Integrated palaeoecological and historical data in the service of fine-resolution land use and ecological change assessment during the last 1000 years in Rõuge, southern Estonia

Aims Our aim is to reconstruct decadal scale development of historical landscapes during the last 1000 years by means of fossil pollen analysis of annually laminated lake sediments, and detailed historical maps and documents. Location Lake Rõuge Tõugjärv (Estonia), a small lake with annually laminated lake sediments situated in a dense prehistoric setting. Methods The chronology of the palaeodata is based on the annual laminations supported by AMS ¹⁴C and ²¹⁰Pb dating and ¹³⁷Cs, ²⁴¹Am, and spheroidal carbonaceous particle marker horizons. The time‐scale and resolution allows fine sampling (the pollen samples generally comprise 3.5 years) and vegetation change reconstruction. Relevant source area of pollen (RSAP) of the lake was estimated, and the statistical zonation, rate of change, palynological richness, and DCA and PCA ordinations were generated on the basis of the pollen data. The historical calibration data set (maps, numerical information on population, domestic stock, farmland division, etc.) is based on archival material preserved in the Estonian Historical Archives. Results The topmost part (0–180 cm) of the sediment column of Lake Rõuge Tõugjärv, covering the last 1000 years, is visibly laminated carbonaceous gyttja. The varve chronology extends from ad 2000 to ad 1339, with a cumulative ± 9‐year error estimate. Beyond this the chronology is extrapolated using the ¹⁴C date and varve age–depth estimations. The simulation of the RSAP of Lake Tõugjärv shows that the major portion of the pollen loading originating from local vegetation is derived from plants growing within 2000 m of the sampling site. The pollen record divides into five statistically significant subgroups, which fall on the PCA plot into three clusters reflecting the general openness–closedness of the landscape. During the period between ad 1000 and 1200 (RT 1) the Rõuge area was generally wooded with birch, spruce and pine forests. The advancement of extensive farming gradually opened up the landscape between ad 1200 and 1650 (RT 2 and RT 3). The maximum openness of the landscape was reached between ad 1650 and 1875 (RT 4), with the most open period in the late eighteenth century. Historical maps from 1684 and 1870–99 and available quantitative data on population, domestic stock, farmland division, etc. show the same trend. The pollen data covering the last 125 years, and maps from 1935 and 1995, show the reduction of arable land in RSAP of the lake under investigation and the reduction of open land to an extent comparable with the end of the seventeenth century. Main conclusions The formation and development of the cultural landscape at Rõuge over the last 1000 years is characterized by rapid changes in floristic richness and rates of vegetation change attributed to certain historic processes in the RSAP. Five phases of landscape and social development are clearly distinguished during the last 1000 years. The decadal scale vegetation response to human‐induced forcing agrees with historical maps and documents and could be used for past landscapes prior to the period with solid historical data.     

Potential novel hosts for the lily leaf beetle Lilioceris lilii Scopoli (Coleoptera: Chrysomelidae) in eastern North America

Abstract.  1. Introduced insects often incorporate native plants into their diets and might be expected to show a predilection for novel hosts that are phylogenetically related to their normal hosts. The lily leaf beetle, Lilioceris lilii (Coleoptera: Chrysomelidae), is an introduced pest of cultivated lilies. Oviposition behaviour, larval behaviour, and development of L. lilii was examined on a range of potential host plants, as well as on the normal host, Asiatic hybrid lilies Lilium sp.
2. Neonate larval feeding behaviour was quantified on 15 food plant species: 10 from the Liliales, three from the Asparagales and two eudicots. Larvae fed plants closely related to the genus Lilium were more likely to initiate feeding, less likely to abandon their food leaf, and consumed more leaf area.
3. In no-choice tests, females oviposited on the novel hosts Lilium philadelphicum , Medeola virginiana , Clintonia borealis , Streptopus amplexifolius , and Polygonatum biflorum ; however, all but L. philadelphicum received very few eggs. Non- Lilium novel hosts were not used for oviposition when presented along with Asiatic lilies in choice tests.
4. A single individual was reared to the adult stage on the novel host S. amplexifolius . Several larvae survived to the pupal stage on M. virginiana , although no adults emerged from those pupae. Larvae reared on the native wood lily L. philadelphicum performed equally well or better than on the Asiatic cultivar.
5. Our results indicate that the lily leaf beetle poses a threat to native Liliaceae. Several native Lilium species, including L. philadelphicum , are threatened or endangered in certain jurisdictions throughout their range; these species should be monitored closely for colonisation by the beetle.     

New ecological information onScytalina cerdale (Pisces: Scytalinidae) from a central California rocky intertidal zone

