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Patterns of b-diversity and similarity reveal biotichomogenization of epiphytic lichen communitiesassociated with the spread of black locust forests

Juri NASCIMBENEa,*, Lorenzo LAZZAROb, Renato BENESPERIb

aDepartment of Life Sciences, University of Trieste, via Giorgieri 10, I-34100 Trieste, ItalybDepartment of Biology, University of Florence, via G. La Pira 4, I-50121 Florence, Italy

a r t i c l e i n f o

Article history:

Received 24 January 2014

Revision received 8 August 2014

Accepted 27 October 2014

Available online

Corresponding editor:

Peter D Crittenden

Keywords:

Functional homogenization

Nitrogen-tolerant lichens

Richness agreement

Species turnover

* Corresponding author.E-mail address: junasc@libero.it (J. Nasci

http://dx.doi.org/10.1016/j.funeco.2014.10.0061754-5048/ª 2014 Elsevier Ltd and The Britis

a b s t r a c t

We compared epiphytic lichen communities of native broadleaved and secondary black

locust (Robinia pseudoacacia) forests to detect possible differences in community structure

that could be indicative of biological homogenization enhanced by the replacement of

native by black locust forests. The study was carried out in two areas of Italy with different

bioclimatic conditions using a balanced stratified random sampling. Results reveal a dif-

ferent pattern of community structure between native and black locust forests across the

two regions that may reflect a process of biological homogenization. In particular, lichen

communities of black locust forests share several species between the two study regions.

This pattern of floristic homogenization parallels with a functional homogenization related

to the spread of highly competitive species. This research provides early evidence that the

decrease of native forests associated with the spread of black locust is a mechanism

triggering biological homogenization of the epiphytic lichen biota.

ª 2014 Elsevier Ltd and The British Mycological Society. All rights reserved.

Introduction 2001), its influence on shaping epiphytic lichen communities

Biotic homogenization (BH) is a process that threatens bio-

diversity, leading to an increase of similarity among biota

worldwide (Baiser et al., 2012). The invasion of alien species

that replace local species over both space and time is among

the main drivers of BH (McKinney and Lockwood, 1999; Olden

and Rooney, 2006; Rahel, 2002). While this mechanism is well

documented for vascular plants and several faunistic groups

(Blair, 2001; Duncan and Lockwood, 2001; Gaertner et al., 2009;

Hors�ak et al., 2013; McKinney, 2004; Radomski and Goeman,

1995; Rahel, 2000; Rooney et al., 2004; Scott and Helfman,

mbene).

h Mycological Society. Al

still awaits clarification.

In general, epiphytic lichens are known to be sensitive to

forest habitat disturbance (Aude and Poulsen, 2000; Giordani,

2012; Hauck et al., 2013; Johansson, 2008; Nascimbene et al.,

2010, 2013a; Pyk€al€a, 2004) their response often being detect-

able in terms of replacement of forest specialists with gen-

eralist species (Friedel et al., 2006; Matteucci et al., 2012;

Nascimbene et al., 2007; Rogers and Ryel, 2008). Severe

shifts in lichen composition are also associated with the

invasion of alien trees, such as black locust (Robinia pseudoa-

cacia), that replace native temperate forests (Nascimbene and

l rights reserved.

2 J. Nascimbene et al.

Marini, 2010). In this perspective, black locust invasion has

both direct and indirect effects on biodiversity, respectively

changing tree forest and epiphytic community composition.

The change of substratum and differences in forest man-

agement between native and black locust forests are invoked

as potential drivers of the observed shifts in lichen compo-

sition which aremainly related to the establishment of highly

competitive, nitrogen-tolerant and light-demanding species

(Nascimbene et al., 2012). The invasiveness of these lichens in

disturbed habitats (Benesperi et al., 2013; Giordani et al., 2010)

has many similarities with that of several alien species that

behave as biotic homogenizers. For example, a few nitrogen-

tolerant lichens are known to be the only species that are

re-colonizing many European towns, being enhanced by

increasing nitrogen pollution (Davies et al., 2007; Lisowska,

2011; Van Herk et al., 2003). They are also known to estab-

lish in intensively managed woodlands where forest

specialists do not meet their ecological requirements

(Nascimbene et al., 2007).

