Earthworm richness, abundance and biomass in differentland use systems in northern Paraná, Brazil (Oligochaeta)

Marie L. C. Bartz, Amarildo Pasini, and George G. Brown

Abstract. We evaluated carthworm abundance, biomass and specics divcrsity in four agrocco-sytems and a natural forest in Northem Paraná State, Brazil. Five sites were sampled: native forest(NF), pasture (PA), coffee plantation (CP), no-tillagc eropping (NT) and subsoiled no-tillagccropping (SNT). Nine samplcs werc taken in each site over a onc-ycar period (March 2008 toMarch 2009) every three months, using the TSBF (Tropical Soil Biology and Fcrtility) rncthodol-ogy. Elcven species (sevcral ofthem new for science) were found overall representing three farni-lies. Highest species richness was recorded in PA (7 spp.), followed by NT (6 spp.), NF (5 spp.),SNT (3 spp.) and CP (only 2 spp.). Two species were found only in NF and three were found onlyin PA. Of the total, six species were native and four were exotic (three Dichogaster spp. of Afri-can origin and Pontoscolex corethrurus presumably of the East Amazonian origin). Mean densityand biomass tended to be much higher in PA (up to -200 indiv. m·2 and 20 g m") and significant-Iy differcnt from NT, SNT and CP depending on the sample date. The highest abundances wercobserved in Junc and Septcmber 2008, at the beginning and end of the dry scason. Ali sitesshowcd a dccrcase in dcnsity and biomass in the beginning and cnd ofthc rainy scason in Decern-bcr 2008 and March 2009 (only significant for PA). Historical rnanagcmcnt practices affected theearthworm community present in eaeh land use systems, but several na tive specics survivcd in aliagroecosystems, confirming their rclative tolerance to disturbance.

Key words: Oligoehaeta, bioindieators, Atlantie forest, annual eropping, eoffee plantation, pas-ture.

IntroductionThe Northem par! of Paraná State (Brazil) was colonized only in the early zo" century. Thecolonization resulted in almost complete forest c1earance and the establishment of settlerfamilies and agricultural lands (ANONYMOUS1975). Early agriculture consisted mainly ofcoffee, maize and rice cultivation and the raising of chickens and pigs for subsistence(A ONYMOUS1975). From 1968 to 1978 the area under soybean and wheat production in-creased tenfold. Two frosts in 1975 and 1979 decimated coffee plantations that contributedto lhe consolidating the establishment of crops like soybean, wheat, com and sugarcane(DERPSCHet aI. 1991). At the beginning, these crops were produced using the Europeanconventional tillage model (intensive soil disturbance for seedbed preparation), that causedsevere soil erosion and degradation due to heavy rainfall. ln the 1980's and 1990's the agri-cultural production diversified (coffee, oranges, sugar cane, soybeans, wheat, com, oats,cattle, chicken, pigs, etc.), and no-tillage was widely adopted to prevent soil degradation and

Tomás Pavliéek, Patricia Cardet, Maria Teresa Almeida, Cláudia Pascoal, Fernanda Cássio (Eds.): Advances inEarthworm Taxonomy VI (Annelida: Oligochaeta). - Proceedings of the 6th International Oligochaete TaxonomyMeeting (6th IOTM), Palmeira de Faro, Portugal, 22- 25 April, 2013.

ISBN 9783-925064-69-2 © Kasparek Verlag, Heidelberg

60 Advanccs in Earthworm Taxonomy VI

erosion (DERPSCH et aI. 1991). These practices positively affected the soil fauna, leading tolarge increases particularly in earthworrn populations (BROWN et aI. 2002, 2003).

The diversity, density and biomass of earthworrns are strongly influenced by soil cultiva-tion (LAVELLE et aI. 1989; HENDRIX et aI. 1992) and the earthworm populations can be usedas soil quality indicators in agroecosystems (PAOLETTI et aI. 1998; PAOLETTI 1999; HUERTA2009). Several studies and surveys on earthwonn populations have been conducted in Para-ná, aiming to use them as soil quality indicators in agroecosystems (T ANCK et aI. 2000; BE-NITO 2002, BROWN et aI. 2003, 2004a, 2008; NUNES et aI. 2006; BROWN & JAMES, 2007;SAUTTER et aI., 2007; BENITO et aI. 2008; BARTZ et aI. 2009; FERNA DES 2009; BARTZ et aI.2013), but very few of them identified the species collected. Hence, the following study wasconducted to evaluate the abundance, biomass and species diversity in five different land usesystems (LUS) in Northem Paraná State, Brazil, aiming to use them as soil quality bioindica-tors.

