,,

BULLETIN bE L'INSTITUT ROYAL DES SC IENCES NATURELLES DE BELG IQUE ENTOMOLOG IE, 75: 305-3 I9 , 2005, BULLETIN VAN HET KONINKLIJK BELGISCH INSTITUUT VOOR NATUURWETENSCHAPPEN ENTOMOLOGIE, 75: 305-3 I9 , 2005

Succession of dance fauna (Diptera: : , , Microphoridae) in ancient forests and afforested former agricultural land: a case-study in the "Voerstreek" (Belgium, Flanders): faunistics and new species for the Belgian fauna

by Patrick GROOTAERT, Wouter DEKONINCK & Konjev DESENDER

Abstract Why dance ?

I I2 species of Empididae sensu latu were found in forests at the In contrast to ' rare or uncommon' groups that are extreme eastern border of Flanders in a region known as the Voer­ streek. Seven species are recorded for the first time in Flanders. Two frequently used in site quality assessments, dance flies or species are also new records for the Belgian fa una: Rhamphomyia empidid flies are common and widespread. Too often, (Pararhamphomyia) murina Collin and Rhamphomyia (Rhampho­ only mammals, birds or butterflies are used in site quality myia) mg entata von Roder. Distribution of Red Data Book species is commented. assessment and they are not always representative for Four species supposed to be Extinct were observed; one species the area. On the contrary, dance flies are always present, Critically endangered was recorded: Rhamphomyia (Pararhampho­ even in small plots. During an annual cycle, up to 50 myia) marginata (Fabricius); four species are Endangered (3 .6%); four species can be observed in a particular biotope (station) species are Vulnerable (3 .6%); 35 species are Susceptible (31 %), one Near threatened and seven are Data Deficient (6%). 49 species are (GROOTAERT et al., 1988). Many species have a very tight Safe/low risk (43 %). Only 43 % of the species are safe and under low microhabitat preference and hence they are good indica­ ri sks, so even when th e Data Deficient species are not taken into tors for a specific habitat or enviromnental conditions. Of account, still 5 1% of the species are more or less threatened. Young forests of at least 20 years old show a higher species diversity course, most species are very common and belong to the than th e old or very young forests. However, if we consider the true Red Data Book status (RDB): Safe/Low risk. But some­ forest species, the reference forests (ancient) have more true forest times up to 30% of a species assembly are rare or threa­ species and the younger forests have less forest species. Forest planta­ tions and spontaneous afforestations that are more than 20 years old, tened. The combination of total diversity, i.e. the total start to have a dance fl y fau na resembling that of the old reference number of species, the munber of specific species for a forests. Forests yo unger than 15 years old contain onl y genera li st forest particular habitat or microhabitat (target species) and the species. The plantation of 1989 in Altenbroek approaches strongly the fau na of the reference forest. Colonisation of the plantation proceeds amount of individuals of a species combined with the more rapidly than in a spontaneous afforestation. rarity factor (Red Data Book status) allows to make site quality assessments (POLLET & GROOTAERT, 1999). Key words: Diptera Empididae, succession, ancient forests, afforesta­ tion, fa uni stics Niche of the dance flies

The larvae of all empidids, as far as known, are carnivo­ Introduction rous and are living in the soil or in decaying wood (xylobionts). A very important limiting factor for the In order to compare the differences in natural quality of occurrence of larvae in the soil is the water saturation. spontaneous afforestation with artificial plantation of Apart from a few exceptions of species living in wells or new forest, a study was set up in the Voeren region in streams, the larvae are not adapted to living in an aquatic the extreme east of Flanders (Belgium). The fauna of environment. The adult flies are either obligate carnivo­ forest of various age, various origin and with a different rous or nectar feeders. The predators catch their prey grazing were compared to two ancient forests, the Alten­ either on a solid substrate (soil, surface of leaves or broek and Alserbos. These reference forests are known to vetiical walls), floating on a water surface or in flight. be there unaltered since more than 225 years and are so­ However, many species feed on nectar and hence might called Ferraris-forest since they are represented on the play an important role in pollination. Finally, there are Ferraris-maps. species that have a combined feeding strategy. They are Since the "Voerstreek" is situated in the extreme east nectar feeders, but the male captmes a prey to present to · of Flanders, it has a Central European fauna in contrast to the female during mating. In early spring, flower visitors the mainly Atlantic faun a of Flanders. This explains the belonging to the genera and Rhamphomyia are huge number of new or rare species that were found especially abundant. Probably, they play an important during this study. role in pollination. From June on, it are above all pre- II

306 Patrick GROOTAERT, Wouter DEKONINCK & Konjev DESENDER

dators that are abundant and dominant. They are vora­ Material and methods cious and probably play a role in the population regula­ tion of plant parasitic Diptera (leafminers and gall­ The Voeren region has the oldest sites in Flanders where midges). Dance flies constitute a food source for many afforestation was planned and canied out on fonner insectivorous such as spiders and birds. agricultural land on loamy soils. In the neighbourhood The occurrence of dance flies is above all determined of two forest relics (the Altenbroek and the Alserbos), by the stmcture of the habitat and landscape. In some relatively large areas have been designated for sponta­ surveys we showed that Empididae need different habi­ neous afforestation or to be altered to forest by plantation tats to complete their Iifecycle (DELETTRE et a!., 1992; of indigenous trees (VERSTRAETEN et a!. 2001; DEKO­ 1998) e.g. the larvae of Hilara live in a particular soil NJNCK et a!., 2005). At present, these two forests consist type, the male collects prey on water surfaces while the of many small plots with different age, structure and female swarms in areas with a particular stmcture. Em­ history and are as such are ideal to evaluate ctment on­ pididae also show a preference for habitats nonexposed going afforestation. to the sun, i.e. shaded locations with a high relative Dance flies were sampled in five sites of the Alten­ humidity. Consequently, forests are an evironment that broek forest and six sites of the Alserbos forest. The host many species. sampling stations situated on Fig. 1. Characteristics of all 1 I sampling stations are given in Table 1, whereas Systematics of dance flies details on soil and vegetation characteristics can be found in DEKON INC K et a!. (2005). In each station (VOERO I­ Approximately 272 species occur in Flanders (360 in VOER05 and VOER07-VOER12) 3 pitfalls (PT), 3 white Belgium). They are grouped in the superfamily of the water traps (WT) and one Malaise trap (MT) were in­ · Empidoidea (C!-IVALA, 1975) comprising the families stalled. All pitfalls (glass jam jars, diameter of 9.5 em) Empididae, Hybotidae, Microphoridae, Atelestidae and and white water traps ( 17x 10 em and 5 em high) were Dolichopodidae. In the present study, we envisage the installed in a row, spaced 3-5m apart. A 3.5% fonnalde­ fonner family of the Empididae sensu lata that groups the hyde solution was used for killing and fixation and some four families of the Empididae, Hybotidae, Microphori­ detergent was added to lower surface tension. Each Ma­ dae and Atelestidae (not found during this study). The laise trap collecting-vial was filled with a 75% alcohol Dolichopodidae or long-legged flies are dealt with in solution. All traps were emptied 12 times from 02-IV- another paper. A Red Data Book of the dance flies in 2003 until 08-X-2003. Flanders is available (GROOTAERT eta!. , 2001).

Fig. I - Sampling stations in " Voeren" region. I'

Afforestation: Case study "Voeren": Empidoidea 307

Table I - Code, history, description and age of the sampling sites.

