Initial effects of afforestation on ground beetle (Coleoptera: carabidae) assemblages in Irish grasslands and peatlands
Erkki Palmu (2009)
[email protected] Supervisors: Anne Oxbrough and Kajsa Åbjörnsson Examinator: Per Nyström Examination paper - 30 ECTS credits Environmental Science
Contents Preface ....................................................................................................................................... 1 Abstract ..................................................................................................................................... 2 1
Introduction ....................................................................................................................... 3
2
Materials and Methods ..................................................................................................... 4
3
4
2.1
Sampling design ........................................................................................................... 4
2.2
Environmental characteristics ..................................................................................... 5
2.3
Species traits ................................................................................................................ 6
2.4
Data analysis ............................................................................................................... 6
Results ................................................................................................................................ 8 3.1
Species richness and abundance ................................................................................. 8
3.2
Carabid beetle assemblages ...................................................................................... 11
3.2.1
Grassland vs. Peatland features .......................................................................... 11
3.2.2
Open vs. Hedgerows features ............................................................................. 14
Discussion......................................................................................................................... 15 4.1
Data analysis ............................................................................................................. 15
4.2
Species richness and abundance ............................................................................... 16
4.3
Carabid beetle assemblages ...................................................................................... 17
5
Conclusions ...................................................................................................................... 18
6
Acknowledgements ......................................................................................................... 19
7
References ........................................................................................................................ 19
8
Appendix 1 ....................................................................................................................... 20
9
Appendix 2 ....................................................................................................................... 23
Preface Beauty lies within. An expression true for most ground beetles. Unfortunately, they do not look very pretty even when viewed through a stereo-microscope at 50x magnification. However, these perfectly adapted creatures play a vital role in many ecosystems. Their complexity and amazing diversity of design truly amazes me. Female carabids can be caring mothers; Mrs. Pterostichus anthracinus guards her eggs until they hatch (Thiele, 1977). Ground beetles can be carnivorous, phytophagous or omnivorous. Most species are mainly predatory but some species feed mostly on e.g. plant material or scavenge arthropod carcasses. Adding to their ecological significance, carbids can also be useful as biological indicators of different habitats. They are indeed true marvels of nature! In this study, ground beetles were used for investigating changes in ground-dwelling invertebrate diversity in the early stages of sitka spruce afforestation. Afforestation is on the rise in Ireland. Non-native tree species like sitka spruce are used to great extent. Therefore there is a need for more knowledge concerning how this change will affect the overall landscape biodiversity.
1
Abstract In Ireland exotic tree species such as the sitka spruce (Picea sitchensis) make up a large portion of new forests established since the middle of the 20th century. The Irish forest cover has expanded from 1% in the early 20th century to 10% today and a further increase in forest cover to 14.5% by 2030 is supported by government policies. The BIOFOREST (Biodiversity in Irish Plantation Forests) project, a collaborative project involving amongst others the University College of Cork, project was a large-scale 5-year project running from 2001 to 2006 with the aim of gathering basic information on biodiversity in Irish plantation forests. The present study was laboratory based which involved the identification to species level of ground beetles (Coleoptera: Carabidae) which were caught in pitfall traps set previously during the Bioforest project. A paired-site approach was used where unplanted improved grassland, wet grassland and peatland sites (which are typically used for afforestation in Ireland), were matched with similar sites, in terms of underlying habitat type, after they had undergone afforestation. The present study aimed at providing more insight into how species composition changes during the early stages of the forest cycle, and the potential indicators derived can be used to inform future management plans. The study showed that afforestation initially causes a large drop in effective species richness in improved grasslands and that rare species disappear or decline in peatlands. Initially wet grasslands experience less adverse effects on carabid diversity than improved grasslands. However, the relatively rare Carabus clatratus was present in unplanted wet grasslands and declined after planting, whereas it was not at all present in improved grasslands. Effective species richness in wet grasslands and peatlands did not differ significantly but peatlands support very rare species like Carabus nitens, which are lost after afforestation. It might be preferable to focus afforestation efforts in a balanced selection of improved and wet grasslands and to avoid afforestation of peatlands. Future research on effects of afforestation on Carabid assemblages should if possible take into account the entire forest rotation, since forest dwelling carabids may migrate into the forest at later stages. Furthermore, complementing the sampling design with alternative sampling methods such as sweeping of vegetation would ensure adequate representation of all the species in the carabid assemblage.
