Browsing by Subject "soil temperature"

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  • Islam, Md. Safiqul (Helsingfors universitet, 2016)
    Mulching, as a cultivation technique, has been adopted since the early twentieth century in agriculture for improving various aspects of crop production. However, the use of mulching was boosted by the introduction of plastic mulch, which has been reported as a harmful substance to the farm environment. Therefore, the need for an environmentally benign mulch material is obvious. The present study investigated the effects of paper and biodegradable plastic mulches on the cucumber yield, soil temperature and moisture content (at 10 cm depth), and the control of weed growth in an agricultural field located at the University of Helsinki in Southern Finland. The degradability of mulches was also investigated. The null hypothesis was that all the mulches would have a similar effect on the abovementioned aspects. Four paper mulches, i.e., BP, KB, CK, and OB, accompanied by biodegradable mulch (BIO) and a bare soil (BG) treatment were under investigation. Each of these treatments had 4 replicates, and a randomized complete block design (RCBD) was adopted. Sensors were installed at 10 cm depth in each study plot to measure the soil temperature and moisture content. In addition, the experimental plots were watered by drip irrigation. All the attained data were analyzed using SPSS statistical software. The results of the study revealed noteworthy positive effects (P<0.05) of mulch application on cucumber yields together with soil temperature, early fruiting, and weed growth regulation compared to the un-mulched bare ground, exclusive of soil moisture content. The daytime soil temperature (DST) was higher than at night (NST), indicating a positive association of the mulch effect with plant growth and crop earliness. However, no suggestive improvement in soil moisture was found through mulch application during the study period. Edge degradation was only found for paper mulches during the study period, suggesting their environment friendliness. The CK and KB papers were the most effective and most environmentally positive mulch materials, and could be a suitable choice for Finnish vegetable growers. The findings of this study could assist paper manufacturers in improving the qualities of mulch papers regarding vegetable production. Future research aims at assessing the effects of mulches on the physiology of plants studied under mulched techniques together with the development of cheaper and more environmentally benign mulch materials.
  • Aalto, Juha; Scherrer, Daniel; Lenoir, Jonathan; Guisan, Antoine; Luoto, Miska (2018)
    Soil temperature (ST) has a key role in Arctic ecosystem functioning and global environmental change. However, soil thermal conditions do not necessarily follow synoptic temperature variations. This is because local biogeophysical processes can lead to a pronounced soil-atmosphere thermal offset (Delta T) while altering the coupling (beta Tau) between ST and ambient air temperature (AAT). Here, we aim to uncover the spatiotemporal variation in these parameters and identify their main environmental drivers. By deploying a unique network of 322 temperature loggers and surveying biogeophysical processes across an Arctic landscape, we found that the spatial variation in Delta T during the AAT 0 period, Delta T was controlled by soil characteristics, vegetation and solar radiation (Delta T = -0.6 degrees C +/- 1.0 degrees C). Importantly, Delta T was not constant throughout the seasons reflecting the influence of beta Tau on the rate of local soil warming being stronger after (mean beta Tau = 0.8 +/- 0.1) than before (beta Tau = 0.2 +/- 0.2) snowmelt. Our results highlight the need for continuous microclimatic and local environmental monitoring, and suggest a potential for large buffering and non-uniform warming of snow-dominated Arctic ecosystems under projected temperature increase.
