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Changes of ground vegetation, soil chemical properties and microbiota following the surface fires in Scots pine forests. .

Introduction

Nowadays, forest fires are recognized as an important ecological factor affecting vegetation structure and composition, energy fluxes and biogeochemical processes in boreal and hemiboreal forest landscapes (Shugart et al. 1992; Parviainen 1996; Angelstam 1998; Bergeron et al. 2002; Kuuluvainen 2002; Ryan 2002; Wallenius et al. 2007). Modern forest management should consider the impact of fire as the increases in the frequency and intensity of natural and anthropogenic forest fires are expected to occur in the coming decades as a consequence of global climate changes (Paatalo 1998; IPCC 2007; Flannigan et al. 2009).

The effect of fires on forest ecosystems depends on intensity and duration of the fire (Ice et al. 2004; Certini 2005). Severe crown fires can eliminate above-ground biomass, change successional rates and alter vegetation species composition, belowground physical, chemical and microbial processes. Fire changes forest soils properties including increased bulk density and altered physical structure (Boyer, Miller 1994; Arocena, Opio 2003), increased soil cation stocks (Liechty et al. 2005; Neff et al. 2005), and decreased carbon (C) and nitrogen (N) stocks in soils (Choromanska, DeLuca 2001; Carter, Foster 2004; MacKenzie et al. 2004; Certini 2005). In addition, during severe crown fires some heavy metals could release from the ash to the soil (Breulmanna et al. 2002; Pereira, Ubeda 2010). In excessive amounts they could have negative effects on forest ecosystem processes (Alloway 1995; Vasarevicius, Greiciute 2004; Ignatavicius et al. 2006; Baltrenaite, Butkus 2007; Pundyte et al. 2011).

Surface forest fires mainly affect the species composition of the ground vegetation; can promote an herbaceous flora, tree regeneration conditions and short-time increase of plant available nutrients in the soil (Parviainen 1996; Granstrom 2001; Gromtsev 2002; Ryoma, Laaka-Lindberg 2005; Jayen et al. 2006; Marozas et al. 2007; Parro et al. 2009). The effects of surface fires on soil chemical properties are generally relatively minor. In fact, the mineral soils appear to be unchanged in the face of low-intensity surface forest fires (Richter et al. 1982; Ferran et al. 2005; DeLu ca, Sala 2006; Neill et al. 2007).

Fires have effect on soil microbial abundance and composition (Tateishi, Horikoshi 1995; Mabuhay et al. 2006). It is focused that forest fires induce the changes in microbial populations mainly through the shift of soil moisture content (Hanson et al. 2000; Pietikainen et al. 2000) and through the increased supply of organic C and N from the burned soil organic layer to the mineral topsoil (Klopatek et al. 1988; Ojima et al. 1994; Neary et al. 1999; Simard et al. 2001; Neff et al. 2005). Mineral top soil drying followed by soil moisture retention and capacity reduction on behalf of the burned vegetation and underlying soil organic layer decreases the abundance of microbial communities (Baath et al. 1995; Pietikainen et al. 2000). Thus, proceeding into the stationary phase, the ability of recovering and recolonizing of microbial communities is declined (Prieto-Fernandez et al. 1998; Wutrich et al. 2002).

Forest fires induce the loss of organic matter along the burning of the ground vegetation and soil organic layer. As the potential organic matter input to soil is decreased, the decrease in the abundance of microbial communities could be also estimated (Almendros et al. 1990). Thus, in mineral soil due to the increase of belowground root mass the microbial abundance could increase in burned stands (Ojima et al. 1994). Regarding the changes in soil moisture as well as soil C and N content, the mostly reduced microbial population in the burned stands could be soil micromycetes, thus soil bacteria and actinobacteria, in contrast, could be the most abundant in the burned stands (Klopatek et al. 1988; Prieto-Fernandez et al. 1998; Joos et al. 2001).

Mainly the observations on surface fire impact to vegetation of pine forest ecosystems were presented in European hemiboreal forest zone (Zackrisson 1977; Marozas et al. 2007; Parro et al. 2009). Moreover, there is a lack of more complex investigations on the vegetation reestablishment, the changes in soil chemical properties and microbial population that occur after surface fires.