However, classical analyses of species composition may

only partially reveal the mechanisms determining BH, that

can be better elucidated exploring the contribution of the

components of b-diversity and similarity that are more

informative of the ecological process shaping community

structure (Baeten et al., 2012; Su et al., 2004). This approach

was recently applied to lichen communities with promising

results (Nascimbene et al., 2013b). In particular, using the

conceptual framework provided by Podani and Schmera

(2011), it is possible to evaluate the relative importance of b-

diversity (reflecting species turnover among sites), defined as

the additive result of relative species replacement (R; repre-

senting the fraction of turnover related to the substitution of

species among sites), and relative richness difference

(D; representing the fraction of turnover related to differences

in species richness among sites), versus other possible eco-

logical phenomena, namely nestedness (when species in poor

sites are a subset of species in rich sites) and richness

agreement (representing the largest subset of species for

which two sites are equally species rich), which result from

the additive effects of similarity (S; indicating the degree of

compositional similarity among sites) with the other two

complementary components (S þ D and S þ R respectively).

For further details on this conceptual framework see Podani

and Schmera (2011).

In the present study, we compared epiphytic lichen

communities of native broadleaved-dominated forests and

black locust forests in terms of b-diversity components and

similarity. First, pairwise-comparisons were conducted

between plots of both native broadleaved-dominated and

black locust forests across two bio-climatically different

study regions with the aim of detecting possible differences

in community structure that could be indicative of a process

of BH driven by the replacement of native forests by black

locust forests. Second, we conducted pairwise-comparisons

between plots of both native broadleaf-dominated and

black locust forests within each study region to test whether

or not, at the local level (i.e under similar bioclimatic con-

ditions), lichen community structure is determined by sim-

ilar ecological phenomena between native and black locust

forests.

Materials and methods

Study areas

The study was carried out in two forested areas of Italy with

different bioclimatic conditions: (1) Veneto, Montello, in NE

Italy (46�480 N, 12�080 E), in the dry sub-Mediterranean region

where the epiphytic lichen flora is generally poor (Nimis and

Martellos, 2008), and (2) Tuscany, the hilly region in the

province of Pistoia, in Central Italy (43�590 N, 10�530 E), in the

humid sub-Mediterranean regionwhich is under the influence

of humid maritime winds, promoting more favorable con-

ditions for epiphytic lichens (Nimis and Martellos, 2008).

In Veneto, the study area was a large hill in the northern

part of the Venetian plain, extending over 5 000 ha. The mean

elevation is 200 m (maximum 369 m), 100 m higher than the

surrounding plain. Mean annual temperature is 12.9 �C, Jan.being the coldest month (mean temperature 3e4 �C) and Jul.

the warmest one (mean temperature 22.7 �C). Mean annual

rainfall is 1 100mm,withmaxima in spring and autumn. Forty

percent of the study area is managed for agriculture (arable

fields, hay meadows and vineyards), while the remnant is

covered by forests. The forest landscape is a continuous black

locust matrix with interspersed oak-dominated patches. Pure

black locust stands are the main forest type, covering over

90 % of the forested area. Remnant patches of oak forest

(Quercus petraea and Q. robur) can be found in the central part

of the hill. These formations are coppiced for firewood

production.

In Tuscany, the study area was a hilly landscape in the

Province of Pistoia that is delimited northward by the Tuscan-

Emilian Apennines ridge and southward by the Pistoia plain.

Elevation ranges between 100 and 900 m. Mean annual tem-

perature is 14.4 �C and 9.4� in the lower (100e500 m) and

higher (500e900 m) areas respectively. Mean annual rainfall

ranges between 1300 and 1900mmwith twomaxima in spring

and autumn. At lower elevations, the landscape is dominated

by cultivated (olive-groves and vineyards) and forested areas

mainly dominated by black locust formations. At higher ele-

vations, native forests prevail, while black locust formations

are interspersed in a matrix of deciduous broadleaf for-

mations including chestnut (Castanea sativa), oak (Q. cerris) and

hop hornbeam (Ostrya carpinifolia), coppiced for firewood

production.