Site code Forest History Description of the site Forested since VOEROI Altenbroek Ancient forest Ancient oak-birch forest < 1775 de FeiTaris VOER02 Altenbroek Arable field Afforestation and low density grazing (Galloways), Salix sp. and 1996 birch. VOER03 Altenbroek Grassland Afforestation and low density grazing (Galloways), no shrubs or 1996 trees VOER04 Altenbroek Arable field Afforestation and intensive summer grazing, Salix sp. and birch 1996 VOER05 Altenbroek Arable field Plantation of Quercus robur 1989 VOER07 Alserbos Ancient forest Ancient oak-birch forest < 1775 de Ferraris VOER08 Alserbos Grassland Afforestation of birch 1980 VOER09 Alserbos Arable field Afforestation of birch 1980 VOERJO Alserbos Grassland Plantation of Prunus avium with fragments of spontaneous Callu- 1985-1990 na vulgaris VOERII Alserbos Arable field Afforestation of birch 1980 VOER12 Alserbos Grassland Plantation of Quercus robur 1985-1990

Results faunistics they can get at most the Red Data Book status of "Sus­ ceptible" or " Data deficient" since no records before the General results faunistics pivot year of 1980 are available. The trend criterion or percentage of decrease of the number of records after 9.639 individuals belonging to 112 species were collected pivot date of 1980 is the first criterion for the Red Data and identified (Table 2). Most specimens were caught Book. Their habitat not being threatened is a second with the Malaise traps (5.397), followed by the white criterion for not placing them in a threatened category. pan traps ( 4.153) and the pitfall traps ( 109). All data were combined in the final analyses. - Rhamphomyia (Pararhamphomyia) murina COLLIN , The dance fly fauna of the Voerstreek is very special in 1926 -New for Belgium and Flanders comparison to the other regions in Flanders. The "Voer­ Material examined: Altenbroek, 1 male, l-14.V.2003 streek'' abuts the Central European Province of the (VOER02, MT). Palaearctic Region whereas the rest of Flanders mainly Rh. murina was described by CoLLIN from Scotland hosts an Atlantic fauna with a few scattered Central and later only recorded from the Czech Republic European elements (relics). For the first time, a very (CHVALA, 1989; 2004). This is apparently a very rare intensive sampling campaign was performed in the Voer­ species with an Atlantic and Central European distribu­ streek, resulting in a total number of 112 species as to 272 tion. In the present study, the species was found in rather species known from Flandres. 63 species of them have a young spontaneous developing afforestation on arable Red Data Book status (see Table 2). Seven species are land. It is probably not a forest species. recorded for the first time in Flandres, 4 species were suppose<;! to be "Extinct", 1 species is "Critically - Rhamphomyia (Rhamphomyia) argentata VON Rc>DER, endangered", 4 species have the status "Endangered", 1887 -New for Belgium and Flanders 4 species are "Vulnerable", 35 species are "Suscepti­ Material examined: Alserbos, 1 female, 14-30.V.2003 ble", 1 species is "Near Threatened" and 7 species are (VOER08, PT). " Data Deficient". Two species are recorded for the first This species is only known from Central Europe: time in Belgium. This large amount of Red Data Book Germany, Switzerland, Austria, Czech Republic and species can be explained by the fact that many of these Hungary (CHVALA, 1989; 2004). It has been found in species are occurring on the edge of their distribution area spontaneous forestation on grassland, aged 23 years. It is and as a consequence they are rather rare in the remaining not known whether it is a h·ue forest species. pmis of Flanders. Another reason is that we are dealing with old forests which have an extraordinary fauna. - Oedalea apicalis LOEW, 1859- New for Flanders Furthermore, the sampling was very intensive, in an area Material examined: Alserbos, 1 female, 30.V- never sampled before in detail. 14.VI.2003 (VOER09, MT); 1 female, 30.V-14.VI.2003 (VOER09, MT); Altenbroek, 1 female, 30.V-14.VI.2003 New species for Flanders (VOER02, MT). Previous records: Flanders: Wijnendale bos, 1 female, Seven species are recorded for the first time in Flanders. 14.VI.2000, M. PoLLET; Beiaardbos, 1 female, 16.V. According to the criteria used in GROOTAERT eta/., 2001 , 2000. These two records have not yet been published. w 0 Tabl e 2 -Abundance of dance flies collected in each plot (sum of Malaise traps, white pan traps and pitfall traps): code, species name, abundance and Red Data Book status. 00

- Altenbroek Al serbos

Code Species name Red data book status VO ER VOER VOER VOER VO ER VO ER VOER VOER VOER VOER VO ER Total 01 02 03 04 05 07 08 09 10 II 12 "'ij I» Bice ni gr Bicell ari a ni gra (Meigen, 1824) 2. Endangered I I 2 9'. (') Bice sul c Bicellaria sul cata (Zetterstedt, 1842) 4. Susceptible I 8 24 2 4 39 0"' Bice vana Bi cellaria vana Collin, 1926 6. Safe\Low ri sk I 5 22 2 4 34 ;:o 0 Chpo voca Chelipoda vocatori a (Fall en, 18 15) 6. Safe\Low risk 4 278 11 6 20 5 II 134 568 0...., Cros mini Crossopalpus minimus (Meigen, 1838) 6. Safe\Low ri sk I I ?;; Cros nigr Crossopalpus nigritellus (Zetterstedt, 1842) 6. Safe\Low risk I I 2 I 3 8 -~ Doli irro Dolichocephala irrorata (Fall en, 18 15) 6. Safe\Low risk I I 2 ~ 0 Drap pari Drapetis parilis Coll in, 1926 6. Safe\ Low risk 2 I I 3 7 t= ro- Ecop albi Empis (Coptophlebi a) albinervis Meigen, 1822 6. Safe\Low ri sk I 2 2 18 I I 25 ..., t) Eemp acin Empis (Empis) acinerea Chva la, 1985 4. Susceptible I 3 2 I 10 3 3 21 4 2 1 69 t'T'l ~ Eemp aest Empis (Empis) aesti va Loew, 1867 6. Safe \Low risk 3 8 4 23 7 6 6 5 36 2 2 102 0 Eemp albo Empi s (Empis) albopilosa de Meij ere, 1935 4. Susceptible I I 2 ~ Eemp caud Empis (Empi s) caudanil a Loew, 1867 4. Susceptible I I n ~ Eemp chio Empis (Empis) chi optera Meigen, 1804 6. Safe\Low ri sk 3 I 2 2 5 5 I 7 17 5 7 55 1 p,o ~ Ee mp ni gr Empis (Empis) ni gripes Fabricius, 1794 6. Safe\Low risk 2 47 13 74 5 5 I I 2 4 !54 0 t:l "-. Eemp nunt Empis (Empis) nuntia Meigen, 193 8 6. Safe\Low risk 12 I 2 9 8 I I 15 5 13 67 ('!) < Eemp penn Empis (Empis) pennipes Linnaeus, 1758 4. Susceptible I I t) t'T'l Ecmp plan Empis (Empis) planeti ca Collin, 1927 6. Safe\Low risk 3 2 II 2 18 (/) t'T'l Eemp prae Empis (Empis) praevia Collin, 1927 6. Safe\Low risk 2 2 a t'T'l Eemp prod Empis (Empis) prodromus Loew, 1867 6. Safe\Low risk 4 7 II ;:o Eemp wood Empis (E mpis) woodi Collin, 1927 4. Susceptible I I 2 Ee ue cili Empis (Euempis) ciliata Fabricius, 1787 4. Susceptible 6 2 I I 7 I 18 Eeue tess Empis (Euempis) tessell ata (Fabricius, 1794) 6. Safe\Low risk 2 13 14 22 2 I 20 10 10 4 98 Ekri li vi Empis (Kritempis) li vida Linnaeus, 1758 6. Safe\Low risk 75 308 62 !59 74 231 548 709 445 429 556 3596 Elap eph i Elaphropeza ephippiata (Fallen, 18 15) 6. Safe\Low ri sk 3 7 76 4 3 10 2 4 109

