Drivers of above-ground understorey biomass and nutrient stocks in temperate deciduous forests
Landuyt, Dries ; Maes, Sybryn L. ; Depauw, Leen ; Ampoorter, Evy ; Blondeel, Haben ; Perring, Michael P. ; Brūmelis, Guntis ; Brunet, Jörg ; Decocq, Guillaume ; Ouden, Jan den; Härdtle, Werner ; Hédl, Radim ; Heinken, Thilo ; Heinrichs, Steffi ; Jaroszewicz, Bogdan ; Kirby, Keith J. ; Kopecký, Martin ; Máliš, František ; Wulf, Monika ; Verheyen, Kris - \ 2020
Journal of Ecology 108 (2020)3. - ISSN 0022-0477 - p. 982 - 997.
ecosystem functioning - ground layer - herb layer - PhytoCalc - piecewise SEM - productivity
The understorey in temperate forests can play an important functional role, depending on its biomass and functional characteristics. While it is known that local soil and stand characteristics largely determine the biomass of the understorey, less is known about the role of global change. Global change can directly affect understorey biomass, but also indirectly by modifying the overstorey, local resource availability and growing conditions at the forest floor. In this observational study across Europe, we aim at disentangling the impact of global-change drivers on understorey biomass and nutrient stocks, from the impact of overstorey characteristics and local site conditions. Using piecewise structural equation modelling, we determine the main drivers of understorey biomass and nutrient stocks in these forests and examine potential direct and indirect effects of global-change drivers. Tree cover, tree litter quality and differences in former land use were the main drivers of understorey biomass and nutrient stocks, via their influence on understorey light and nitrogen availability and soil acidity. Other global-change drivers, including climate and nitrogen deposition, had similar indirect effects, but these were either weak or only affecting nutrient concentrations, not stocks. Synthesis. We found that direct effects of global-change drivers on understorey biomass and nutrient stocks were absent. The indirect effects of global change, through influencing resource availability and growing conditions at the forest floor, were found to be less important than the effects of overstorey cover and composition. These results suggest that understorey biomass and nutrient stocks might respond less to global change in the presence of a dense overstorey, highlighting the buffering role of the overstorey in temperate forests.
Low probability of a dilution effect for Lyme borreliosis in Belgian forests
Ruyts, Sanne C. ; Landuyt, Dries ; Ampoorter, Evy ; Heylen, Dieter ; Ehrmann, Steffen ; Coipan, Elena C. ; Matthysen, Erik ; Sprong, Hein ; Verheyen, Kris - \ 2018
Ticks and Tick-borne Diseases 9 (2018)5. - ISSN 1877-959X - p. 1143 - 1152.
Bayesian belief network - Biodiversity - Borrelia afzelii - Ixodes ricinus - Tick - Vector-borne disease
An increasing number of studies have investigated the consequences of biodiversity loss for the occurrence of vector-borne diseases such as Lyme borreliosis, the most common tick-borne disease in the northern hemisphere. As host species differ in their ability to transmit the Lyme borreliosis bacteria Borrelia burgdorferi s.l. to ticks, increased host diversity can decrease disease prevalence by increasing the proportion of dilution hosts, host species that transmit pathogens less efficiently. Previous research shows that Lyme borreliosis risk differs between forest types and suggests that a higher diversity of host species might dilute the contribution of small rodents to infect ticks with B. afzelii, a common Borrelia genospecies. However, empirical evidence for a dilution effect in Europe is largely lacking. We tested the dilution effect hypothesis in 19 Belgian forest stands of different forest types along a diversity gradient. We used empirical data and a Bayesian belief network to investigate the impact of the proportion of dilution hosts on the density of ticks infected with B. afzelii, and identified the key drivers determining the density of infected ticks, which is a measure of human infection risk. Densities of ticks and B. afzelii infection prevalence differed between forest types, but the model indicated that the density of infected ticks is hardly affected by dilution. The most important variables explaining variability in disease risk were related to the density of ticks. Combining empirical data with a model-based approach supported decision making to reduce tick-borne disease risk. We found a low probability of a dilution effect for Lyme borreliosis in a north-western European context. We emphasize that under these circumstances, Lyme borreliosis prevention should rather aim at reducing tick-human contact rate instead of attempting to increase the proportion of dilution hosts.
Year-to-year variation in the density of Ixodes ricinus ticks and the prevalence of the rodent-associated human pathogens Borrelia afzelii and B. miyamotoi in different forest types
Ruyts, Sanne C. ; Tack, Wesley ; Ampoorter, Evy ; Coipan, Elena C. ; Matthysen, Erik ; Heylen, Dieter ; Sprong, Hein ; Verheyen, Kris - \ 2018
Ticks and Tick-borne Diseases 9 (2018)2. - ISSN 1877-959X - p. 141 - 145.