In both sites, black locust forests are managed with

20e30 yr rotation cycles, mainly for firewood production.

Stands are usually clear-cut and spontaneously replaced by a

new generation of trees.

Sampling design

Mature stands, including trees ready to be harvested with a

circumference>60 cm,were selected both for black locust and

native forests. Ten 30 � 30 m plots were randomly selected in

different parts of the two study areas to encompass the vari-

ability of each forest type. In total 40 plots were surveyed.

In Veneto, native forests were generally older (60e90 yr)

and had higher mean DBH than any mature black locust for-

est, while in Tuscany it was possible to find native stands

Patterns of b-diversity and similarity reveal biotic homogenization of lichen 3

whose age (30e50 yr) and mean DBH were comparable to

those of black locust mature stands (Table 1).

Slope and canopy cover, were comparable among stand

types in each area, in particular, canopy cover was always

higher than 75 %; elevation slightly differs only for native

forests in Veneto (Table 1). Minimum distance between plots

of the same forest type was greater than 500 m to reduce

spatial dependence. The borders of the plots were at least

30 m from the forest edge to mitigate possible edge-effects. In

black locust stands, only black locust individuals were con-

sidered for the lichen sampling, while in native tree stands the

dominant species were considered: oaks in Veneto, and

chestnut (4 plots) and oak (6 plots) in Tuscany. In each plot, six

trees (circumference �40 cm) were selected for lichen inven-

tory by random sampling, for a total of 240 trees (60 in each

stand type in each of the two study areas).

The lichen sampling followed the European guidelines for

lichen monitoring (Asta et al., 2002). Lichens were sampled

using four standard frames of 10 � 50 cm as sampling grids,

subdivided into five 10 � 10 cm quadrats, which were verti-

cally attached to the tree trunk at the cardinal points with the

lower side at 100 cm from the ground. All lichen species inside

the frames were listed, and their frequency was computed as

the number of 10 � 10 cm quadrats in which the species

occurred. Nomenclature of lichens followed Nimis and

Martellos (2008).

Data analysis

After a preliminary ShapiroeWilk test that indicated a non-

normal distribution of data, a non-parametric KruskaleWallis

ANOVA test was used to detect differences between stand

types for: (1) species richness (cumulative number of species

per plot calculated as the sum of the species found on the six

trees), (2) the species richness of sub-oceanic lichens accord-

ing to Nimis and Martellos (2008), and (3) the contribution of

the guild of nitrogen-tolerant species (expressed as percentage

of the plot species richness) defined by the ecological indicator

value for eutrophication ranging from four (high eutrophica-

tion) to five (very high eutrophication) in the on-line checklist

of Italian lichens (Nimis and Martellos, 2008). In these analy-

ses, the plot was used as replicate to avoid pseudo-replication.

According to Siegel and Castellan (1988), after the Krus-

kaleWallis a test for multiple comparison was applied to

detect differences between forest types (significance level:

P < 0.05).

Table 1 e Mean features (±SD) of the two types of stands in thdifferent letters (a, b) are significantly different at P < 0.05. BL [tree species

Veneto

Black locust

Mean circumference (cm) 85.5 � 13.4a 17

Mean number of trees/plot 88.5 � 8.2a

Canopy cover % 86.1 � 7.2a 8

Slope (%) 7.5 � 5.4a

Elevation (m) 250 � 48.76 ab

The SDR simplex approach (Podani and Schmera, 2011)

was used to estimate the relative importance of b-diversity

components and similarity in our presence/absence data

matrices. The SDR partitions pairwise gamma diversity into

additive components, which are calculated as three comple-

mentary indices measuring similarity, relative species

replacement and relative richness difference. Pairwise-com-

parisons weremade between plot of the same forest type both

across the two study areas and at the local level (i.e. within

each study area). Calculations were computed using the

computer program SDR Simplex (Podani, 2001). In particular,

the three indices were calculated as follows (further details in

Podani and Schmera, 2011).

Similarity (S) was calculated according to the Jaccard

coefficient of similarity:

SJac ¼ a=n (1)

where a is the number of species shared by two sites (plots, in

our context), and n is total number of species.

