Fig 3 - uploaded by Mathieu Dassot
Content may be subject to copyright.
Relation between the number of tree seedlings per square metre for each of the 4 years following treatment, i.e. 2010, 2011, 2012 and 2013 and light (measured in 2009) for the PP site
Source publication
This study aimed at evaluating alternative methods to ensure regeneration success in temperate low-mountain forest stands by (1) estimating the effects of seed availability, competition from the adult stand and from neighbouring vegetation and interaction with the litter layer on seedling density, and by (2) comparing the effects of various silvicu...
Similar publications
Exotic plant species commonly exploit disturbances more successfully than native plants. This outcome is widely attributed to the fact that disturbance reduces biotic resistance from native plant competitors. However, biocrusts, communities of mosses, lichens, and micro‐organisms, are a prominent component of semi‐arid grasslands occurring in the i...
Citations
... Distance from seed source is a major determinant of regeneration success for all tree species (Clark et al., 1999;Nathan & Muller-Landau, 2000), and was shown to predominate over competition from tree seedlings or neighbouring vegetation in mixed forests in north-eastern France (Dassot and Collet, 2015). Long distances from potential seed sources reduce seedling density according to patterns that may differ among tree species (Clark et al., 1998;Hewitt & Kellman, 2002;Rozman et al., 2015). ...
Oak (Quercus petraea (Matt.) Liebl. and Quercus robur L. grouped), European beech (Fagus sylvatica L.) and hornbeam (Carpinus betulus L.) are three major species of western and central European forests. When conditions are suitable for the three species, silvicultural management often favours oak because of its greater economic interest. Forest managers know that beech and hornbeam are strong competitors for oak during the regeneration phase, but the conditions that influence the relative success of the regeneration of the three species growing in mixture are still poorly characterised. The natural regeneration of the three species 20 years after canopy openings was studied based on 108 study sites established in 2001 in French forests impacted by the windstorms Lothar and Martin in 1999. In spring and summer 2018 and 2019, all saplings over 0.1 m in height were counted, species were identified and diameter at breast height (DBH) was measured for all saplings over 1.30 m. The height of the saplings with the highest and median DBH in each plot was recorded for each species. Mixed models were used to analyse the combined effects of former stand type, distance from the edge of the gap and soil conditions on species presence, sapling abundance, DBH and height. The modelling approach highlighted the preponderant role of the initial seed rain on the presence and sapling density of the three species compared to interspecific competition or distance from the edge. The two latter factors had a secondary effect on sapling DBH and height. Beech and hornbeam saplings were more abundant than oak saplings regardless of soil conditions (on average, 3097, 3063 and 344 saplings ha
... Rhododendron leaves will all eventually become part of the litter layer in a rhododendron forest community, contributing nutrients to the forest soil and playing a vital role in the ecosystem (Zhou et al. 2014). However, the chemical substances contained in these leaves will also enter the soil as leaves decompose (Zhou et al. 2014;Dassot and Collet 2015). As these chemicals accumulate, they can have a toxic effect on the growth of understory plants, impeding forest regeneration . ...
Field investigations conducted in the wild alpine rhododendron forest in the Baili Rhododendron Nature Reserve found that the natural regeneration of the forest was hindered. This paper used GC-MS to identify and analyze the most abundant chemical compounds in the leaves of four of rhododendron species (Rhododendron simsii, