Monchegorsk ecology of beautiful tundra



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Polar Science (National Institute of Polar Researce, Japan), Volume 4, issue 3, December 2010.

Stability of palsa at the southern margin of its distribution on the Kola Peninsula

Valery Sh. Barcan

Lapland Nature Resent. 8 Zeleny Street. Monchegorsk 184505. Russian Federation
Received 28 April 2009; revised 18 February 2010; accepted 7 July 2010
Available online 17 August 2010


Abstract

This study investigated palsa located at the southern margin of palsa extent upon the Kola Peninsula, Russia, Thirteen palsa bogs were analyzed, two of which had intervals between surveys of either 67 years (1935-2002) or 82 years (1920-20021, The thickness of the active layer of paisa during the warm season varied from 44 to 64 cm. consistent with existing data. The height and number of bog mounds, as well as the thickness of the active layer, are unchanged over the past 80 years.

1. Introduction

The Kola Peninsula, Russia, has no genuine permafrost, but as with other northern Fennoscandia regions with an average annual air temperature of about 10C or lower, palsa bogs, which consist of ice cores within small hillocks, are widespread, as shown on a map of vegetation upon the Kola Peninsula in the "Alias of Murmansk Oblast" (Chernov, 1971). The features and origin of palsa bogs have been studied in many parts of the world, including Alaska, northern Canada, northern and northeastern Siberia, and especially northern Fennoscandia. including the Kola Peninsula (Seppiila. 1972, 1982a, 1983, 1994. 1997: Sollid and Sorbel. 1998). Palsas have attracted increasing attention in receni years in connection with the global wanning hypothesis (e.g. Kukkonen and Safanda, 2001: Nelson et al., 2001: Luoto and Seppala. 2002. 2003) and a palsa research project was recently initiated in Norway (Hofgaard. 2003). Palsas of (he Kola Peninsula have been well studied, with the first known descriptions reported by Kihlman (1890). Anufriev (1922) conducted a research expedition during the Russian Civil War, describing in detail the palsa bogs in Transactions of the Soviet Geographic Institute. In addition, the Permafrost Committee of Russia was active in the 1930s (Lavrova. 1934; Rikhter. 1934; Sumgin, 1934; Vlastova and Nikonov, 1940: Yegorov, 1938). According to data published since 1890, bog hillocks on the Kola Peninsula thaw to a depth of 3035 cm by the end of summer.

2. Aim

The aim of this study is to evaluate palsa stability on the Kola Peninsula during the past 6580 years. The focus here is not palsa in general, which covers 20-25% of the Kola Peninsula, but is palsa at the southern margin of its distribution. The palsa (bog hillocks with permafrost) at the southern margin of its distribution is susceptible to minor changes in temperature. Thus, the stability or instability of palsa provides evidence of temporal trends in temperature.

3. Materials and methods

Palsa at the southern margin of the Kola Peninsula lies at about 67050'N, south of the town of Monchegorsk along the northern shore of Vite Gulf at Imandra Lake (Rikhter, 1934: Sumgin. 1934; Yegorov. 1938), as shown schematically in Fig. 1. The study area, which covers about 40 km in an east-west direction and 50 km northsouth, contains 13 bogs. Fig. 1 also shows several local landmarks, including Nyud Lake and Lumbol Lake. Average annual air temperature, as calculated from data in Reports of Monchegorsk Meteorological Station (see MMS in Fig. 1 for the station location), varies from -3.00C to +2-80C, with an average value of -0.40C for the past 67 years (1936-2003) (Fig. 2). The sum of mean monthly summer temperature (May-September) for the period 1936-2003 ranged from 10740C to 17360C, with an average of 141315710C (Fig. 3, upper). The sum of mean monthly winter temperature (October-April) for the same period ranged from -8990C to -23450C, with an average of -15343460C (Fig. 3, lower). Thirteen palsa bogs were investigated (numbered 1-13 in Fig. 1), two of which have been studied at intervals greater than 50 years: the palsa near Nyud Lake was re-assessed after 67 years (1935 and 2002), and that near Yagel Bor halt was re-assessed after 82 years (1920 and 2002). Fifteen palsa hillocks were randomly chosen for analysis in each bog. The thickness of ihe active layer at each hillock was estimated using a steel measuring rod in the second half of September (i.e. before the first frost). This sampling period was chosen due to the peculiarity of the transpolar climate: the seasons change quickly, meaning that the active layer of palsa has no time to grow. The size of the area covered by palsa was determined by ground measurements in 1920 or 1935 (previous studies) and again in 2002 (present study).





Fig. 1. Schematic map of palsa layout in the study area. The area covers about 40 km eastwest and 50 km northsouth. The area contains 13 hogs (siles). and the bog numbers in the figure correspond to those in Tables 1 and 2. MMS: Monchegorsk Meteorological Station. The numbers in the rose diagram indicate wind strength for the corresponding directions.






