Terrestrial feeding migration and life history of the stream-dwelling caddisfly, Desmona bethula (Trichoptera: Limnephilidae)

1981 ◽  
Vol 59 (9) ◽  
pp. 1658-1665 ◽  
Author(s):  
Nancy A. Erman
Keyword(s):  
Sierra Nevada ◽  
Vapor Pressure Deficit ◽  
Early Summer ◽  
Population Estimates ◽  
Field Station ◽  
Diel Migration ◽  
Air Temperatures ◽  
Caddisfly Larvae ◽  
History Of ◽  
Feeding Migration

A caddisfly larva, Desmona bethula (Trichoptera: Limnephilidae), lives in slow, unshaded stretches of small spring streams at the Sagehen Creek Field Station in the Sierra Nevada, California, U.S.A. On early summer nights, while in the fifth instar, it leaves the water and feeds on several species of semiaquatic plants. It returns to the water when air temperatures approach freezing and on warm, still nights stays out until dawn. Three factors (light intensity, vapor pressure deficit and temperature) determine when diel migration begins and how long it lasts. Mark–recapture estimates indicated that 14–16% of the population migrated on 2 nights during the primary feeding period. Population estimates were 1220/m2 and 1662/m2. Desmona bethula is a univoltine autumn-emerging caddisfly. It may represent an evolutionary link between the few secondarily terrestrial Limnephilidae larvae and the majority of aquatic caddisfly larvae.

Recent tree-limit history of Piceaabies in the southern Swedish Scandes

1986 ◽  
Vol 16 (4) ◽  
pp. 761-771 ◽  
Author(s):  
L. Kullman
Keyword(s):  
Frost Damage ◽  
Early Summer ◽  
Climatic Warming ◽  
Subsequent Growth ◽  
Long Distance ◽  
Air Temperatures ◽  
Increased Risk ◽  
History Of ◽  
Ca 50 ◽  
Tree Limit

The recent history of Piceaabies (L.) Karst. at its altitudinal tree limit has been studied in the southern Swedish Scandes. Altitudinal transects (131) were evenly distributed over a tract of mountains of ca. 40 × 200 km. The age of spruces growing at the tree limit and downhill were estimated by annual ring counts. The spruce tree limit had risen (on average by ca. 50 m altitudinally) in ca. 70% of the studied transects as a result of the subsequent growth in height of old, established, formerly stunted individuals. Their growth in height accelerated during the 1930's, in response to the general climatic warming. A rise in the tree limit because of the establishment of new individuals (after 1915) was noted in only 7% of the studied transects. Most of the spruces growing in the tree-limit ecotone established around the 1860's and the 1940's, which were epochs with relatively snowy winters. After 1860, spruce establishment was not correlated with the summer mean temperature. Successful regeneration of spruce at the tree limit is dependent of a deep and stable snow cover and the requisite balance between precipitation–meltwater and evaporation being maintained in the early summer. The importance of air temperatures in May for successful growth and natural regeneration was evident. High air temperature in May is detrimental, since it promotes a too early initiation of growth and a consequent increased risk of frost damage. The spruce populations at the tree limit are recruited both from local seed parents and from long distance dispersal of seed from trees growing at lower altitudes.

The Gastropod Genus Bembicium Philippi

1958 ◽  
Vol 9 (4) ◽  
pp. 546 ◽  
Author(s):  
H Anderson
Keyword(s):  
Early Summer ◽  
Egg Masses ◽  
Estuarine Species ◽  
History Of ◽  
Living Species ◽  
The Times

A history of the nomenclature of the littorinid genus, Bembicium Phllippi, 1846, and its characters are given, and the anatomy of species of the genus is discussed. Three species are recognized and redescribed: a reef-living species, B. nanum (Lamarck); an estuarine species, B. auratum (Quoy & Gaimard); and the species B. melanostoma (Gmelin) which normally inhabits sheltered bays and inlets. Although all are intertidal animals, and show some measure of adaptability, each appears to be best suited to a particular habitat. B. melanostoma and B. nanum are usually found where the chlorinity of the water is close to that of the sea. B. auratum can withstand considerable variation in the chlorinity of its environment for periods of time which are not likely to be exceeded in its normal habitat. B. melanostoma mostly lives at higher tidal levels than B. nanum. In the aquarium B. nanum proved the most susceptible to desiccation. The egg masses of B. melanostoma contain fewer and larger eggs than those of B. auratum. In the laboratory spawning of B. auratum occurred during the spring and early summer. Under the same conditions specimens of B. melanostoma deposited eggs in October. The differences between the eggs and their development, and between the times of spawning of the two species collected from different littoral regions are also discussed.