Richness difference (D) was calculated as the ratio of the

absolute difference between the species numbers of each site

(b, c) and the total number of species, n:

D ¼ 1eðaþ 2minfb; cgÞ=n (2)

Finally, species replacement (R) was given by

R ¼ 2minfb; cg=n (3)

where in (2) and (3) b is the number of species present only in

the first site and c is the number of species present only in the

second site, so that min{b,c} is the smaller number between b

and c representing the number of species in the less rich site

that are replaced by new species in the richest.

The SDR results were graphed with a ternary plot using the

Ternary Plot option in the NonHier routine of the SYN-TAX

2000 package (Podani, 2001). In the ternary plot, each vertex

corresponds to one index (S, D, or R). Each pair of data in the

presence/absence data matrix is plotted according to its sim-

ilarity, richness difference and species replacement values, so

that the proximity of a point to a vertex is proportional to the

respective coefficient value. Non-parametric KruskaleWallis

ANOVA was used to check the significance of the differences

in species replacement, richness difference and similarity

among plots belonging to the two forest types at both spatial

scales (regional and local). A non-parametric multiple com-

parisons test, based on the Siegel and Castellan (1988)

Bonferroni-corrected asymptotic normality-based multiple

comparisons (see also Gr€omping, 2013), was applied after the

e two sites (Veneto and Tuscany). Values marked withblack locust stands; Native[ stands composed by native

Tuscany

Native Black locust Native

4.2 � 44.3b 88.9 � 16a 102.4 � 4.9a

42 � 16b 80.6 � 23a 59.8 � 24b

5.3 � 6.5a 86.4 � 6.2a 84.1 � 7.1a

9 � 5.6a 11.8 � 11a 9.5 � 10a

214 � 33.7b 410 � 226.6a 519.5 � 277.5a

Table 2 e Results of the post hoc test for multiple comparisons (mean values ± SD). Values marked with different letters(a, b) are significantly different at P < 0.05. BL [ black locust stands; Nat [ stands composed by native tree species

Region Stand type Total speciesrichness

Plot level speciesrichness

Plot level richness ofsub-oceanic species

% Nitrophytic species

Veneto Nat 20 3.73 � 1.5a 2.8 � 1.1a 13.11 � 11a

Veneto BL 15 5.33 � 1.1b 1.3 � 0.4b 69.3 � 10b

Tuscany Nat 59 12.1 � 4.3b 3.4 � 1.1a 19.6 � 7.2a

Tuscany BL 30 4.7 � 1.8b 1.0 � 0b 50.1 � 3b

Veneto þ Tuscany Nat 67 7.9 � 5.2a 3.1 � 1.1a 16.35 � 9.6b

Veneto þ Tuscany BL 35 4.9 � 1.4a 1.1 � 0.3b 59.7 � 15a

4 J. Nascimbene et al.

KruskaleWallis to detect differences between S, D and R val-

ues (P < 0.05). ShapiroeWilk test of normality, and Krus-

kaleWallis tests were performed using the shapiro.test and

kruskal.test functions in the stats package of R software ver.

3.01 (R Core Team 2013). Multiple comparison test between

treatments after the KruskaleWallis test was performed using

the kruskalmc function in pgirmess package (Giraudoux, 2013)

of R software ver. 3.01 (R Core Team 2013).

Results

Species richness and biological traits

Seventy threespecieswere found(SupplementaryAppendix1),

35 in black locust and 67 in native forest. Study area, as well as

forest type, had a significant effect on species richness. The

total number of species in each forest typewas lower inVeneto

than inTuscany (Table2). Plots ofnative forests inTuscanyhad

the highest species richness. The number of sub-oceanic spe-

cies was comparable among regions, while it was higher in

native than inblack locust stands.Lichencommunities inblack

locust forests were mainly composed of nitrogen-tolerant

species that represent more than 50 % of their total flora.

Patterns of b-diversity components and similarity

Pairwise-comparisons across the two study areas yielded

significant differences in the structure of lichen communities

Fig. 1 e SDR simplex ternary plots for the two stand type data se

richness difference and species replacement, respectively. Dots

(A), and Black locust forests (B). Mean values of S, D, and R (±SD)

significantly different at P < 0.05.

between native and black locust forests. The latter had higher

similarity (S) and species replacement (R), and lower richness

difference (D) than native forests (Fig 1). Accordingly, black

locust forests had a higher richness agreement (S þ R) and a

lower b-diversity (R þ D) (Fig 1).