  • Kubin, Eero; Kemppainen, Lauri (The Society of Forestry in Finland - The Finnish Forest Research Institute, 1994)
    The effect of scarification, ploughing and cross-directional plouhing on temperature conditions in the soil and adjacent air layer have been studied during 11 consecutive growth periods by using an unprepared clear-cut area as a control site. The maximum and minimum temperatures were measured daily in the summer months, and other temperature observations were made at four-hour intervals by means of a Grant measuring instrument. The development of the seedling stand was also followed in order to determine its shading effect on the soil surface. Soil preparation decreased the daily temperature amplitude of the air at the height of 10 cm. The maximum temperatures on sunny days were lower in the tilts of the ploughed and in the humps of the cross-directional ploughed sites compared with the unprepared area. Correspondingly, the night temperatures were higher and so the soil preparation considerably reduced the risk of night frost. In the soil at the depth of 5 cm, soil preparation increased daytime temperatures and reduced night temperatures compared with unprepared area. The maximum increase in monthly mean temperatures was almost 5 °C, and the daily variation in the surface parts of the tilts and humps increased so that excessively high temperatures for the optimal growth of the root system were measured from time to time. The temperature also rose at the depths of 50 and 100 cm. Soil preparation also increased the cumulative temperature sum. The highest sums accumulated during the summer months were recorded at the depth of 5 cm in the humps of cross-directional ploughed area (1127 dd.) and in the tilts of the ploughed area (1106 dd.), while the corresponding figure in the unprepared soil was 718 dd. At the height of 10 cm the highest temperature sum was 1020 dd. in the hump, the corresponding figure in the unprepared area being 925 dd. The incidence of high temperature amplitudes and percentage of high temperatures at the depth of 5 cm decreased most rapidly in the humps of cross-directional ploughed area and in the ploughing tilts towards the end of the measurement period. The decrease was attributed principally to the compressing of tilts, the ground vegetation succession and the growth of seedlings. The mean summer temperature in the unprepared area was lower than in the prepared area and the difference did not diminish during the period studied. The increase in temperature brought about by soil preparation thus lasts at least more than 10 years.
  • Haapala, Tapani; Palonen, Pauliina; Tamminen, Antti; Ahokas, Jukka (2015)
  • Haapala, Tapani; Palonen, Pauliina; Korpela, Antti; Ahokas, Jukka (2014)
  • Karvonen, Juha (Helsingfors universitet, 2008)
    Experiments with outdoor viticulture were started in Southeast and Southwest Finland in the 1930s. Our rather short growing season and lack of suitable varieties have hindered professional extensive outdoor viticulture. The grapevine varieties bred for northern conditions and the forecasted prolongation of our growing season will likely lead to viticulture in Southern Finland within the next few decades. Soil temperature has an important influence on the survival and growth of the grapevine. Soil temperature is affected by air temperature, cultivation site, soil cultivation, vegetation, soil type and wintertime snow cover. The aim of my Master`s thesis was to measure soil temperatures of grapevine sites and, based on the reults, to estimate the optimal planting depth of a grapevine in Southern Finland. The effect of changes in air and soil temperatures on grapevine growth and development in Tuusula, Vehmersalmi and some Central European localities was also followed. Measurements revealed that soil temperature was at its lowest in March, when in Tuusula at a depth of 20 cm it decreased to -0.7ºC and at a depth of 60 cm to 2.0ºC. Compared with soil temperatures measured by the Finnish Meteorological Institute in other localities, the temperatures at a depth of 20 cm in Maaninka fell to -0.8ºC, in Juva to -0.3ºC and in Jokioinen to -1.6ºC and at a depth of 50 cm in Maaninka to 0.0ºC and in Jokioinen to -0.3ºC. In Tuusula, the annual average soil temperatures at a depth of 20 cm was 6.0ºC and at a depth of 60 cm 7.9ºC. In regression analysis, strong correlations (r2 = 0,497 - 0,684) were obtained between air temperatures measured at grapevine sites at a heigth of 150 cm, ground surface temperatures and soil temperatures measured at a depth of 20-60 cm. In the winter months of December, January, March and April, when the snow cover remained thin, the correlation between snow cover and soil temperatures was weak. The soil temperature during the coldest winter month at a depth of 20 cm fell to slightly below 0.0ºC, at a depth of 40 cm it remained at about 0ºC and at a depth of 60 cm it remained at 2ºC. Based on this, the depth of 40-60 cm can be regarded as the optimal planting depth for grapevines in Southern and Eastern Finland. At this depth, the freezing risk for roots in winter is minor, and in spring solar radiation quickly raises the soil temperature. In 2002-2007, the grapevine growing season had begun in Tuusula as a weeping at the earliest on April 24th. The buds began to swell and break earliest on May 1st. The flowering began earliest on June 16th and lasted for about two weeks. The earliest harvest began on September 14th. From the start of flowering to the start of harvest, the time elapsed was 75-92 days. Growth slackened as the soil temperatures fell and ceased altogether in September. In Central Europe, the weeping of the grapevines starts because of higher air and soil temperatures a couple of months earlier than in Southern Finland, but the flowering begins no more than one month and the harvest only 2-3 weeks earlier. The quicker growth and development in the north can be explained by the quicker warming of the air and soil, the longer days and the abundant supply of light in early summer.