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the abiotic or biotic state of the environment or represents the impact of environmental change on habitats, communities or ecosystems. It can also indicate the diversity of other species (McGeoch, 1998; Rainio and Niemelä, 2003). A good indicator is measurable, precise, consistent, relevant and sensitive (e.g. Groom et al., 2006). Environmental change can cause different effects in the indicator, including physiological changes or changes in species number or abundance. The response of the species can be seen within the organism (e.g. heavy-metal concentrations), at species level (species number and abundance) or at the community level (relations between species, e.g. pest–predator). Changes in species richness or abundance can be directly caused by change in abiotic and/or biotic factors (Blake et al. 1996) or indirectly by change of species assemblage of other species (Haila et al. 1994). The carabid family as a group can function as sensitive indicators of temperature and moisture gradients and different habitat types support characteristic species communities (Thiele, 1977; Butterfield, 1995). As an indicator for biodiversity, ground beetles have been used frequently in the past. It has been recognised that the carabid family can be used to reflect the way in which invertebrate communities respond as a whole to the afforestation of open habitats (Butterfield, 1995; Mullen et al., 2008). In the present work, ground beetles from the BIOFOREST catch were used which gives valuable insight into how species composition changes during the early stages of the forest cycle. Also the potential indicators derived can be used to inform future management plans. The aim of the present study was to: (1) assess the diversity of Irish ground beetles in three habitat typically used for afforestion: improved grasslands, wet grasslands and peatlands; (2) identify potential indicators of biodiversity using environmental variables and species traits; (3) suggest possible management measures that will minimise negative impact on carabid diversity.
1 Introduction Habitat disturbance and destruction along with the introduction of non-native species plays an important role in shaping forest ecosystems. In Ireland exotic tree species such as the sitka spruce (Picea sitchensis) make up a large portion of the plantation forests established since the middle of the 20th century. The Irish forest cover has expanded from 1% in the early 20th century to 10% today and a further increase in forest cover to 14.5% by 2030 is supported by government policies (Forestry 2030, 2009). As a result, forest habitats comprised of exotic tree species have increasing influence on biodiversity. As with all European member states, forests in Ireland have to be managed in a sustainable way, which means that enhancement of biodiversity must be considered during all stages of the forest cycle (EPA, 2008). The Forest Biodiversity Research Programme PLANFORBIO (Planning and Management tools for Biodiversity in a range of Irish Forests) is a collaborative project involving amongst others the University College of Cork and Coillte Teoranta, Ireland’s largest forestry company. PLANFORBIO runs from 2007 until 2012 and aims at improving knowledge of floral and faunal diversity in Ireland’s forest estate. The programme looks at plantation forests composed of single species of conifers and mixtures of conifers with broadleaves, both in first and second rotation (Planforbio, 2009). The ‘Biodiversity in Irish Plantation Forests’ project (BIOFOREST) was a precursor to the current PLANFORBIO programme. It was a largescale 5-year project running from 2001 to 2006 with the aim of gathering basic information on biodiversity in Irish plantation forests. As part of BIOFOREST, ground-dwelling ground beetles (Coleoptera: Carabidae) to be used as biological indicators were collected from late May to late July during the summer of 2004, using pitfall traps (BIOFOREST, 2006). A biological indicator can be defined as a species or a species group that reflects 3
2 Materials and Methods This was a laboratory based study which involved the identification to species level of carabid beetles sampled with pitfall traps during the BIOFOREST project. The sampling protocol is outlined in Oxbrough et al. (2006) and a brief summary is given here. The ground beetles were identified to species level using Luff (2007) and to a lesser extent Forsythe (2000). In addition the methodology outlined in Martin L. Luff (1990) was used to distinguish the recently separated species Pterostichus nigrita and Pterostichus rhaeticus.