In Lithuania the annual number of forest fires is about 700 (from 200 to 1600 per year) (LME/SFS 2010). The total burned forest area ranges from 100 to 700 ha annually with an average burned area per one fire of 0.45 ha. Even 84% of fires emerge in Scots pine forests. The most common are surface fires (97.3%), while crown fires and underground fires amount only to 1% and 1.7%, respectively.

The aim of the study was to investigate the influence of low severity surface fires on the development of ground vegetation, soil chemical changes and soil microbiota in Scots pine (Pinus sylvestris) stands on sandy soils (Arenosols).

1. Materials and Methods

1.1. Study site

The study area was located in the eastern part of Lithuania (Zarasai district) (55[degrees] 35'N, 26[degrees] 07'E) and it falls in the transitional deciduous coniferous mixed forest hemiboreal zone of Europe (Ahti et al. 1968) (Fig. 1).

[FIGURE 1 OMITTED]

The altitude above sea level is about 150-180 meters. The mean annual temperature ranges from +5.4 to +5.8 [degrees]C, with a mean January (coldest month) temperature of -6.4[degrees]C and a mean July (warmest month) temperature of 16.9[degrees]C. Annual mean precipitation is between 600 and 700 mm. Period with permanent snow cover continues from 100 to 110 days (Bukantis 1994). Hilly landscape, sandy soils and pure Scots pine (Pinus sylvestris) stands prevail in the forests of the study area.

The study was carried out in 60-year-old pure Scots pine stands with the undergrowth of Norway spruce (Picea abies). All studied stands were growing on nutrient-poor sandy Arenosols (forest type - Vaccinio - myrtillo Pinetum). In the ground vegetation cover prevail: Vaccinium myrtillus, V. vitis-idaea, Calluna vulgaris, Festuca ovina, Linaria vulgaris, Luzula pilosa and Melampyrum pratense in the dwarf shrub and herb layer, and Dicranum polysetum, D. scoparium, Hylocomium splendens and Pleurozium schreberi in the moss layer. In these stands surface fires occurred in the end of April of 2006 and 2009. Since the fires were of low severity, Scots pine trees were not damaged, while Norway spruce undergrowth and shrubs were totally killed and the ground vegetation cover was burned. The area of fires was about 60 ha in 2006 and about five ha in 2009.

1.2. Ground vegetation study and soil sampling

In total 4 permanent transects (20 x 1 m) with 20 sampling plots (1 x 1 m) were established for the ground vegetation study in the burned site (the surface fire occurred in April of 2006) and in the untouched nearby not-burned site (control) of Scots pine stand. Vegetation studies were conducted annually in June-July of 2006-2009. Each year species composition (species names according to Jankeviciene 1998) and projection cover (in per cent) of shrubs, saplings, dwarf shrubs, herbs and mosses were recorded in transects.

The soil sampling for the estimation of soil chemical properties and evaluation of the abundance of soil microbiota was carried out in July, 2009 in two burned sites in which surface fires occurred one and four years ago (in April of 2006 and 2009, respectively) and in untouched control sites. In each site, three composite samples of the organic layer (forest litter) and three samples from 0-5 cm mineral topsoil were collected at nine systematically distributed points along 16 meters transects. The organic layer was sampled using a 1000 [cm.sup.2] metallic circular frame. Then samples were dried at 105[degrees]C and oven-dry weight (kg [m.sup.-2]) was determined. Mineral soil was sampled with metallic auger of 2.5 cm diameter.

1.3. Analyses of soil chemical properties and soil microbiota

For chemical analyses, the organic and mineral soil samples were dried at 40[degrees]C. Mineral soil samples were sieved through a 2x2 mm sieve. The mobile potassium ([K.sub.2]O) and mobile phosphorus ([P.sub.2][O.sub.5]) were determined in soil samples using the Egner-Riehm-Domingo (A-L) method (Egner et al. 1960); and pH was potentiometrically measured in a 1 M KCl suspension (ISO 10390). Cadmium was determined by flame and electrothermal atomic absorption spectrometric method (ISO I1047-9), whereas Cr, Pb, Ni, Cu, Mn, Zn and Fe were determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES) (ISO 22036:2008). These analyses were conducted in the Agrochemical Research Laboratory of LRCAF. The total nitrogen (N) (ISO 11261) and organic carbon (org. C) (ISO 10694) concentrations were determined using the ECS 4010 analyser (COSTECH) in the Ecology Department of Institute of Forestry of LRCAF. Results were calculated on the mass of dry soil.