Material and MethodsStudy sites. The study was conducted in the municipalities ofRolândia, Arapongas and Londrina(Table I). The soils in the region are predominantly Oxisols of basaltic origin, with high levels ofclay (ANONYMOUS1994; ANO YMOUS1999a). The climate is typical subtropical Cfa, accordingto Kõppen's classification, characterized by having hot, humid summers and no defined dryseason. Annual rainfall is below 1600 mm and average annual temperatures in the summer arearound 25°C. During the sampling year of 2008, annual rainfall was 1480 mm, and rainfall inJune and December 2008 was much lower than the recorded historical means and much higher inMarch and August 2008 and particular1y in February 2009 than the historical means (Fig. I).

The following land use systems (LUS) were evaluated: native forest (NF), pasture (PA), coffeeplantation (CP), no-tillage (NT) and sub-soiled no-tillage (SNT). The main characteristics of thestudy sites are shown in Tables I and 2. Some additional information on each agroecosystem are:• PA - Brachiaria sp. planted in 1991, following annual cropping with conventional tillage. InMay 2008 the pasture area was cut to 50% of the area and the other half was converted to annualcropping. Sampling was performed in the remaining pasture area in June and September 2008. InNovember 2008 the other half was also converted to annual cropping. Soil preparation during theconversion was perfonned by sub-soiling and inversion plowing with heavy machines to destroya compacted layer in the "A" horizon and application of herbicides to kill the grass. Crops plant-ed were soybean (G/ycine max) in the summer and wheat (Triticum aestivum) in the winter of2008/2009. Herbicides, insecticides and fungicides were used to control weeds and pests. Earth-wonn samples were taken in the cropped area in December 2008 and March 2009, identified asPA-CT (Table 3).• CP - In the 1970's pesticides ofhigh toxicity (classified as class I - High toxicity, A ONY-MOUS2012) had been used but beginning in 2003 weed management between the rows was byweeding and mowing and occasionally with herbicides. In alternate years coffee trees werepruned, and the last pruning was in 2008. Fertilizer (ammonium nitrate) was applied annually.• NT - Up to 2007, herbicides and fungicides were used to control pests and diseases. Insecti-cides were used only sporadically, when the insect pressure was very high and control with inte-grated pest management was not effective (began in 1987). In the first half of 2008 the area wasreduced to 2 ha and conventional pest management was adopted (use of pesticides in ali crops).Earthwonn samples were taken in the remaining NT area in the last three sampling dates;

SNT - From 1990 to 2003 conventional tillage was used and from 1990 to 2007 maize wasplanted in both summer and winter. In 2008 the area was rented out and in the harvest year

Oligochacta 61

Table 1. Selected details of each LUS in the present study.

Native Coffee SubsoiledPasture No-tillage

Forest Plantation No-tillage(NF) (PA) (CP) (NT) (SNT)

ç~~l1ty ..Ar<iPCl~g<i~ 1=(?~~!:i.l1a Londrina Rolândia'<\E<lPCl~gasAI~it~<li!(IJ.l) 699 66_6____ 688 675 700

23° 24'S 23°24'S 23° 24'S 23°23' S 23°24'S51° 1 51°1 1019'W 51° 21.477'W 51019'W

19.2 28.8 12 48 50. _ .._.>100 16 31 36 18

Rhodic Rhodic Rhodic Rhodic Rhodic.}::I<lpl~clCl)(~ Kandiudox .......}1aplll~Clx tI<iP111clCl)( tI<ipl11~Clx

No-tillage with No-tillagecrop rotation with crop

(soybean, successioncom, wheat, (soybean,

oats) com, wheat)

Location

.~i:lI!J~a) .Agi!(Y':).

Soil type

Vegetation &management

Mixed om-brophliloussecondary

forest

Brachiariasp.

CoiJeaarabica L.cv. Mundo

Novo

• 2008/2009 - soybean (Glycine max) was planted in the summer and wheat (Triticum aes-tivum) in the winter. Herbicides, insecticides and fungicides were used to control weeds andpests. Every four years sub-soiling (chisel plowing) was used and the last plowing was performedin 2007.

Earthworm and soil sampling. Earthworms were collected between March 2008 and March2009, every three months, totaling fíve sampling dates: March, June, September & December2008 and March 2009. On each date nine points per site were sampled, spaced at least 10 metresapart. Soil monoliths with dimensions of 25x25x20 em depth were hand sorted following theTSBF (Tropical Soil Biology and Fertility) method (ANDERSON& r GRAM 1993) and the collect-ed earthworms were fíxed in 5% formaldehyde water solution for at least 2 months and thentransferred to 70% alcohol solution. The worms were counted, weighed and identifíed to family,genus and species levels. The identifícation keys used for identifícation and description of fami-lies, genera and species were the ones by R1GHI(1990, 1995) and BLAKEMORE(2002).