At the local scale, different patterns were found between

the two study areas (Fig 2). In Veneto, black locust forests had

higher similarity than native forests while richness difference

and replacement were comparable. Black locust forests had a

higher richness agreement (S þ R) and a lower b-diversity

(R þ D). In Tuscany, the contribution of b-diversity and sim-

ilarity in structuring lichen communities was comparable

between black locust and native forests (Fig 1).

Discussion

Thisstudy revealedadifferentpatternofcommunitystructure,

in terms of b-diversity components and similarity, between

native and black locust forests across the two study regions

that may reflect a process of biological homogenization.

In native forests, the pattern of b-diversity ismainly related

to richness differences between plots of the two study regions,

Tuscany hostingmore rich communities according to itsmore

favorable bioclimatic conditions. In black locust forests, the

contribution of richness differences was far lower than in

native forests, indicating that changes in lichen communities

associated with the spread of black locust tend to reduce the

gap (in terms of species richness) between bio-climatically

ts. The abbreviations S, D and R refer to relative similarity,

represent pairs included in the data sets of native forests

are reported. Values marked with different letters (a, b) are

Fig. 2 e SDR simplex ternary plots for the four data sets at local scale. The abbreviations S, D and R refer to relative similarity,

richness difference and species replacement, respectively. Dots represent pairs included in the data sets of native forest

plots in Tuscany (A); black locust forest plots in Tuscany (B); native forest plots in Veneto (C); black locust forest plots in

Veneto (D). Mean values of S, D, and R (±SD) are reported. Valuesmarkedwith different letters (a, b) are significantly different

at P < 0.05.

Patterns of b-diversity and similarity reveal biotic homogenization of lichen 5

different regions, leading to a general taxonomic pauper-

ization of the lichen biota over large areas. This view is cor-

roborated by the fact that lichen communities exhibited a

balanced richness between the two study regions as suggested

by the high richness agreement in shaping community

structure (Podani and Schmera, 2011). This phenomenon is

the additive result of replacement and similarity that had

higher values in black locust than in native forests. The former

also indicates that a fraction of species turnover contributes to

maintain balanced richness through the substitution of a

given species in one area with another species in the other

area. The latter indicates that lichen communities of black

locust forests share a large part of their species pool between

the two study areas, thus exhibiting a degree of floristic

homogenization (Winter et al., 2009). Since these commun-

ities are dominated by species with similar ecological

requirements, namely nitrogen-tolerant species, it is likely

that the process of floristic homogenization would parallel a

process of functional homogenization that, in this case, leads

to the large scale spread of highly competitive species that are

enhanced by both bark features and management regime

based on frequent disturbances of black locust stands (Pividori

and Grieco, 2003; Motta et al., 2009). This hypothesis is sup-

ported by the pattern of sub-oceanic species whose richness

in native forests is similar between study areas, indicating

that habitat quality may compensate for less favorable cli-

matic conditions (Ellis et al., 2009). In contrast, black locust

forests are scarcely suitable for sub-oceanic species even

under favorable climatic conditions.

At the local scale (i.e under similar bioclimatic conditions),

richness differences were less influential for both native and

black locust forests, reflecting the fact that comparisons were

performed within the same pool of species. However, while in

Tuscany both native and black locust lichen communities

were shaped by a balanced contribution of replacement and

similarity, in Veneto between plot similarity was higher in

black locust than in native forests. This pattern suggests that

in climatically favorable conditions communities of both for-

est types are ruled by the same mechanisms that lead species

to occupy each suitable habitat patch, tending to an even

distribution across the region. In less favorable climatic con-

ditions (i.e. dry climate), environmental filtering may be

responsible for a more patchy composition of lichen com-

munities in native forests that reflect local differences in

habitat conditions. Similarity is instead higher between black

locust plots, indicating that nitrogen-tolerant species com-

posing their communities are able to spread in each suitable

habitat also in this environmental context.