Soil microbiota was determined by the standard method of the sowing of organic or mineral soil suspension on the agarised nutrient medium (Thompson, Vincent 1967). Well homogenized 5 g of natural moist soil was suspended for one hour in the 50 ml of sterile water. Soil solutions for the sowing were gradually diluted by 10, 100 and 1000 times. The sowing was performed in three replicates using standard media agar (PlateCount-Agar/standard methods) for the estimation of total soil microbiota abundance (Annand et al. 2003). Microbiota plates were incubated at 27[degrees]C. After 5-7 days the morphology of the bacteria, actinobacteria and micromycetes colonies on plates was assessed by the needle strike and the optical microscopy. The count of colony forming units (CFU) of the microbiota was performed and the abundance of microbiota was counted per 1 g of the constant dry (in 90[degrees]C) weight of the soil (according to Bradshaw 1992; Hassen et al. 2001).

1.4. Data statistical analysis

Vegetation data generally do not follow normal distribution (Greig-Smith 1983; Jongman et al. 1995). Chisquare test confirmed not normality of vegetation data; therefore we used nonparametric Wilcoxon test to test differences between pairs of data set in different years. Wilcoxon test was used, because we compared the depended data (time series) (Cekanavicius, Murauskas 2002). Soil chemical and microbiota parameters followed normal distribution (checked by chi-square test), therefore we used Student t-test. Statistical analyses were conducted using the STATISTICA 8.0.

2. Results and discussions

2.1. Changes in ground vegetation

In total 28 different species were found during four years period in the ground vegetation cover of burned and control sites of Scots pine stands. Average species number per 1 [m.sup.2] significantly (p < 0.05) decreased within first year after the low severity surface fire (Fig. 2).

In the subsequent years post-fire the average species number slightly increased, and in the fourth year after the surface fire it was even higher than that in the non-burned control site of pine stand. This increase in species number was mainly determined by spread out of pioneer early succesional herb species (Calamagrostis epigejos, Equisetum hyemale, Pteridium aquilinum, Rubus idaeus, R saxatilis, Scorzonera humilis, Solidago virgaurea, Ceratodon purpureus, Polytrichum juniperinum).

[FIGURE 2 OMITTED]

The similar decline in the number of species immediately after the fire and the subsequent increase within a few further years was reported by Nuzzo (1996) and Parro et al. (2009).

In the cover of ground vegetation of Scots pine stand prevailed herbaceous, moss and dwarf species (Table 1).

Only two species of shrubs (Frangula alnus and Sorbus aucuparia) and two species of saplings (Quercus robur and Picea abies) occurred rarely before the fire. Besides, only F. alnus was found in the burned site.

In total nine herbaceous and dwarf shrub species occurred in the ground vegetation cover before the fire (Table 1). While, there were 15 species in the burned site. Dwarf shrub Vaccinium myrtillus and V. vitis-idaea were the most abundant in the control site. These dwarf shrubs were declined by surface fire, however, there were recovered, especially V. myrtillus, within 3-4 years.

Herbaceous species of Calluna vulgaris, Luzula pilosa and Polygonatum odoratum were found only in the control site and still did not occur in the 4-year-old fire site (Table 1). Meanwhile Rubus saxatilis, Scorzonera humilis, Calamagrostis epigejos, Pteridium aquilinum, Trientalis europaea, Peucedanum oreoselinum, Solidago virgaurea, Equisetum hyemale, Rubus idaeus occurred only in the burned site.

The reduction of the average projection cover of herbaceous and dwarf shrub species due to the surface fire was observed only during the first year. Projection cover recovered in the second year after the surface fire. Moreover, in the third year the projection cover of herbaceous and dwarf shrub species was even higher than that in the control site (Fig. 3). This increase was mainly because in the burned sites the coverage of V. myrtillus (near 50%) was almost 3-folds higher than its coverage in Scots pine stand before the fire.

