus cinereus (Scribn. & Merr.) Á. Löve), Altai wildrye (Leymus angustus [Trin.] Pilg.), slender wheatgrass (Elymus trachycaulus [Link] Gould ex Shinners), squirreltail (Elymus spp.), and Indian ricegrass (Achnatherum hymenoides [Roem. & Schult.] Barkworth) possessed lower stand persistence (≤ 32%) than the majority of the other species, and Indian ricegrass (0%) possessed the lowest stand persistence of any of the species. Correlations between environmental conditions and stand establishment and persistence showed mean annual study precipitation to have the most consistent, although moderate effect (r = ∼0.40) for establishment and persistence. This relationship was shown by the relatively poor stand establishment and persistence of most species at sites receiving less than 310mm of annual precipitation. These results will be a tool for land managers to make decisions concerning the importance of stand establishment, stand persistence, and annual precipitation for revegetation projects on disturbed sites.

Patterns of Climate Change in Xinjiang Projected by IPCC SRES

Accompanied by global climate change, the annual mean air temperature has experienced a strongly increasing trend in the western China, especially in Xinjiang. The Global Climate Model (GCM) provides an efficient and direct method to assess the process of global climate change and project future climate driven by various factors, especially human activity. Since GCMs' low spatial resolution cannot capture the characteristics of local climate change due to the land surface's complexity, downscaling methods, including Regional Climate Model (RCM), Bias Correction method and Statistical Method, are proposed to process raw data from GCMs for local climate change assessment. This study applied the delta method, one of Bias Correction methods, to make horizontal resolution of 24 GCMs models' monthly outputs into 0.5 °C for analyzing Xinjiang's future climate pattern under three IPCC SRES. A comparison between the results from downscaled dada and raw data from GCMs shows that downscaling methods can improve local climate changing feature in complex land surface and topography and to reduce the uncertainty of climate data generated from GCMs in Xinjiang. The results showed that scenarios A1B, A2 and B1 generated similar patterns and trends in annual mean air temperature and annual precipitation in the early 21st century with fluctuations in the middle of the 21st century. The annual mean air temperature will reach 10°C 11.1°C and 8.5°C in A1B, A2 and B1 by the end of the 21st century, respectively, while the annual precipitation during the projection period will experience an increasing trend with a little fluctuation. During 2020 and 2070, the annual temperature in A1B scenario is greater than the other scenarios on regional average. The annual precipitation in the A1B scenario is also greater than other scenarios during 2020 and 2040 on regional average. However, there exists a large uncertainty within different SRES with an range of 6°C in annual temperature and about 200 mm in annual precipitation. Regionally, annual temperature increases less in the middle Tianshan Mountains, Yili River Basin, the Southern Tianshan Mountains, and downstream of Tarim River than in the Junggar Basin, Pamirs and the northern slope of Kunlun Mountains by the late 21st century. In the western portion of southern Xinjiang, the annual precipitation shows a slightly decreasing trend, but a significant increasing trend was found in eastern Changji, Turpan, Hami and northern Kunlun—Altun Mountains.

Wheat Cultivar Performance and Stability between No-Till and Conventional Tillage Systems in the Pacific Northwest of the United States

In Washington, over fifty percent of the wheat produced under rainfed conditions receives less than 300 mm of annual precipitation. Hence, a winter wheat-summer fallow cropping system has been established to obtain adequate moisture for winter wheat production. Current tilled fallow systems receive significant soil erosion through both wind and water. As a result, no-till chemical fallow systems are being adopted to mitigate erosion concerns. The objective of this study was to evaluate current Pacific Northwest cultivars under no-till chemical fallow and tilled fallow systems to identify cultivars adapted to a late-planted no-till system. Twenty-one cultivars were planted in a split-plot design with fallow type as the main plot and genotype as the sub-plot. Four replications were planted at two locations over three years. Data was collected on heading date, grain yield and grain volume weight. Analysis of variance was conducted on data from each year and location. Results were significant for all traits. Cultivars in the late-planted no-till system yielded an average of 39% less than the tilled fallow system. It is evident that cultivars vary in their adaptability and yield stability across production systems. Chukar and Eltan displayed the highest levels of yield stability, and growers who wish to plant winter wheat in a late-planted no-till system may benefit from choosing these cultivars.

