Factors influencing late-Holocene vegetation dynamics and biodiversity on Hallands Väderö, SW Sweden: A statistical evaluation

The Holocene ◽  
2021 ◽  
pp. 095968362110417
Author(s):  
Gina E Hannon ◽  
Chiara Molinari ◽  
Richard HW Bradshaw
Keyword(s):  
Vegetation Dynamics ◽  
Grazing Pressure ◽  
Forest Composition ◽  
Large Numbers ◽  
Ancient Forest ◽  
Winter Temperatures ◽  
South West Coast ◽  
Composition Characteristic ◽  
Potential Factors ◽  
Old Trees

Forest composition characteristic of the Mid-Holocene has survived on Hallands Väderö, an island nature reserve off the south west coast of Sweden. Current veteran Tilia and Quercus trees contribute to a remarkably rich biodiversity of fungi, bryophytes, lichens and insects. Understanding which potential factors influence Holocene vegetation dynamics can support efforts to protect biodiversity, but the role of grazing and browsing has previously been difficult to evaluate because of the lack of long-term datasets. Palaeoecological analyses over the last c. 3000 years from a pond on the island reveal sustained presence of Quercus, Alnus, Tilia, Corylus and Ulmus, alongside increasing Fagus in recent centuries. Changes in grazing pressure have been documented since AD 1665 and a statistical approach was used to calculate the relative importance of grazing pressure, climate variability, and fire activity on the dynamics of selected taxa. Grazing was the main factor reducing population size of Fagus, Alnus, Tilia and Corylus on the island over the period AD 1665–1858, with warm winter temperatures and summer humidity having significant positive influences in the last millennium for Quercus, Alnus, Tilia and Corylus. The survival of large numbers of red-listed species is likely to be due to the continuity of large old trees, ancient forest composition and a distinctive disturbance history in a favourable climate.

Declining breeding populations of White-naped Cranes in Eastern Mongolia, a ten-year update

2016 ◽  
Vol 26 (4) ◽  
pp. 490-504 ◽  
Author(s):  
MARTIN GILBERT ◽  
BAYARBAATAR BUUVEIBAATAR ◽  
AMANDA E. FINE ◽  
LOSOLMAA JAMBAL ◽  
SAMANTHA STRINDBERG
Keyword(s):  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Distance Sampling ◽  
Grazing Pressure ◽  
Occupancy Models ◽  
Wet Meadow ◽  
Wetland Ecosystems ◽  
Breeding Populations ◽  
Large Numbers ◽  
Eastern Mongolia

SummaryEastern Mongolia supports one of the most important breeding populations of the White-naped Crane Antigone vipio (WNC), which is classified as ‘Vulnerable’ by the IUCN. Large numbers of WNCs were found to be breeding at high densities within the Ulz River basin during surveys conducted in 2000 and 2001, along a 270 km section of the river. Following these surveys, an extended drought continuing for at least a decade has threatened wetland ecosystems throughout Eastern Mongolia. This study reports the findings of surveys conducted in 2010 and 2011 along the same section of the Ulz River surveyed a decade earlier, as well as a generalised survey of other sites where breeding WNCs had previously been recorded. Along the Ulz River, populations declined from 42 territorial pairs in 2001 to 17 in 2011. Estimates of detection probability using distance sampling and occupancy methods at two locations gave consistent results of 23%–27% detectability. With a minimum population of 234 WNCs observed across all sites in 2011, these detection probabilities suggest that the areas surveyed support the majority of breeding WNCs in the western population. Although we cannot exclude the movement of WNCs beyond the survey area, these findings also suggest that the population has declined between 2001 and 2011. Exploration of key habitat variables using occupancy models and generalized linear mixed models found that WNCs favoured areas of high wet vegetation (estimated as ‘wet meadow’ coverage and using normalized difference vegetation index), and low grazing pressure. Given the importance of water resources to WNCs and nomadic herding communities, use of wetland habitat must be carefully managed to balance the needs of cranes and people, particularly during periods of drought.