Fig. 2. Average annual atmospheric temperature at Ihe Monchegorsk Meteorological Station, at ihe northern margin of the paka zone on Kola Peninsula. Year numbers (1-67) correspond to the years from 1936 to 2003 (Anonymous. 1936-2006).






Fig. 3. Dynamics of summer and winter temperatures at Monchegorsk Meteorological Station, at the northern margin of the palsa zone. Kola Peninsula (Anonymous, 19362006).


4. Results

Table 1 provides descriptions of the studied bogs. The numbering system for the bogs is the same as thai in Fig. I. The altitude of the bogs ranges from 132 m (No.6) to 230 m (No.10). The area occupied by each bog did not change (from 1920 or 1935 until 2002) for Nos. 1-7 and 11-13, while it decreased slightly for Nos. 8-10. The key statistical parameters related to the variance rows for thickness of the active layer of palsa are as follows:





Table 1
Description of ibe studied palsa bogs.
No. Bog location (latitude, longitude site name) Altitude above sea level, m Area occupied by palsa. ha (observed year) Thickness of the active layer in palsa at the end of warm season. Extent of vegetable cover on the bog (2002)
1 6756'30"N, 3251'E.
Grass Lake
151 1 (1935),
1 (2002)
57 6 (2002) Plants are dead
2 6755'N. 3252'E.
Nyud Lake
145 5 (1935),
5 (2002)
35-60 (1935),
64 6 (2002)
Plants are dead
3 6758'N. 3252'E.
Monche Lake, north end
133 4 (1935),
4 (2002)
48 4 (2002) Plants are dead
4 6757'N. 3254'E. Lumbol Lake 133 10 (1920)
10 (2002)
55 6 (2002) Plants are dead
5 6757'3O"N, 324S'30"E. Monche Lake, north end 151 1 (1935)
1 (2002)
566 (2002) Plants are dead
6 6758'30"N. 3254'E. Road M-18, 1267km 132 4 (1935)
4 (2002)
50 3 (2002) Plants are dead
7 6758'N. 3253'E. Road M-18 exit at 25 km 134 1 (1935)
1 (2002)
52 4 (2002) Plants are dead
8 6758'25"N. 3315'4O"E. Pustaya Gulf at Imandra Lake 147 12 f 1920)
10 (2002)
44 6 (2002) 100%
9 6803'N. 3323'E. Yagel Bor halt 137 10 (1920)
9 (2002)
55-93 (1920)
64 10 (2002)
100%
10 6815'N. 33 22'E. Laplandia Railway Station 230 5 (1920)
4 (3002)
61 12 (2002) 100%
11 6811'N. 3333'E. Keresyavrench Lake 187 3 (1920)
3 (2002)
38 5 (2002) 100%
12 6833'20'E. Pike Lake 170 3 (1920)
3 (2002)
61 13 (2002) 100%
13 6750'N. 3255'E. North of Vile Gulf al Imandra Lake 147 4(1920)
4 (2002)
65 9 (2002) 100%


The above parameters were calculated for each of the 13 palsa hillocks selected for analysis in each bog (Table 2). The mean square deviation of each parameter varies from 3 to 6 in most cases (column 5 in Table 2), although it is 10-13 in three cases (Nos. 9, 10. 12). The confidence interval is 0.95 and the coefficient of variation (column 8) ranges from 6% (No. 6) lo 20% (No. 12). The reliability of the parameters is indicated by the mean error of the arithmetic mean (13%; column 6). Based on the results in Table 2, the bogs were divided into two groups: those with live surface vegetation and those with dead surface vegetation (see Table 3). Vegetation on palsa surfaces at bogs 1-7 (all close to Monchegorsk town) perished due lo SO2 pollution from smeiter emissions. Table 3 compares the mean thickness of the active layer for palsas with dead vegetation (bogs 1-7) versus those with live vegetation (bogs 8-13). Table 4 lists the statistical values of variance rowsmean thickness of the active layer for palsa with live (row 1) and dead (row 2) vegetation.

Table II
Statistical values for thickness measurements of the active layer at each bog sue.
M m M tM=M/mM v %
1575513961.538.0 10.5
2645624061.542.7 9.4
3481821341.143-6 8.3
4554623361.536,7 10.9
5565811261.537.3 10.7
6501451030.862.5 6.0
7522571841.147.3 7.7
8445554061.529.3 13.6
9641447103102.624.6 15.6
10612118151123.119.7 18.8
11384193051.329.2 13.2
12612249161133.318.5 20.3
136312599092.327.4 14.3


Site numbers and names of bogs are as follows: 1 Grass Lake; 2 - Nyud Lake: 3 Monche Lake, north end; 4 - Lumbol Lake; 5 - Monche Lake, north end; 6- Road M-18. 1267 km; 7 - Road M-18. exit at 25 km; 8 - Puslaya Gulf al Imandra Lake; 9 - Yagel Bor halt; 10 - Laplandia Railway Slalion; II - Keresyavrench Lake; 12- Pike Lake; 13 - North of Vite Gulf al Imandra Lake.