2.1 Sampling design Experimental design A paired-site approach was used where sites which had not been planted were matched, in terms of underlying habitat type, with sites which had undergone afforestation of sitka spruce. Paired-site sampling designs have been utilised successfully in previous studies (Kladivko et al., 1997; Berger et al., 2002; Barnett et al., 2003; Oxbrough et al., 2006). This approach allows the impacts of afforestation on ground beetle species composition to be investigated in one field season rather than over a number of years. Sampling was carried out in three habitats which are typically used for afforestation in Ireland: (1) improved grasslands, (2) wet grasslands and (3) peatlands. The sites encompassed a wide spread across Ireland but also reflected current trends in afforestation (Figure 1). A total of 16 site pairs consisting of 136 plots were used in this study. The improved grasslands (50 plots) and wet grasslands (62 plots) consisted of 6 pairs each and the peatlands (24 plots) comprised 4 pairs.
Figure 1. Distribution of the study sites, each point represents a pair of one unplanted and one planted site. The three main habitats are (●) improved grassland; (▲) wet grassland and (■) peatland.
habitat that has been reseeded and/or regularly fertilised. Furthermore it is heavily grazed and/or used for silage making. Improved grassland typically has poor plant species richness. Lolium spp. is usually abundant and may entirely dominate the sward (Fossitt, 2000). Common plant species in the unplanted improved grassland sites of the present study were: Lolium perenne, Agrostis stolonifera, Holcus lanatus and Cynosurus cristatus. Wet grassland is defined by its occurrence on wet or waterlogged mineral or organic soils that are poorly-drained or, in some cases, subjected to seasonal or periodic flooding. On sloping ground, wet grassland is mainly confined to clay-rich gleys and loams, or organic soils that are wet but not waterlogged. Plant speciescomposition varies considerably. Grasscover in wet grassland should exceed 50%, except in areas where rushes or small sedges predominate. The total cover of reeds, large sedges and broadleaved herbs should be less than 50% (Fossitt, 2000). Common plant species in the unplanted wet grassland sites were: Juncus acutiflo-
Study sites Habitats were defined using Fossitt (2000). Improved grassland is an intensively managed or highly modified agricultural
4
rus, J. effuses A. stolonifera and Molinea caerulea. Peatlands are subdivided into two main types, bogs and fens. In bogs, almost all inputs of water to the system are derived from precipitation and acid, oligotrophic peat deposits accumulate. Fens are, in addition to precipitation, fed by groundwater or moving surface waters. They have a higher nutrient status than bogs and can be either acid or base-rich. Flushes, which may or may not form peat, are included with fens as they support similar vegetation communities (Fossitt, 2000). Common plant/moss species in the unplanted peatland sites were: M. caerulea, Calluna vulgaris, Eriophorum angustifolium, E. vaginatum and Sphagnum spp. mosses.
traps were arranged in a line within the hedgerows, with each trap spaced 2 m apart. The traps were in use during MayJuly (63–65 days) in the year 2004. During this period they were changed three times, approximately every 21 days.