Physiological differences between races of Teleogryllus commodus (Walker) (Orthoptera : Gryllidae) related to a proposed genetic approach to control

1966 ◽  
Vol 14 (2) ◽  
pp. 245 ◽  
Author(s):  
TW Hogan
Keyword(s):  
Low Temperature ◽  
Population Control ◽  
Temperate Climate ◽  
Genetic Approach ◽  
Field Release ◽  
Teleogryllus Commodus ◽  
Large Numbers ◽  
Winter Temperatures ◽  
Probability Of Success ◽  
Threshold Of Development

A method of population control for a diapausing race of Teleogryllus commodus, based on the introduction of a non-diapausing population, is postulated. One factor that could influence the degree of probability of success of the method is the susceptibility of eggs of the northern tropical race to winter temperatures when exposed to the temperate climate of the south. Tests were conducted which showed that eggs of the tropical race were more vulnerable to low temperature and had a higher threshold of development. Hybrid eggs appear to be intermediate in their ability to survive low temperature. A comparison of the diapausing characteristics of races from widely separated localities in Australia confirmed the non-diapausing characteristic of northern Queensland races; all others showed the ability to enter diapause but varied in the proportion of eggs in which diapause was averted by exposure to high temperature. A method of rearing crickets, suitable for the production of large numbers for field release, is described.

Past and future climate change: response by mixed deciduous–coniferous forest ecosystems in northern Michigan

1992 ◽  
Vol 22 (11) ◽  
pp. 1727-1738 ◽  
Author(s):  
Allen M. Solomon ◽  
Patrick J. Bartlein
Keyword(s):  
Climate Change ◽  
Vegetation Dynamics ◽  
Climate Model ◽  
Coniferous Forest ◽  
Mixed Forest ◽  
Future Climate ◽  
Forest Composition ◽  
Future Climate Change ◽  
The Past ◽  
Gap Models

During the 21st century, global climate change is expected to become a significant force redefining global biospheric boundaries and vegetation dynamics. In the northern hardwood–boreal forest transition forests, it should, at the least, control reproductive success and failure among unmanaged mixed forest stands. One means by which to predict future responses by the mixed forests is to examine the way in which they have responded to climate changes in the past. We used proxy climate data derived from Holocene (past 10 000 years) pollen records in the western Upper Peninsula of Michigan to drive forest gap models, in an effort to define regional prehistoric vegetation dynamics on differing soils. The gap models mimic forest reproduction and growth as a successional process and, hence, are appropriate for defining long-term tree and stand dynamics. The modeled period included a mid-postglacial period that was warmer than today's climate. Model failures, made apparent from the exercise, were corrected and the simulations were repeated until the model behaved credibly. Then, the same gap model was used to simulate potential future vegetation dynamics, driven by projections of a future climate that was controlled by greenhouse gases. This provided us with the same "measure" of vegetation in the past, present, and future, generating a continuously comparable record of change and stability in forest composition and density. The resulting projections of vegetation response to climate change appear to be affected more by the rate than by the magnitude of climate change.

scholarly journals The relative contributions of seed bank, seed rain, and understory vegetation dynamics to the reorganization of Tsuga canadensis forests after loss due to logging or simulated attack by Adelges tsugae

2012 ◽  
Vol 42 (12) ◽  
pp. 2090-2105 ◽  
Author(s):  
Elizabeth J. Farnsworth ◽  
Audrey A. Barker Plotkin ◽  
Aaron M. Ellison
Keyword(s):  
Seed Bank ◽  
Tree Species ◽  
Vegetation Dynamics ◽  
Tsuga Canadensis ◽  
Adelges Tsugae ◽  
Seed Rain ◽  
Forest Composition ◽  
Similarity Indices ◽  
Standing Vegetation ◽  
Tree Composition

Profound changes are occurring in forests as native insects, nonnative insects, or pathogens irrupt on foundation tree species; comprehensive models of vegetation responses are needed to predict future forest composition. We experimentally simulated hemlock woolly adelgid ( Adelges tsugae Annand) infestation (by girdling trees) and preemptive logging of eastern hemlock ( Tsuga canadensis (L.) Carrière) and compared vegetation dynamics in replicate 90 m × 90 m treatment plots and intact hemlock stands from 2004 to 2010. Using Chao–Sørensen abundance-based similarity indices, we assessed compositional similarities of trees, shrubs, forbs, and graminoids among the seed bank, seed rain, and standing vegetation over time and among treatments. Post-treatment seed rain, similar among treatments, closely reflected canopy tree composition. Species richness of the seed bank was similar in 2004 and 2010. Standing vegetation in the hemlock controls remained dissimilar from the seed bank, reflecting suppressed germination. Recruits from the seed rain and seed bank dominated standing vegetation in the logged treatment, whereas regeneration of vegetation from the seed bank and seed rain was slowed due to shading by dying hemlocks in the girdled treatment. Our approach uniquely integrates multiple regeneration components through time and provides a method for predicting forest dynamics following loss of foundation tree species.