Bioretention Design for Xeric Climates Based on Ecological Principles1

Abstract: Bioretention as sustainable urban stormwater management has gathered much recent attention, and implementation is expanding in mesic locations that receive more than 1,000 mm of annual precipitation. The arid southwestern United States is the fastest growing and most urbanized region in the country. Consequently, there is a need to establish design recommendations for bioretention to control stormwater from expanding urban development in this ecologically sensitive region. Therefore, we review the ecological limits and opportunities for designing bioretention in arid and semiarid regions. We incorporated USEPA Stormwater Management Model (SWMM) simulations to synthesize ecologically based design recommendations for bioretention in arid climates. From our review, an ideal bioretention garden area should be 6 to 8% of the contributing impervious drainage area (depending on region) with two layers of media, a 0.5‐m low‐nutrient topsoil layer above a 0.6‐m porous media layer that acts as temporary storage during a storm event. When planted with the suggested vegetation, this design maximizes stormwater treatment by promoting ecological treatment in the topsoil while promoting infiltration and evapotranspiration of stormwater by deep‐rooted shrubs that require no irrigation after establishment. This synthesis improves water resources management in arid and semiarid regions by introducing a sustainable bioretention design that protects local surface waters while reducing regional water demands for irrigation.

Distribution of Testudo graeca in the western Mediterranean according to climatic factors

Despite being one of the most charismatic elements of the Mediterranean Basin fauna and its threatened status, the western Mediterranean range of Testudo graeca is at present very poorly known. The present work provides the most detailed geographical and ecological description for the North African clade of T. graeca so far. We gathered 283 occurrence data of T. graeca in North Africa and modelled the distribution by means of presence-only distribution modelling tools. The obtained model was then projected to southern Europe in order to explore whether the environmental characteristics of European populations fall into the predicted niche of the species in North Africa. T. graeca showed a wide environmental range in North Africa. Presence localities ranged from the sea level to 2090 m of altitude and from 116 to 1093 mm of annual precipitation. The presence-only model indicates that distribution in North Africa is mainly related to rainfall, specifically rainfall values in the wettest and coldest quarter of the year. The distribution model showed a range of ca. 1 000 000 km2. The projection of the model to southern Europe showed that the southern Iberian and Balkan Peninsulas, as well as most Mediterranean islands, present climatic conditions within those found in the range of the species in North Africa.

Adaptability of Wheat Cultivars to a Late-Planted No-Till Fallow Production System

In Washington, over fifty percent of the wheat produced under rainfed conditions receives less than 300 mm of annual precipitation. Hence, a winter wheat-summer fallow cropping system has been adopted to obtain adequate moisture for winter wheat production. Current tilled fallow systems are exposed to significant soil degradation from wind and water erosion. As a result, late-planted no-till fallow systems are being evaluated to mitigate erosion concerns. The objective of this study was to evaluate current cultivars under late-planted no-till fallow systems to identify whether current breeding schemes in tilled fallow systems could select productive cultivars in late-planted no-till fallow systems. Thirty cultivars were planted in a split-plot design with fallow type as the main plot and genotype as the sub-plot. Fallow types evaluated were a tilled fallow system and a late planted no-till fallow system. Data were collected on heading date, plant height, grain volume weight, grain yield, and grain protein content. Analysis of variance was conducted on data across locations. Results were significant for all traits except for grain protein content. The late-planted no-till fallow system headed 16 days later was 5 cm shorter, yielded 36% less, and had a grain volume weight 3% less than the tilled fallow system. The lower yield and grain volume weight potential is hypothesized to be due to the 16 day delay in heading date leading to warmer temperatures during grain fill and a shorter duration. In order to breed wheat to be highly productive under a late-planted no-till fallow system, directly selecting in this system for early spring growth and earlier heading dates will be essential.

Potential of Kochia prostrata and Perennial Grasses for Rangeland Restoration in Jordan

Abstract Six varieties of forage kochia ( Kochia prostrata [L.] Schrad.), two Atriplex shrubs native to North America, and four drought-tolerant perennial grass varieties were seeded and evaluated under arid rangeland conditions in Jordan. Varieties were seeded in December 2007 and evaluated in 2008 and 2009 at two sites. Conditions were dry with Qurain receiving 110 mm and 73 mm and Tal Rimah receiving 58 mm and 43 mm of annual precipitation during the winters of 2007/2008 and 2008/2009, respectively. Plants were more abundant and taller ( P P = 0.90) to that observed in 2008 and plant height increased ( P P P

Carbon Cautious: Israel’s Afforestation Experience and Approach to Sequestration

During the past 60 years, afforestation has transformed Israel's land- scape, with forests planted or planned on 10% of the country's land, much of it with less than 300 mm of annual precipitation. After early efforts to establish a suc- cessful commercial timber industry failed, recreation and ecosystem services came to dominate forestry policy objectives. Given Israel's status as a 'developing country' under the Kyoto Protocol, forests' economic potential through carbon sequestration has been explored, but has not yet proven to be compelling. Several considerations cooled initial enthusiasm for seeking international carbon credits through afforestation. These include administrative obstacles associated with international accreditation, limited potential economic profitability, and ethical considerations. Rather, a voluntary offsetting program was adopted, allowing donors to plant trees in Israel, that balance individual carbon emissions. Affores- tation in drylands exhibit meaningful potential to counteract chronic carbon loss due to land degradation. As trees planted in Israel's semi-arid regions exhibit surpris- ingly high carbon sequestration properties that are comparable to forests in tem- perate Europe, the potential for offsetting may become a growing factor in local forestry policy once Israel begins to regulate CO2 emissions.