i Elep vari Empis (Leptempis) variegata Meigen, 1804 0. Extinct I 7 8 I Epac fe mo Empis (Pachymeri a) femorata Fabricius, 1798 0. Extinct 2 3 3 3 I 12 I 'Epol opac Empis (Polybl epharis) opaca Meigen, 1804 6. Safe\Low risk I 10 32 24 I 6 5 10 4 4 97 E ut h gyll Euthyneura gyllenhali (Zetterstedt, 1838) 4. Susceptible I 3 4 Euth myrt Euthyneura my1tilli Macquart, 1836 6. Safe\Low risk 7 I 2 7 7 6 4 7 4 1 Exan lute Empis (Xanthempis) lutea Meigen, 1804 4. Susceptible I I Exan punc Empis (Xanthempis) punctata Meigen, 1804 4. Susceptible I I 2 Exan ster Empis (Xanthempis) stercorea Linnaeus, 176 1 6. Safe\ Low risk 33 160 25 80 29 5 24 22 12 25 8 423 Exan trig Empis (Xanthempis) trigramma Wiedemann, 1822) 6. Safe\Low risk 3 5 5 427 375 195 355 140 1505 Glom fuse Gloma fuscipennis Meigen, 1822 4. Susceptible I I Hila albi Hilm·a albipennis von Roser, 1840 4. Susceptible I I Hila com Hilara comicula Loew, 1873 6. Safe\Low risk 2 I 40 14 2 2 61

Hila fuse Hi lm·a fuscipes (Fabricius, 1794) 3. Vulnerable 5 I I 7 Hila li to Hilara litorea (Fallen, 1816) 2. Endangered 3 10 I 25 2 3 1 48 79 3 29 2 233 Hila !uri Hilara lurida (Fallen, 18 16) 2. Endangered I I I 3 Hila mani Hi lara manicata Meigen, 1822 4. Susceptible 2 I 5 8 Hi la maur Hi lm·a maura (Fabricius, 1776) 6 . Safe\ Low risk I 2 I 4

Hila prim Hilara primula Collin, 1927 0. Extinct I I Hybo culi Hybos culicifonnis (Fabricius, 1775) 5. Near threatened 12 I 2 I 8 6 24 16 23 9 102 >­ ~ Hybo femo Hybos femoratus (Miler, 1776) 3. Vulnerable I I 0 @ Lept bore Leptopeza boreal is Zetterstedt, 1842 8. New for Flanders I 2 3 Vl EJ...... Lept tlav (Meigen, 1820) 4 . Susceptible 2 2 2 6 c; · ::; Micr holo Microphor holosericeus (Meigen, 1804) 4. Susceptible I I 36 2 1 4 26 65 13 7 3 177 (")

Ocyd glab Ocydromia g labricula (FallOn, 18 16) 6. Safe\Low risk I I 4 4 4 3 I I 19 Vl "'(T.) Oeda apic Oedalea apicalis Loew, 1859 8. New for Flanders I I I 3 Vl 2 16 13 I I 3 50 a. Oeda flav Oedalea tlavipes Zetterstedt, 1842 6. Safe\ Low risk 4 I II '-< Oeda holm Oedalea holmgreni Zetterstedt, 1852 6. Safe\Low risk I 2 12 9 18 II I 54 0< Oeda hybo Oedalea hybotina (Fallim, 18 16) 4 . Susceptible I I (T.) @ Oeda tibi Oedalea tibialis Macquart, 1827 6. Safe\Low risk I I I 2 3 8 ::; 4 2 2 3 9 8 I 29 Oeda zett Oedalea zetterstedti Collin, 1926 4. Susceptible tTl I 7 4 12 a Orop sphe Oropezella sphenoptera (Loew, 1873) 8. New for Flanders '0 0.: Phyl mela Phyllodromia melanocephala (Fabricius, 1794) 6. Safe\ Low risk 12 2 3 17 0 a. Plat agil Platypalpus agilis (Meigen, 1822) 6. Safe\ Low risk 2 10 II 15 6 5 8 2 I 60 (T.) "' Plat albi Platypalpus a lbiseta (Panzer, 1806) 4. Susceptible I I

Plat alco Platypalpus a lbicornis (Zetterstedt, 1842) 4. Susceptible I 3 4 Plat anal Platypalpus analis (Meigen, 1830) 0. Extinct 2 2 VJ 0 \.0 .....w Table 2 - Continued. 0

Altenbroek Alserbos

Code Species name Red data book status VOER VOER VOER VOER VOER VOER VOER VOER VOER VOER VOER Total 01 02 03 04 05 07 08 09 10 I I 12 'i:l Plat anpe Platy palpus annulipes (Meigen, 1822) 6. Safe\Low risk I 5 2 1 2 3 3 13 48 ~ ~. 0 Plat aris Platypalpus aristatus (Collin, 1926) 4. Susceptible 5 I I I 14 I I 3 7 34 ::-;- 0 Plat aroi Platypalpus articulatoides (Frey, 1918) 6. Safe\Low risk I 2 3 E5 Plat arus Platypalpus articulan1s Macqumi, 1827 6. Safe\Low risk I I 0 >-l Plat aust Platy palpus australominutus Grootaert, 1989 6. Safe\Low risk I I ~ Plat calc Platypalpus calceatus (Meigen, 1822) 6. Safe\ Low risk 3 I 30 2 4 4 5 13 3 4 69 :::0 ~>-l Plat cili Platy palpus ciliaris (Fallen, 18 16) 6. Safe\ Low risk 99 2 I 36 19 2 13 I I 2 176 ~ Plat clar Platypalpus c larandus (Collin, 1926) 6. Safe\ Low risk 0 2 2 s= Plat curs Platypalpus cursitans (Fabricius, 1775) 6. Safe\Low risk I I ....,~ t) Plat divi Platypalpus divisus Walker, 1851 8. New for Flanders 2 2 t1i ~ Plat cxil Platypalpus exilis (Meigen, 1822) 4. Susceptible 3 2 7 6 5 23 46 0 Plat flav Platypalpus flavicomis (Meigen, 1822) 4 . Susceptible I 2 3 Plat infe Platypalpus infectus (Collin, 1926) 4 . Susceptible 4 4 (")~ ~ Plat loco Platy palpus longicomis (Meigen, 1822) 6. Safe\ Low risk I 2 I 5 14 2 2 I 28 Ro Plat lose Platypalpus longiseta (Zetterstedt, 1842) 6. Safe\ Low risk 2 3 3 3 6 I 4 4 26 :r:: 0 Plat lute Platypalpus luteus (Meigen, 1804) 4 . Susceptible I I I 2 5 2. (1) < Plat minu Platypalpus minutus (Meigen, 1804) 6. Safe\Low risk I 2 2 2 7 t::J t1i Plat nita Platypalpus nigritarsis (Fallen, 18 16) 6. Safe\ Low risk I I [/) Plat nive Platypalpus niveiseta (Zetterstedt, 1842) 4. Susceptible I I 2

Plat obsc Platypalpus obscurus (von Roser, 1840) 8. New for Flanders I I t1i~ :::0 Plat pall Platypalpus pallipes (Fallen, 18 15) 4. Susceptible I I I 3

Plat pave Platypalpus pallidiventris (Meigen, 1822) 6. Safe\Low risk 3 30 7 23 2 5 9 10 7 8 5 109

Plat pect Platypalpus pectoralis (Fallen, 18 15) 6. Safe\Low risk 87 I I 5 4 I I 100