[FIGURE 3 OMITTED]

Only two moss species, Pleurozium schereberi and Hylocomium splendens, occurred before the fire in observed Scots pine stand but it comprised almost 90% of ground vegetation cover (Table 1). The decline of these mosses was still in fact total in the four year after the fire. Instead of mentioned mosses, four new moss species (Dicranum polysetum, D. scoparium, Ceratodon purpureus, Polytrichum juniperinum) occurred in the burned sites. However, the average projection cover of the mosses was still very low (comprised only 1-2%) in 4-yearold fire sites.

Surface forest fires had considerable effect on the ground vegetation coverage. Fire destroyed above-ground part of vegetation, but the herbs and, especially, dwarf shrubs recovered quite rapidly within 3-4 years. It has been reported that the recovery of moss layer is much slower and it takes more than 10 years (Marozas et al. 2007; Parro et al. 2009). Skre (Skre et al. 1998) found that the biomass of Calluna vulgaris, Polytrichum. Deschampsia flexuosa and Pteridium aquilinum increased after the fire in pine forests of western Norway while regrowth of Vaccinium myrtillus and V. vitis-idaea was slower. Other investigations also suggested (Ryoma, Laaka-Lindberg 2005) that Ceratodon, Funaria, Pohlia nutans, Polytricum spp. appears quickly after the fire in boreal forests. Investigation of the post-fire recovery of species in Scots pine forest in the central part of the Kola Peninsula (Gorshkov, Bakkal 1996) showed that the herb and dwarf shrub layers recovered within 5-15 years after the fire while the mosses recovered within 90-140 years after the fire.

2.2. Soil chemical properties

There were no differences in the organic layer mass of Arenosols between the burned and control sites with average values of approximately 6.5 kgDM m 2 at each site (data not shown). The fact that no influence on the mass was detected in the 4-year-old burned site shows that the mineralization of organic layers was not intensified after the fire. However, fire-caused changes in chemical properties were mostly pronounced in the organic layer. Integrated parameter pHKCl of organic layer was significantly higher (p < 0.05) in both burned sites to compare to control sites, indicating the alkaline effect of fires (Table 2).

In the first year after surface fire total N concentrations in the soil organic layer were lower in the burned site than that in the control (Table 2). Four years after fire, total N concentrations were higher in the burned site and exceeded the pre-fire level. Since there were no significant differences in org. C concentrations in the soil organic layer, the observed changes (increase in 1-year and decrease in 4-year-old burned sites) in the C/N ratio were obviously determined by the changes in total N concentrations. We have not found significant differences in concentrations of mobile [K.sub.2]O and [P.sub.2][O.sub.5] between the burned and the control sites.

Only the concentrations of mobile [K.sub.2]O was slightly higher in the upper 0-5 cm mineral topsoil in both 1 and 4-year-old burned sites to compare to control sites (Table 2). Other chemical soil parameters (pH, total N, org. C, mobile P2O5) did not differ significantly in the mineral topsoil. The observed saturation of mineral topsoil with [K.sub.2]O could be related to the distribution of the ash after surface fire. Unchanged concentrations of mobile [K.sub.2]O in soil organic layers of burned sites indicated intensive leaching of [K.sub.2]O from organic layers to the mineral topsoil.

Data on heavy metals show that the concentrations of Cd, Cr, Cu Mn, Zn and Fe significantly (p < 0.05) increased in 0-5 cm mineral topsoil after surface fire, while the concentrations of Pb and Ni did not differ between burned and control sites (Table 3). However, the increased concentrations were considerably lower to compare to critical or, even, background levels (HN 60:2004).

The effects of forest above-ground (surface and crown) fires on soil chemical properties strongly depend on fire severity. Crown fires that are severe could lead to significant chemical changes in the mineral soils (Smithwick et al. 2005; Hammana et al. 2007). The study of a short time change (one week after fire) in soil properties due to the fire was conducted in Pinus densiflora stands in Korea (Choonsig et al. 1999). It was found that high intensity forest fire increased soil pH, total N, available P, K, Ca, and Mg in the mineral topsoil (0-5 cm). However, no marked changes were observed in the deeper mineral soil layer (5-25 cm). Other studies confirmed that forest crown fires increase soil cation stocks (Liechty et al. 2005; Neff et al. 2005), but decrease carbon and nitrogen stocks in the surface layer of mineral soils (Choromanska, DeLuca 2001; Carter, Foster 2004; MacKenzie et al. 2004; Certini 2005).

