Beskydy, 2009, 2 (2): 195–200 © Mendelova zemědělská a lesnická univerzita v Brně ISSN: 1803-2451
Habitat preferences of small terrestrial mammals in the mountain forest clearings J. Suchomel1, J. Krojerová-Prokešová 2, M. Heroldová2, L. Purchart1, M. Barančeková2, M. Homolka2 doc. Ing. Josef Suchomel Ph.D., Ing. Luboš Purchart, Ph.D., 1Institute of Forest Ecology, Mendel University of Agriculture and Forestry, Zemědělská 3, 61300 Brno, Czech Republic, e-mail:
[email protected] Mgr. Jarmila Krojerová-Prokešová, RNDr. Marta Heroldová,Ph.D., Mgr. Miroslava Barančeková, Ph.D., RNDr. Miloslav Homolka, CSc. 2Institute of Vertebrate Biology, AS CR, Květná 8, 60365 Brno, Czech Republic, e-mail:
[email protected]; Abstract: Suchomel J., Krojerová-Prokešová J., Heroldová M., Purchart L., Barančeková M., Homolka M. 2009: Habitat preferences of small terrestrial mammals in the mountain forest clearings – Beskydy, 2 (2): 195–200 In last ten years strong intention to replace forest monocultures of coniferous species to mixed coniferous – broadleaved stands which are close to nature composition is promoted. Mountains forests under study are of different character. In Beskydy Mts forests of beech-spruce mixture prevail but in Jeseniky spruce monocultures prevail. In both, reforestation activities are complicated by impact of rodents and influence of industrial immission. Small mammal species were monitored during two successive years on clearings with artificial plantations. In both total abundance of species was similar but with different dominance of the species. Under influence of beech mast year Apodemus flavicollis was dominant in Beskydy Mts but Myodes glareolus in Jeseniky Mts. Higher dominance of Soricidae was in Jeseníky Mts (19%) against Beskydy (6%). The diversity and equitability was similar in both (Jeseniky Mts – 1.63, Beskydy Mts – 1.49; 0.84 resp. 0.72). Notable was the high dominance of Microtus agrestis (23 resp. 27%) in both. Abundance of the dominant species was synchronized. Canonic correspondence analyses (CCA) of clearing characteristics show the significant preferences of M. agrestis for higher elevation, more grassy and grassy wastage (higher humidity) environment. This was above all problem of emission clearings. As to M. glareolus, forest weeds preferably of Rubus sp. were responsible for its dominance. These results can contribute to understand rodent habitat preferences and help in prevention against their impact by the way of herb layer management. Key words: mountains, forest clearings, small mammal species, habitat preference Introduction Small terrestrial mammal species are natural and important part of mountain areas forests. From the forestry point of view most of the species significantly influence forest regeneration. But the more detailed information about the mutual relations is low especially when new situations in forestry management strategy starts. In reforestation, proportion of broad leaved trees compared to coniferous will increase in all Czech Republic areas. With this
strategy broad leaved trees are more negatively influenced by small mammal species especially by rodents (Bryja et al. 2001a, b). Mountain forests, predominantly coniferous are above all also negatively influenced by industrial immissions (mostly in Beskydy Mts) and by destructive influence of strong winds (hurricanes mostly in Jeseniky Mts). Under these conditions some clearings are of large extent. Forest regeneration by forest plantings on such clearings needs a special attention to all negative factors.
