100 Influential Papers - page 25

PHYS I OLOG I CA L ECOLOGY
Lloyd, J. & Taylor, J.A. (1994)
On the temperature dependence of soil respiration.
Functional Ecology, 8, 315-323.
Interest in decomposition increased enormously when it was widely realised that rising temperatures meant that the carbon cycle was
no longer in equilibrium. In the late 1980s and early 1990s research on the carbon cycle had a new impetus. The measurement of ‘soil
respiration’ became commonplace. The analysis of data sets had followed the well-trod path of fitting the
Q
10
model. The enquiry of Lloyd
and Taylor turned out to be more than a statistical exercise. The authors delved deeply into the literature, going back to the original work
on the temperature sensitivity of chemical reactions by van’t Hoff and Arrhenius. They concluded that the
Q
10
model is ‘inadequate’ and
that the relationship between respiration and temperature can be accurately represented by an Arrhenius type equation where the effective
activation energy for respiration varies inversely with temperature. The success of the paper owes much to its timeliness (its exponential
citation pattern from 1995 to 2011 follows closely the citation pattern of papers on soil respiration), and to its thoroughness (wise old
supervisors everywhere recognise scholarship when they see it, and push such papers to their students). Many of today’s students use the
clearly ‘inadequate’
Q
10
model but, they nevertheless cite the Lloyd & Taylor paper showing that they, too, respect scholarship.
John Grace
47
Körner, C. (1991)
Some often overlooked plant characteristics as
determinants of plant growth: a reconsideration.
Functional Ecology, 5, 162-173.
Acknowledging the progress in photosynthesis measurement
technology and rapid increase of information on leaf-level gas-
exchange rates, Körner (1991) has importantly pointed out that
a number of plant traits with major significance for productivity
and competitiveness is often left out. In addition to traditional
characteristics such as leaf area ratio, specific leaf area, and
biomass allocation traits with already recognized importance
for plant growth rate and plant size, Körner highlighted a series
of other characteristics which at that time were not routinely
studied. Among these key traits commonly neglected were leaf
longevity, plant longevity, root turnover, and maximum plant
height, meristem activities and cell sizes and division rates. By
now, the research community has learned that all these traits
have huge impact in determining plant ecological strategy. In an
era of increasing use of technology in functional plant ecology - in
particular, portable instruments for gas-exchange and chlorophyll
fluorescence measurements, the paper of Körner (1991) made a
major point that simple measures of plant performance should
not be left out. This message is today as fresh as it was when the
paper came out.
Ülo Niinemets
48
Koerselman, W. & Meuleman, A.F.M. (1996)
The vegetation N:P ratio: a new tool to detect the
nature of nutrient limitation.
Journal of Applied
Ecology, 33, 1441-1450.
Papers which provoke a sense of incredulity within a research
community make a unique and valuable contribution to science
by inspiring sceptics to prove them wrong and progressing
understanding by doing so. The paper by Koerselman and
Meuleman concerns a basic issue in ecology: whether particular
communities are limited by the supply of N or P. Arguably the
best way to test for nutrient limitation is a fertilizer experiment,
but this is time consuming and expensive. Koerselman
and Meuleman asked whether simple analyses of the N:P
stoichiometry of leaves provides a useful alternative. Their
results were elegant and compelling: they plotted the mean N
and P concentrations of 40 European wetland communities,
using different symbols to indicate whether fertilizer experiments
had found N or P to be limiting. Remarkably, with only one
exception, N:P > 16 indicated P-limitation, N:P < 14 indicated
N-limitation and intermediate values indicated co-limitation.
The authors proceeded to argue that variation in N:P among the
species in a community may indicate species-level differences
in nutrient limitation. Could it really be so simple? Do the same
rules apply to other vegetation types? What is the physiological
explanation for such patterns? This paper rekindled an old
debate and inspired a new generation of ecologists to find out.
David Coomes
49
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