Plat poli Platy palpus politus (Collin, 1926) 4. Susceptible I I

Plat puli Platypalpus pulicarius (Meigen, 1830) 7. Data deficient I I

Plat rapi Platypalpus rapidus (Meigen, 1822) 2. Endangered I 12 13

Plat stig Platypalpus stigma (Collin, 1926) 7. Data deficient I I Plat veiT Platy palpus verralli (Collin, 1926) 3. Vulnerable 3 3

Rae! a lbo Rhamphomyia (Aclonempis) albohirta Collin, 1926 7. Data de ficient I I

w w

- --

no . . 9 9 fo r est est s pecie s s 1 8 8 3 9 9 3 1 7 7 1 6 6 1 2 2 17 17 1 5 5 1 2 2 1 2 2 29 29

n o. o. s p ec i es es 48 42 42 48 34 34 5 5 5 58 58

46 46 4 5 5 5 2 2 5

1 1 35 35 45 45 11 2 2 I" I"

('1) ('1)

0: 0:

t o t a l l ind. ind. 754 754 662 662 77 9 9 22 4 4 426 426 8 40 40 1 3 74 74 1517 1517 991 991 104 4 4 1 02 8 8 9 639 639

0 0

0: 0:

Tr im im fl av av Tri c h i n o m y i a a fl a v ip es es ( M e i ge n , , 1 83 0 ) ) 4 . S . u sce p t i bl e e

2 5 5 13 13 2 0 0 2 2 14 14 I I 7 5 5

.g .g

Tr i e c l o n n Tric h i n a e a l o n gata gata 1-! a lid ay, ay, 1 833 833 5 5 4. 4. S u scep tibl e e 9 6 6 9 4 6 6 4 1 2 2 3 3 l l 46 46 tT1 tT1

Ta p e e nubi nubi T ac h y eza eza p nubil ( a M e i ge n , , 1 8 04 ) ) 6 . . S a f e \ L ow ow ri s k k 6 6 l l 3 3 l l l l 2 2 4 4 l l l l l l 21 21

::l ::l

@ @ Tad r r umbr umbr Tac h ydro mi a a u mbra ru

m m H a li day , , 1 833 833 4 . . Suscept i b l e e l l I I

('1) ('1)

0 0

< <

Tadr Tadr a r ro ro T ac h y d ro mi a a r roga n s s ( Linn ae u s, s, 1 76 1 ) ) 6 . . S a f e \ L ow ow ri s k k 3 3 3 3

Tadr Tadr a n nu nu Tac h ydro mi a a n nu l i m a n a a Meige n , , 1 822 822 6 . . Safe \ Low Low ri s k k l l

l l '< '<

0.. 0..

s:: s:: Tad r r aemu aemu T ac h ydro mi a a aemu 4. 4. l a a S ( u L scep oew tibl , , 1 864) 864) e e l l 2 2 4 4 I I

......

Vl Vl

R r h a s a u lc lc Rh a mph o m y i a a (RJm nph o m y i a) a) s ulc a t a ( a M e i ge n , , 1 8 0 4) 4) 6. 6. S 1 afe 9 3 3 9 \ L ow ow I I ri s k k l l l l 1 3 3 l l l l 2 2 2 ll ll 2 1 1 94 94 ('1) ('1)

Vl Vl

(:>) (:>)

Rh a (J (J mph o m y i a a (RJ1am 7. 7. Rr h D a a ph a l t aev aev o a a m de y i a) a) fi c i l e aev nt nt i pes pes (Fa ll e n , , 1 8 1 6) 6) l l l l

::l ::l

1 887 887

0 0

Rr h a a g_ g_ arge arge Rh a m p h o m y i ( a Rh 8 a . . mph New New o fo m y r r i a) a) Fl a a nd r ge e r nt s s a t a a vo n n R o d e r , , l l l l

Vl Vl

Me i ge n , , 1 822 822 @ @

0 0

Rpar Rpar tars tars RJ mm p h 9 9 o m yia yia ( P ara 4 rh . . a mp Su sce ho m p t y ibl i a) a) 2 2 2 2 e e t arsa t a a 4 4 l l ~ ~

)> )>

Co lli n, n, 1 926 926

Rpar Rpar 8. 8. New New m uri uri for for Fl a nd e Rl r s s 1 a m p h o m y i a a (Pa r a r ha mp ho m yia) yia) murin I I a a l l

(Fa b r i c iu s , , 1 787) 787)

3 3 R h a mph 2 2 10 10 o m y i a a (Pa 4 4 l l r a R rh l p . C . a ar ar mph ri m t i arg arg o ca m ll y y e y i a ) m ) nd a argi n ge n r a e t d d a a

(Zet t e r s t ed t , , 1 842) 842)

l l l l 4 4 l l 7. 7. I I D ata ata d e fi c i e nt nt Rl1 a mph o m y i ( a P R ara a p rh r r dent dent a mph o m y i a) a) d e n t ip es es

(Fa ll e n , , 1 8 1 6) 6)

6 6 240 240 22 22 58 58 76 76 5 5 38 38 23 23 ll ll l l Rh a m p h o m y i a a (Megacytta 3. 3. Rmeg Rmeg V uln eras eras era ru bl s) e e c r ass i rostr i s s

1822 1822

2 2 l l I I Rl1 a m p h o m y i a a (Megacytta Rm 7. 7. D eg eg ata ata a ru n o s) s) d m m e a fici n o e m nt nt a lip e nni s s M e i ge n , ,

26 26 I I 10 10 1 4 4 RJ I I 1 a m pho m yia yia (Ho l R oc 7 h . . l o era) era) D lum a t a a um b defic r r b r ip i e e nn nt nt is is Me i ge n , , 1822 1822

53 53 1 8 8 8 8 16 16 6 6 4 4 Rh I I a mph o m y i a a (H o l oclera) oclera) 6 . . S afe ni \ L gr ow ow ip e tmi ri s k k s ( s F a b r i c iu s , , 1 794) 794) R h o l l ni gr gr

6 6 2 2 4 4 4. 4. Su scep tibl e e Rha m p h o m y i a a (Ho l oc l e r a) a) fl ava ava ( F a ll e n , , 1 8 1 6) 6) R h o l l fl av av

3 3 1 4 4 I I I I I I 2 2 6 6 4 . . Suscep t i bl e e R h a mp ho m y i a a (Amy d roneura) roneura) gi bb a a (Fa ll en , , 1 8 1 6) 6) Ramy Ramy gibb gibb

ge n , , 1 83 0 0

3 3 348 348 5 5 17 17 39 39 I I I I 2 2 4 4 275 275 4. 4. S u scep tibl e e I I Rh a m pho m y i a a (A m ydro n e ur a) a) ery th ro ph tha lm a a e M i - Ramy Ramy eryt eryt

35 35 I I 2 2 25 25 5 5 2 2 6 . . Safe\Low Safe\Low r i sk sk Rha m pho m yia yia (Aclo n empis) empis) l ong ip es es (Me i gen , , 1 804) 804) Rac l l l o n g g I I

312 Patrick GROOTAERT, Wouter DEKONINCK & Konjev DESENDER

South Belgium: Virelles, 1 female, 14.VI.1986; 1 fe­ 1 female, IO.IX.I948, A COLLART; I female, l.VI.I949, male, 16.VII.l986, N. MAGIS (MT in swamp in forest A. COLLART; Ellezelles, I female, 24.V.I959, M. along Lac de Virelles). BEQUAERT; Chatillon, I female, 29.V.I981, JAC; This species is known from Great Britain, Gennany Ottignies, I female, 24.VII.l982, P. DESSART; Sart, I fe­ and Poland (CHV ALA & WAGNER, 1989), Denmark and male, 2.VI.l982, R. DETRY; Fairon, 1 female, 3.V.l983, Hungary (CHVALA, 2003). It is evident that this species R. DETRY. is very rare but apparently it is widespread. It is a forest This species is quite conunon in South Belgium and is species and most probably a xylobiont. widespread in Europe (CHVALA & KOVALEV, 1989).