Shannon diversity index (H') was calculated using density data (ODUM 1983). When only uni-dentifíed or juvenile worms were found, we considered the LUS as having one species.

Soil samples were collected in September 2008 for analysis of pH CaC12 (pH), aluminum(A13+), exchangeable acidity (A13++H+), potassium (K+), calcium (Ca2+), magnesium (Mg2+),phosphorus (P) and carbon (C) according to ANONYM(1999b) methodology and for analysis ofbulk density, macro, micro and total porosity and texture, following methods of ANONYMOUS(1997) (Table 2).

Data analysis. All variables were subjected to normality test (Shapiro-Wilk). The biologicalvariables (abundance, biomass and species richness) were submitted to analysis of variance(Kruskal-Wallis) and mean test (Dunn), using the program BioStat 5.0 (AYRES et al. 2007). Soilchemical and physical attributes were subjected to analysis of variance (ANOVA) and compari-son of means (Tukey) using the program Sisvar (FERREIRA2003). The Shannon index was calcu-lated using Biostat 5.0 and compared by using the t test contrast, according to PIELOU(1975). Tocalculate the index, juveniles were excluded from the data set.

Table 2. Chemical and physical characteristics of the soils at each sample site. NF = forest; PA = pasture; CP = coffee planta-tion; NT = no-ti li; SNT = sub-soiled no-til!. *Values accompanied by different lowercase letters in the same column representtreatments with significant differences, using Tukey test at P< 0.05.

AI H+AI K Ca Mg P CBulk Macro- Micro- Total

Clay Silt SandSites pH Density porosity porosity Porosity

CaCl2 cmol.dm' mg dm' g dm' g cm' % g kg

NF 4.2a* 2.0e 8.9d O.2a 2.2a I.Oa 4.la 32.lc O.9a 27.5b 41.9a 69.5b 828be 44a 129a

PA 5.4b O.3ab 4.5ab O.7c 6.3b 2.7c 15.lb 22.7b I.lb 16.5a 49.6b 66.lab 814abe 54a 133a

CP 4.5a O.9b 5.8e O.3ab 2.6a l.7b 1.9a 24.0b I.lb 17.2a 48.lb 65.3ab 834c 51a 115a

NT 5.5b O.la 4.2b O.6c 7.8b 1.5ab 56.0e 20.2ab l.2b 16.7a 47.3b 64.0a 788ab 69a 144a

SNT 6.6e O.Oa 2.4a O.4bc 9.5b 2.7c 3.4a 17.5a l.2b 11.8a 49.0b 60.8a 785a 85a l30a

Table 3 (Explanations): *No earthworms found. **Significant differenees, using Kruskal-Wallis analysis of variance and Dunn mean testoLowcrease letters show differenees bctween LUS on the same sampling date while upperease letters show differences between sampling datesin the same site LUS. (NF=nativc forest; PA=pasture; CP=coffee plantation; NT=no-tillagc; SNT=sub-soiled no-tillage; Fbar=Fimoscolexbartzi; Ggio=Glossoscolex giocondoi; Ubra=Urobenus brasiliensis; Pcor=Ponloscolex corethrurus; Daff=Dichogaster affinis; Dgra=D.gracilis; Dsal=D. saliens; Dspp=Dichogasler spp.; Bemi=Belladrilus (S) emilianii; Bspl=Belladrilus sp.l.; Bsp2=Belladrilus sp.2; NIspl=notidentified spccie; JUV=juveniles not identifiable to species levcl, but not Pontoscolex and Dichogasler). t A dash (-) was used when no wormsor only juveniles wcre collected. A O value was used when only one species was found. tValues shown for each sampling date are the totalnumber of spccies eneountered in eaeh LUS, and over all sampling dates. y Percentage abundance of identified native worms, i.e., numbcr ofnative speeies/(total- juveniles + Dspp).

o.IV

;J>o-<"'"()~sm"'ª"~o3...,"'xo"o:3'<s

ºTable 3. Earthwonn (per species and total) abundance (no. indiv. m-2) and biomass (g m-2) and values of the Shannon index

11and total species richness in ea ch LUS on each sampling date. Explanations see under Table 2.

Earthworm families and species

Glossoscolccidac Acanthodrilidac Ocncrodrilidac Total Total ShannonTolal :\lean

-/0 nauveLUSFbar Gaio Ubra OafT Os.1 Ospp Bem! Bsp2 Nlspl. JUV Abund. Blemass indu

spcetesr~:~~i::sspcctes'Pcor Dgra Bspl rtchncss

native cxotic exorte nntivc nativc?~F , 2 9 llab** 0.05 Ot It 0.11 100PA 5 11 25AB 16 7 20 84bABC 2.89AB 0.54b 4 0.44 50

03/08 CA 4 4a 0.03 O I 0.11 100NT 2 4 4 2 12 24ab 0.30 0.45. 3 0.33 67SNT 4 5 9ab 0.03 O I 0.11 100NF 4 5 2 2 9 22ab 1.09ab 0.58c 4 0.44 75PA 7 14 531l 78 9 37 198bC 4.72bB 0.45b 4 0.44 50

06/08 CP 2 2a 0.02a O I 0.11 O~T 4 2 7 l3a 0.26a 0.28. 2 0.22 50S~T 4 4 2 5 15. 0.16. 0.46b 3 0.33 67~F 5 12 2 9 28ab 2.47.b 0.38b 3 0.33 33PA 30 2 46 4A 30 11 82 205bC 20.26bB 0.55c 5 0.56 40

09/08 CP 4 5 9. 0.09. O I 0.11 100NT 9 2 7 18ab 0.18. 0.21. 2 0.22 100SNT 2 7 11 20ab 0.18. 0.23. 2 0.22 50~F 4 2 6 0.42 0.28 2 0.22 OPA-CT 9 OA 7 18 34AB 3.3IAB 0.30 2 0.22 O

\2/08 CP 0.00NT 2 2 0.17 O I 0.11SNT 0.11NF 2 2 0.11 O I 0.11PA-CT OA 2 2A 0.02A O 0.00

03/09 CP 4 4 0.02 0.00~T 2 2 2 5 11 0.15 0.48 3 0.33 OS~T 2 18 20 0.09 O I 0.11 100~F 2 5 I I 0.5 5 14 0.83 0.50b 5' 0.24b 60+

PA 7 4 11 3 16 11 19 2 32 105 6.24 0.75c 7 0.33. 43Annual CP 0.5 I 2 4 0.03 O 2 0.07b 50Average

~T I I I 0.5 I 2 0.5 6 13 0.21 0.58b 6 0.24b 50S~T I 3 0.5 8 12 0.09 0.24. 3 0.16b 67

IO"-<.H

64 Advanccs in Earthworm Taxonomy VI

The biological data (total and per species abundance & biomass) were used to obtain the gradi-ent length using a Detrended Correspondence Analysis. Since this length was <3 (indicatinglinear response), we applied a Redundancy Analysis (RDA) to explore correlations between themean annual values of the biological (species, total abundance, total biomass, Shannon index andnumber of species) and environmental variables (chemical - pH, AI3+, H++AI3+, K+, Ca2+, Mg2+,P and C - and physical attributes - bulk density, macro, micro and total porosity, texture, temper-ature and rainfall). A Monte Carlo permutation was conducted to statistically test whether thebiological data were significantly correlated with the environmental variables (C, K+,macroporosity, temperature and rainfall). Those analyses were perforrned using the programCanoco 4.0 (TER BRAAK& SMILAUER1998).

ResultsSoils in each LUS. In spite of the fact that ali analysed soils were very clayey (ali >78%clay) and belonged to the same class (Rhodic Oxisols according to ANONYMOUS 1999b;Table 1), significant differences were found between chemical and physical properties of thesoils representing the five LUS (Table 2). No significant differences were found betweenLUS regarding sand and silt contents, but NF and CP had significantly higher clay contentsthan SNT, and these LUS had the highest C contents. As typical in forests, soil C content inNF as well as the soil bulk density, total and macro-porosity were significantly higher andmicroporosity lower than in the other LUS. Soils in NF were also significantly more acidthan the other LUS (except CP), accompanied by higher AI3+, H++Ae+ and lower cation(Ca2+ and K+) contents. Fertility management for annual cropping maintained higher pH andthe cation contents as well as very low A13+ and H++AI3+ in SNT and NT. Soil pH was high-est and C contents lowest in SNT, due to soil disturbance and recent liming. P contents werehighest in NT due to recent crop fertilization. PA had fertility values (P levels, cation con-tents) close to the annual cropping systems (SNT and NT), resulting from higher pH andlower H++AI3+.Total earthworrn density and biomass. Total earthworrn densities were significantly dif-ferent between LUS on three of the five sampling dates: March, June and September 2008(Table 3). In March and September densities were around 20 times higher in PA (84 and 205indo m", respectively) than CP (4 and 9 indo m", respectively) and in June densities werehigher in PA compared to the remaining agroecosystems (CP, NT, SNT). Comparing sam-pling dates, significantly differences over time were only found for PA, with highest densi-ties in June and September (198 and 205 ind rn", respectively), significantly higher than onthe last two sampling dates (December 2008 and March 2009; 34 and 2 indo m", respective-Iy).