Our study showed that the effects of surface forest fires of low severity on soil chemical properties were not significant. Surface fires did not affect the mass of organic layer, the contents of org. C and mobile [P.sub.2][O.sub.5]. Only slight increase of pH and the short-term decrease of total N in the soil organic layer, as well as the increased concentrations of mobile [K.sub.2]O and some heavy metals were detected in mineral topsoil. Previous studies have reported similar results. Wagle and Kitchen (1972) found no difference in extractable P among 3 years and 14 years old burned and control sites in ponderosa pine forest in the northern Arizona. Very little differences in soil properties, mainly total N decrease within first year after the fire, were found in soils within the low severity burn sites in the coniferous stands of the central and eastern Cascade Mountains of Washington State (Baird 1998; Hatten et al. 2005).

2.3. Soil microbiota

The surface fires mainly affect the changes of soil microbial populations in the soil organic layer and in the mineral topsoil (Klopatek et al. 1988). Concerning that, the abundance of soil microbiota in the organic layer and in the mineral topsoil layer (0-5 cm in depth) in Scots pine stands was determined.

In our study the mean total abundance of soil microbiota in the organic layer was 5.01 mln. and 5.91 mln. of colony forming units (CFU) per [g.sup.-1], respectively, in one year and 4-year-old burned sites (Table 4).

In the mineral topsoil, the mean microbial counts ranged from 0.82 mln. CFU [g.sub.-1] (1-year-old burned site) to 0.94 mln. CFU [g.sub.-1] (4-year-old burned site). In control sites soil microbiota counts were lower than in the burned sites. Since the estimated differences were not significant (p > 0.05), the obtained results are indicating only the tendencies that the increase in soil microbiota counts could be fire-induced.

Crown fires, which burn the organic layers totally, decline microbial communities (Prieto-Fernandez et al. 1998; Wutrich et al. 2002). In our study low severity surface fires might have been not essentially destructive for soil microbiota since soil organic layer was not burned. On the other hand, the surface fires in studied sites seemed to produce the substances as growth promoting substrates for soil microbiota as reported by Neary et al. (1999). Thus, the increase of soil microbiota in burned sites might be caused by the decreased acidity of organic layers and the slight saturation of mineral topsoil mobile [K.sub.2]O (see Table 2).

The distribution of soil microbiota communities is presented in Table 4 as well. Soil bacterium was dominant in the organic layer as well as in the mineral topsoil. However, mean counts of soil bacteria were not significantly (p > 0.05) higher in the burned sites than in the control sites. Though it was expected, no increase in soil bacteria populations was not found even in the 4-year-old burned site, where the saturation with N was increased, especially in the organic layer. Mroz et al. (1980) and Klopatek et al. (1988) reported that an increase in soil nitrogen ratios after the burning should promote an increase in total bacteria populations. It shows, as Astaraei (2008) assumed, that soil bacteria populations were not sufficiently provided with excess of the nitrogen.

Actinobacteria abundance was found to be increasing in the burned sites (Table 4). Only in 1-year-old burned site the significant 1.5- and 2.2- fold increase in actinobacteria abundance was found in the organic layer and in the mineral topsoil, respectively. Actinobacteria in the soil is sensitive to acidity and tolerate the soils with alkaline or neutral pH values (Klopatek et al. 1988; Joos et al. 2001). Since in burned sites of our study soil acidity had decreased, that likely influenced the growth of soil actinobacteria populations.

The abundance of micromycetes decreased in average by 1.4 and 2.8 times in the mineral topsoil in 1-year and 4-year-old burned sites, respectively (Table 4). It has been reported that the most of soil micromycetes are sensitive to decreased of moisture retention (Baath et al. 1995; Pietikainen et al. 2000). In our study, mineral topsoil layers in the burned sites might have been drying and causing decreases in the soil micromycetes populations. The decrease in soil acidity also could cause the decline in micromycete abundance.