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J. Suchomel, J. Krojerová-Prokešová, M. Heroldová, L. Purchart, M. Barančeková, M. Homolka
The knowledge of environmental preferences of particular small mammal species, especially Microtus agrestis reported as a pest of young trees in mountains, is extremely important. It may help in better management of clearings as prevention against negative impact of rodent species. Small mammal communities were studied in Jeseniky Mts by Nesvadbova and Gaisler 2000 and in Beskydy Mts by Bryja et al. (2001b) and Suchomel et al. (2007), but in our contribution we concentrated on artificial forest plantation areas (various types of clearings in various elevations, not only immission one) and influence of habitat on small mammal distribution there. Another question was whether, in each of the two mountains system studied, same or different response of terrestrial small mammal communities on habitat variability would be expressed. Material and methods The study was carried out in two mountain areas: Jeseníky Mts and Moravian-Silesian Beskydy Mts. Small mammal communities were monitored during two successive years (2007 and 2008) on clearings with artificial plantations. At the each study area 18 monitoring plots were
established, which differed in the habitat structure and age. Most of the plots were broadleaved trees plantations. Elevation extent was from 550 to 1205 m a.s.l. in Beskydy Mts and from 680 to 1185 m a.s.l. in Jeseniky Mts. The trapping was realised during autumn. Snap traps were laid in lines of 34 traps each, 3 m apart so the total length of each line was about 100 m. Traps were baited with peanut butter, exposed for three successive nights and inspected daily. The complete trapping effort was 7344 trap-nights, resulting in a total of 501 captured small mammals. To assess diversity of small mammal communities, frequently used indices, such as the number of species (S), Shannon’s index of diversity based on natural logarithms (H0), and Shannon evenness (E = H0/Hmax), were used. Vegetation composition of each monitoring plot was assessed (Table 1). The effect of habitat vegetation structure on small mammal community composition was analysed by canonical correspondence analysis (CCA) using Canoco 4.5 for Windows (Ter Braak & Šmilauer, 2002). We used Monte-Carlo permutation tests (499 permutations) to determine significance of the first canonical axis (Ter Braak & Šmilauer, 2002). Input data were square-root transformed.
Tab. 1: Inter set correlations of environmental variables with canonical axes. Abbreviations of vegetation variables used in biplot projection are given. Mapping variables elevation Monitoring plot (MP)
age
CCA1
CCA2
elevation
−0.171
−0.288
0.368
−0.002
agecl
cover of herb layer
coverE1
−0.198
0.057
height of herb layer
heightE1
0.139
0.184
cover of grasses
grasscl
−0.302
0.241
cover of forest weeds
weedcl
0.176
−0.036
cover of forbs
forbscl
0.157
−0.199
amount of grassy wastage
wastcl
−0.238
0.233
coverE2
0.292
0.116
height of shrub layer
heightE2
0.469
0.076
clearings
clearings
0.060
−0.185
sterile forests without understorey
sterilfor
0.029
0.089
cover of shrub layer
Surrounding of the MP
Abbreviations
old forests with understorey fertile beech/oak forests coniferous forests cover of grasses cover of forest weeds and other forbs
oldfor
−0.099
0.127
beech/oak
−0.086
0.382
confor
−0.105
0.242
grassur
−0.179
0.116
0.048
−0.188
weed/forbs
cover of herb layer over 50%
E1over50
−0.168
−0.150
cover of shrub layer over 50%
E2over50
0.125
−0.157
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Habitat preferences of small terrestrial mammals in the mountain forest clearings
Results and discussion In both mountains localities total abundance of species was similar but with different dominance of the species. Under influence of beech mast year in autumn 2007, Apodemus flavicollis was the most dominant in Beskydy Mts but Myodes glareolus in mostly coniferous forests in Jeseniky Mts. Higher dominance of Soricidae was in Jeseníky Mts (19%) against Beskydy (6%). This was also reported by Nesvadbova and Gaisler (2000) where dominance of Sorex araneus was about 50% in Jeseníky Mts immission clearings. The diversity and equitability was similar in both (Table 2). By Bryja et al. 2001b highest diversity of species was found in Beskydy Kněhyně Mt. in small clearings with presence of both, forest as well as open habitats small mammal species. Notable was the high dominance of Microtus agrestis (23 resp. 27%) in both mountain areas. In Beskydy immission clearings in Smrk Mt. field vole was a dominant species (Bryja et al. 2001b). The CCA performed to relate habitat effects on small mammal species abundance was significant (Monte Carlo permutation test of the first canonical axis: F-ratio = 12.352, P = 0.02). The first two canonical axes accounted for 20.8% and 12.5% of explained variance of species data,
respectively. Explained variance of species-environment relation was 47.1% and 28.4% by CCA axis 1 and CCA axis 2, respectively (Table 3). The first canonical axis of the CCA was mainly positively related to presence of fertile beech forests in the surrounding of the clearing. It represents the gradient from higher elevation with higher number of clearings in the surrounding of the monitoring plot (preferred by Microtus agrestis and Sorex araneus) to lower elevation in more forested areas (preferred by Microtus arvalis). The second canonical axis was mainly positively related to height of shrub layer. It represents the gradient from young clearings with high cover of herb layer formed mainly by graminoid species and presence of grassy wastage (preferred by Arvicolinae and by Sorex araneus) to older clearings with higher height and shrub cover with weed forest species (as Rubus sp.) dominating in herb layer (preferred by genus Apodemus) (Table 1, Fig. 1). By Heroldova et al. (2008a) distribution of small mammal species in artificial plantations is related above all to food availability and also on density of cover to shelter. Strong preference of field vole for grasses and grassy wastage is in accordance with our findings as particularly planting infested by grass cover is more exposed to harmful effects of
Tab. 2: Basic characteristics of small terrestrial mammal communities obtained at two localities in the Jeseníky Mts and Beskydy Mts. Jeseníky Mts
MS Beskydy Mts
2007
2008
07/08
2007
2008
07/08
Apodemus flavicollis
10
34
44
15
78
93
Apodemus sylvaticus
-
2
2
1
10
11
Apodemus sp.