도시화에 의한 장기 지하수 함양량 변화

To solve a problem of water supply on urban areas, groundwater recharge has to be assessed not only for evaluating the possibility of groundwater development but also for identifying a sustainable aquifer system for water resource development. The assessment of groundwater recharge has been challenged since the land use has been changed constantly. In this study, the groundwater recharge and its ratio were assessed from 1961 to 2007 in Su-yeong-gu, Busan, South Korea by analyzing precipitation, land use, and soil characteristics. For land use analysis, the urbanization change was considered. The land use areas for the residential, agricultural, forest, pasture, bare soil, and water in 1975 occupy 18.6 %, 30.0%, 48.8%, 0.1%, 2.0%, and 0.5% of total area, respectively. The land use ratios were sharply changed from 1980 to 1985; the agricultural area was decreased to 18.3%, and the residential area was increased to 15.0%. From 1995 to 2000, the agricultural area was decreased to 5.5%, and the residential area was increased to 5.4%. The annual averages of precipitation, groundwater recharge, and its ratio were 1509.3 mm, 216.0 mm, and 14.3% respectively. The largest amount of the groundwater recharge showed in 1970 as 408.9 mm, comparing to 2138.1 mm of annual rainfall. Also, the greatest ratio of the groundwater recharge was 19.8% in 1984 with 1492.6 mm of annual rainfall. The lowest amount and ratio of the groundwater recharge were 71.9 mm and 8.0% in 1988, relative to 901.5 mm of annual precipitation. As a result, it is concluded that rainfall has increased, whereas groundwater recharge has decreased between 1961 and 2007.

Evaluating the indicator value of Tibetan pollen taxa for modern vegetation and climate

Pollen taxa of known indicator value are of great potential in the qualitative interpretation of pollen diagrams. Here we apply several numerical approaches to a lake-sediment based pollen data-set from the eastern and central Tibetan Plateau (112 samples) to assess the indicator value of Tibetan pollen taxa for modern vegetation types and for modern climate. Results from Multi-Response Permutation Procedures indicate that the differences between groups of pollen spectra originating from the same vegetation type (temperate desert, temperate steppe, alpine desert, alpine steppe, high-alpine meadow, subalpine shrub, and patchy forest) are statistically significant. Indicator Species Analyses identify several indicator taxa for most vegetation types. Multivariate regression tree analysis indicates that about 390 mm of annual precipitation is the most critical threshold for the modern pollen spectra. This roughly separates desert and steppe vegetation from high-alpine meadow, subalpine shrub, and patchy forest vegetation. A strong pollen–climate relationship on the Tibetan Plateau is confirmed by the large number of statistically significant pollen taxa–climate (annual precipitation or/and annual temperature) relationships as evaluated by statistical response-modelling, involving generalised linear models.

Natural Groundwater Recharge Response to Urbanization: Vermillion River Watershed, Minnesota

Urban development of rural land can be a concern for water resources and wildlife. The quantity and quality of surface water runoff and groundwater recharge can be significantly affected by urbanization. Base flow in streams and cold-water habitat, e.g., for trout, depend on groundwater. If water recharge to aquifers is reduced, and surface runoff is increased, streamflow and cold-water habitat can be adversely affected. An investigation of the changes to groundwater recharge resulting from the urbanization of a rural/natural area in the Vermillion River watershed in Minnesota was conducted. Well established principles and relationships for the estimation of infiltration (Soil Conservation Service (SCS) and Green-Ampt (GA) methods] and evapotranspiration [Food and Agriculture Organization (FAO)-56 Penman-Monteith) were applied, and percolation or groundwater recharge was determined using a water budget approach. The relationships were assembled in three models called the FAO-SCS, the FAO-GA, and the GA models. Four scenarios of land development representing progressive stages of urbanization (past, present, plus 50years, and plus 100years) were developed and groundwater recharge was simulated for each scenario from predevelopment to fully developed. In 2005, about 60% of the 6.78km2(1,675acres) watershed of a tributary to the Vermillion River was undeveloped agricultural and natural land, and about 40% was developed urban residential and commercial land. Model estimates of groundwater recharge under the 2005 land-use conditions ranged from 12 to 24% of 829mm of annual precipitation. The full urban development of the study site would result in a decrease of groundwater recharge to a range of 9 to 14% of precipitation. To make this projection, the impervious areas were raised from an average of 18% for the present scenario to an average of 36%. The case study shows that the increase of 18% in impervious area may decrease the recharge by about 20 to 40% of its present value. A change of this magnitude will substantially affect the water supply to the aquifer which discharges into the Vermillion River which is classified as a cold-water (trout) stream.

