Do Svalbard reindeer regulate standing crop in the absence of predators?

Oecologia ◽  
1998 ◽  
Vol 116 (1-2) ◽  
pp. 202-206 ◽  
Author(s):  
Christina Wegener ◽  
Ann Marie Odasz-Albrigtsen
Keyword(s):  
Standing Crop ◽  
Svalbard Reindeer

STANDING CROP NITROGEN CONTENT (FIFE)

1994 ◽  
Author(s):  
T. G. F. KITTEL ◽  
W. J. PARTON ◽  
D. S. SCHIMEL
Keyword(s):  
Nitrogen Content ◽  
Standing Crop

Litter fall of epiphytic macrolichens in two old Picea abies forests in Sweden

1985 ◽  
Vol 63 (5) ◽  
pp. 980-987 ◽  
Author(s):  
Per-Anders Esseen
Keyword(s):  
Standing Crop ◽  
Annual Variation ◽  
Length Distribution ◽  
Forest Stand ◽  
Epiphytic Lichens ◽  
Litter Fall ◽  
Alectoria Sarmentosa ◽  
Usnea Longissima ◽  
Tree Litter ◽  
Thallus Length

The seasonal and annual variation in the litter fall of epiphytic lichens and tree litter was studied over a period of 2 to 3 years at two forested hills in the eastern part of central Sweden. Litter fall was measured using traps and for one species, Usnea longissima, by collecting specimens present on the ground. Total litter fall amounted to 2.5 and 2.8 tons ha−1 year−1 of which lichens constituted 4.6 and 5.7% at the two sites. Lichen litter fall was highest during the period from late autumn to the beginning of summer. Both the lichens and the tree litter showed significant between-year differences. Usnea longissima had an annual turnover of 7.0 and 10.0% of the standing crop at the two sites. The thallus length distribution of U. longissima was positively skewed. It is concluded that dispersal of thallus fragments by wind evidently plays an important role for many of the filamentous lichens studied. It is suggested that U. longissima disperses over a much shorter distance than Alectoria sarmentosa and Bryoria spp. within a forest stand.

scholarly journals Changes in ecosystem processes induced by land use: Human appropriation of aboveground NPP and its influence on standing crop in Austria

2001 ◽  
Vol 15 (4) ◽  
pp. 929-942 ◽  
Author(s):  
Helmut Haberl ◽  
Karl-Heinz Erb ◽  
Fridolin Krausmann ◽  
Wolfgang Loibl ◽  
Niels Schulz ◽  
...  
Keyword(s):  
Land Use ◽  
Standing Crop ◽  
Ecosystem Processes

Relationships between Cell-Wall Fractions, Nitrogen, and Standing Crop in Aquatic Macrophytes

Ecology ◽  
1972 ◽  
Vol 53 (3) ◽  
pp. 484-488 ◽  
Author(s):  
J. M. Polisini ◽  
Claude E. Boyd
Keyword(s):  
Cell Wall ◽  
Standing Crop ◽  
Aquatic Macrophytes

The Standing Crop of Net Plankton in Lakes

1953 ◽  
Vol 10 (5) ◽  
pp. 224-237 ◽  
Author(s):  
D. S. Rawson
Keyword(s):  
Standing Crop ◽  
Seasonal Fluctuation ◽  
Western Canada ◽  
Inverse Relation ◽  
Secondary Effects ◽  
Eutrophic Lakes ◽  
Trophic Condition ◽  
The Past

Plankton sampling has been a part of the program in a number of investigations of lakes in western Canada during the past 20 years. The techniques chosen for this work are discussed and criticized. The resulting data on average standing crop of net plankton are summarized and considered in relation to the kinds of lakes represented. The standing crop in 20 lakes shows an inverse relation to mean depth which is interpreted as indicating that, in most of these lakes, the trophic condition is greatly influenced by morphometry. Deviations from this relation appear to be explained by the secondary effects of climate and edaphic situation.The difference in quantity between the standing crops of net plankton in oligotrophic and eutrophic lakes is not large, and, of course, these lake types intergrade. This lack of sharp differentiation is further obscured by rapid and extensive seasonal fluctuation in amounts of plankton and by the difficulties inherent in present methods of sampling. These circumstances render measurements of standing crop difficult and of only moderate utility in suggesting the trophic type or the possible productivity of a lake.

Postharvest recovery of beds of the edible red alga Porphyra perforata

1984 ◽  
Vol 62 (9) ◽  
pp. 1968-1970 ◽  
Author(s):  
William G. Roland ◽  
L. Michael Coon
Keyword(s):  
Standing Crop ◽  
Negative Impact ◽  
Control Area ◽  
Percent Cover ◽  
Annual Fluctuation ◽  
Queen Charlotte Islands ◽  
Negative Effect ◽  
Large Plot ◽  
Small Plot ◽  
Whole Plants

Recovery of intertidal Porphyra beds following hand harvest was studied near the northwest tip of the Queen Charlotte Islands, B.C. Twenty-six percent of the standing crop of Porphyra perforata J. Ag. was removed in a large plot in June 1981; no negative effect on standing crop was apparent in May 1982 as compared with the adjacent control area. There was no negative impact on percent cover of Porphyra (mostly P. perforata) within 1 year after hand harvest of seven, approximately 1-m2 plots, as compared with respective controls. Annual fluctuation in cover, biomass, and relative mix of Porphyra species was large. Porphyra cover in a small plot harvested in early June 1981 increased to 86% of the June value by mid-July 1981, indicating substantial growth of the remaining thallus fragments and small, whole plants within one season. It was concluded that sustained yield of Porphyra beds can be assured if harvest is restricted to gathering by hand.

Influence of Reservoir Transit on Riverine Algal Transport and Abundance

1984 ◽  
Vol 41 (12) ◽  
pp. 1803-1813 ◽  
Author(s):  
D. M. Søballe ◽  
R. W. Bachmann
Keyword(s):  
Water Temperature ◽  
Retention Time ◽  
Standing Crop ◽  
Algal Biomass ◽  
Chlorophyll Concentration ◽  
Light Limitation ◽  
Des Moines ◽  
Flow Dependence ◽  
Major Loss ◽  
Chlorophyll Concentrations

The Des Moines River lost 65–75% of its algal standing crop (chlorophyll a) in passing through each of two impoundments (mean retention times 11 and 16 d), and chlorophyll concentrations within both impoundments were 50–90% below the predictions of empirical chlorophyll–nutrient models. Sedimentation of river-borne algae and light limitation within the impoundments were identified as major loss processes. A reduction in algal size from upstream to downstream in one reservoir paralleled the loss of algal biomass. Algal losses in each impoundment increased with both increasing retention time and water temperature so that chlorophyll concentration below the dams was uncoupled from the temperature and flow dependence seen in river reaches not influenced by impoundments. The reduction in riverine algal transport associated with reservoir transit was cumulative over the two-reservoir series; this reduction can be interpreted as a "reset" to river headwater conditions.

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