Conclusions

This research provides early evidence that the loss of native

forests associatedwith the spread of black locust forests could

6 J. Nascimbene et al.

be a mechanism triggering biological homogenization of the

epiphytic lichen biota in which highly competitive, nitrogen-

tolerant species are involved. This mechanism produces

similar effects to those observed in studies on the effects of

nitrogen pollution (Van Herk et al., 2003), forest management

(Arag�on et al., 2010; Nascimbene et al., 2007) and global

warming (Aptroot and van Herk, 2007). This indicates that

different types of human disturbances may produce a con-

vergent ecological selection enhancing nitrogen-tolerant

species that act as generalists and outcompete more sensi-

tive lichens. These mechanisms tend to level out species

composition resulting in homogenized biota across regions.

As a consequence, there is mounting evidence that forest

epiphytic lichens are among the most threatened organisms

thorough Europe (Kriebitzsch et al., 2013).

Supplementary data

Supplementary data related to this article can be found at

http://dx.doi.org/10.1016/j.funeco.2014.10.006.

r e f e r e n c e s

Aptroot, A., van Herk, C.M., 2007. Further evidence of the effectsof global warming on lichens, particularly those withTrentepohlia phycobionts. Environmental Pollution 146,293e298.

Arag�on, G., L�opez, R., Mart�ınez, I., 2010. Effects of Mediterraneandehesa management on epiphytic lichens. The Science of theTotal Environment 409, 116e122.

Asta, J., Erhardt, W., Ferretti, M., Fornasier, F., Kirschbaum, U.,Nimis, P.L., Purvis, W., Pirintsos, S., Scheidegger, C., VanHaluwyn, C., Wirth, V., 2002. Mapping lichen diversity as anindicator of environmental quality. In: Nimis, P.L.,Scheidegger, C., Wolseley, P.A. (Eds.), Monitoring With Lichense Monitoring Lichens, vol. 7. Kluwer Academic Publishers,Dordrecht, The Netherlands, pp. 273e279.

Aude, E., Poulsen, R.S., 2000. Influence of management on thespecies composition of epiphytic cryptogams in Danish Fagusforests. Applied Vegetation Science 3, 81e88.

Baeten, L., Vagansbeke, P., Hermy, M., Petrken, G., Vanhuyse, K.,Verheyen, K., 2012. Distinguishing between turnover andnestedness in the quantification of biotic homogenization.Biodiversity and Conservation 21, 1399e1409.

Baiser, B., Olden, J.D., Record, S., Lockwood, J.L., McKinney, M.L.,2012. Pattern and process of biotic homogenization in the NewPangaea. Proceedings of the Royal Society B: Biological Sciences 279,4772e4777.

Benesperi, R., Lastrucci, L., Nascimbene, J., 2013. Humandisturbance threats the red-listed macrolichen Seirophoravillosa (Ach.) Fr€od�en in coastal Juniperus-habitats: evidencefrom western peninsular Italy. Environmental Management 52,939e945.

Blair, R.B., 2001. Birds and butterflies along urban gradients in twoecoregions of the United States: is urbanization creating ahomogeneous fauna? In: Lockwood, J.L., McKinney, M.L. (Eds.),Biotic Homogenization. Kluwer Academic/Plenum Publishers,New York, pp. 33e56.

Davies, L., Bates, J.W., Bell, J.N.B., James, P.W., Purvis, O.W., 2007.Diversity and sensitivity of epiphytes to oxides of nitrogen inLondon. Environmental Pollution 146 (2), 299e310.

Duncan, J.R., Lockwood, J.L., 2001. Spatial homogenization ofaquatic fauna of Tennessee: extinction and invasion followingland use change and habitat alteration. In: Lockwood, J.L.,McKinney, M.L. (Eds.), Biotic Homogenization. KluwerAcademic/Plenum Publishers, New York, pp. 245e258.

Ellis, C.J., Yahr, R., Coppins, B.J., 2009. Local extent of old-growthwoodland modifies epiphyte response to climate change.Journal of Biogeography 36, 302e313.

