Spatial pattern of trees influences species productivity in a mature oak-pine mixed forest

Spatial pattern has a key role in the interactions between species in plant communities. These interactions influence ecological processes involved in the species dynamics: growth, regeneration and mortality. In this study, we investigated the effect of spatial pattern on productivity in mature mixed forests of sessile oak and Scots pine. We simulated tree locations with point process models and tree growth with spatially explicit individual growth models. The point process models and growth models were fitted with field data from the same stands. We compared species productivity obtained in two types of mixture: a patchy mixture and an intimate mixture. Our results show that the productivity of both species is higher in an intimate mixture than in a patchy mixture. Productivity difference between the two types of mixture was 11.3% for pine and 14.7% for oak. Both species were favored in the intimate mixture because, for both, intraspecific competition was more severe than interspecific competition. Our results clearly support favoring intimate mixtures in mature oak-pine stands to optimize tree species productivity; oak is the species that benefits the most from this type of management. Our work also shows that models and simulations can provide interesting results for complex forests with mixtures, results that would be difficult to obtain through experimentation

HETEROFOR 1.0: A spatially explicit model for exploring the response of structurally complex forests to uncertain future conditions-Part 2: Phenology and water cycle

Climate change affects forest growth in numerous and sometimes opposite ways, and the resulting trend is often difficult to predict for a given site. Integrating and structuring the knowledge gained from the monitoring and experimental studies into process-based models is an interesting approach to predict the response of forest ecosystems to climate change. While the first generation of models operates at stand level, one now needs spatially explicit individual-based approaches in order to account for individual variability, local environment modification and tree adaptive behaviour in mixed and uneven-Aged forests that are supposed to be more resilient under stressful conditions. The local environment of a tree is strongly influenced by the neighbouring trees, which modify the resource level through positive and negative interactions with the target tree. Among other things, drought stress and vegetation period length vary with tree size and crown position within the canopy. In this paper, we describe the phenology and water balance modules integrated in the tree growth model HETEROFOR (HETEROgenous FORest) and evaluate them on six heterogeneous sessile oak and European beech stands with different levels of mixing and development stages and installed on various soil types. More precisely, we assess the ability of the model to reproduce key phenological processes (budburst, leaf development, yellowing and fall) as well as water fluxes. Two two-phase models differing regarding their response function to temperature during the chilling period (optimum and sigmoid functions) and a simplified one-phase model are. used to predict budburst date. The two-phase model with the optimum function is the least biased (overestimation of 2.46 d), while the one-phase model best accounts for the interannual variability (Pearson's r D 0:68). For the leaf development, yellowing and fall, predictions and observations are in accordance. Regarding the water balance module, the predicted throughfall is also in close agreement with the measurements (Pearson's r D 0:856; biasD 1:3 %), and the soil water dynamics across the year are well reproduced for all the study sites (Pearson's r was between 0.893 and 0.950, and bias was between 1:81 and 9:33 %). The model also reproduced well the individual transpiration for sessile oak and European beech, with similar performances at the tree and stand scale (Pearson's r of 0.84 0.85 for sessile oak and 0.88 0.89 for European beech). The good results of the model assessment will allow us to use it reliably in projection studies to evaluate the impact of climate change on tree growth in structurally complex stands and test various management strategies to improve forest resilience. © 2020 Author(s)

A harmonized database of European forest simulations under climate change

Process-based forest models combine biological, physical, and chemical process understanding to simulate forest dynamics as an emergent property of the system. As such, they are valuable tools to investigate the effects of climate change on forest ecosystems. Specifically, they allow testing of hypotheses regarding long-term ecosystem dynamics and provide means to assess the impacts of climate scenarios on future forest development. As a consequence, numerous local-scale simulation studies have been conducted over the past decades to assess the impacts of climate change on forests. These studies apply the best available models tailored to local conditions, parameterized and evaluated by local experts. However, this treasure trove of knowledge on climate change responses remains underexplored to date, as a consistent and harmonized dataset of local model simulations is missing. Here, our objectives were (i) to compile existing local simulations on forest development under climate change in Europe in a common database, (ii) to harmonize them to a common suite of output variables, and (iii) to provide a standardized vector of auxiliary environmental variables for each simulated location to aid subsequent investigations. Our dataset of European stand- and landscape-level forest simulations contains over 1.1 million simulation runs representing 135 million simulation years for more than 13,000 unique locations spread across Europe. The data were harmonized to consistently describe forest development in terms of stand structure (dominant height), composition (dominant species, admixed species), and functioning (leaf area index). Auxiliary variables provided include consistent daily climate information (temperature, precipitation, radiation, vapor pressure deficit) as well as information on local site conditions (soil depth, soil physical properties, soil water holding capacity, plant-available nitrogen). The present dataset facilitates analyses across models and locations, with the aim to better harness the valuable information contained in local simulations for large-scale policy support, and for fostering a deeper understanding of the effects of climate change on forest ecosystems in Europe

Implémentation d'un modèle individu centré avec distribution de voisinage : le module oakpine2 dans Capsis4