Table 3
Thickness of the active layer at palsa with dead and live surface vegetation. Mean values and standard deviations are provided, with the amplitude and range of variations of the depth of permafrost given in parentheses, along with the number of samples.
Site Bogs with dead vegetation. cm Site Bogs with dead vegetation. cm
1 576 (4966. n = 15) 8 44x6 (3553. n - I5)
2646 (5175. n = 15)96410 (4575. n = 15)
3484 (4052. n = 151106112 (5084. n = 15)
4556 (4965. n= 15)II385 (3046. n = 15)
5566 (4765. n = 15)126113 (4984. n = 15)
6503 (4555. n = 15}13639 (4572. n = 15)
7524(4560. n = 15)


According to Railion and Sparling (1973) and Zuidhoff and Kolslrup (2000), the absorption and loss of heat by palsa depend on vegetation cover, yet the measurements in 2002 showed ihat the active layer in mounds was 55 5 cm deep in bogs with dead vegetation and 55 11 cm deep in bogs widi live vegetation (Table 4). This finding appears to contradict existing data regarding thickness of active layer (Anufriev. 1922; Chernov. 1971: Lavrova, 1934: Rikhter. 1934: Sumgin, 1934: Vlastova and Nikonov, 1940; Yegorov. 1938): however, the present results may be explained by the peculiarities of the vegetation cover on the palsasof the Kola Peninsula, as it is very thin and sparse. It is difficult to imagine that such vegetation cover would significantly alter the heat exchange in the bogs. The thickness of the active layer in the bog near Nyud Lake was 35-60 cm in 1935 and 64 6 cm in 2002; in the bog near Yagel Bor halt, the thickness was 55-93 cm in 1920 and 64 10 cm in 2002. The data indicate no change in the past 80 years in terms of the area covered by palsa. palsa altitude, number of bog mounds, or depth of the active layer in mounds (Table 1).

5. Discussion

Permafrost in palsa on the Kola Peninsula is not a relic of the last Great Ice Age (10-12 thousand years ago), as Yegorov (1938) indicated thai paleobotanist G.A. Blagoveshchensky has dated the liming of palsa formation back to approximately 3000 years ago based on an analysis of pollen in peat near Nyud Lake at the town of Monchegorsk. This proposal has subsequently been supported by Lavrova (1934), Bradley and Jones (1993). and Grove (1988).

Several studies have described the process of preservation and contemporary formation of paisa (Seppala, I982a.b, 1994, 1998: Tyrtikov, 1969). The palsa near Nyud Lake can serve as an example in this regard, as freezethaw action in this area is controlled in pan by topography. The bog is open and exposed to the winds that blow into the Nyud Lake valley through a passage between Mt. Nyud and Mt.SopchelYegorov, 1938; see also Fig. 1).

Strong, cold winds blowing along Nyud Lake in wintertime are the main factor thai controls the preservation and contemporary formation of palsa in this area, as the winds blow snow off the peat mounds. Similar meteorological conditions can be found in other areas near the town of Monchegorsk and in remote areas located 15, 22. and 36 km north of Nyud Lake. All these bogs are located approximate^ along the same NNE-SSW line. Previous studies have reported die same process of preservation and contemporary formation of palsa (Matthews et al 1997; Sollid and Sorbel. 1998; Zuidhoff, 2002; Zuidhoff and Kolstrup, 2000). Previous observations have revealed several stages of palsa evolution (Seppala, 1988. 1998>. Palsa formation begins when the snow cover is locally sufficiently ihin to enable winter frost to penetrate deep enough to prevent thawing by summer heal. In such a case, the surface of the bog increases in area (Figs. 47), although no incipieni patsas were discovered during the present study. Yegorov (1938) and Seppiila (1982b) conducted field experiments on the formation of new palsa; they observed the formation of new small palsa in the present time.

During the winter following summertime palsa formation, the frost penetrates deeper still. The formation process accelerates and the hump continues to grow due to the freezing of pore water and ice segregation. As the surface grows, the wind becomes increasingly effective in drying the surface peat and keeping it clear of snow. Degradation begins, leading to the collapse of peat blocks, and the palsa surface becomes to decrease in area, for example, by rain erosion (Fig- 8). Older palsas are partially destroyed by thermal karst. It is clear lhat the active layer thickness has changed during ihe past 7080 years, influenced by rluciualions in air temperature. Some palsas have presumably deteriorated by cracking, flattening out. etc.. but in general the palsa bogs have remained. Palsas are amazingly stable: some have been crossed by heavy trucks or power poles, but the permafrost has remained for dozens of years following such disturbances. The frozen core of each peat hillock is covered by a thick pear layer, which is an efficient thermal insulator, meaning that positive summer temperatures by the end of summer. The core remains frozen for centuries, although positive average annual temperatures ai the southern margin of palsa distribution could lead to their thawing.

6. Conclusion

The present results demonstrate that the palsa at the southern margin of its distribution on the Kola Peninsula has not thawed out during the past 80 years.

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