Conclusions

1. Surface fires have destroyed the above-ground part of ground vegetation in Vaccinio-myrtillo Pinetum forests. Nevertheless, ground vegetation began to recover in the subsequent years. Within 3-4 years after the fires the burned sites have had even higher number of species and ground vegetation coverage than in the unburned sites. The pioneer herb species and dwarf shrubs, mainly Vaccinium myrtillus, were spread out. However, the recovery of moss cover was still non-significant.

2. Surface fires did not affect the mass of soil organic layer, and the effect on soil chemical properties was minor. Only slight increases of pH and of the content of total N were detected in soil organic layer. Also, slightly increased concentrations of mobile [K.sub.2]O and some heavy metals (Cd, Cr, Cu Mn, Zn and Fe) were found in the mineral topsoil.

3. Surface fires have caused slight changes of microbiota abundance in the soil organic layer and the mineral topsoil (0--5 cm in depth). Although mean abundance of soil bacteria in the burned sites were not significantly higher than in the control sites, actinobacteria abundance tended to increase in the soil organic layer and the mineral topsoil of burned sites. In opposite, the abundance of micromycetes decreased in the mineral topsoil after the surface fires.

4. Our study showed that low severity surface fires mostly affected above-ground part of ground vegetation in Scots pine stands on Arenosols that prevail in Lithuanian forests. The influence of surface fire on soil chemical properties and soil microbiota was minor.

doi:10.3846/16486897.2012.663087

Acknowledgements

The research was supported by Lithuanian Agency for Science Innovation and Technology (Award Numbers 2009 No. 31V-52; 2008 No. 31V-104) and Research Council of Lithuania (No. COST-50/2010). The research was conducted in the frame of COST action FP0701 Post-Fire Forest Management in Southern Europe and COST action ES0805 The Terrestrial Biosphere in the Earth System (TERRABITES).

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Vitas Marozas (1), Kestutis Armolaitis (2), Jurate Aleinikoviene (3)

(1) Department of Ecology, Lithuanian University of Agriculture, Studentu g. 11, Akademija, LT-53361 Kaunas distr., Lithuania

(2,3) Department of Ecology Institute of Forestry, Lithuanian Research Centre for Agriculture and Forestry (LRCAF), Liepu g. 1, Girionys, LT-53101 Kaunas distr., Lithuania

(3) Department of Soil Science and Plant Nutrition, Lithuanian University of Agriculture, Studentu g. 11, Akademija, LT-53361 Kaunas distr., Lithuania

E-mails: (1) vitas.marozas@lzuu.lt (corresponding author); (2) k.armolaitis@mi.lt; (3) j.aleinikoviene@mi.lt,

Submitted 14 Mar. 2011; accepted 09 Nov. 2011

Vitas MAROZAS. Dr, head of Ecology Department, Lithuanian University of Agriculture. Doctor of Biomedical Sciences (Forestry). Publications: author of over 40 scientific publications, participant of over 20 international conferences. Research interests: forest vegetation ecology, biodiversity conservation.

Kestutis ARMOLAITIS. Dr, senior research scientist of Ecology Department, Institute of Forestry of Lithuanian Research Centre for Agriculture and Forestry (LRCAF), part-time senior scientist of Perloja Experimental station of LRCAF and part-time associate professor of Siauli? University. Doctor of Biomedical Sciences (Forestry), Byelorussian Technology University (Minsk), 1984. More than 100 scientific publications. Research interests: forest decline, forest soil chemical condition, soil renaturalization, carbon and nitrogen turnover in forest ecosystems.

Jurate ALEINIKOVIEN?. Dr, junior research scientist of Ecology Department, Institute of LRCAF, part-time lecturer of Lithuanian University of Agriculture. Doctor of Biomedical Sciences (Ecology and Environmental Science), Lithuanian Forest Research Institute and Vytautas Magnus University, 2009. Author of 5 scientific publications, participant of over 20 international and national conferences. Research interests: abundance and diversity of soil microbiota, carbon and nitrogen in microbiota biomass, soil biological renaturalization.
Table 1. Changes of the average projection cover (%)
of shrubs, herbaceous, dwarf shrub, herbaceous and moss
species in the burned and control areas