The Expansion of Leptospermum laevigatum on the Yanakie Isthmus, Wilson's Promontory, Under Changes in the Burning and Grazing Regimes

1994 ◽  
Vol 42 (5) ◽  
pp. 555 ◽  
Author(s):  
LT Bennett
Keyword(s):  
Vegetation Dynamics ◽  
National Park ◽  
Land Use Changes ◽  
Grazing Pressure ◽  
Aerial Photographs ◽  
Vegetation Types ◽  
Bare Ground ◽  
Grey Kangaroo ◽  
Before And After ◽  
History Of

The distribution of selected vegetation types on the Yanakie Isthmus, Wilson's Promontory National Park, was mapped from aerial photographs from 1941, 1972 and 1987. The main changes in the vegetation dynamics were: (1) an expansion of Leptospevmum laevigatum into grasslands and into Banksia integrifolia woodlands with herbaceous understoreys, and (2) a stabilisation of dunes by shmbs dominated by Leptospennum laevigatum. The total area of L. laevigatum shrubland and scrub increased from 2179 ha in 1941 to 3436 ha in 1972 and 4516 ha in 1987. Land-use changes in this period included the exclusion of fire in the early 1970s, after a history of regular burning, and an increase in grazing pressure primarily due to population expansions of the rabbit and the eastern grey kangaroo. Fire was not a prerequisite of the L. laevigatum expansion on the Isthmus because the spread continued after fire was excluded; nor was fire the primary cause of the expansion because the percentage yearly increase in the area of L. laevigatum was, on average, similar before and after 1972. An increase in grazing pressure was identified as the probable cause of the L. laevigatum expansion due to: (1) the exposure of bare ground, and (2) the restriction of the feeding range of cattle (known to graze both L. laevigatum and Acacia sophorae on the Isthmus).

Cytoplasmic Granules in Lymphocytes from Rats Dosed with SK&F 14336-D

1971 ◽  
Vol 29 ◽  
pp. 556-557
Author(s):  
T. G. Merrill ◽  
B. J. Payne ◽  
A. J. Tousimis
Keyword(s):  
Lipid Storage ◽  
Pokeweed Mitogen ◽  
Electron Microscopic ◽  
Cytoplasmic Granules ◽  
Storage Diseases ◽  
Tay Sachs Disease ◽  
Large Numbers ◽  
Microscopic Studies ◽  
Neurovisceral Lipidosis

Rats given SK&F 14336-D (9-[3-Dimethylamino propyl]-2-chloroacridane), a tranquilizing drug, developed an increased number of vacuolated lymphocytes as observed by light microscopy. Vacuoles in peripheral blood of rats and humans apparently are rare and are not usually reported in differential counts. Transforming agents such as phytohemagglutinin and pokeweed mitogen induce similar vacuoles in in vitro cultures of lymphocytes. These vacuoles have also been reported in some of the lipid-storage diseases of humans such as amaurotic familial idiocy, familial neurovisceral lipidosis, lipomucopolysaccharidosis and sphingomyelinosis. Electron microscopic studies of Tay-Sachs' disease and of chloroquine treated swine have demonstrated large numbers of “membranous cytoplasmic granules” in the cytoplasm of neurons, in addition to lymphocytes. The present study was undertaken with the purpose of characterizing the membranous inclusions and developing an experimental animal model which may be used for the study of lipid storage diseases.