2.2 Environmental characteristics The management regime varied among the habitat types: the unplanted improved grasslands were subject to heavy grazing and were usually fertilised at least once per year. The wet grasslands and the peatlands were generally under low to heavy grazing pressure, but roughly half of the wet grasslands were also subject to annual silage cutting and fertilisation. In the planted sites the ground was generally prepared by mounding, with drains established at frequent intervals. However, drainage was much less common in improved grassland. Fertiliser was generally applied in planted wet grasslands and peatlands but not in the improved grasslands. Use of herbicides was most frequent in the grasslands in the years following planting. In all planted habitats the spruce trees were planted with standard spacing for conifers of 2 m × 2 m. Mean tree height was 3.1 m (S.D. ±1.2) in improved grasslands, 4.3 m (S.D. ±2.6) in wet grasslands and 1.6 m (S.D. ±0.7) in the peatlands. The following environmental variables were measured at each sampling plot: Gr veg = ground vegetation cover 0-10cm Herb lay = herb layer vegetation (10-50cm) cover Drainage = amount of drainage on an estimated scale (1-3) of poormoderate-good, with ‘poor’ (1) indicating very wet conditions and ‘good’ (3) indicating dry conditions Grazing = amount of grazing on an estimated scale (0-3) of none-lowmedium-high, with ‘none’ (0) indicating no sign of mammal grazing and ‘high’ (3) indicating high level of mammal grazing
Sampling protocol Two types of sampling plots were established. Plots that were located in areas of homogenous vegetation cover which took into account the major vegetation types present were termed ‘open’ plots. Hedgerows are typical landscape elements in grasslands which may contribute to the biodiversity of a site and were also sampled. These were termed ‘hedgerow’ plots. Comparable areas (i.e. open and hedgerow) within each site pair were sampled. Plots were located a minimum of 50 m apart and at least 50 m from the edge of the site. Hedgerow plots were not sampled in the peatlands as these habitat features were not present in this site type. Pitfall traps were used to sample the ground-dwelling carabid assemblages within and among the habitat types. The pitfall traps consisted of a plastic cup (7 cm diameter by 9 cm depth), which had two drainage slits cut 1cm from the edge of the cup and were filled to 1cm depth with ethylene glycol. The cup was placed into a whole made with a bulb corer so that the edge of the cup was aligned with the surface of the ground. The open plots consisted of five pitfall traps, which were arranged in a 4 m × 4 m grid, with one trap at each corner and one in the centre in the standard plots. In the hedgerow plots the 5
LOI = organic matter content expressed in percent of matter lost on ignition. Some pitfall trapping plots did not have matching floristic plots; therefore some plots have extrapolated values for the environmental variables.
Forest = relative abundance of carabids with preference for forest habitats Finally the carabids were categorised by body size. The classification of beetle size used the same criterion as that of Mullen et al. (2008): Small = relative abundance of small sized carabids (16mm) Source mainly used for habitat preferences included Luff (2008), Forsythe (2000) and the Habitas (2009) website of Irish ground beetles.
2.3 Species traits Since flight capable carabids (high dispersal capability) are associated with frequently disturbed habitats and flightless carabids (low dispersal capability) are associated with more stable habitats (Thiele, 1977), carabids were divided into three categories of wing development based on their relative abundance within a particular sample: Brachy = relative abundance of brachypterous carabids with underdeveloped wings Dimorph = relative abundance of dimorphic carabids with either fully developed or underdeveloped wings Macro = relative abundance of macropterous carabids with fully developed wings Furthermore the carabids were divided into three categories by moist preference: Dry = relative abundance of carabids with preference for dry habitats Inter = relative abundance of carabids with preference for habitats of intermediate moist type Moist = relative abundance of hygrophilous carabids with preference for wet habitats Habitat preference also divided the Carabid assemblage into three categories: Open = relative abundance of carabids with preference for open habitats Shade = relative abundance of carabids with preference for shaded habitats
2.4 Data analysis To examine the differences in ground beetle species composition within and between the habitat types, Global Non-metric Multidimensional Scaling (NMS), Multi Response Permutation Procedures (MRPP) and Indicator Species Analysis (ISA) were used. NMS in PC-ORD is largely based on Mather's program NMS (Mather 1976). The central computational algorithm in NMS is based on Kruskal (1964). The NMS ordinations were performed with the PC-ORD ‘auto-pilot’ setting activated. PCORD selects the dimensionality by comparing the final stress values among the best solutions, one best solution for each dimensionality. Additional dimensions are considered useful if they reduce the final stress by 5 or more (on a scale of 0-100). The software selects the highest dimensionality that meets this criterion. Final dimensionality was confirmed by checking scree plot (stress in relation to dimensionality). The NMS auto-pilot was pre-set to use: Sørensens distance measure; random starting coordinates; 250 real runs and 250 randomised; 500 iterations. MRPP is a non-parametric procedure for testing the hypotheses of no difference in paired-sample data. Since the sampling design comprises paired sites, a Blocked 6
MRPP (MRBP) would have been preferable. But the sampling design was not balanced, so a MRPP test was performed instead. Indicator Species Analysis (ISA) can be used with MRPP; it supplements the test of no multivariate difference between paired samples with a description of how well each species separates between pairs (McCune et al., 2002). The ISA was used to describe the affinity of a particular species within each habitat type for either planted or unplanted conditions. It combines information on the concentration of species abundance and the faithfulness of occurrence of a species in a particular group. From this it produces indicator values for each species in each group. These are tested for statistical significance using a Monte Carlo randomisation technique (McCune et al., 2002). The PC-ORD ISA uses Dufrene and Legendre’s (1997) method of calculating species indicator values. The PC-ORD for Windows V5.10 software bundle was used for NMS ordination, MRPP and ISA analysis. SPSS V17.0 was used for paired t-test analysis. The Shannon index and ‘true diversity’ was used to further characterise the impact of afforestation on species richness in the different habitats. The Shannon index (𝐻′) is given by:
Where S = total species richness, ni = abundance of species i and N = abundance of all species. The latter part of the equation (in square brackets) is a bias correction module (Chao & Shen, 2003). To facilitate a direct comparison between the habitats, the Shannon index was converted to ‘true diversity’, i.e. the exponential of the Shannon index (𝑒 𝐻′ ). True diversity is a measure of the effective number of species in a habitat (MacArthur, 1965; Hill, 1973; Jost, 2006). For example, if one community has a true diversity of 5 and another has 15 based on the same index; the second community is three times as diverse as the first. This conclusion could not have been drawn from the raw index alone, since it uses a non-linear scale. In order to facilitate a comparison of the abundance data between sub-habitats (Figure 2 and Figure 3) the data was standardised so that all the sub-habitats had equal number of sampling sites. This was done by dividing the carabid abundance from one habitat by the number of sampling sites (n) in the same habitat; then multiplying by 8 which was the lowest number of sampling sites from a single sub-habitat (planted improved grassland hedgerows, Appendix 1). Otherwise ‘raw’ unbalanced data was used for data analysis.
Equation 1. 𝑆
𝐻 ′ = − ∑(𝑛𝑖 ⁄𝑁)ln(𝑛𝑖 ⁄𝑁) − [(𝑆 − 1)⁄2𝑁] 𝑖=1
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(Figure 3). With the exception of Nebria brevicollis, these species were present in all of the habitats. Neither the planted improved grassland hedgerows nor the unplanted and planted peatlands supported N. brevicollis. However, abundance of all six species differed greatly among the habitats. A relatively large number of P. melanarius along with most of P. niger and A. parallelepipedus were caught in the planted open improved grasslands. Furthermore, C. granulatus and A. fuliginosum were both mainly caught in open grasslands and N. brevicollis mainly in the unplanted open improved grasslands (Figure 3).
Results
3
3.1 Species richness and abundance In total 16,774 individuals from 74 species of Carabid beetles were sampled across the three habitat types. The highest species richness and abundance was in the unplanted open improved grasslands and the lowest was found in the planted peatlands (Figure 2). For more detailed species and environmental data see Appendix 1 and Appendix 2. The most abundant species was Pterostichus melanarius which accounted for 25% of the total catch across all habitats and the top six species accounted for 66.2% of the total catch Species richness
Open Hedgerow Open Hedgerow Open
Improved grasslands
Wet grasslands
Peatlands
Carabid abundance
0
500
Standardised abundance 1000
1500
2000
2500
3000
3500
Planted Unplanted Planted Unplanted Planted Unplanted Planted Unplanted Planted Unplanted
Species richness 0
5
10
15
20
25
30
35
40
45
50
Figure 2. Original carabid species richness and standardised abundance across the 10 sub-habitats. Also displaying ± S.E. for each habitat.
