Effects of vegetation height and density on soil temperature variations

Abstract

Reduction in vegetation cover caused by human activities has a great impact on soil temperature. It is important to assess how soil temperature responds to reduction of vegetation height and density. In this paper we first report the trends of mean annual soil surface and air temperatures recorded at the meteorological stations near the Ecological Research Station for Grassland Farming (ERSGF) from 1961 to 2007, then we setup an experiment using reed (Phragmites australis) stalks with different heights and densities to simulate effects of different vegetation height and density on soil and air temperatures. The warming rates of the mean annual soil and air temperatures were 0.043 and 0.041°C a 1 , respectively. Changes of soil temperature were characterized by both increased mean annual maximum and minimum soil temperatures. At the experimental site, mean daily temperature, mean daily maximum soil and air temperatures increased significantly. In contrast, mean daily minimum soil temperature increased significantly while mean daily minimum air temperature decreased significantly as the height and density of reed stalks reduced during the experimental period. Mean diurnal soil temperature ranges were smaller than mean diurnal air temperature ranges. These results highlight that the importance of vegetation cover on soil and air temperatures. There is general consensus that the global climate has changed rapidly, and the global mean surface temperature has increased by 0. 74C between 1906 and 2005 [1]. The warming pattern shows that mean annual minimum temperature has increased almost two orders of magnitude of maximum temperature, i.e. an asymmetric diurnal temperature increase [2,3]. Apart from studies on atmospheric temperature continuously published, more focus on variation of soil temperature and its factors has emerged recently [4][5][6][7][8][9]. Soil temperature is a crucial factor involved in determining/affecting the rates of biochemical reactions and has a strong influence on plant and root growth [2,6]. Diurnal soil temperature range is particularly important in plant growth, such as seed germination and early season growth which are highly correlated with daily maximum temperature of the soil rather than with air temperature [7]. Similar to increased air temperature, soil temperature also increases based on the long-term trend. Hu and Feng [8] reported that soil temperature at 10 cm depth increased 0.031C a 1 from 1967 to 2002 in the contiguous United States. A study recorded 27-year soil temperature at 5 depths showed a significant increase at a grassland in the Netherlands, and the warming rate of soil temperature was higher than air tem-

Plant species, temperature, and bedrock affect net methane flux out of grassland and forest soils

“…Of course, the highest of the three temperatures tested (i.e. 37°C) within the present investigation does not represent standard soil temperatures but might be possible in soils under certain conditions as especially the upper soil layers easily heat up in summer and can reach high temperatures (Song et al 2013). A further idea behind applying higher temperatures was to reach a temperature range more suitable for methanogens (Le Mer and Roger 2001) and -in combination with psychrophilic and mesophilic temperatures-to investigate quite great temperature steps which should indicate the direction of temperature caused effects.…”

CMIP5 Models Predict Rapid and Deep Soil Warming Over the 21st Century

“…None of the models appeared to capture the slightly higher Δ T surf seen in the observational data from grassland sites as compared to forested sites (Figures a and a). Field studies have shown substantial differences in Δ T surf as a result of land cover (Beltrami & Kellman, ; Nitoiu & Beltrami, ; Song et al, ). Grassland sites tended to have a higher Δ T surf than the forested sites in our observation data set (Figure a).…”

How do Soil Moisture and Vegetation Covers Influence Soil Temperature in Drylands of Mediterranean Regions?

“…A consensus is that tree canopies modify water and energy balances below them by intercepting rainfall and solar radiation. Thus, temperatures have usually been considered to be lower below tree canopies than in grasslands in summer, and the opposite in winter [8,[10][11][12]. Conversely, the influence of vegetation cover on soil water content has been a more controversial issue since it has been found to be lower under tree crowns than in grasslands in drylands and humid lands, although opposite results have also been observed [13][14][15][16].…”