Host community - Lyme borreliosis - Mast year - Spatiotemporal dynamics - Tick-borne disease risk
The human pathogens Borrelia afzelii, which causes Lyme borreliosis and B. miyamotoi, which causes relapsing fever, both circulate between Ixodes ricinus ticks and rodents. The spatiotemporal dynamics in the prevalence of these pathogens have not yet been fully elucidated, but probably depend on the spatiotemporal population dynamics of small rodents. We aimed to evaluate the effect of different forest types on the density of infected nymphs in different years and to obtain more knowledge about the spatial and temporal patterns of ticks and tick-borne pathogens. We analysed unfed nymphal ticks from 22 stands of four different forest types in Belgium in 2009, 2010, 2013 and 2014 and found that the density of nymphs in general and the density of nymphs infected with B. afzelii and B. miyamotoi varied yearly, but without temporal variation in the infection prevalence. The yearly variation in density of infected nymphs in our study thus seems to be caused most by the variation in the density of nymphs, which makes it a good predictor of disease risk. The risk for rodent-associated tick-borne diseases also varied between forest types. We stress the need to elucidate the contribution of the host community composition to tick-borne disease risk.
Species interactions increase the temporal stability of community productivity in Pinus sylvestris-Fagus sylvatica mixtures across Europe
Río, Miren del; Pretzsch, Hans ; Ruíz-Peinado, Ricardo ; Ampoorter, Evy ; Annighöfer, Peter ; Barbeito, Ignacio ; Bielak, Kamil ; Brazaitis, Gediminas ; Coll, Lluís ; Drössler, Lars ; Mohren, Frits ; Ouden, Jan den; Bravo-Oviedo, Andrés - \ 2017
Journal of Ecology 105 (2017)4. - ISSN 0022-0477 - p. 1032 - 1043.
Asynchrony - Mixed-species forests - Niche complementarity - Organizational levels - Overyielding - Plant-plant interactions - Temporal variability
There is increasing evidence that species diversity enhances the temporal stability (TS) of community productivity in different ecosystems, although its effect at the population and tree levels seems to be negative or neutral. Asynchrony in species responses to environmental conditions was found to be one of the main drivers of this stabilizing process. However, the effect of species mixing on the stability of productivity, and the relative importance of the associated mechanisms, remain poorly understood in forest communities. We investigated the way mixing species influenced the TS of productivity in Pinus sylvestris L. and Fagus sylvatica L. forests, and attempted to determine the main drivers among overyielding, asynchrony between species annual growth responses to environmental conditions, and temporal shifts in species interactions. We used a network of 93 experimental plots distributed across Europe to compare the TS of basal area growth over a 15-year period (1999-2013) in mixed and monospecific forest stands at different organizational levels, namely the community, population and individual tree levels. Mixed stands showed a higher TS of basal area growth than monospecific stands at the community level, but not at the population or individual tree levels. The TS at the community level was related to asynchrony between species growth in mixtures, but not to overyielding nor to asynchrony between species growth in monospecific stands. Temporal shifts in species interactions were also related to asynchrony and to the mixing effect on the TS. Synthesis. Our findings confirm that species mixing can stabilize productivity at the community level, whereas there is a neutral or negative effect on stability at the population and individual tree levels. The contrasting findings regarding the relationships between the temporal stability and asynchrony in species growth in mixed and monospecific stands suggest that the main driver in the stabilizing process may be the temporal niche complementarity between species rather than differences in species' intrinsic responses to environmental conditions.
Data from: Species interactions increase the temporal stability of community productivity in Pinus sylvestris-Fagus sylvatica mixtures across Europe
Río, Miren del; Pretzsch, Hans ; Ruíz-Peinado, Ricardo ; Ampoorter, Evy ; Annighöfer, Peter ; Barbeito, Ignacio ; Bielak, Kamil ; Brazaitis, Gediminas ; Coll, Lluís ; Drössler, L. ; Mohren, G.M.J. ; Ouden, J. den; Bravo-Oviedo, Andrés - \ 2016
Wageningen University & Research
Main data are basal area increments by triplet, species composition and year, for the study period 1999-2013. Dataset includes data at community level (stand basal area increment), population level (species basal area increment in mixed and monospecific stands), and individual tree level (basal area increments by core, two cores by tree). Moreover data describing the trees used in the analysis is included.