8
Open Hedgerow Open Hedgerow Open
Improved grasslands
Wet grasslands
Peatlands
Pterostichus melanarius
Carabus granulatus
Planted Unplanted Planted Unplanted Planted Unplanted Planted Unplanted Planted Unplanted 0
250
500
750
1000
1250
1500
0
250
500
Open Hedgerow Open Hedgerow Open
Peatlands Wet grasslands Improved grasslands
Open Hedgerow Open Hedgerow Open
1500
Unplanted Planted Unplanted Planted Unplanted Planted Unplanted Planted Unplanted 250
500
750
1000
1250
1500
0
250
500
Pterostichus niger Peatlands
1250
Planted
0
Wet grasslands
1000
Agonum fuliginosum
Nebria brevicollis
Improved grasslands
750
750
1000
1250
1500
Abax parallepipedus
Planted Unplanted Planted Unplanted Planted Unplanted Planted
Unplanted Planted Unplanted 0
250
500
750
1000
1250
1500
0
250
500
750
1000
1250
1500
Figure 3. Standardised abundance of the top six most common carabid species before and after planting.
9
Open Hedgerows Open Hedgerows Open
Peatlands Wet grasslands Improved grasslands
Planted Unplanted Planted Unplanted Planted Unplanted Planted Unplanted Planted
Unplanted 0
2
4
6
8
10
12
14
16
18
Figure 4. Exponential of the Shannon diversity of the carabid assemblage in each of the 10 sub-habitats. Also displaying ± S.E.
There was a considerable decrease in Shannon diversity in the improved grasslands and the open wet grasslands after planting (Figure 4). In both open improved grasslands and hedgerows of improved grasslands the effective number of species had decreased by approximately half after planting. The open wet grasslands experienced a drop by roughly a quarter.
The remaining habitats showed no significant change in effective species richness after planting. Across the sites some scarce species were sampled in the pitfall traps (Table 1). These species differed from the others by being present in only one of the sub-habitat types. Rare or threatened species among the catch were Carabus clatratus, Carabus nitens and Chlaenius nigricornis. The large and amphibious C. clatratus, which was sampled mainly in unplanted wet grasslands and peatlands, is local and in general decline in Western Europe and extinct in England and Switzerland. The smaller C. nitens, which was sampled exclusively in unplanted peatland, is strongly decreasing in frequency in many areas of Europe. It is very local all over its distribution area in central and northern Europe and the Northern Irish populations appear to be somewhat important in a European context since suitable peat-rich habitats still exist there (Habitas, 2006). The medium sized Chlaenius nigricornis, which was sampled only in unplanted grasslands, appears to decline all over its northern European range. Furthermore, it has experienced a significant decline in Eastern areas of Ireland and Britain. This pattern has been linked to
Table 1. The 10 sub-habitats and carabid species only found in sites belonging to one of these subhabitats. Species abundance can be seen in brackets after species name. Unplanted open improved grasslands Planted open improved grasslands Unplanted improved grassland hedgerows Planted improved grassland hedgerows Unplanted open wet grasslands Planted open wet grasslands Unplanted wet grassland hedgerows Planted wet grassland hedgerows
Amara familiaris (1) Amara ovata (12) Amara similata (1) Bembidion lunulatum (29) Bradycellus verbasci (1) Demetrias atricapillus (2) Ophonus rufibarbis (1) Badister sodalis (1) Bembidion clarkii (7) Notiophilus biguttatus (2) -
Unplanted peatlands
Carabus nitens (4) Nebria salina (21) Notiophilus geriminy (1) Paranchus albipes (2)
Planted peatlands
Patrobus assimilis (2)
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increased soil acidification from agricultural and industrial sources (Habitas, 2006).
