Energy flow through populations of small mammals in the Alaskan taiga forest

Abstract

The prim ary n et production an d th e n u m b ers of sm all m am m als w ere estim ated in a w h ite spruce forest (Ptcea plauca). D aily m etabolic rates and food h abits w ere stu d ied in th e voles (C lethrionom ys ru tilu s, M icrotus oeconomus), sq u irrels (Tam iasciurus hudsonicus, G laucom ys volans) and shrew s (Sorea: cinereus). P ro d u ctio n of th is taiga fo rest am ounts to only 10.2 m illion k c a l/h a y*ar. Due to d ifferen t food h ab its of sm all m am m als th eir to tal food available in th e fo re st reaches as m uch as 1,320,000 kcal/ha (i . e. 12.EK>/0 of p rim ary production). Daily energy budgets described by functions of body size give th e follow ing m ean values: S. cinereus -8.3 kcal, C. ru tilu s -12.2 kcal, M. oeconom us -15.1 kcal, G. sabrinus -39.6 kcal and T. hudsonicus -58.4 kcal/day. The m ean num bers of sm all m am m als w ere found to be ab o u t 15 voles of b oth species, 2-3 sq u irrels an d 4 shrew s p e r 1 h ectare. T he total an n u a l production of these populations w as estim ated as approx. 2,500 kcal/ha, th e ir assim ilation -143,900 kcal, an d consum ption -178,600 kcal. D uring th e populatio n cycle of voles an d sq u irrels all these values can flu ctu ate w ith in a broad ran g e; production 600-8,000, assim ilation 38,000-400,000, consum ption 47,000-500,000 kcal/ha year. In d ifferen t years sm all m am m als m ay th e re fo re consum e from 3 to 38tyo of the p o te n tia l food supply provided by th e taiga forest. T hese values are considerably higher th a n those found in any other w oodland.

The Normalized Difference Vegetation Index (NDVI): unforeseen successes in animal ecology

“…However, the studies conducted in the 1960s-1980s were performed at very small spatial scales (study sites usually encompassed one to a few hectares) as the methods of estimating habitat productivity relied on laborious direct sampling of vegetation (e.g. Grodziński 1971, Pelikan 1982. Since the 1980s, it has become more and more evident that patterns in small rodent abundance are better explained in macroecological scale, and several geographical gradients in vole population dynamics have been described (Hansson & Henttonen 1985, Mackin-Rogalska & Nagab8o 1990, Tkadlec & Stenseth 2001.…”

Supplementary food and the winter dynamics of bank vole populations

“…Several authors observed a low utilization of the potential food supply by rodent populations (Grodziński, 1961(Grodziński, , 1971aGórecki & Gębczyńska, 1962;Ryszkowski, 1969;Gębczyńska, 1970;Trojan, 1970;Babińska, 1972; A u 1 a k, 1973, and others). For example Buchalczyk et al (1970) showed that Microtus oeconomus (Pallas, 1776) utilizes barely 3.1% of its food supply but it damages over 60% of young deciduous trees, out of which 6 to 7% subsequently die.…”

Revising the fundamentals of ecological knowledge: the biota–environment interaction

“…considerably exceed the size of a single ecosystem unit. The share of energy consumption allocated to such animals in natural undisturbed ecosystems does not exceed several per cent of the ecosystems' primary productivity (Bray, 1964;Wiegert and Owen, 1971;Grodzinski, 1971;Humphreys, 1979;Gorshkov, 1981;Makarieva et al, in review). Mobile animals can be therefore regarded as a certain component of the environment, which is shared by different local ecological communities and can be regulated by them in the same manner as the concentrations of globally regulated biogens.…”