-
2
2
-
-
-
Myodes glareolus
25
47
72
7
68
75
Microtus arvalis
9
5
14
2
4
6
Microtus agrestis
30
38
68
20
29
49
-
-
-
1
-
1 16
Microtus subterraneus Sorex araneus
38
6
44
14
2
Sorex minutus
1
-
1
-
-
-
Crocidura suaveolens
2
-
2
-
-
-
Muscardinus avelanarius
-
-
-
1
-
1
115
134
249
61
191
252
7
6
7
8
6
8
Number of trap-nights
1836
1836
3672
1836
1836
3672
I (ind./100 trap-nights)
6.3
7.3
6.8
3.3
10.4
6.9
Shannon diversity index
1.572
1.460
1.626
1.611
1.303
1.492
Shannon evenness
0.808
0.815
0.836
0.775
0.727
0.717
Total Number of species
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J. Suchomel, J. Krojerová-Prokešová, M. Heroldová, L. Purchart, M. Barančeková, M. Homolka
Tab. 3: Results of canonical correspondence analysis. Statistic
Axis 1
Axis 2
Axis 3
Axis 4
Eigenvalues
0.271
0.163
0.091
0.050
Species-environment correlations
0.782
0.638
0.606
0.488
Total variance 1.302
Cumulative percentage variance of species data
20.8
33.3
40.4
of species-environment relation
47.1
75.5
91.3
44.2 100
Sum of all eigenvalues
1.302
Sum of all canonical eigenvalues
0.575
1.0
this species. On some plantations grasses of genus Calamagrostis were dominant. By Heroldová et al. (2008a) the cover of grasses was highly correlated with the level of impact on young trees (r = 0.8; p = 0.01). On large immissions clearings on Smrk Mts. grasses were also the dominant species. On that area great damage above all on broad leaved young trees was recorded (Heroldová 1995, 2002). The same situation was known from the other mountains immission areas as from Krušné Hory Mts. (Tichý 1977, 1987, Heroldová 1992). Open area grasses ecosystems
become suitable environment for field vole outbreaks and this species was the main pest species damaging the tree plantations (Bryja et al. 2001a, b). Also shrub cover on plots was in negative correlation with damage (r = −0.51; p = 0.17) but with no significant influence. On such plots mice species were in dominance. By Heroldová et al. (2008b) these species impact on forest regeneration is by tree seed predation.
Microarv
beech/oak
grasscl wastcl
confor
grassur
heightE1 oldfor
sterilfor
CCAAxis2
coverE1
coverE2 Apodflav
Sorexar Microagr Myodes
weedcl
heightE2 agecl
Apodsyl
E1over50
-0.8
E2over50 clearings weed/forbs forbscl elevation
-0.8
CCAAxis1
Fig. 1: The first factorial plane of the canonical correspondence analysis
0.8
Habitat preferences of small terrestrial mammals in the mountain forest clearings
Conclusion In both of the mountains same habitat preferences of the small mammal species were observed. Large clearings overgrown by grasses are the preferable habitat of the field vole. The forest regeneration by artificial tree plantation is then the most endangered on these localities. Vegeta-
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tion removals with herbicides, grazing or cutting are widely recognized control techniques for many rodent species (Gill 1992). But the herb layer manipulation as vegetation removal on reforestation plots is costly and in mountain terrain difficult to manage.
Acknowledgements The study was supported by NAZV QH72075, MSM 6215648902, and by LC06073.
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