3.2 Carabid beetle assemblages 3.2.1 Grassland vs. Peatland features NMS and MRPP For the open habitat sites NMS recommended a three dimensional solution which accounted for 79.5% of the variation in the original species data (Figure 5). Axis 3, 2 and 1 accounted for 31.3%, 27.3% and 20.9% respectively. The two dimensions that accounted for most of the variation are shown in Figure 5. As axis 1 did not represent any differences in the species assemblage by habitat or planting type it is not shown here. Across Axis 3 the unplanted improved grassland sites were separated from all of the other sites. The unplanted and planted sites from the other habitats were also separated along this axis. The unplanted and planted wet grasslands and planted improved grasslands formed a tightly clustered group on the ordination and were not separated by habitat or planting regime. There was a significant difference in assemblage structure between the unplanted and planted sites of both peatlands (MRPP: A = 0.095, p = 0.000) and improved grasslands (MRPP: A = 0.180, p = 0.000) but not wet grasslands (MRPP: A = 0.012, p = 0.124). The only variable that was positively related to Axis 3 was relative abundance of carabids with preference for shaded habitats. Variables negatively related to axis 3 were total species richness, grazing, ground vegetation cover and relative abundance of macropterous carabids. Across Axis 2, peatland sites were separated from those of the grasslands. Variables positively related to axis 2 were organic matter content (LOI), and relative abundance of carabids with preference for dry habitats. Variables negatively related to axis 2 were ground drainage and soil pH.
Figure 5. NMS ordination graph of planted and unplanted open-type plots. Habitat variables with Pearson correlation square (r2) value >0.1 are shown. Final stress for 3-dimensional solution = 15.54; final instability = 0.00098. Habitats: (○) unplanted improved grasslands, (●) planted improved grasslands, (□) unplanted wet grasslands (■) planted wet grasslands, ( ) unplanted peatlands and (▲) planted peatlands.
Paired samples test Species traits Among the species traits, paired samples test (Table 2) showed that relative abundance of medium sized carabids was significantly higher in unplanted improved grasslands and unplanted peatlands. On the other side, relative abundance of large carabids was significantly higher in planted improved grasslands and planted peatlands. Relative abundance of macropterous carabids was significantly higher in unplanted improved grasslands. In contrast there was a significantly higher relative abundance of brachypterous carabids in planted improved grasslands. In the peatlands there was a significantly higher abundance of moist habitat preferring carabids in unplanted sites. Also there was a significantly higher relative abundance of habitat generalist carabids and intermediately moist habitat preferring carabids in planted peatlands.
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Table 3. Paired samples test of unplantedplanted habitat open habitat sites. Species traits are tested by carabid species richness.
Environmental variables Paired samples test of environmental variables (Table 2) showed that ground vegetation cover was significantly higher in unplanted improved grasslands, unplanted wet grasslands and unplanted peatlands. Grazing intensity was significantly higher in unplanted improved grasslands and unplanted peatlands. Soil pH was significantly higher in unplanted improved grasslands. Herb layer cover was significantly higher in planted wet grasslands.
Improved grasslands Unplanted-Planted Species trait
t
n
p
Brachypterous
-4.851
6
0.005
Macropterous
7.424
6
0.001
Medium
5.736
6
0.002
Open
4.049
6
0.010
-7.625
6
0.001
Forest
Wet grasslands Unplanted-Planted Species trait
Indicator Species Analysis The ISA of the open sites (Table 4) showed that 5 out of 6 of the six most common species were among the indicator species. The only one of the six most common species not present was Carabus
n
p
Brachypterous
-3.014
6
0.030
Macropterous
8.621
6
0.000
Medium
9.296
6
0.000
Large
-5.335
6
0.003
t
n
p
Grazing intensity
4.318
6
0.008
Ground veg cover