  • Robinson, Sinikka I.; McLaughlin, Órla B.; Marteinsdóttir, Bryndís; O'Gorman, Eoin J. (2018)
    1. Global warming is predicted to significantly alter species physiology, biotic interactions and thus ecosystem functioning, as a consequence of coexisting species exhibiting a wide range of thermal sensitivities. There is, however, a dearth of research examining warming impacts on natural communities. 2. Here, we used a natural warming experiment in Iceland to investigate the changes in above-ground terrestrial plant and invertebrate communities along a soil temperature gradient (10 degrees C-30 degrees C). 3. The alpha-diversity of plants and invertebrates decreased with increasing soil temperature, driven by decreasing plant species richness and increasing dominance of certain invertebrate species in warmer habitats. There was also greater species turnover in both plant and invertebrate communities with increasing pairwise temperature difference between sites. There was no effect of temperature on percentage cover of vegetation at the community level, driven by contrasting effects at the population level. 4. There was a reduction in the mean body mass and an increase in the total abundance of the invertebrate community, resulting in no overall change in community biomass. There were contrasting effects of temperature on the population abundance of various invertebrate species, which could be explained by differential thermal tolerances and metabolic requirements, or may have been mediated by changes in plant community composition. 5. Our study provides an important baseline from which the effect of changing environmental conditions on terrestrial communities can be tracked. It also contributes to our understanding of why community-level studies of warming impacts are imperative if we are to disentangle the contrasting thermal responses of individual populations.
  • Shamsuzzaman, Md (Helsingin yliopisto, 2019)
    Soil respiration (Rs), especially from drained peatland, has a significant role in the global carbon cycle. Drained peatland adds more CO2 effluxes due to the aerobic condition and fast decomposition rate of organic matter. In such condition, peatlands are no more carbon sink rather than a source. However, soil respiration (Rs) is known to be markedly variable with time and space. Many ecological studies showed an exact measurement of Rs is critical. Even a spatial variability of Rs is less known at a plot scale. This study investigated the spatial variation of Rs and its relationship with some explanatory factors (soil temperature, water-table level, moss cover, drainage ditch distance, and vegetation cover) in Lettosuo-peatland, Tammela, Finland. Soil respiration (Rs), soil temperature (Ts), and water-table level (WTL) were measured at 98 sampling plots during May to August 2017. A closed chamber system is known as Environmental Gas Monitor (EGM) was used to measure soil respiration. Once at the end of the measurement in August, vegetation site type (St), ditch distance (Dd), field layer vegetation (FLV), and ground layer vegetation (peat moss (Mp), forest moss (Mf)) were measured. The results showed that the mean rate of CO2 efflux was 0.49 ± 0.1 ( ± Std) g CO2 m-2 h-1 at 13.51 ± 0.8 ( ± Std) °C (at 5 cm depth) ranging from 0.15 to 0.98 g CO2 m-2 h-1. A multiple linear model indicated (R2 =0.18) that about 18% of the spatial variation of Rs could be explained by Ts, WTL, and Dd collectively, but only WTL (R2 = 0.12) could explain 12% variation alone. The spatial variability of soil respiration was mainly driven by the variability in WTL.