Friedel, A., Oheimb, G.V., Dengler, J., H€ardtle, W., 2006. Speciesdiversity and species composition of epiphytic bryophytes andlichens -a comparison of managed and unmanaged beechforests in NE Germany. Feddes Repertorium 117, 172e185.

Gaertner, M., Breeyen, A.D., Hui, C., Richardson, D.M., 2009.Impacts of alien plant invasions on species richness inMediterranean-type ecosystems: a meta analysis. Progress inPhysical Geography 33, 319e338.

Giordani, P., Incerti, G., Rizzi, G., Ginaldi, F., Viglione, S., Rellini, I.,Brunialti, G., Malaspina, P., Modenesi, P., 2010. Land useintensity drives the local variation of lichen diversity inMediterranean ecosystems sensitive to desertification. In:Nash III, Thomas H., et al. (Eds.), Biology of Lichens e

Symbiosis, Ecology, Environm. Monitoring, Systematics, CyberApplications. Bibliotheca Lichenologica, vol. 105. J. Cramer inder Gebr€uder Borntraeger Verlagsbuchhandlung, Stuttgart,pp. 139e148.

Giordani, P., 2012. Assessing the effects of forest management onepiphytic lichens in coppiced forests using differentindicators. Plant Biosystems 146 (3), 628e637.

Giraudoux, P., 2013. Pgirmess: Data Analysis in Ecology. R packageversion 1.5.8 http://CRAN.R-project.org/package¼pgirmess(accessed 30.10.13).

Gr€omping, T., 2013. The R primer. Journal of Statistical Software 52(Book Review 3).

Hauck, M., de Bruyn, U., Leuschner, C., 2013. Dramatic diversitylosses in epiphytic lichens in temperate broad-leaved forestsduring the last 150 years. Biological Conservation 157, 136e145.

Hors�ak, M., Lososov�a, Z., �Cejka, T., Ju�ri�ckov�a, L., Chytr�y, M., 2013.Diversity and biotic homogenization of urban land-snailfaunas in relation to habitat types and macroclimate in 32Central European cities. PLoS One 8 (8), e71783. http://dx.doi.org/10.1371/journal.pone.0071783.

Johansson, P., 2008. Consequences of disturbance on epiphyticlichens in boreal and near boreal forests. Biological Conservation141 (8), 1933e1944.

Kriebitzsch, W.U., Bultmann, H., von Oheimb, G., Schmidt, M.,Thiel, H., Ewald, J., 2013. Forest-specific diversity of vascularplants, bryophytes, and lichens. In: Kraus, D., Krumm, F.(Eds.), Integrative Approaches as an Opportunity for theConservation of Forest Biodiversity. European Forest Institute,pp. 158e169.

Lisowska, M., 2011. Lichen recolonisation in an urban-industrialarea of southern Poland as a result of air quality improvement.Environmental Monitoring and Assessment 179, 177e190.

Matteucci, E., Benesperi, R., Giordani, P., Piervittori, R.,Isocrono, D., 2012. Epiphytic lichen communities in chestnutstands in central-North Italy. Biology 67, 61e70.

Motta, R., Nola, P., Berretti, R., 2009. The rise and fall of the black-locust (Robinia pseudoacacia L.) in the “Siro Negri” forest reserve(Lombardy, Italy): lessons learned and future uncertainties.Annals of Forest Science 66, 410e419.

McKinney, M.L., 2004. Measuring floristic homogenization bynon-native plants in North America. Global Ecology andBiogeography 13, 47e53.

McKinney, M.L., Lockwood, J.L., 1999. Biotic homogenization: afew winners replacing many losers in the next massextinction. Trends in Ecology & Evolution 14, 450e453.

Nascimbene, J., Marini, L., 2010. Oak forest exploitation and blacklocust invasion caused severe shifts in epiphytic lichen

Patterns of b-diversity and similarity reveal biotic homogenization of lichen 7

communities in northern Italy. Science of the Total Environment408, 5506e5512.

Nascimbene, J., Marini, L., Nimis, P.L., 2007. Influence of forestmanagement on epiphytic lichens in a temperate beech forestof northern Italy. Forest Ecology and Management 247, 43e47.

Nascimbene, J., Marini, L., Nimis, P.L., 2010. Epiphytic lichendiversity inold-growthandmanagedPiceaabiesstands inAlpinespruce forests. Forest Ecology and Management 260, 603e609.