Prolonged Fixation Studies For Spaceflight

1973 ◽  
Vol 31 ◽  
pp. 332-333
Author(s):  
Robert Corbett ◽  
Delbert E. Philpott ◽  
Sam Black
Keyword(s):  
High Pressure ◽  
Living Systems ◽  
Prolonged Storage ◽  
Time Intervals ◽  
Early Signs ◽  
Large Numbers

Observation of subtle or early signs of change in spaceflight induced alterations on living systems require precise methods of sampling. In-flight analysis would be preferable but constraints of time, equipment, personnel and cost dictate the necessity for prolonged storage before retrieval. Because of this, various tissues have been stored in fixatives and combinations of fixatives and observed at various time intervals. High pressure and the effect of buffer alone have also been tried.Of the various tissues embedded, muscle, cartilage and liver, liver has been the most extensively studied because it contains large numbers of organelles common to all tissues (Fig. 1).

Analysis of the Anterior Secretory Cells of Onchidohs Muricata (Nudibranchia)

1981 ◽  
Vol 39 ◽  
pp. 614-615
Author(s):  
Roy Skidmore
Keyword(s):  
Endoplasmic Reticulum ◽  
Secretory Granules ◽  
Golgi Body ◽  
The Body ◽  
Secretory Cells ◽  
Secretory Vesicles ◽  
High Magnification ◽  
Large Numbers ◽  
Membrane Bound ◽  
Sole Of The Foot

The long-necked secretory cells in Onchidoris muricata are distributed in the anterior sole of the foot. These cells are interspersed among ciliated columnar and conical cells as well as short-necked secretory gland cells. The long-necked cells contribute a significant amount of mucoid materials to the slime on which the nudibranch travels. The body of these cells is found in the subepidermal tissues. A long process extends across the basal lamina and in between cells of the epidermis to the surface of the foot. The secretory granules travel along the process and their contents are expelled by exocytosis at the foot surface.The contents of the cell body include the nucleus, some endoplasmic reticulum, and an extensive Golgi body with large numbers of secretory vesicles (Fig. 1). The secretory vesicles are membrane bound and contain a fibrillar matrix. At high magnification the similarity of the contents in the Golgi saccules and the secretory vesicles becomes apparent (Fig. 2).

Selective Sampling and Orientation of Non-Homogeneous Tissues

1968 ◽  
Vol 26 ◽  
pp. 98-99
Author(s):  
C. C. Clawson ◽  
L. W. Anderson ◽  
R. A. Good
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Light Microscopy ◽  
Random Sampling ◽  
New Method ◽  
Microscope Examination ◽  
Small Areas ◽  
Selective Sampling ◽  
Large Numbers ◽  
Specific Orientation

Investigations which require electron microscope examination of a few specific areas of non-homogeneous tissues make random sampling of small blocks an inefficient and unrewarding procedure. Therefore, several investigators have devised methods which allow obtaining sample blocks for electron microscopy from region of tissue previously identified by light microscopy of present here techniques which make possible: 1) sampling tissue for electron microscopy from selected areas previously identified by light microscopy of relatively large pieces of tissue; 2) dehydration and embedding large numbers of individually identified blocks while keeping each one separate; 3) a new method of maintaining specific orientation of blocks during embedding; 4) special light microscopic staining or fluorescent procedures and electron microscopy on immediately adjacent small areas of tissue.

Microanalysis of precipitates in a ferritic steel

1978 ◽  
Vol 36 (1) ◽  
pp. 618-619
Author(s):  
J.M. Titchmarsh
Keyword(s):  
Ferritic Steel ◽  
Particle Identification ◽  
Energy Dispersive ◽  
Objective Lens ◽  
Ferritic Steels ◽  
Replica Technique ◽  
X Ray ◽  
Large Numbers ◽  
Scanning Transmission ◽  
Made In

The advances in recent years in the microanalytical capabilities of conventional TEM's fitted with probe forming lenses allow much more detailed investigations to be made of the microstructures of complex alloys, such as ferritic steels, than have been possible previously. In particular, the identification of individual precipitate particles with dimensions of a few tens of nanometers in alloys containing high densities of several chemically and crystallographically different precipitate types is feasible. The aim of the investigation described in this paper was to establish a method which allowed individual particle identification to be made in a few seconds so that large numbers of particles could be examined in a few hours.A Philips EM400 microscope, fitted with the scanning transmission (STEM) objective lens pole-pieces and an EDAX energy dispersive X-ray analyser, was used at 120 kV with a thermal W hairpin filament. The precipitates examined were extracted using a standard C replica technique from specimens of a 2¼Cr-lMo ferritic steel in a quenched and tempered condition.

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