- Oropezella sphenoptera (LOEW, 1873) - New for Flanders Species previously considered as "Extinct" Material examined: Alserbos, 1 female, 30.V- 14.VI.2003 (VOER08, MT); 1 male, 30.V-14.VI.2003 The following four species were presumed to be extinct in (VOER09, MT); I male, 30.V-14.VI.2003 (VOERll, Flanders (GROOTAERT et al., 2002). All these species MT); 2 males, I female, I4-26.Vl.2003 (VOER09, seem to occur on the limit of their distribution area MT); 1 male, I female, 14-26.VI.2003 (VOERll, MT); (C!-IV ALA & KovALEV, I989). Their Red List status has 1 female, 26.VI-Il.VII.2003 (VOER09, MT); I female, to be revised in the frame of the criteria: decline, rarity 26.VI-11.VII.2003 (VOER1I, MT). and the threat of their habitat. They probably will receive Previous records: South Belgium: Hockai, 1 indivi­ the status "Critically endangered". dual, 9.VII.l947, M. BEQUAERT; Mirwart, 6 individuals, 6.VII.I943, R. TOLLET. - Empis (Leptempis) variegata MEIGEN, 1804 This species is present all over Europe, including the Material examined: Altenbroek, 1 male, I4.V- south and is perhaps less abundant in Northern Europe 30.V.2003 (VOER03, MT); I male, 6 females, 14.V- (CHVALA, 1983). 30.V.2003 (VOER04, MT). Previous records: Flanders: Buizingen, 1 female, - Platypalpus divisus WALKER, 1851 -New for Flanders 13 .V.1880, J. JACOBS. Material examined: Altenbroek, 1 male, 30.V- South Belgium: Fleron, 1 female, 16.V.1894, CoucKE; 14.VI.2003 (VOER05, WT); 1 female, 30.V-14.VI.2003 Hamoir, I female, I8.V.1896, CANDEZE; 1 female, (VOER05, MT). 5.VI.l896; Hockaifagne, 1 female, 8.VI.l911, M. GOET­ Previous records: South Belgium: Ottignies, 1 female, GHEBUER; Dalheim, 1 male, I female, 23 .V.1917, 16.V.I98I; I male, 30.V.I981; l male, 22.VI.l981, M. GOETGHEBUER; Aubel, 1 male, I female, 6.V.l934, P. DESSART (MT in garden); Vallee du Rabais, I male, M. BEQUAERT; Vise, l male, 1 female, 12.V.1946, 30.VI.l980, P. GROOTA ERT. A. COLLART; Le Mesnil, l female, I5.V.1947, A. COL­ This rare species is known from Great Britain, Czech LART; Borgoumont, I female, !9.V.1950, R. TOLLET; Spa, Republic, Austria and Hungary (C!-IVALA & KOVALEV, I male, 22.V.l976, SBA; Elsenborn, 2 males, 3 females, 1989). 7.VI.I98I; Krinkelt, 3 males, 5 females, 20.V.l98l, NMP; Rocherath, 1 male, I female, 26.V.l981; Vallee - Platypalpus obscurus (voN RosER, I840) - New for de Ia Jansbach, I male, l female, 1982. Flanders E. variegata is a remarkable large Empis species with Material examined: Altenbroek, I female, 26.VI­ spotted wings. It has a Central European distribution ll.VII.2003 (VOER02, MT). (C!-IVALA, 2003). Most records in Belgium are quite Previous records: South Belgium: Treignes, 1 female, old and almost all are from South Belgium and the 3l.VIII)984, KHO; Logne, 2 females, 2l.VII.I989, "Hautes Fagnes" only. It is not astonishing that it is R. DETRY; Torgny, 1 female, 1O.VII.1948, M. Bequaert; found in the Voeren region as this region abuts the Hautes Buzenol, 1 male, 28.VII.l981 , P. GROOTAERT. Fagnes. It appears to be a very rare species, previously only known from 5 individuals in South Belgimn. It is wide­ - Empis (Pachymeria)femorata FABRICIUS, 1798 spread in Europe: Denmark, Italy, Switzerland, Spain, Material examined: Altenbroek, I male, l-l4.V.2003 Hungary and Romania (CHVALA & KOVA LEV, 1989). (VOERO l , MT); I male, l-14. V.2003 (VOER02, MT), · P. obscurus does not occur in Northern Europe and is I male, 14-30.V.2003, I female, 14-26.VI.2003 found in the southern and eastern parts of Europe. (VOER01, WT), I female, 14-26.VI.2003 (VOER02, MT); Alserbos, 3 females, 30.V-14.Vl. 2003 (VOER07, - Leptopeza borealis ZETTERSTEDT, 1842 - New for WT), I female, 30.V-14.VI. 2003 (VOERIO, MT), I fe­ Flanders male, 30.V-I4.VI. 2003 (VOERIO, WT), I m ale, Material examined: Altenbroek, I male, 14-30.V.2003 (VOERI1, MT), 1 male, I4-26.VI.2003 (VOERIO, WT). (VOER05, MT); 1 male, 30.V-14.VI.2003 (VOER04, Previous records: Flanders: Willebroek, I male, l female, MT); I female, 30.V-14.VI.2003 (VOER05, MT). VII.l878, J. JACOBS. Previous records: South Belgium: Mirwart, 1 female, South Belgium: Beyne, I female, 31. V .1 94 1, M. L E­ l4.VI.l946, M. Bequaert; I female, I8.VI.l946, M. CLERCQ; Wanze, 4I males, 26 females, 30.V.l982; BEQUAERT; Hockai, 1 female, 28.VII.I946, A. COLLART; 4 males, 2 females, 6.VJ.l982, l female 13.VI.l982, I I