Similar pattems were observed for total earthwonn biomass that was much higher (18 to225 times more) in June and September in PA compared with the other agroecosystems (CP,NT, SNT, with total biomass ::::0.26 g m"), where earthworrns were mostly small ocnerodri-lids and juveniles (Table 3). Once again, the only LUS for which biomass was significantlydifferent between sampling dates was PA, where biomass was significantly higher in Juneand September (4.72 and 20.26 g m", respectively), than in March 09 (0.02 g m"), Totalmean abundances (density & biomass) were not significantly different between LUS, butthere was a clear tendency for higher values in PA compared with the other LUS (Table 3).

Oligochaeta 65

450.0 25

350.0 20

400.0

~ 300.0EE';' 250,0.~ee'5, 200,0';:)'"...

.::~~~-~~15 g

a:Scp Oct Nov Dez Jan Feb Mar Abr May Jun .Iul Ago Scp Oct Nov Dez Jan Fcb Mar

c:::::J Precipitation (mm) l lisrorical Average _I'rccipitation (mm) SeL07 to Mar.09 -+-TempcralUre (Oe)

Fig. I. Mean monthly precipitation (mm) just before and throughout the five sampling dates(black bars), and historical mean (1977-2009; white bars) for the region ofRolândia, as well asmean monthly temperature (0 C) from September 2007 to March 2009 (Source: Solana Ag-ropecuária Ltda. and Agência Nacional de Águas). White arrows indicate earthworrn samplingdates.

Earthworm species abundance, richness and diversity. Overall sampling dates and LUSII species from four families were found: four from Glossoscolecidae, and three each fromthe Ocnerodrilidae and Acanthodrilidae families (Table 3). Of the total, six species werenative and four were exotic. An unidentifiable specimen (N Isp.l) could represent a nativespecie. However, only a few individuais were found on one occasion and only in PA. Twocollected species were new for science and described accordingly (Fimosco/ex bartzi Bartz& James, 2012 and G/ossoco/ex giocondoi Bartz & James, 2012), while two others werepossibly new species (Befladri/us sp.1 and sp. 2). The total species richness ranged from 2(CP) to 7 (PA) species, with NT and NF having intermediate species richness (6 and 5 spe-cies) and SNT lower richness (3 species). On each sampling date, richness ranged from O(CP on the last two sampling dates) to as many as 5 species (PA in September). The annualmean species richness was higher in PA (Table 3).

Two native glossoscolecids (F. bartzi and G. giocondoi) were found only in PA and NT,the forrner reaching 30 indiv. m", while the latter :SI I indiv. m". A native ocnerodrilid Bel-ladrilus (Santomesia) emilianii Righi, 1984 was found only in the cropping systems (CP,NT, SNT) while Urobenus brasiliensis 8enham 1886 and another native ocnerodrilid (Bel-ladrilus sp.2) were found only in NF (the latter species only one sample date, June 2008).Belladrilus sp.! was found in NF, NT and SNT, but only on the fírst three sampling dates.

66 Advances in Earthworm Taxonomy VI

Ali the ocnerodrilids were found in very low densities (::::9 indiv. m"), as well as U. brasili-ensis (4 and 5 indiv. m"),

The exotic species like Pontoscolex corethrurus (MÜLLER,1857) and the acanthodrilidsDichogaster gracilis (Michaelson, 1892), D. ajjinis (MICHAELSON,1890) and D. saliens(BEDDARD,1893) were present mainly in PA, where their abundance reached values of 145indiv. m-2 (Dichogaster spp. only) in June 2008 and 91 indiv. m-2 in September 2008 (aliexotics together). These were the most abundant species encountered in the present study.

No significant differences were found between the densities of individual species in eachLUS on any sampling date ar using annual mean values. Furthermore, the only species andLUS for which significant differences between sampling dates were found was D. gracilis inPA; density was significantly higher in June 2008 compared with the last two samplingdates, when this species was not encountered in PA and only found in very low abundance inNF and NT.

The earthworm diversity (Shannon index) in March 2008 was higher in PA than NT, inJune 2008 was higher in NF than in SNT and PA, while in September 2008 it was higher inPA than ali the other LUS, being lowest in NT and SNT. ln Dec. 2008 only NF and PA hadvalue for the index and in March 2009 just NT, the other LUS had O or no recorded earth-worms. Considering the annual average, the diversity was higher in PA, intermediate in NFand NT and lowest in CP.