Ce document décrit comment nous avons implémenté un modèle de croissance individu-centré qui utilise des distributions de voisinage. Ces distributions de voisinage permettent de reconstruire un voisinage pour chaque arbre du peuplement puis de calculer des indices de compétition qui sont utilisés dans le modèle de croissance. Les voisinages sont mis à jour au cours du temps pour tenir compte de la croissance et des éclaircies. Le modèle a été implémenté dans le module oakpine2 de la plate-forme Capsis4

Influence à long terme de la structure spatiale d'un état initial sur la dynamique d'un modèle forestier MADD : étude simulatoire avec le module Mountain

Dans cette présentation orale, nous présentons les résultats concernant l'influence de la structure spatiale de l'état initial sur des simulations à long terme effectués sous le module Mountain de la plate-forme CAPSIS

Influence à long terme de la structure spatiale d'un état initial sur la dynamique d'un modèle de croissance forestière : une étude simulatoire sur la plate-forme CAPSIS

International audienceSpatially explicit Individual Based Models are more and more often used in forest modelling, especially because they take into account the influence of the spatial structure on the dynamics. However, they are potentially very sensitive to the initial spatial structure used for a simulation, which can be problematic if the initial state is not known, or is simulated in an unrealistic way. The aim of our paper is to study this sensitivity to initial spatial structure in the case of the Mountain model, an individual based model of irregular spruce stands implemented in the Capsis platform. In order to characterise the influence of the initial spatial structure on the dynamics of the model, we simulated different initial spatial structures and compared the results of long term simulations. We showed that the initial spatial structure can highly influence the dynamics of the model, not only during the first cycle of the evolution, but also at very long term in the evolution of the next generations. We also illustrated how some disturbances, such as a periodic gap opening through storms, can modify both the long term dynamics of the stand and the duration of the influence of the initial spatial structure.Les modèles individus centrés et spatialement explicites sont de plus en plus souvent utilisés en modélisation forestière, en particulier parce qu'ils prennent en compte l'influence de la structure spatiale sur la dynamique. Cependant, ils peuvent être très sensibles à la structure spatiale initiale utilisée dans les simulations, ce qui peut poser problème si on ne connait pas l'état initial, ou si il n'est pas simulé de façon réaliste. L'objectif de cet article est d'étudier cette sensibilité à la structure spatiale initiale dans le cas du modèle "Mountain", un modèle individus centré de pessières irrégulières de montagne implémenté dans la plate-forme CAPSIS. Pour caractériser l'influence de la structure spatiale initiale sur la dynamique du modèle, nous avons simulé des états initiaux de différentes structures spatiales, et comparé les résultats de simulations à long terme. Nous avons montré que la structure spatiale initiale peut influencer fortement la dynamique du modèle, non seulement pendant le premier cycle de l'évolution, mais également à très long terme dans les générations suivantes. Nous avons également montré comment des perturbations, comme l'ouverture de clairières par des tempêtes, peut modifier à la fois la dynamique à long terme du modèle, et la durée de l'influence de la structure spatiale initiale

Long-term influence of the spatial structure of an initial state on the dynamics of a forest growth model: a simulation study using the Capsis platform

A-06-28International audienceSpatially explicit individual-based models are used more often in forest modeling, especially because they take into account the influence of the spatial structure on the dynamics. However, they are potentially very sensitive to the initial spatial structure used for a simulation, which can be problematic if the initial state is not known or is simulated in an unrealistic way.The aim of this article is to study this sensitivity to initial spatial structure in the case of the "Mountain" model, an individual-based model of irregular spruce stands implemented in the Capsis platform.To characterize the influence of the initial spatial structure on the dynamics of the model, the authors simulated different initial spatial structures and compared the results of long-term simulations. They showed that the initial spatial structure can highly influence the dynamics of the model, not only during the first cycle of the evolution but also in the very long term in the evolution of the next generations. They also illustrated how some disturbances, such as a periodic gap opening through storms, can modify both the long-term dynamics of the stand and the duration of the influence of the initial spatial structure

CAPSIS, logiciel d'aide à la décision pour la sylviculture

National audienc

Création d’une représentation initiale du territoire en entrée du module SIMMEM

National audienceDéveloppement de modèles d'état dendrométriques initiaux des peuplements forestiers pour l'initialisation du module SIMME

EcoAF on CAPSIS, simulates the economics effects of your choices when building and managing an agroforestry field !

International audienceWith EcoAF, download a group of concrete farm parcels, place if needed the polygons of main soil types, then play with possible futures! You can choose whatever combinations of lines, straight or broken or in spots, around or inside the field, decide where to plant trees, shrubs and grasses, in hedges or placed points, the species/varieties and the quality of the bundles of plants. The growth will depend on further choices on how you intend to manage the bundle of plants, the plantation, then all the components during their life. A further development will include simplified crop/animal productions, and the possible impact of the growth of trees and shrubs on them. Each simulation will include variability and aleas. 2D and 3D graphic interfaces and visualizations, at once and delayed datasheets let compare the consequences of different choices. The EcoAF module is developed in French and English on CAPSIS (Computer-Aided Projec-tion of Strategies In Silviculture ; http://www.inra.fr/capsis), with the aims to be user-friendly and transparent about the degree of reliability of parameters. Its conception and evolution take into account the need of advisors in agroforestry. We illustrate some consequences of genetic and silvicultural choices: plant an ordinary or improved variety, densify or not the plantation, take great care or not of the young plants while planting etc