3.152
6
0.025
Soil pH
4.456
6
0.007
Environmental variable
Wet grasslands Unplanted-Planted Environmental variable
t
n
p
Ground veg cover
2.765
6
0.040
Herb layer cover
-2.815
6
0.037
Peatlands Unplanted-Planted Species trait
t
n
p
Medium
4.164
4
0.025
Large
-6.018
4
0.009
Intermed moist
-3.919
4
0.030
Moist
3.538
4
0.038
Habitat generalist
-5.594
4
0.011
t
n
p
Grazing intensity
6.063
4
0.009
Ground veg cover
4.745
4
0.018
Environmental variable
P
Brachypterous
-3.485
6
0.018
Macropterous
7.004
6
0.001
Habitat generalist
-4.772
6
0.005
Improved grasslands Particularly Agonum muelleri and Nebria brevicollis were typically sampled in unplanted rather than planted open improved grasslands. Both species are medium sized (M), macropterous (W), and eurytopic with reference to moisture preference (E); A. muelleri prefers open habitats (O) and N. brevicollis is a habitat structure generalist (G). Furthermore N. brevicollis is a favoured species of disturbed or synanthropic situations. The high abundance of N. brevicollis in unplanted compared to planted grasslands shown in Figure 3 supports this pattern. The large (L), brachypterous (B), forest habitat preferring (F) and moisture eurytopic species (E) Abax parallelepipedus showed to be more frequently sampled in planted rather than unplanted improved grassland. This was also indicated by the abundance comparisons shown in Figure 3. Paired samples test within the open improved grasslands (Table 3) showed that relative species richness of forest habitat preferring and brachypterous carabids was significantly higher and in planted rather than unplanted sites. The relative species richness of medium sized carabids, macropterous carabids and open habitat prefer-
Improved grasslands Unplanted-Planted t
n
granulatus, which did not have significant indicator value.
Table 2. Paired samples test of unplantedplanted habitat open habitat sites. Species traits are tested by carabid abundance.
Species trait
t
12
ring carabids was significantly higher in unplanted rather than planted sites.
a typical member of planted rather than unplanted wet grasslands. Paired samples test within the open wet grasslands (Table 3) showed that relative species richness of brachypterous carabids and habitat generalist carabids was significantly higher in planted rather than unplanted sites. The relative species richness of macropterous carabids was significantly higher in unplanted rather than planted sites.
Wet grasslands In the wet grasslands, Pterostichus nigrita was indicated as a typical member of unplanted rather than planted sites. The medium sized, macropterous P. nigrita is a habitat generalist and moderately hygrophilous (H) or preferring relatively moist habitats. Similarly to the improved grasslands, A. parallelepipedus was indicated as
Table 4. Indicator Species Analysis of open plots within each habitat combination. Body size: S = small, M = medium, L = large; Habitat: F = forest (preferring forest habitats), G = generalist (can cope with different habitats), O = open (preferring open habitats); Moisture: E = eurytopic (can cope with varied moisture in habitat), H = hygrophilous (preferring moist habitats), X = xerophilous (dry habitat preference); Wings: B = brachypterous (underdeveloped wings), D = dimorphic (either fully developed or underdeveloped wings), W = macropterous with fully developed wings. Indicator species
Species traits
Improved grasslands Unplanted Planted
Wet grasslands Unplanted Planted
Peatlands Unplanted Planted
Agonum muelleri
M/O/E/W
98***
0
16
2
0
0
Nebria brevicollis
M/G/E/W
98***
1
42
1
0
0
Loricera pilicornis
M/O/H/W
90***
1
29
3
9
0
Pterostichus vernalis
S/G/H/D
90***
1
50***
0
36
0
Pterostichus strenuus
S/G/H/B
71**
19
58**
8
33
1
Bembidion lampros
S/O/E/D
64*
3
0
0
2
24
Anchomenus dorsalis
M/O/X/W
60**
0
0
0
9
0
Pterostichus nigrita
M/O/H/W
59**
1
62**
0
9
0
Abax parallelepipedus
L/F/E/B
8
88***
8
54***
1
28
Pterostichus melanarius
L/G/E/D
8
86**
25
57
0
0
Trechus obtusus
S/G/X/B
0
64**
1
22
2
12
Bembidion mannerheimii
S/G/H/B
2
62*
16
44
0
0
Pterostichus rhaeticus
M/O/H/W
20
1
24
1
85**
4
Agonum fuliginosum
M/G/H/B
31
41
51
31
72*
10
Pterostichus niger
L/F/E/W
27
57
57
32
20
70**
*P