Afforestation: Case study "Voeren": Empidoidea 313

R. DETRY (in MT); Lixhe, 1 male, 4.V.1938, M. B E­ South Belgium: Genval, 1 female, 6.VII.l917, A. TON­ QUAERT; Virelles, 1 female, 16. VII.1986, N. MAGIS . NOIR; Steinbach, I female, VII.1902, Gu1 ; Buzenol, E. Jemorata is a Central European species, not known 2 females, 25.VIII.1981, P. GROOTAERT; Buzenol, 2 fe­ from Scandinavia but it is found in Great Britain (com­ males, ll.VIII.1981 , P. GROOTAERT; Logne, 1 female, mon only in Southern England), Belgium, The Nether­ 17.VII.l986, R. D ETRY; Forge-Phillipe, 1 female, lands (the most northerly found populations) and the 25. Vl.1981, P. GROOTAERT; Wanze, I female, remaining parts of Central Europe. In the south its dis­ 24.VI.l981, R. DETRY; Logne, 1 male, 2.Vll.l986, tribution area reaches to in France and Italy. J. B ERTAUX; Logne, 1 male, 1 female, 2.Vll.1989, In South Belgium, the species is known from 4 popula­ R. DETRY . tions: Wanze (1982), Beyne (1941), Lixhe (1938) and Platypalpus analis is encountered in forests. In Virelles (1986). In Wanze, the population counts many addition, it is known from Great Britain, France, The tens of indivuals. In Flanders, there is only one record of a Netherlands, Derunark, Germany, Sweden, Italy, Czech female found in July 1878 in Willebroek. Probably, the Republic and Switzerland (CHVALA, 2003). Apparently, species was once more common and Flanders makes part P. analis has an Atlantic and Central European dish·i­ of its distribution area. bution. The species occurs in lowland forests, especially in mixed deciduous forest. The males fonn small swarms, Critically endangered species flying stationary between pending branches at a height of 0.5 to 2m while holding their prey. Females are found on Anthriscus sylvestris (cow parsley) and composite - Rhamphomyia (Pararhamphomyia) marginata (FABRI­ flowers. Flight time: mid of April till June (VAN DER CIUS , 1787) GoOT, 1989). Material examined: Altenbroek, 1 female, 17.IV­ I.V.2003, (VOER01, MT); 3 females, 14-V.2003 - Hilara primu/a COLLIN, 1927 (VOER05, MT); 2 males, I female, 14.IV-l.V.2003 Material examined: Alserbos, I male, 14-26.VI.2003 (VOER01, MT); I female, 14-30.V.2003 (VOER04, (VOER10, MT). MT); 1 female, 30.V-14.VI.2003 (VOER04, MT); Alser­ Previous records: Flanders and Brussels: Elsene, l fe­ bos, 1 female, 14-30.V.2003 (VOER04, MT). male, I O.V. I896, CoucKE; Wiekevorst, 5 females, Previous records: Flanders: Meerdaal, 1 male, 23.IV.l926, GAB; Mollem, 1 male, I female, 20.IV.1999, L. DE BRUYN. 15 .V. 1901 , GsE; Heusden, 1 male, 19.1V.1944, Jean South Belgium: Buzenol, 2 females, 19.V.1981 , Verbeke; Lo-Reninge, 1 male, I female, 4.V.1920, P. GROOTAERT. GSE; Munte, 1 male, 1 female, 17.1V.1937; Destel­ In the present survey, 10 specimens were encountered. bergen, 1 male, 5 females, 17.1V.1912, M. GOETGHEBUER; This is a lot more than the amount yet present in the St. Amandsberg, 2 males, 7.IV.1942, Jean VERBEKE; collections of the RBINS. This very remarkable species Waarschoot, 2 males, 1 female, 24.IV.1942; Heusden, has broadened wings with a black edge. In flight, this fly 1 male, 26.IV.1945, Jean Verbeke; Hageven, I male, resembles a moth and it has frequently been cited in this 26.1V.2000, P. GROOTAERT. way. There are only 2 confirmed records from Belgium: South Belgium: Vise, 3 males, I female, 30.V.1941, one from Meerdaalwoud and the other from Buzenol in A. COLLART. the most southern region of Belgium. Rh. marginata is This species has been identified as Hilara primula but widespread in Western Europe from Great Britain up to has to be re-examined. H. primula is a very early spring Hungary and Romania in the east; in the north in Scandi­ species; already found in April. The observation in the navia but it is not reported from Southern Europe (Spain present survey is quite late and therefore questions its and Italy). identification. Possibly, it concerns an unknown sister species. H. primu/a is probably more abundant than sup­ Endangered species posed to be but it is likely not recorded since there are less sampling campaigns in early spring. - Bicellaria nigra (MEIGEN, 1824) H. primu/a is known from Great Britain, The Nether­ Material examined: Altenbroek, 1 female, l-14.V.2003 lands, Belgium, Denmark, France, Czech Republic and (VOERO 1, MT) Hungary (CHvALA, 2003). This species is known from 5 localities in Flanders and - Platypalpus analis (MEIGEN, 1830) 4 in South Belgium. Material examined: Alserbos, 2 males, 25.VII- 7.VIII.2003 (VOER12, PT). - Hilara lito rea (FALL EN, 1816) Previous records: Flanders: St. Jan-in-Eremo, 1 male, Material examined: see Table 2. 5.VII.l956, M. B EQUAE RT; Nukerke, 3 females, There are 17 previous records from Flanders and 19 8.VIJ.1944, M. GOETGHEBUER; Oostakker, I female, from South Belgium. [n the present survey, the species is 5.VII.1945, M. GO ETG HEBUER; Merelbeke, 1 female, very abundant in Altenbroek and in Alserbos. Perhaps, its 9.VII.1944, M. GOETGHEBUER. Red Data Book status has to revised. I I

314 Patrick GROOTAERT, Wouter DEKONINCK & Konjev DESENDER

- Hilara lurida (FALLEN, 1816) P. verralli is found in forest margins, especially in Material examined: Altenbroek, 1 male, 14-26.VI.2003 heathland. (VOER01 , WT); 1 male, 26.VI-1l.VII.2003 (VOER05, Flight time: activity from mid May till mid of July. It is WT); Alserbos, 1 female, 14-26.VI.2003 (VOER08, MT). a caracteristic species ofheathlands and forest margins of There are 22 previous records of this species in heath lands. Flanders and 8 in South Belgium. Dish·ibution in Europe: in Scandinavia it is present up to in the high North; it is quite common in Great Britain - Platypalpus rapidus (MEIGEN, 1822) and less common in Cenh·al Europe; the species is absent Material examined: Altenbroek, 1 female, 26.VI- in Southern Europe. In South Belgium it is known from 1l.VII.2003 (VOER04, MT); 1 female, 11-25.VII.2003 5 populations (I 0 records), particularly in the Hautes (VOER03, MT); 6 females, 11-25.VII.2003 (VOER04, Fagnes. In Flanders, we have a total amount of 6 popula­ MT); 3 females, 25.VII-7.VIII.2003 (VOER04, MT); 2 tions but after 1980 the species has only be found in females, 7-22.VIII.2003 (VOER04, MT). 2 localities (Melle and Hove). Previous records: Flanders: St. Truiden, 1 female, 26.VII.1985; 1 female, 2.VIII.1985, L. DEBRuYN; Des­ - Rhamphomyia (Megacyttarus) crassirostris (FALLEN, telbergen, l male, 29.VII. l934, A. COLLART. 1816) Brussels: 1 male, .J3 .VI.1933, OSA. Material examined: 240 individuals ( 169 males, 71 South Belgium: 22 records in 10 localities. females), present in all plots in Altenbroek and dominant It is not clear what kind of habitat P. rapidus frequents. in Alserbos. In the present survey it has been found in a young This large species is active in early spring. Previously it afforestation. P. rapidus is a summer species and this is was known from 3 localities in Flanders. Its Red Data quite uncommon for Platypalpus that are either spring or Book status should be revised. autumn species. It is a very common species in Europe and very wide­ spread. Vulnerable species Data deficient species - Hi lara jitscipes (FABRICIUS, 1794) Material examined: Altenbroek, I male, 1 female, Seven species have the Red List status of ' 'Data defi­ 14-26.VI.2003 (VOER01, MT); 2 females, 26.VI- cient". This status was been assigned to the following 1l.VII.2003 (VOEROl, MT); 1 female (VOER01 , BT); species since we judge that there is a lack of information Alserbos, 1 male, 11-25.VII.2003 (VOER07, MT); I on their distribution in Flanders or because their habitat female (VOER09, MT). was unknown (GROOTAERT et al. , 2002). There are 22 previous records from Flanders and 34 from South Belgium. - Platypalpus pulicarius (MEIG EN, 1830) Material examined: Alserbos, I female, 30.V- - Hybos f emoratus (MOLLER, 1776) 14.Vl.2003 (VOER10, MT). Material examined: Altenbroek, 1 female, 25.VII- There are 12 records in Flanders however, limited to 7.VIII.2003 (VOER05, MT). Oostende and Wijnendale bos. Furthermore, the species There are 206 previous records from Belgium (33 is widespread in South Belgium with 23 records in localities in Flanders). 13 localities, indicating that this species has a Central Normally · this is a very common species of forest European distribution and that the populations occurring margins . .Nevertheless, there is only one record of this in Flanders are rather relics. species. On the contrary, Hybos culiciformis was very abundant in both localities (Altenbroek and Alserbos), - Platypalpus stigma (COLLIN , 1926) with a total amount of I 02 individuals. Material examined: Altenbroek, 1 male, 14-26.VI.2003 Hybos f emoratus is widespread in Europe: from Scan­ (VOER02, MT). dinavia on to the most southern patt of North Africa. It is Platypalpus stigma was been described by COLLIN very widespread in South Belgium and is found com­ (1926) from Great Britain. Nevertheless, this species is monly in the Hautes Fagnes. In Flanders, it is known from rather rare in Western Europe. It is rather rare in Western 8 UTM squares in the period after 1979. Flight time: from Europe, but common in South and Southeast Europe, up June till September. to in Turkey (GROOTAE RT , in !itt.). There are additional A decline of 82% is noted but as it occurs in more than records from Wijnendale bos, Gembloux and Virelles. 5% of the UTM squares, the species is assigned the status " Vulnerable". It is unknown why there is a decline of the - Rhamphomyia (Ac!onempis) albohirta COLLIN, 1926 Hybos species. Material examined: Alserbos, 1 male, l-14.V.2003 (VOER07, MT). - Platypalpus verralli (COLLIN, 1926) Previous records: Flanders: Hoeilaart, 5 males, 2 fe­ Material examined: Alserbos, 1 male, 2 females, 30.V- males, 2.V.l997; 4 males, 15.V.l997, L. DE BRUYN; 14.VI.2003 (VOER10, MT). Wijnendale bos, 1 male, 25.V. l986, M. PoL LET. I I Afforestation: Case study "Voeren": Empidoidea . 315