Synopsis New information regarding the ecology ofScytalina cerdale was obtained over a four year period as a consequence of a long-term marine ecological study at the Diablo Canyon Power Plant (DCPP), San Luis Obispo County, California. Twenty intertidal fish surveys were conducted at approximately quarterly intervals, between March 1979 and June 1983, at three separate rocky shore locations (stations). During each survey, a total of 108 square meters (36 m² per station) was searched for fish during periods of low tide. A total of 280S. cerdale were collected, identified, measured, and released back into the same 4 m² area, from the same intertidal station (Diablo Cove), throughout the study period. This limited intertidal occurrence most likely reflectsS. cerdale microhabitat requirements; a combination of intertidal elevation (mean = +0.3 MLLW), substratum specificity (loose gravel, 5–10mm size range, overlying a base of sand and shell fragments), and degree of wave exposure (semi-protected). Throughout the study,S. cerdale was seasonally more abundant during summer months (June through August) and less abundant during winter months (November through February). The only exception to this abundance trend followed the 1982 winter storms, which coincided with an El Niño event, whenS. cerdale abundance uncharacteristically dropped during the subsequent 1983 spring and summer surveys. Mean total lengths did not vary greatly, reflecting the absence of early juvenile fishes, and relatively high mean fish densities (3.5 fish per m² for 20 surveys) were recorded. Qualitative comparisons betweenS. cerdale abundance and seasonal changes in water temperature indicated an inverse relationship. Gravid females, demersal egg masses, and early juvenile individuals were never observed during the four years of the study. This suggests that unlike most other intertidal fishes, particularly other blennioids,S. cerdale may not utilize the intertidal zone for reproductive and recruitment purposes; Diablo Canyon is the most southerly reported distribution for this intertidal species, and therefore, may not entirely represent the species' biology as a whole.     

Four centuries of cumulative impacts on a Finnish river and its estuary: an ecosystem health-approach

Changes in forest cover and draining of wetlands for agriculture appear to have caused changes in the aquatic ecosystem of the River Kyrönjoki by the 16th century. In the 19th century, a decline of salmonid fish populations was widely observed as a further sign of degradation. During the latter half of the present century intensified use of naturally acidic soils has resulted in increased acidic run-off. Deterioration of water quality has extended to the estuary, where it has caused large fish-kills and affected the reproductive success of coastal species. Degradation of the coastal ecosystem, first observed in the decline of salmonids and later as a more general decline of other coastal fish populations, can be linked to spatially restricted events. The loss of key river and estuarine habitats exerted an effect over the reproduction and abundance of species migrating throughout the system. This effect contributed to observed temporal and spatial discontinuities in the degradation history. Monitoring changes in critical habitats may prove to be an early indicator of changes in the health of estuarine and coastal aquatic ecosystems.     

Rubus host range of rubus yellow net virus and its involvement with other aphid-borne latent viruses in inducing raspberry veinbanding mosaic disease

After graft inoculation with rubus yellow net virus (RYNV), 12 of 34 Rubus species and cultivars developed noticeable symptoms. R. macraei developed the most conspicuous symptoms and is recommended as an improved indicator plant. In attempts to determine the cause of raspberry veinbanding mosaic, a disease in which RYNV is involved, several European and North American red raspberry cvs were graft-inoculated with RYNV and three other aphid-borne viruses, black raspberry necrosis (BRNV), raspberry leaf mottle (RLMV) and raspberry leaf spot, singly and in all combinations. In periods of up to 4 yr, classical veinbanding mosaic symptoms developed in sensitive cvs only when they contained both RYNV and RLMV. These symptoms were intensified in plants co-infected with additional viruses. Veinbanding mosaic disease did not develop in any of 11 cvs infected with RYNV + BRNV, the combination of viruses previously assumed to be responsible for this disease in Britain and North America.     

Home Range and Frugivory Patterns of Mountain Gorillas in Bwindi Impenetrable National Park,Uganda

Mountain, western, and Grauer's gorillas exhibit broad differences in ecological patterns with western gorillas eating more fruit and having larger home ranges than their largely folivorous counterparts in the Virunga Volcanoes. We studied the home range and frugivory patterns of one group of Gorilla beringei beringei in the little-studied population of Bwindi Impenetrable National Park, Uganda, to compare with other populations and to investigate whether there was any relationship between patterns of frugivory and home range size. During the 3-year study, the gorillas ate 16 species of fruit on 27% of observation days. There was high variability in frugivory among the 3 years and no consistent seasonal pattern. Annual home range size was ca. 21 km² for Years 1 and 2, and it increased dramatically to 40 km² in Year 3. Home range size varied considerable between months and seasons, but there is no clear relationship between occurrence of fruit-eating and home range size. The group exhibited more fruit-eating and a larger home range size those ofthe gorillas in the Virunga Volcanoes. Their home range size is comparable to that of western gorillas, though Bwindi gorillas consumed less fruit. Home range size and utilization by all gorillas probably depends on a complex relationship between the distribution and abundance of both fruit and herbaceous vegetation and social factors such as male mating tactics.     

The effect of the armored scale,Rhizaspidiotus donacis (Hemiptera: Diaspididae), on shoot growth of the invasive plant Arundo donax (Poaceae: Arundinoideae)

The effect of feeding by the armored scale, Rhizaspidiotus donacis (Leonardi, 1920) (Hemiptera: Diaspididae) on the growth of the plant Arundo donax L. (Poaceae) was evaluated under field conditions in its native range. The study was designed to evaluate the impact of R. donacis, a candidate agent for biological control of A. donax which is invasive in arid riparian ecosystems of the Southwestern USA and Mexico. The study was carried out at five A. donax sites in the Province of Alicante, Spain, differing in altitude and climate. At each site, 30 infested lateral shoots were selected and 15 were randomly treated monthly with imidacloprid insecticide. Shoot lengths were measured monthly over a 1-year period in a comparative growth analysis. Shoots infested with R. donacis had an over 2-fold reduced growth rate as compared to treated shoots. Growth of shoots varied by site, and the effect of R. donacis on growth was most pronounced in the late spring, when mature females produced first instar scale crawlers. The impact of R. donacis on A. donax growth under field conditions in the native range, combined with its narrow host specificity, indicate that R. donacis is a promising candidate for biological control of A. donax in North America and other areas invaded by this weed.