Dry Open Habitats Research Articles

Drivers of floristic change in large cities – A case study of Frankfurt/Main (Germany)

The main aim of the study is to reconstruct diversity of established vascular plants between 1800 and 2000 in today's area of Frankfurt/Main (Germany, Hesse) – using historical literature, herbarium vouchers, and a recent landscape survey – and to interpret changes (extinctions and gains) in the light of land use changes (drivers). Species numbers declined from 1800 (1232 species; 926 indigenous–228 archaeophytes–78 neophytes) to 1900 (1200 species; 871–219–110), and 2000 (1107 species; 698–166–252). The most important drivers for the loss of species (319 spp.) are use of fertilizers and herbicides, abandonment of wood pastures, abandonment and melioration of wet grassland. Most species gained (193 spp.) were intentionally introduced as ornamentals. Among the neophytes naturalized after 1800, short-living plants adapted to dry open habitats dominate. Plants using the C4 carbon fixation pathway (C4-plants) are predominantly neophytes. Drivers for the loss of species are general changes in land use. Nature conservation slackened the loss of species in the last decades; today about 3% of the vascular plants are conservation dependent. Comparatively high rates of short-living plants adapted to dry open habitats and C4-plants among neophytes indicate a warming of the climate. We expect a rising number of garden escapes. Furthermore, the flora will become more dependent on conservation measures. Remnants of now obsolete forms of land use like low nutrient grassland shall be integrated into parks and urban open spaces.

Forest Succession Endangers the Special Ant Fauna of Abandoned Quarries along the River Meuse (Wallonia, Belgium)

In Western Europe, old abandoned mining sites and quarries are often of high biodiversity and conservation value due to the presence of a number of endangered species. In the southern part of Belgium (Wallonia), many ancient quarries near the river Meuse are rather small and were abandoned from 50 to more than 100 years ago. In 2003, we collected 26 ant species by pitfall trapping in four of these quarries. In addition to common ones, several rare species, usually associated with mesomorphic to xeromorphic grasslands, were found in high numbers. Quarries undergoing forest succession were dominated by eurytopic species and by species typical of wet shadowy places, a fauna far less valuable in terms of nature conservation. Therefore, we suggest a management that halts further forest succession of open mesomorphic and xeromorphic habitat patches in these quarries. To assess and monitor the nature value of the ant fauna of these sites, we propose a so‐called habitat preference approach, wherein each species is assigned to one of the following three habitat preference categories: (1) eurytopic, (2) bound to wet shadow‐rich habitats, or (3) bound to dry open habitats. The stenotopic species of the last category are all endangered in Belgium and of high conservation value. The proportion of the total number of captured specimens included in the latter habitat preference category group is strongly reduced as scrub and tree encroachment advances. This proportion can therefore be used as a proxy to monitor the effects of management measures that prevent further forest succession.

Butterfly life history and temperature adaptations; dry open habitats select for increased fecundity and longevity

Summary 1 Evidence suggests that changes of temperature-related performance curves can trigger a selective response in life-history traits. Hence, it should be expected that insects adapted to different temperature regimes should exhibit optimal performance at the temperature to which they are adapted. 2 To test this idea we investigated how fecundity and longevity are influenced by ambient temperatures in a set of satyrine butterflies adapted to live in dry open landscapes or in closed forest landscapes, respectively, by keeping egg-laying adult females at five different constant temperatures ranging between 20 and 40 °C. 3 We studied four species, two of which are confined to dry and hot open habitats, namely the grayling (Hipparchia semele) and the small heath (Coenonympha pamphilus), and two of which are shade dwelling, namely the ringlet (Aphantopus hyperantus) and the speckled wood butterfly (Pararge aegeria). 4 As predicted, the results showed that lifetime fecundity exhibited bell-shaped curves in relation to temperature with the open landscape group peaking at a higher temperature, 30 °C, compared with the shade-dwelling group that peaked at 25 °C. Longevity decreased with increasing temperatures among all species, but the open landscape living species survived better at higher temperatures. Moreover, although the magnitude of reproductive effort measured as lifetime egg mass did not differ between the two ecological groups, lifetime fecundity did with open landscape species laying more and smaller eggs than the shade-dwelling species. 5 This difference in life-history character traits suggests either that dry and relatively warm open habitats open life-history opportunities in terms of higher fecundity and longevity that remain closed to butterflies adapted to cooler temperatures, or that life in dry open habitats actively selects for higher fecundity and survival as a result of increased offspring mortality.