South Belgium: Virelles, 33 males, 27 females, 3,5 - Altenbroek 21.VI.l986, N . MAGIS. 3 - Alserbos 2,5 - - Rhamphomyia (Holoclera) umbripennis MEIGEN , 1822 Material examined: Alserbos, 1 male, 14-30.V.2003 2 ------

(VOER10, MT ); Altenbroek, 1 male, 17.IV- l.V.2003 1,5 ------1- - - (VOEROI,MT); 7 males, 1 female, l-14.V.2003 (VOERO I, MT); 4 males, 1 female (VOER05, MT); 4 males, 1 female, 1 ------1- -- - - 14-30.V.2003 (VOEROI, MT); 5 males (VOER05, MT); 0,5 ------1- - - 1- - - 1 female, 30.V- 14.VI.2003 (VOER02; MT). 0 - Previous records: Flanders: Mechelse Heide, 1 male, 08 SP Gr ref SP APAk 08 SPGr SP APGr SP APAk 27.V. 1997, JGo; Rekem, 1 female, 22.V. l997. Ak1 SP Ak2 Ak1 Ak2 South Belgium: Virelles, 2 males, 14. V1.1986, N. MAGIS. Fig. 2 -Shannon's diversity indexes per site with OB = ancient forest, SP = spontaneous afforestation, - Rhamphomy ia (Megacyttarus) anomalipennis MEIGEN, AP = plantation, Gr = former grassland and Ak = 1822 former arable land. Material examined: Alserbos, 1 male, l 4-30.V.2003 (VOER07, MT); . Altenbroek, 1 male, 14-30.V.2003 (VOER01, MT). forests of at least 20 years old show a higher species Previous records: Flanders: Wij nendale bos, 1 male, diversity. 9.V.1987; 1 male, 3.V. l 987, 1 female, 17.V.1987, However, if we consider the true forest species, the M. POLLET. reference forests have more true forest species and the .In Belgium, this remarkable species with its aberrant younger forests have less forest species. Forest planta­ wing venation, was only known from Wijnendale bos. tions and afforestations that are more than 20 years old, start to have a dance fly fauna resembling that of the old - Rhamphomyia (Pararhamphomyia) dentipes (ZETTER­ reference fo rests. Forests younger than 15 years old STEDT, 1842) contain much less true forest species. The plantation of Material examined: Altenbroek, 1 male, l-14.V.2003 1989 in Altenbroek (VOER05) approaches already more (VOER05, MT); 1 female, 30.V-14.VI.2003 (VOER04, the fauna of the reference forest. Coloni sation in the MT); Alserbos, 1 female, 14-26.VI.2003 (VOER09, MT); plantations proceeds more rapidly than in a spontaneous 1 female, (VOER12, MT). afforestation. Previous records: Flanders: St. Martens-Latem, 1 fe­ male, 16.V.l999; 5 females, 24.V.l999; 2 females, Shannon 's diversity index H (Fig. 2) 30.V.l999; 1 female, 20.VI.l 999, P. GROOTAERT. Instead of considering the absolute figures, the South Belgium, 2 males, 1 female, Virelles, SHANNON index is applied: 21. VI.l986, N. MAGIS . Rhamphomyia (Pararhamphomyia) dentipes was only H =-I (Pi * In Pi) recorded from 2 localities in Belgium: St. Martens-Latem and Virell es. with Pi the proportion of individuals of species i, i.e. the number of indivuals of species i as to the number of - Rhamphomyia (Rhamphomyia) laevipes (FALLEN, 1816) individuals collected in a particular site (Fig. 3). Material examined: Alserbos, 1 male, 1- 14.V.2003 3,4 (VOE~l2 , MT).

Previous records: Flanders: St. Martens-Latem, 1 fe­ 3,2 male, 2l.V.l 999, P. GROOTA ERT. 3,0 South Belgi um, Rocherath, 1 female, 26.V.l981. I J: 2,8 ~

~ "~ c ,., 2,6 Results diversity ·~ ~ 2,4 0

How do we have to interprete diversity? ) 2,2 C/l 2,0 I I Table 2 gives a summary of the abundance of the species I I in the various plots. The old reference forests had respec­ 1,8 f '"' I :C ±Std. Dev. tively 48 species in Altenbroek and 46 species in Alser­ D ±Std. Err. 1,6 bos. In the plantation in Altenbroek (VOER05) 58 species ALT ALS o Mean are found. The old spontaneous afforestation (VOER09) Fig. 3 - Categori zed Box-Whisker plot (mean/ SE/SD) of th e in Alserbos has 52 species and the old plantation in average Shannon's diversity of the sites per forest Alserbos (VOER I 0) counts 51 species. Briefly, young complex (ALT = Altenbroek en ALS = Alserbos). \.;..) Table 3 - Abundance of Platypa/pus species per site (codes see Table 2). True forest species are hi ghli ghted. -0\ Altenbroek Alserbos Species VOEROI VOER02 VOER03 VOER04 VOEROS VOER07 VOEROS VOER09 VOER IO VOERII VOER12 Total Habitat P/atypalpus agilis 2 10 I I 15 6 5 8 2 I 60 eurytopic '"d P/atvpalpus albiseta l'l> I I 3". P/atypalpus albicornis I 3 4 gTassland (") ~ Platypalpus ana/is 2 2 forest 0 Platypalpus mmulipes ?;:i I 5 2 1 2 3 3 13 48 edge 0 P/atypalpus aristatus 5 I I I 14 I I 3 7 34 edge ,...,0 Platypalpus articulatoides I 2 3 grassland 6; Platypalpus arliculaws I I grassland Platypalpus australominutus I I eurytopic -~ Plcuypalpus ca /ceallls 3 I 30 2 4 4 5 13 3 4 69 ewytopic ::E 0 Platvpalpus ciliaris 99 2 I 36 19 2 13 I I 2 176 forest c: ....,~ Platypalpus clarandus 2 2 edge u Platypalpus cursiwns I I edge tn 0 Platypalpus divisus 2 2 0 Platypalpus exilis 3 2 7 6 5 23 46 forest Platypalpus jlavicomis ~ I 2 3 grassland 0 P/atypalpus infec/Us 4 4 grassland 0 Platypalpus /ongicomis I 2 I 5 14 2 2 I 28 eurytopic R:o 0 P/atypalpus /ongiseta 2 3 3 3 6 I 4 4 26 eurytopic 0 2. Platvpalpus lweus I I I 2 5 forest (1) < Platypalpus minwus I 2 2 2 7 eUiy topic u Plmypalpus nigriwrsis I I heath land tn C/) Placypalpus niveiseta I I 2 tn Platypalpus obscurus I I atn Pia typo/pus pallipes I I I 3 ?;:i Platypalpus pallidiven lris 3 30 7 23 2 5 9 10 7 8 5 109 eurytopic Platypalpus pecTOralis 87 I I 5 4 I I 100 forest Platypalpus polilus I I Platypalpus pulicarius I I Platypalpus rapidus I 12 13 Platypalpus stigma I I eurytopic Platypalpus verral/i 3 3 heathl and total ind. 203 49 34 103 95 47 30 58 53 21 65 758 no. species 9 9 12 17 12 9 8 II 14 7 12 32 no. forest species 3 0 2 3 3 4 1 3 3 2 4 5 lnd/forest species 199 0 3 3 43 31 2 20 7 3 28 I I