Precipitation variability and soil water content in Pampean Flatlands (Argentina)

&#x0D; &#x0D; &#x0D; The goal of this paper is to show the precipitation variability in pampean flatlands during the last decades and the con- sequential changes in soil water content. Two periods of 30 years each (1947-1976 and 1977-2006) were analyzed and an increase in annual precipitation all over the region was found in the last one. Areas with different increase in precipitation were located and these varied between 50 and 200 mm in annual precipitation. The bigger increase was found in the warm semester (October-March) in the center-western part of the region. One of the consequences of this was the increase in soil water supplies, which is very important for the development of agricultural activities.&#x0D; &#x0D; &#x0D;

Efecto del nitrato de potasio, fosfato de potasio y ethephon en la inducción floral de la feijoa o goiabeira serrana (Acca sellowiana [O. Berg] Burret)

El ensayo se llevó a cabo en la finca El Cortijo (La Vega, Cundinamarca, Colombia [04°55'N y 74°18'W], 2350 m altitud, 17°C temperatura media, 1423 mm precipitación anual, 85% humedad relativa, 1377 horas brillo solar/año). Se utilizaron árboles de feijoa o goiabeira serrana de seis años, Clon 41 ('Quimba'), evaluando fertilizantes foliares KNO3 (Nitrato de Potasio 13-0-46® 1%, 1,5% y 2%) y KH2PO4 (fosfato de potasio; Cosmofoliar 0-32-43®; 0,5%, 0,75% y 1,0%) y la fitohormona ethephon (Ethrel® 48 SL; 100, 150 y 200 mg L-1). Se determinaron el número de botones florales inducidos, flores formadas, además, el porcentaje de flores formadas y nivel de eficacia de los productos inductores. El KH2PO4 al 0,5% obtuvo resultados favorables en cada una de las variables evaluadas, comparado con el 0,75% y 1% del mismo producto y, sin embargo hubo un alto número de flores inducidas y formadas, no se presentaron diferencias significativas con el testigo. Ethephon a 150 mg L-1 en la inducción de botones florales y a 100 mg L-1 en la de formación de flores mostró resultados favorables, pero tampoco pudo superar el testigo por falta de significancia. La respuesta generada por KNO3 mostró una baja inducción de botones florales, y una eficacia negativa en la proporción de flores formadas; asimismo fitotoxicidad, cuando se emplearon concentraciones al 2% de este producto.

Methodological basis for quantitative reconstruction of air temperature and sunshine from pollen assemblages in Arctic Canada and Greenland

This study presents a modern database including 831 pollen assemblages from lakes of the Boreal, Subarctic and Arctic biomes of North America and Greenland, and corresponding temperature, sunshine and precipitation. Pollen data include the 39 most common vascular taxa (18 woody plants and 21 herbs). Multivariate ordinations using correspondence analysis (CA) and canonical correspondence analysis (CCA) reveal that temperature and sunshine account, respectively, for 45.5% and 44.4% of the variance within pollen assemblages, whereas precipitation only accounts for 10.2% of total variance. CCA further demonstrates that the climatic information encapsulated in pollen assemblages is not the same for the three biomes. In the Boreal biome, precipitation and temperature account for most of the variance, whereas sunshine and precipitation are more determinant in the Subarctic biome, and the temperature and sunshine seem to exert the main control on the pollen distribution in the Arctic biome. The modern analogue technique (MAT) and CCA regressions were tested for reconstructing climate parameters. MAT yields better results than CCA regressions and validation tests indicate a root mean square error (RMSE) of 1.35 °C for July air temperature, 2.3% for July sunshine, 3.10 °C for January air temperature and 143 mm for annual precipitation. Two examples of reconstructions are presented from recent (<450 years) lake-sediment cores of eastern Baffin Island, Arctic Canada and southwest Greenland. They demonstrate that July air temperature and July sunshine can be reconstructed independently from Arctic pollen assemblages, but January air temperature and annual precipitation must be interpreted with caution. They also suggest that reconstruction of past sunshine variations can serve to document climate changes at synoptic scale including the North Atlantic Oscillation (NAO).