Name of species               Control      Year after fire

                                         1     2      3      4

Shrubs
  Frangula alnus                 +       +     +      -      +
  Sorbus aucuparia               +       -     -      -      -
Saplings
  Quercus robur                  +                    -
  Picea abies                    +                    -
Herbs and dwarf shrubs
  Calamagrostis arundinacea     0.1     0 1   0 2    0.3    0 2
  Calamagrostis epigejos         -       +    0.1    0.1     +
  Calluna vulgaris              0.3      -     -      -      -
  Convallaria majalis           0.6      +    2.6    1.9    1.8
  Equisetum hyemale              -       +     +      +      +
  Festuca ovina                  +       +     +     0.3    0.5
  Luzula pilosa                 0.2      -     -      -      -
  Melampyrum pratense           0.2      -     +     0.9    1.0
  Peucedanum oreoselinum         -       +    0.1     +      -
  Polygonatum odoratum           +       -     -      -      -
  Pteridium aquilinum            -      0.9   1.5    4.2    4.5
  Rubus idaeus                   -       -     -      -     0.1
  Rubus saxatilis                -      0.8   2.8    2.8    2.6
  Scorzonera humilis             -       +    0.2    0.3    0.2
  Solidago virgaurea             -       +     +      -      -
  Trientalis europaea            -      0.1   1.2     +      +
  Vaccinium myrtillus          17.5     2.7   23.2   50.4   47.6
  Vaccinium vitis-idaea        13.4     0.4   2.0    3.9    4.4
Mosses
  Dicranum polysetum             -       -     -      -      +
  Dicranum scoparium             -       -     -      -      +
  Hylocomium splendens         35.7      -     -      -      -
  Pleurozium schreberi         60.5      -     -      -      +
  Ceratodon purpureus            -       -     -      -     0.8
  Polytrichum juniperinum        -       -     -             +

+-projection cover < 0.1%

Table 2.The chemical parameters (mean [+ or -] SD) of organic and
mineral topsoil layers of Arenosols in control and burned sites of
Scots pine stands

Soil                           [pH.sub.KCl]       N, g [kg.sup.-1]
sampling

                                        Organic layer

1-year-old      control     2.8 [+ or -] 0.2     15.3 [+ or -] 0.3
burned site   burned site   3.2 [+ or -] 0.1 *   13.4 [+ or -] 0.7 *

4-year-old      control     2.8 [+ or -] 0.2     12.9 [+ or -] 0.5
burned site   burned site   3.2 [+ or -] 0.1 *   14.3 [+ or -] 0.8 *

                               Mineral topsoil (0-5 cm in depth)

1-year-old      control     3.4 [+ or -] 0.2     2.4 [+ or -] 0.1
burned site   burned site   3.4 [+ or -] 0.1     2.4 [+ or -] 0.1

4-year-old      control     3.7 [+ or -] 0.1     2.4 [+ or -] 0.1
burned site   burned area   3.4 [+ or -] 0.2     2.4 [+ or -] 0.1

Soil                            Org. C, g                 C/N
sampling                        [kg.sup.-1]

1-year-old      control     431.9 [+ or -] 18.1   28.2 [+ or -] 1.2
burned site   burned site   432.0 [+ or -] 23.5   32.5 [+ or -] 1.2 *

                                          Organic layer

4-year-old      control     441.4 [+ or -] 26.8   34.3 [+ or -] 2.1
burned site   burned site   438.9 [+ or -] 28.6   30.6 [+ or -] 0.9 *

                               Mineral topsoil (0-5 cm in depth)

1-year-old      control     25.3 [+ or -] 2.7     10.6 [+ or -] 0.7
burned site   burned site   23.2 [+ or -] 0.7     9.8 [+ or -] 0.6

4-year-old      control     25.2 [+ or -] 1.3     10.5 [+ or -] 0.7
burned site   burned area   28.3 [+ or -] 0.7     11.9 [+ or -] 0.1

Soil                        [P.sub.2][O.sub.5],     [K.sub.2]O,
sampling                     mg [kg.sup.-1]        mg [kg.sup.-1]

                                         Organic layer

1-year-old      control     195 [+ or -] 27        421 [+ or -] 15
burned site   burned site   283 [+ or -] 49        390 [+ or -] 36

4-year-old      control     244 [+ or -] 39        434 [+ or -] 32
burned site   burned site   245 [+ or -] 13        415 [+ or -] 14

                               Mineral topsoil (0-5 cm in depth)

1-year-old      control     77 [+ or -] 12         48 [+ or -] 4
burned site   burned site   88 [+ or -] 21         61 [+ or -] 5 *

4-year-old      control     117 [+ or -] 8         48 [+ or -] 3
burned site   burned area   115 [+ or -] 18        64 [+ or -] 7 *

* -indicates the significant (p < 0.05) changes in burned sites.

Table 3. Concentrations (mg [kg.sup.-1] mean [+ or -] SD)
in the mineral topsoil (0-5 cm) in 4-year-old burned
sites and controls

Soil sampling             Cd                      Cr

Burned site     0.036 [+ or -] 0.008 *   2.78 [+ or -] 0.56 *
Control         0.017 [+ or -] 0.004     1.48 [+ or -] 0.38

Soil sampling          Pb                 Ni

Burned site     7.5 [+ or -] 0.6   1.1 [+ or -] 0.4
Control         5.5 [+ or -] 1.2   0.5 [+ or -] 0.1

Soil sampling           Cu                   Mn

Burned site     1.1 [+ or -] 0.1 *   96.4 [+ or -] 7.1 *
Control         0.5 [+ or -] 0.1     26.4 [+ or -] 10.1

Soil sampling            Zn                     Fe

Burned site     6.86 [+ or -] 1.25 *   3488 [+ or -] 1387 *
Control         3.94 [+ or -] 1.23     1449 [+ or -] 417

* -indicates the significant (p < 0.05) increase in burned sites.

Table 4. The abundance of soil microbiota in the organic
layer and the mineral topsoil in Scots pine stands in
control and burned sites (mean [+ or -] SD)

                            Abundance of total      Abundance of
Soil                         microbiota, mln.        bacteria,
sampling                      CFU [g.sup.-1]          mln. CFU
                                                     [g.sup.-1]

                                       Organic layer

1-year-old    control       4.62 [+ or -] 0.51   3.81 [+ or -] 0.32
burned site   burned site   5.01 [+ or -] 0.78   4.03 [+ or -] 0.57

4-year-old    control       5.36 [+ or -] 0.55   4.33 [+ or -] 0.40
burned site   burned site   5.91 [+ or -] 0.64   4.86 [+ or -] 0.32

                               Mineral topsoil (0-5 cm in depth)

1-year-old    control       0.71 [+ or -] 0.16   0.52 [+ or -] 0.15
burned site   burned site   0.82 [+ or -] 0.15   0.60 [+ or -] 0.13

4-year-old    control       0.93 [+ or -] 0.21   0.62 [+ or -] 0.18
burned site   burned site   0.95 [+ or -] 0.29   0.70 [+ or -] 0.28

                               Abundance of
Soil                         actinobacteria,
sampling                    mln. CFU [g.sup.-1]

                               Organic layer

1-year-old    control       0.28 [+ or -] 0.01
burned site   burned site   0.61 [+ or -] 0.18 *

4-year-old    control       0.32 [+ or -] 0.03
burned site   burned site   0.42 [+ or -] 0.19

                            Mineral topsoil
                            (0-5 cm in depth)

1-year-old    control       0.12 [+ or -] 0.00
burned site   burned site   0.17 [+ or -] 0.00 *

4-year-old    control       0.20 [+ or -] 0.00
burned site   burned site   0.21 [+ or -] 0.00

                               Abundance of
Soil                          micromycetes,
sampling                    mln. CFU [g.sup.-1]

1-year-old    control       0.53 [+ or -] 0.18
burned site   burned site   0.37 [+ or -] 0.03

4-year-old    control       0.71 [+ or -] 0.12
burned site   burned site   0.63 [+ or -] 0.13

1-year-old    control       0.07 [+ or -] 0.00
burned site   burned site   0.05 [+ or -] 0.01 *

4-year-old    control       0.11 [+ or -] 0.02
burned site   burned site   0.04 [+ or -] 0.01 *

* -indicates the significant differences
(p < 0.05) between the control and burned sites.
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Author:Marozas, Vitas; Armolaitis, Kestutis; Aleinikoviene, Jurate
Publication:Journal of Environmental Engineering and Landscape Management
Geographic Code:4EXLT
Date:Mar 1, 2013
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