Nascimbene, J., Nimis, P.L., Benesperi, R., 2012. Mature non-nativeblack-locust (Robinia pseudoacacia L.) forest does not regain thelichen diversity of the natural forest. Science of the TotalEnvironment 421-422, 197e202.

Nascimbene, J., Thor, G., Nimis, P.L., 2013a. Effects of forestmanagement on epiphytic lichens in temperate deciduousforests of Europe e a review. Forest Ecology and Management298, 27e38.

Nascimbene, J., Benesperi, R., Brunialti, G., Catalano, I., DelleVedove, M., Grillo, M., Isocrono, D., Matteucci, E., Potenza, G.,Puntillo, D., Puntillo, M., Ravera, S., Rizzi, G., Giordani, P.,2013b. Patterns and drivers of b-diversity and similarity ofLobaria pulmonaria communities in Italian forests. Journal ofEcology 101, 493e505.

Nimis, P.L., Martellos, S., 2008. ITALIC, the Information SystemOnItalian Lichens. Version 4.0. University of Trieste, Dept. ofBiology. IN4.0/1http://dbiodbs.univ.trieste.it/ (accessed30.10.13).

Olden, J.D., Rooney, T.P., 2006. On defining and quantifying biotichomogenization. Global Ecology and Biogeography 15, 113e120.

Pividori, M., Grieco, C., 2003. Evoluzione strutturale dipopolamenti cedui di robinia (Robinia pseudoacacia L.) nelCanavese (Torino e Italia). Schweizerische Zeitschrift f€urForstwesen 154, 1e7.

Podani, J., 2001. SYN-TAX 2000. Computer Programs for DataAnalysis in Ecology and Systematics. User’sManual (Budapest).

Podani, J., Schmera, D., 2011. A new conceptual andmethodological framework for exploring and explainingpattern in presence-absence data. Oikos 120, 1625e1638.

Pyk€al€a, J., 2004. Effects of new forestry practices on rare epiphyticmacrolichens. Conservation Biology 18, 831e838.

Radomski, P.J., Goeman, T.J., 1995. The homogenizing ofMinnesota lake fish assemblages. Fish 20, 20e23.

Rahel, F.J., 2000. Homogenization of fish faunas across the UnitedStates. Science 288, 854e856.

Rahel, F.J., 2002. Homogenization of freshwater faunas. AnnualReview of Ecology and Systematics 33, 291e315.

Rogers, P.C., Ryel, R.J., 2008. Lichen community change inresponse to succession in aspen forests of the southernRocky Mountains. Forest Ecology and Management 256 (10),1760e1770.

Rooney, T.P., Wiegmann, S.M., Rogers, D.A., Waller, D.M., 2004.Biotic impoverishment and homogenization in unfragmentedforest understory communities. Conservation Biology 18,787e798.

Scott, M.C., Helfman, G.S., 2001. Native invasions,homogenization, and the mismeasure of integrity of fishassemblages. Fish 26, 6e15.

Siegel, S., Castellan, J., 1988. Non Parametric Statistics for theBehavioural Sciences. MacGraw Hill Int, New York.

Su, J.C., Debinski, D.M., Jakubauskas, M.E., Kindscher, K., 2004.Beyond species richness: community similarity as a measureof cross-taxon congruence for coarse-filter conservation.Conservation Biology 18, 167e173.

Van Herk, C.M., Mathijssen-Spiekman, E.A.M., de Zwart, D., 2003.Long distance nitrogen air pollution effects on lichens inEurope. The Lichenologist 35, 347e359.

Winter, M., Schweiger, O., Klotz, S., Nentwig, W.,Andriopoulos, P., Arianoutsou, M., Basnou, C., Delipetrou, P.,Did�ziulis, V., Hejda, M., Hulme, P.E., Lambdon, P.W., Pergl, J.,Py�sek, P., Roy, D.B., K€uhn, I., 2009. Plant extinctions andintroductions lead to phylogenetic and taxonomichomogenization of the European flora. Proceedings of theNational Academy of Sciences of the United States of America 106,21721e21725.