Mixing has limited impacts on the foliar nutrition of European beech and Scots pine trees across Europe
Streel, Géraud de; Ammer, Christian ; Annighöfer, Peter ; Barbeito, Ignacio ; Bielak, Kamil ; Bravo-Oviedo, Andrés ; Brazaitis, Gediminas ; Buraczyk, Włodzimierz ; Collet, Catherine ; Hurt, Vaclav ; Kurylyak, Viktor ; Ouden, Jan den; Pach, Maciej ; Pretzsch, Hans ; Skrzyszewski, Jerzy ; Sramek, Vit ; Stankevičiūtė, Jolanta ; Strelcova, Katarina ; Svoboda, Miroslav ; Verheyen, Kris ; Zlatanov, Tzvetan ; Ponette, Quentin - \ 2020
Forest Ecology and Management 479 (2020). - ISSN 0378-1127
Complementarity - Fagus sylvatica L. - Foliar nutrition - Pinus sylvestris L. - Species mixture
Tree species-mixing has been suggested as one option to counteract the adverse effects of global change on tree mineral nutrition, yet the effect of mixing on nutrient availability remains poorly documented. We therefore analyzed the current foliar nutrient (N, P, K, Ca, Mg) quantities and ilr balances (isometric log transformed ratios between elements or groups of elements) for 261 European beech and 248 Scots pine trees from 15 sites, each consisting of one beech-pine mixed stand and the respective monocultures, across a gradient of environmental conditions in Europe. We hypothesized an overall positive effect of mixing on tree foliar nutrient content, and that this mixing effect would be stronger on nutrient-poor sites. Using linear mixed models and multivariate linear regression models, we first tested for the effects of species (beech/pine) and composition (pure/mixed) across all sites; we then investigated whether the species-mixing effect was related to site fertility. The nutrient composition of beech leaves and pine needles differed significantly for all ilr balances. For both species, significant mixing effects were detected for some nutrients and ilr balances; those effects, however, could not be consistently related to contrasted nutrient composition between species. For most nutrients and ilr balances, the mixing effect was influenced by the site nutritional status, but the pattern differed from expectation: absence or minor differences between monocultures and mixtures at the lower end of the chemical fertility gradient, and maximum differences in rich soils. The contrasting foliar nutrient composition of pine and beech trees and the site nutrient status only partly explained the mixing effects on tree mineral nutrition. Our results claim for a better understanding of nutrient-related mechanisms associated with complementarity and points towards the need to further expand the existing frameworks to account for the multivariate nature of tree nutrition.
Effects of crown architecture and stand structure on light absorption in mixed and monospecific Fagus sylvatica and Pinus sylvestris forests along a productivity and climate gradient through Europe
Forrester, David Ian ; Ammer, Christian ; Annighöfer, Peter J. ; Barbeito, Ignacio ; Bielak, Kamil ; Bravo-Oviedo, Andrés ; Coll, Lluis ; Río, Miren del; Drössler, Lars ; Heym, Michael ; Hurt, Václav ; Löf, Magnus ; Ouden, Jan den - \ 2018
Journal of Ecology 106 (2018). - ISSN 0022-0477 - p. 746 - 760.
Allometric equation - Biodiversity - Complementarity - Maestra model - Plant-plant interactions - Resource availability - Tree height
When tree-species mixtures are more productive than monocultures, higher light absorption is often suggested as a cause. However, few studies have quantified this effect and even fewer have examined which light-related interactions are most important, such as the effects of species interactions on tree allometric relationships and crown architecture, differences in vertical or horizontal canopy structure, phenology of deciduous species or the mixing effects on tree size and stand density. In this study, measurements of tree sizes and stand structures were combined with a detailed tree-level light model (Maestra) to examine the contribution of each light-related interaction on tree- and stand-level light absorption at 21 sites, each of which contained a triplet of plots including a mixture and monocultures of Fagus sylvatica and Pinus sylvestris (63 plots). These sites were distributed across the current distribution of these species within Europe. Averaged across all sites, the light absorption of mixtures was 14% higher than the mean of the monocultures. At the whole community level, this positive effect of mixing on light absorption increased as canopy volume or site productivity increased, but was unrelated to climate. At the species population or individual tree levels, the mixing effect on light absorption resulted from light-related interactions involving vertical canopy structure, stand density, the presence of a deciduous species (F. sylvatica), as well as the effects of mixing on tree size and allometric relationships between diameter and height, crown diameter and crown length. The mixing effects on light absorption were only correlated with the mixing effects on growth for P. sylvestris, suggesting that the mixing effects on this species were driven by the light-related interactions, whereas mixing effects on F. sylvatica or whole community growth were probably driven by non-light-related interactions. Synthesis. The overall positive effect of mixing on light absorption was the result of a range of light-related interactions. However, the relative importance of these interactions varied between sites and is likely to vary between other species combinations and as stands develop.
Predicting the spatial and temporal dynamics of species interactions in Fagus sylvatica and Pinus sylvestris forests across Europe
Forrester, David Ian ; Ammer, Ch ; Annighöfer, Peter J. ; Avdagic, A. ; Barbeito, I. ; Bielak, Kamil ; Brazaitis, Gediminas ; Coll, L. ; Río, M. del; Drössler, L. ; Heym, Michael ; Hurt, Václav ; Löf, Magnus ; Matović, B. ; Meloni, F. ; Ouden, J. den; Pach, Maciej ; Pereira, M.G. ; Ponette, Quentin ; Pretzsch, H. ; Skrzyszewski, Jerzy ; Stojanović, D. ; Svoboda, M. ; Ruiz-Peinado, R. ; Vacchiano, G. ; Verheyen, K. ; Zlatanov, T. ; Bravo-Oviedo, A. - \ 2017
Forest Ecology and Management 405 (2017). - ISSN 0378-1127 - p. 112 - 133.
Biodiversity - Climate - Competition - Complementarity - Forest growth model - Mixed-species - Silviculture
The productivity and functioning of mixed-species forests often differs from that of monocultures. However, the magnitude and direction of these differences are difficult to predict because species interactions can be modified by many potentially interacting climatic and edaphic conditions, stand structure and previous management. Process-based forest growth models could potentially be used to disentangle the effects of these factors and thereby improve our understanding of mixed forest functioning while facilitating their design and silvicultural management. However, to date, the predicted mixing effects of forest growth models have not been compared with measured mixing effects. In this study, 26 sites across Europe, each containing a mixture and monocultures of Fagus sylvatica and Pinus sylvestris, were used to calculate mixing effects on growth and yield and compare them with the mixing effects predicted by the forest growth model 3-PGmix. The climate and edaphic conditions, stand structures and ages varied greatly between sites. The model performed well when predicting the stem mass and total mass (and mixing effects on these components), with model efficiency that was usually >0.7. The model efficiency was lower for growth or smaller components such as foliage mass and root mass. The model was also used to predict how mixing effects would change along gradients in precipitation, temperature, potential available soil water, age, thinning intensity and soil fertility. The predicted patterns were consistent with measurements of mixing effects from published studies. The 3-PG model is a widely used management tool for monospecific stands and this study shows that 3-PGmix can be used to examine the dynamics of mixed-species stands and determine how they may need to be managed.
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.