However, this diversity was represented mainly by exotic species: in PA, 4 of the 7 specieswere exotic and proportion of identified natives was 43% (Table 3). ln NF, 3 of the 5 specieswere native, but exotics predominated in abundance, representing around two thirds of theindividuaIs identified. ln SNT and CP, where the proportion of native species was 67 and50%, respectively, their abundance also tended to be more represented than in the remainingLUS. Finally, in NT, 50% ofthe species and ofthe individuaIs identified were native.

Redundancy analysis. ln the redundancy analysis (RDA), the first two axes of the RDAaccounted for 91% of total variance in the data (axis 1 counted for 73% of variance; axis 2counted for 18% of variance) and revealed significant (P<0.05) correlations between thebiological variables (abundance of each species) and environmental variables (soil K and Ccontents and rainfall and temperature) measured (Fig. 2). The environmental parameters C,K, rainfall and temperature explained 43% of the earthworm data, with 73% of the variabil-ity accounted for on the first axis. The RDA separated the LUS into 3 groups:

1. The native vegetation system (NF), associated with Belladrilus sp. 2 and Urobenusbrasiliensis, positively (P<0.05) correlated with soil C content and macroporosityon axis 2.

2. PA related to higher diversity, total abundance, biomass and the density of D. gra-cilis, D. affinis, D. saliens, G. giocondoi, F. bartzi, juveniles and the unidentifiedspecies (Nlspl) on axis I, positively correlated (P <0.05) with soil K content.

3. NT, SNT and CP, related mainly to abundance of B. (S") emilianii, as was correlat-ed to the rainfall.

The species P. corethrurus was not correlated to any environmental parameter, but it isassociated to NF and PA sites. The Belladrilus sp.1 is in the same way being associated toNT site.

Oligochacta 67

oac por 1 C

e1

NF

bon

Pcor•Ubra

!

Rsp2!

Ternperati re~

Axis 1=73%

NIspl ~Dgra IPA-Daff

~Dspp"Fbar Ggio

Ds~l •.JUVarr

Po s iu

SNT.Â.,Remi

:::Ro00

o 11N

'"X«T"""

I

-0.6 1.0Fig. 2. Redundancy Analysis (RDA) using the mean annual abundance of each species (Fbar =Fimosco/ex bartzi; Ggio = G/ossoscolex giocondoi; Ubra = Urobenus brasiliensis; Pcor = Pon-tosco/ex corethrurus; Daff = Dichogaster affinis; Dgra = D. gracilis; Dsal = D. saliens; Dspp =Dichogaster spp.; Bemi = Belladri/us (S) emilianii; Bsp I = Belladri/us sp.l.; Bsp2 = Belladri/ussp.2; NIspl=not identified specie 1 and JUV=juveniles, relating selected environmental(macroporosity, temperature, rainfall, carbon and potassium) of the sampling sites (NF = nativeforest, PA = pasture, CP = coffee plantation, NT = no-tillage and SNT = subsoiled no-tillage),

68 Advances in Earthworm Taxonomy VI

DiscussionFor most sampling dates and in the mean annual values, oscillations in earthworm abun-dance, biomass, species richness and diversity followed the decreasing order of importancein LUS: PA>NF>NT>SNT>CP. Contrary to the expected, earthworm density and biomasswas highest in early and late winter (June & September 2008), the period with historicallylowest rainfall, while lowest abundance values occurred in the early and late rainy season(December 2008 and March 2009), related to higher moisture in the soil and which is nor-mally adequate to earthworm activity. The earthwonn activity is closely Iinked to rainfallpattems in tropical regions (EDWARDS 2004).

Lower rainfall and water deficit is common in Northem Paraná in the months of June toSeptember (CORRÊA et ai. 1982; ANONYM 20 I O) and this should theoretically result in lowerearthworm populations in the winter and early spring, that would recover during the summermonths characterized by higher rainfall. However, during the study period, rainfall wasabove average in and Apr. and well above average in Aug. 2008, which positively influencedearthworm activity and survival, resulting in high population densities on the sampling datesof June and September 2008. On the other hand, rainfall in Oct. and Dec. 2008 was lowerthan the average, possibly reflecting negatively on earthworm populations that were verylow at the fourth sampling date (December 2008). Finally, the severe rainstorms of Feb.2009 may have further negatively affected the earthworm populations by saturating the soil,resulting in low numbers of earthworms recovered in March 2009.

Sampling depth (to 20 em on ali sample dates) is another issue that may have resulted inlower earthworm capture in the present study, as many earthworm species are known tomigrate vertically in the soil in search for moisture during drier periods (BOUCHÉ 1984).However, most of the worms found in the present study were epi-endogeics or poly- andrneso-humic endogeics that generally inhabit the upper soil horizons (FRAGOSO et aI. 1999),although Iittle is known of their burrowing habits when faced with drying soil conditions. P.corethrurus is known to enter quiescence in a "diapause" chamber during dry periods until itrains (V A UCCl 1953), and similar behavior was observed for G. giocondoi and F. bartzi (M.L. C. BARTZ, personal observation).