Afforestation: Case study " Voeren" : Empidoidea '317

Especially in Altenbroek forest, the diversity index is Possible reasons for this could be, the more forest higher in younger forests than in the older forest. The succession continues, the more stable the fauna is and differences are much less pronounced in the site of the smaller the chance that occasional species occurring Alserbos. temporarily in the site will increase diversity. The average diversity of both forests is distinctly hi gh­ er in Altenbroek. As both reference sites have a more or Th e Platypalpus less equal diversity, this difference is above all due to the higher diversities in the younger forest sites. In Alserbos, The ecology and habitat preference of the genus Platy­ the general diversity is lower than in those sites of Alten­ palpus is well known and therefore it is interesting to broek which have been recently taken out of agriculture. examine how these species react to alterations. Platypal­ As the forest succession progresses (already more than 20 pus species are predators that forage mainly on horizontal years in Alserbos), the diversity seems to decrease m substrates, i.e. on leafs of sluubs and trees, sometimes on comparison to the young sites in Altenbroek. tree-trunks and a few species hunt on the soil. Some

van History A former arable land Bice sui former grassland * A Plat ari A ancient forest * Rholumb D * Hila cor * Eempa c ~ Rrha sui Plat agi * *Plat los * A E"::mp Voer12 Tric elo N * Platpec Eemp nig en VoerlO * X ~Racllon • <( Plat ca~ 02 A Ramye1y Exan ste Epol opa * * * B Plat pav *Eeue t s * Ekri liv * Hybo cui Micr hot * * Oeda zet

* Exan tri c * Oedajla * *Rholnig Hila lit *

Axis 1

Fig. 4 - DCA diagrams (axis! and 2) of all sites based on all coll ected data of dance fly communities, showing all sites .A and their hi story; species are represented by * All species are abbreviated by the first fom letters of the genus name and the first three of the species name. I I

318 Patrick GROOTAERT, Wouter DEKONINCK & Konjev DESENDER smaller species such as P. articulatus, P. articulatoides an open character, are clustered in group B. Grassland and P. maculatus, are able to hunt of the leaves of grasses species and species common to forest margins are found and they are mainly found in meadows. In general, forest here. The third group (C), is the one of the older sponta­ margins and hedges are the preferable hunting fields for neous forestations (more than 20 years) in Alserbos. Platypalpus. These are spots that break the wind and that A number of forest species are found here and species can be sunny. A lot of are flying along these forest of forest margins. Nevertheless, the fauna of these sites margins and hedges and will take a rest in these areas. seems already to approach the one of the reference site Platypalpus is sitting on leaves, waiting for a possible (VOER07) of Alserbos. True forest species are already prey to land on it. Subsequently, it jumps on its prey, grips found here and the share of species of forest margins is it with its thickened fore- and midlegs and pierces it in the quite obvious. neck region with its powerful snout. The prey consists of In conclusion, 4 types of dance fly fauna could be small insects such as flies and hymenopterans. Its prey determined. Especially, the fauna of the young sponta­ can be as large as itself. There are a few typical forest neous forestations in Altenbroek is distinctly different species (highlighted in the Table 3) and most of them from those of the reference sites. The dance fly fauna have a yellow body, the other species possess a black of the plantations are also distinctly different from the ground-color of the body. older spontaneous forestations but both show some kind In the present survey, 32 species of Platypalpus were of overlap with the fauna of the reference sites. The found in the Voerstreek (Table 3). The number of true faunas appear to be above all dependent on the age of forest species is the highest in the oldest forests and there the forest succession, the type of forest expansion and are are more individuals per forest species as well. Typical less dependent on the history, i.e. the stmting circum­ forest species are P. pectoralis, P. ciliaris, P. exilis, stances arable land versus grassland. P. luteus and P. ana/is. The first three are common species, while the last two species are rather rare. As the forests are younger, the diversity is increasing and General conclusion this is due to the higher number of eurytopic species and grassland species. As a rule we can set that in old forests Colonisation with typical forest species happens more there are less species, but almost all species are true forest rapid in plantations than in spontaneous forestation. species. Moreover, this fenomenon was also observed Colonisation in plantations seems to take place in another when all dance fly data are analysed together. way than in spontaneous forestation. The dominant species are different. The average diversity of both forests is obviously Results community structure analysis higher in Altenbroek. The general diversity in Alserbos is lower than in the sites of Altenbroek recently taken out The dance fly communities and their characteristics were of agriculture. As the forest succession continues (already examined. This was done by applying a DCA with different more than 20 years in Alserbos), the diversity seems to overlays. Species of which less than 25 individuals were decrease in comparison to the younger sites in Alten­ found, were excluded from the multivariate analyses. In broek. Possibles reasons could be that the longer forest that way, 42 species remained for the analyses. The eigen­ succession progresses the more stable the fauna and the values of the axes were respectively AAst= 0.46; AAs2 = 0.25 smaller the chance that occasional species occurring and AA53= 0.06 (the last axis explained very few variation in temporarily in the site will increase diversity. the data set and was therefore excluded for further ana­ Diversity is low in very young forestation, becomes lyses). Figure 4 shows the DCA diagram (axis1-2). high in forests with an age between 15 and 20 years old The first axis seems to group the sites according to their and diversity is lower in the old forests. The number of forest age. From the left to the right, the forest age of the true forest species is the highest in the old forests. Forest sites increases. The youngest forest site is seen at the which are 20 years old approach the species composition utmost left part of the diagram (taken out of agriculture of old forests. The percentage of true forest species is since 1996). Entirely to the right, the reference sites can much lower in younger forests. This applies also to the be found (VOEROI and VOER07: ancient forest) with in genus Platypalpus. The number of Platypalpus species the middle the sites where the forestation process takes increases as the forests are younger and this is due to the place since 1980-1989. high number of eurytopic species and grassland species. The second axis seems to group the sites with a mid­ As a rule we can state that: old forests have less species young forest age according to the type of forest expan­ but they are almost exclusively true forest species. sion. At the top of the diagram the plantations can be found and at the bottom the spontaneous forestations. Although we have only used a restricted number of Acknowledgments sampling units, it can be seen that the sites are distributed in four groups. Group A contains the two old forest sites. We would like to thank AMfNAL afdeling Bos & Groen for fin ancial support (project: AM lNAL/B&G/30/2002) and Alex Zeevaart, conser­ In these reference sites, mostly true forest species are vation officer of the Alserbos in Sint-Pieters-Yoeren, for the authorisa­ found. The young forestations of Altenbroek, sites with tion for the sampling campaign. I I Afforestation: Case study "Voeren": Empidoidea . 319

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