Spatial and temporal variations in mortality of the biennial plant, Lysimachia rubida: effects of intraspecific competition and environmental heterogeneity

Summary We studied mortality, growth and spatial distribution of individuals of Lysimachia rubida to elucidate causes and consequences of temporal and spatial variations in mortality. This short‐lived monocarpic biennial grows in open dry habitats on rocky coastal cliffs of the subtropical Bonin (Ogasawara) Islands, Japan. All individuals of two successive cohorts that appeared in a 8 × 8‐m quadrat were mapped, and their fate and size were recorded at 2–3 month intervals from March 1998 to July 2000. We analysed spatial and temporal changes in the relative importance of plant size, local densities of neighbouring plants and ground surface conditions to determine plant mortality. We also examined spatially non‐random mortality and its spatial scales. Patchy seed dispersal from scattered mother plants resulted in a clumped distribution of seedlings. During the growth cycle of L. rubida, we recognized two growth stages that differed in the relative importance of the factors affecting plant mortality. At the earlier growth stage, after germination in March until July, mortality was caused mainly by local density. Smaller plants within areas of high local densities were more likely to die. The spatial patterns of surviving and dead plants tended to be regular and aggregated, respectively, in comparison with those expected from random mortality. The spatial scale of aggregation of the dead plants was 5–25 cm, corresponding to the distance of direct interactions between neighbours. At the later growth stages, in October until May of the following year, mortality was affected mainly by ground surface conditions. Both surviving and dead plants were spatially aggregated at spatial scales of 20–100 cm. Plants tended to survive in microhabitats of smaller gravel, which had a greater water‐holding capacity. This study also showed the consequence of spatial variations in mortality on population structures of L. rubida. Patchy seed dispersal and subsequent temporal and spatial variations in mortality are likely to contribute to the scattered distribution of L. rubida individuals observed at the study site.

Butterflies (Lepidoptera: Hesperioidea, Papilionoidea) in Narew National Park

The study of butterflies (Lepidoptera: Hesperioidea, Papilionoidea) wascarried out in the Narew National Park, in two strictly protected areas under development: “Grobla pod Kurowem” and “Rynki”. A total of 40 butterfly species representing 5 families: Papilionidae (1 species), Pieridae (7 species), Lycaenidae (9 species), Nymphalidae (21 species) and Hesperiidae (2 species) were registered altogether. Most of these have wide distribution ranges and are commonly found in Poland, especially in various open dry habitats. Only four species: Lycaena dispar, Coenonympha oedippus, C. tulliaand Heteropterus morpheus,are primarily associated with or specific to moist habitats. Three species: Papilio machaon, Apatura ilia and C. oedippusare legally protected in Poland.

Biology, Ecology, and Host Specificity of EuropeanAphthonaspp. (Coleoptera, Chrysomelidae) Used as Biocontrol Agents for Leafy Spurge,Euphorbia esula(Euphorbiaceae), in North America

Leafy spurge (Euphorbia esula) is an herbaceous perennial of European origin that was accidentally introduced into North America where it has become a serious weed in pastures and rangelands. Five species of root-feeding chrysomelid beetles in the genusAphthonahave been released in North America for the biological control of leafy spurge. They originate from central and eastern Europe and occur in different habitats. The brown species,Aphthona cyparissiae, Aphthona flava,andAphthona nigriscutis,occur predominantly in open dry habitats, and the black species,Aphthona czwalinaiandAphthona lacertosa,prefer moister habitats. All five species are univoltine and overwinter as larvae. The host range of these fiveAphthonaspecies is restricted to species in the subgenusEsula.

A New Species of Oplonia (Acanthaceae) from Southern South America

A new species of Oplonia from the province of Jujuy, Argentina, 0. jujuyensis, is de- scribed, illustrated, and compared with its closest relative. It differs markedly from 0. hutchisonii by the corolla, which is weakly zygomorphic, and by the erect limb, with the posterior lip deeply two- lobed. This is the first report of this genus from Argentina. The present study of the Acanthaceae for the flora of the Province of Jujuy, Argentina, has led to the recognition of a new species of Oplonia from that region. The genus belongs to the subfamily Acanthoideae tribe Odontonemeae in accordance with Lindau's (1895) infrafamilial classification of the Acanthaceae, or in the tribe Justicieae subtribe Odontoneminae if one prefers to follow Breme- kamp's (1965) system of subfamilial classification. It is characterized by flowers that are either solitary in the leaf axils or borne in comparatively few- flowered axillary fascicles with minute bracts. This much reduced inflorescence distinguishes Oplonia from Odontonema Nees, the latter of which has flowers borne in terminal racemes or panicles. The corolla is zygomorphic, occasionally only weakly so, with a slender tube and a two-lipped limb, the pos- terior lip is two-lobed and the anterior lip is three- lobed. There are two stamens, which may be ex- serted or included, and two staminodes. Presently, two species are known from northern Peru, eight from the West Indies, and five from Madagascar. This is the first time that the genus is reported from Argentina. Although the genus Oplonia is easily recognized and defined, the delimitation and distribution of the taxa are more complex and somewhat unusual. Most species grow in dry open habitats as part of scrub forest. The new taxon is found in thicket of tran- sitional forest between the Chaco and Yungas (sensu Cabrera, 1976). The evolution of the genus (Stearn, 1971) would appear to be from a mesophytic spine- less South American ancestor, resembling the small- flowered species of Odontonema, by progressive re- duction in leaf size, by the contraction of the inflo- rescence from a narrow panicle or raceme into a few-flowered axillary fascicle or solitary flower, and by the conversion of lateral branches into spines, by which changes they became xerophytic. We be- lieve that Oplonia jujuyensis, with its reduced leaves, an inflorescence of few flowers in axillary fascicles, small, Odontonema-like flowers, and habitat rep- resents an isolated transition between the genera Odontonema and Oplonia.