Nevertheless, other authors also found higher densities in the winter season in NorthemParaná, so that this may reflect a tendency of the earthworms in this region to maintaingreater activity when the weather is cooler (and soil remains wetter), rather than when it ishot and drier or too wet (Figure I). For instance, NUNES et al. (2006) found higher wormdensity in winter than summer in an old pasture in nearby Jaguapitã, where P. corethruruspredominated and BARTZ et al. (2009) found higher abundance and biomasses in an organicCP in the dry season in nearby Lerroville, where Dichogaster spp. worms predominated.Clearly, the adaptation mechanisms to drought ofthe earthwonn species found in this region,and their possible preference/tolerance for lower soil temperatures is a topic that deservesfurther attention and should help explain the present results.

Farm management practices were also very important in determining earthworm abun-dance, particularly in PA and NT in the latter part of the present study. The NT area wasreduced from 40 to 2 ha, and the remaining area was influenced by a border effect of anadjacent roadway. PA was reduced to half its extent in May 2008, and in Nov. 2008 theowners converted the remaining area of PA into annual cropping, so that the last two sarn-plings were done in row crops and not PA. For the conversion to cropping, heavy tillagemachines were used to kill the Brachiaria sp. grass and break the compacted layer caused bycattle trampling, resulting in major soil disturbance. It is well known that earthworm abun-

Oligochacta 69

dance is negatively affected by tillage (CHAN 200 I), and much lower densities have beenfound in conventionally tilled sites compared with NT in Northem Paraná (BROWN et aI.2003). Tillage disrupts burrow continuity, damages earthworms directly, exposes them topredation, and enhances soil C oxidation and mineralization, reducing soil organic mattercontents over the long termo Therefore, it is not surprising that very few earthwonns wererecovered in the last two samplings in PA, compared with the first three samples.

The importance of soil C for at lest two earthworm species was evident from the ROA,that revealed significant correlations between U. brasiliensis and Belladri/us sp. 2 densities,both species associated with NF, where C contents were higher. Unexpectedly, soil K~ con-tents were positively and significantly correlated with the density of several earthwormspecies and parameters, ali of which tended to be more prevalent in PA and NT, the LUSwith highest soil K+ levels. The relationships between earthworms and soil K+ are not wellknown (particularly for native and tropical earthwonns), but K+ is necessary in earthwormphysiology, especially for osmotic and ionic regulation (EDWARDS & BOHLEN 1996) andthey also positively affect K+ availability in soils through mineral weathering, organic matterfragmentation and particle selection (BASKER et a!. 1992, 1993; BARTZ et a!. 2010). This is atopic that certainly merits further investigation.

ln a previous study perfonned in the winter season in one of the same fanns, BENITO et a!.(2008) found higher earthworm densities in a Eucalyptus sp. plantation (295 indiv. m"),followed by NT (57 indiv. m") and PA (38 indiv. m-2

). Compared with the present study,densities were higher in the reforestation and NT, but lower in PA (84-205 indiv. m-2 in thefirst three sampling dates). NUNES et a!. (2006) also found much higher earthwonn abun-dance in PA (from 3 up to >500 indiv. m") compared with NF (3-13 indiv. m") and annualcropping systems (0-29 indiv. m"), although lhe crops they evaluated (soybean, sugar cane)had been recently established using conventional tillage, similar to the practices used in thepresent study. Clearly, the massive soil preparation needed to convert PAto cropping has animportant negative effect on earthworm communities, affecting not only abundance, but alsodiversity. After conversion, species richness decreased from 6-9 spp. in PAto 2-5 spp. in thecropping systems (NUNES et a!. 2006), and only 2 exotic species were found in the PA areaafter conversion in the present study.

Earthworm species richness in the present study (lI spp.) was comparable to others evalu-ating populations in various LUS in the region: BARTZ et a!. (2009, 2013) found 6 and 11species, respectively, while AZEVEDO et a!. (2010) found 9 species and NUNES et a!. (2006)found 14 species. Of the different LUS studied, PA had the highest richness (7 species),although another species - Amynthas gracilis (Kinberg, 1867) - was found in qualitativesampling in September 2008 near lhe sampling points (M.L.e. BARTZ, personal observation),raising richness to 8 species (and overall species richness 10 12 spp.). This was lhe case eventhough the PA was established after at least 10 years of annual cropping using conventionaltillage.

