TY  - JOUR
A1  - Rocha, Marcia R.
A1  - Gaedke, Ursula
A1  - Vasseur, David A.
T1  - Functionally similar species have similar dynamics
JF  - The journal of ecology
N2  - 1. Improving the mechanistic basis of biodiversity-ecosystem function relationships requires a better understanding of how functional traits drive the dynamics of populations. For example, environmental disturbances or grazing may increase synchronization of functionally similar species, whereas functionally different species may show independent dynamics, because of different responses to the environment. Competition for resources, on the other hand, may yield a wide range of dynamic patterns among competitors and lead functionally similar and different species to display synchronized to compensatory dynamics. The mixed effect of these forces will influence the temporal fluctuations of populations and, thus, the variability of aggregate community properties.
 2. To search for a relationship between functional and dynamics similarity, we studied the relationship between functional trait similarity and temporal dynamics similarity for 36 morphotypes of phytoplankton using long-term high-frequency measurements.
 3. Our results show that functionally similar morphotypes exhibit dynamics that are more synchronized than those of functionally dissimilar ones. Functionally dissimilar morphotypes predominantly display independent temporal dynamics. This pattern is especially strong when short time-scales are considered.
 4. Negative correlations are present among both functionally similar and dissimilar phytoplankton morphotypes, but are rarer and weaker than positive ones over all temporal scales.
 5. Synthesis. We demonstrate that diversity in functional traits decreases community variability and ecosystem-level properties by decoupling the dynamics of individual morphotypes.
KW  - compensatory dynamics
KW  - competition
KW  - environmental forcing
KW  - functional diversity
KW  - functional traits
KW  - grazing
KW  - phytoplankton
KW  - plant population and community dynamics
KW  - synchrony
KW  - temporal dynamics
Y1  - 2011
U6  - https://doi.org/10.1111/j.1365-2745.2011.01893.x
SN  - 0022-0477
VL  - 99
IS  - 6
SP  - 1453
EP  - 1459
PB  - Wiley-Blackwell
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Rocha, Marcia R.
A1  - Vasseur, David A.
A1  - Hayn, Michael
A1  - Holschneider, Matthias
A1  - Gaedke, Ursula
T1  - Variability patterns differ between standing stock and process rates
JF  - Oikos
N2  - Standing stocks are typically easier to measure than process rates such as production. Hence, stocks are often used as indicators of ecosystem functions although the latter are generally more strongly related to rates than to stocks. The regulation of stocks and rates and thus their variability over time may differ, as stocks constitute the net result of production and losses. Based on long-term high frequency measurements in a large, deep lake we explore the variability patterns in primary and bacterial production and relate them to those of the corresponding standing stocks, i.e. chlorophyll concentration, phytoplankton and bacterial biomass. We employ different methods (coefficient of variation, spline fitting and spectral analysis) which complement each other for assessing the variability present in the plankton data, at different temporal scales. In phytoplankton, we found that the overall variability of primary production is dominated by fluctuations at low frequencies, such as the annual, whereas in stocks and chlorophyll in particular, higher frequencies contribute substantially to the overall variance. This suggests that using standing stocks instead of rate measures leads to an under- or overestimation of food shortage for consumers during distinct periods of the year. The range of annual variation in bacterial production is 8 times greater than biomass, showing that the variability of bacterial activity (e.g. oxygen consumption, remineralisation) would be underestimated if biomass is used. The P/B ratios were variable and although clear trends are present in both bacteria and phytoplankton, no systematic relationship between stock and rate measures were found for the two groups. Hence, standing stock and process rate measures exhibit different variability patterns and care is needed when interpreting the mechanisms and implications of the variability encountered.
Y1  - 2011
U6  - https://doi.org/10.1111/j.1600-0706.2010.18786.x
SN  - 0030-1299
VL  - 120
IS  - 1
SP  - 17
EP  - 25
PB  - Wiley-Blackwell
CY  - Malden
ER  -