scholarly journals Climatic influence on the composition of snow cover at Austre Okstindbreen, Norway, 1989 and 1990

1994 ◽  
Vol 19 ◽  
pp. 1-6 ◽  
Author(s):  
He Yuanqing ◽  
Wilfred H. Theakstone
Keyword(s):  
Snow Cover ◽  
North Atlantic ◽  
Early Summer ◽  
Late Winter ◽  
Crustal Material ◽  
Air Masses ◽  
The North ◽  
Air Temperatures ◽  
Winter Snow ◽  
Marine Source

Winter snow cover at Austre Okstindbreen is influenced strongly by patterns of atmospheric circulation, and by air temperatures during precipitation. Differences of circulation over the North Atlantic and Scandinavia during the winters of 1988–89 and 1989–90 were reflected in the ionic and isotopic composition of snow that accumulated at the glacier. Early summer ablation did not remove, or smooth out, all the initial stratigraphic differences. In the first half of the 1988–89 winter, most air masses took a relatively short route between a marine source and Okstindan; late winter snowfalls were from air masses which had taken a longer continental route. The snow that accumulated in the first half of the 1989–90 winter was associated with air masses which had followed longer continental routes, and so brought higher concentrations of impurities from forests, lakes and crustal material. The ablation season began earlier in 1990 than in 1989, and summer winds and rain supplied more impurities to the snowpack surface.

scholarly journals Modeling Shoot-tip Temperature in the Greenhouse Environment

1998 ◽  
Vol 123 (2) ◽  
pp. 208-214 ◽  
Author(s):  
James E. Faust ◽  
Royal D. Heins
Keyword(s):  
Energy Balance ◽  
Solar Radiation ◽  
Air Temperature ◽  
Flower Development ◽  
Vapor Pressure Deficit ◽  
Shoot Tip ◽  
Balance Model ◽  
Glass Temperature ◽  
Air Temperatures ◽  
Material Temperature

An energy-balance model is described that predicts vinca (Catharanthus roseus L.) shoot-tip temperature using four environmental measurements: solar radiation and dry bulb, wet bulb, and glazing material temperature. The time and magnitude of the differences between shoot-tip and air temperature were determined in greenhouses maintained at air temperatures of 15, 20, 25, 30, or 35 °C. At night, shoot-tip temperature was always below air temperature. Shoot-tip temperature decreased from 0.5 to 5 °C below air temperature as greenhouse glass temperature decreased from 2 to 15 °C below air temperature. During the photoperiod under low vapor-pressure deficit (VPD) and low air temperature, shoot-tip temperature increased ≈4 °C as solar radiation increased from 0 to 600 W·m-2. Under high VPD and high air temperature, shoot-tip temperature initially decreased 1 to 2 °C at sunrise, then increased later in the morning as solar radiation increased. The model predicted shoot-tip temperatures within ±1 °C of 81% of the observed 1-hour average shoot-tip temperatures. The model was used to simulate shoot-tip temperatures under different VPD, solar radiation, and air temperatures. Since the rate of leaf and flower development are influenced by the temperature of the meristematic tissues, a model of shoot-tip temperature will be a valuable tool to predict plant development in greenhouses and to control the greenhouse environment based on a plant temperature setpoint.

scholarly journals Contrasting prescription burning and wildfires in California Sierra Nevada national parks and adjacent national forests

2021 ◽  
Vol 30 (4) ◽  
pp. 255
Author(s):  
Jon E. Keeley ◽  
Anne Pfaff ◽  
Anthony C. Caprio
Keyword(s):  
Sierra Nevada ◽  
National Parks ◽  
National Park ◽  
National Forests ◽  
Substantial Impact ◽  
Area Burned ◽  
Natural Fires ◽  
Park Service ◽  
History Of ◽  
Lassen Volcanic National Park