Pastures can frequently preserve important numbers of native species, particularly whenestablished over savanna vegetation, where native pastures can be a better mimic of nativevegetation (BROWN et a!. 2004b; OECAENS et a!. 2004). However, when established over NF,pastures tend to have lower species diversity, due to the frequent disappearance of nativeforest species (FRAGOSO et a!. 1999; OECAENS et a!. 2004). ln the present case, PA had high-er total species richness than NF, due to invasion of PA by exotics, and the absence of F.bartzi and G. giocondoi from NF (although they are found in the original NF ofthe region;BARTZ et a!. 2012).

70 Advanccs in EarthwonnTaxonomy VI

As reported by BROW et a!. (2004a) and BARTZ et a!. (2013) native U. brasi/iensis wasfound only in NF and was notably absent from PA and the other agroecosystems, contrary tothe phenomena observed in lhe neighboring state of Santa Catarina, where it is found in PAand NT systems (BARTZ et a!. 20 I I). Furthermore, ali ocnerodrilid species were also absentfrom PA, but present in the other LUS; even in the forrnerly cultivated row-crop agroecosys-tems and CP, where pesticides have been or continue to be applied. These species appear tobe more resistanl to the management practices of agroecosystems, but their density tends tobe very low (NUNES et a!. 2006), although there are exceptions (BARTZ et aI. 2013 reportedlarge abundances in NT). In fact, it was also surprising that F. bartzi was also found in NT,indicating its slight tolerance to row-crop agriculture.

Of the five LUS, CP had the lowest earthworm abundance, biomass and species richness(2 spp.). In the past (from 1950's to 70's) many pesticides toxic to earthworms e.g., BHC(1,2,3,4,5,6-Hexachlorocyclohexane, now banned) and organo-chlorinated insecticides,carbamates and copper-based fungicides (PAOLETTI 1999; EDWARDS& BOHLEN 1996) wereregularly used in conventional coffee cultivation against pests and coffee rust (O. Giocondo,personal communication; AMBROVAY 1999). The low earthworm populations in CP in thepresent site may be due to the accumulation or residual effect of these pesticides. BARTZ eta!. (2009) also found only 2 species in five CP in nearby Lerroville, although abundanceswere generally much higher than in the present study, reaching up to 48 indiv. m" (mainlyjuvenile Dichogaster spp.) in conventional coffee and up to 600 indiv. m'2 in organic CP,c1early showing lhe value of no pesticide use and organic matter for earthworms in thesesystems.

Agroecosysterns of Northern Paraná are generally dominated by Dichogaster spp. and P.corethrurus, although some native species of the genera Andiorrhinus, Belladrilus, Glos-soscolex and Fimoscolex also are present, but in low densities (SAUTTERet a!. 2007). In lhepresent study three of these genera were found, and native earthworms predominated in CPand SNT, and represented half of the identified individuais in NT. This contrasts with resultsof BARTZ et a!. (2009) who found only exotics in CP, but confirms results of NUNES et a!.(2006) and BARTZ et a!. (2013) who found many native individuais of Fimoscolex and Oc-nerodrilidae in cultivated cropping systems in Northem and Western Paraná.

In most cases, particularly where soil disturbance is great, it is expected that annual cropswill have lower biomass, very low diversity and few (if any) native earthworm species(LAVELLE et a!. 1994), that seldom withstand major disturbances; these are normally re-placed by the more adaptable exotic and invading species (FRAGOSOet a!. 1997). In North-em Paraná, it appears that despite lhe inlensive agriculrural management practices adoptedover lhe last few decades (mainly since the 1950's), many native species have survived,although in very low densities. The future of these populations cannot however be consid-ered guaranteed, since changing management practices and weather conditions (e.g., globalwarrning and more extreme climatic events) play a critical role in determining their survivalover lhe long terrn.

Acknowledgements: This paper is pari of a PhO Thesis of the first author. The first and last authorsacknowledge Capes and C Pq for a PhO scholarship and a productivity fellowship, respectively.The authorsthank Agrisus Foundation, UEL and Embrapa for financial support (dissemination of results in scientificevents, field work, soil analyses), as well as the farmcr Mr. Octavio Giocondo (owncr ofthe São José Farm,inArapongasfLondrina)and Mr. Adrian von TreunfcIs, manager of the Solana Agropecuária (owners of theRhenânia Farm, in Rolândia)for the opportunity to perform this study on their properties.

Oligochaeta 71

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Authors' addresses: Marie L. C. Bartz, Universidade Positivo, Curitiba, PR, Brazil. - AmarildoPasini, Universidade Estadual de Londrina, Londrina, PR, Brazil. - George G. Brown, EMBRAPA-Florestas, Colombo, PR, Brazil. - Contact email: bartzmarie@gmail.com.