History of prescription burning and wildfires in the three Sierra Nevada National Park Service (NPS) parks and adjacent US Forest Service (USFS) forests is presented. Annual prescription (Rx) burns began in 1968 in Sequoia and Kings Canyon National Parks, followed by Yosemite National Park and Lassen Volcanic National Park. During the last third of the 20th century, USFS national forests adjacent to these parks did limited Rx burns, accounting for very little area burned. However, in 2004, an aggressive annual burn program was initiated in these national forests and in the last decade, area burned by planned prescription burns, relative to area protected, was approximately comparable between these NPS and USFS lands. In 1968, the NPS prescription burning program was unique because it coupled planned Rx burns with managing many lightning-ignited fires for resource benefit. From 1968 to 2017, these natural fires managed for resource benefit averaged the same total area burned as planned Rx burns in the three national parks; thus, they have had a substantial impact on total area burned by prescription. In contrast, on USFS lands, most lightning-ignited fires have been managed for suppression, but increasing attention is being paid to managing wildfires for resource benefit.

When did We Start to Change Things?

2009 ◽  
Author(s):  
Thomas N. Sherratt ◽  
David M. Wilkinson
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Science Fiction ◽  
Early Summer ◽  
Current Evidence ◽  
Future Climate Change ◽  
Worst Case ◽  
History Of ◽  
The Subject ◽  
James Lovelock

As we wrote the first draft of this chapter (during early summer 2007), the potential dangers of ‘global warming’ had moved up the news agenda to a point where most major politicians were starting to take the problem seriously. Our opening quotation comes from a book published in early 2006, which seemed to coincide with the growth of this wider concern with global warming. Lovelock was not alone in trying to raise awareness of the problem; around the same time another book on climate change by the zoologist and palaeontologist Tim Flannery also attracted global attention to this issue, as did the lecture tours (and Oscar-winning film) of Al Gore—the former US presidential candidate and campaigner on the dangers of climate change. Indeed, in his role as a climate campaigner Gore won a share in the 2007 Nobel Peace Prize. It is possible that future historians will see the period 2005–2007 as the start of a crucial wider engagement with these problems. Things may not be as bad as James Lovelock suggests—in his book he deliberately emphasized the most worrying scenarios coming from computer models, and other evidence, in an attempt to draw attention to the critical nature of the problem. However, all these worst case scenarios were drawn from within the range of results that most climate scientists believed could plausibly happen—not extreme cases with little current evidence to support them. That one of the major environmental scientists of the second half of the twentieth century could write such prose as science—rather than science fiction—is clearly a case for concern about future climate change. It also raises another important question, relating to the history of human influence on our planet: when in our history did we start to have major environmental impacts on Earth as a whole? This is clearly an important issue from a historical perspective, but the answers may also have implications for some of our attempts to rectify the damage. Our discussion of this question comes with various caveats. Many of the arguments we consider in this chapter are still the subject of academic disagreement.

Reproductive cycle of purple clam, Amiantis purpurata (Bivalvia: Veneridae) in northern Patagonia (Argentina)

2005 ◽  
Vol 85 (2) ◽  
pp. 367-373 ◽  
Author(s):  
Enrique M. Morsan ◽  
Marina A. Kroeck
Keyword(s):  
Reproductive Cycle ◽  
Continuous Process ◽  
Early Summer ◽  
Maturation Stage ◽  
Reproductive Pattern ◽  
Oocyte Diameter ◽  
Histological Techniques ◽  
Northern Patagonia ◽  
History Of ◽  
Quantitative Indicators

The reproductive cycle of the purple clam (Amiantis purpurata) northern Patagonian population was studied throughout a 19-month period (September 1993–March 1995) using standard histological techniques and quantitative indicators (oocyte diameter distributions, oocytes per ocular field and relative oocyte area). In this species gametogenesis is a continuous process involving a complete gonadal restitution after the end of the reproductive season (no resting period). The proliferation phase occurs during the coldest half of the year (April to September) and maturation takes place during spring (September to December). Several partial emissions of gametes, with subsequent restitution of the gametogenic series, occur during the summer months. During the total maturation stage, oocytes never filled the whole alveolar area: maximum per cent of alveolar sections occupied by oocytes (46%) was observed in late spring–early summer. Implications of the reproductive pattern in the context of palaeogeographic history of northern Patagonia, and the isolation of this population are discussed.

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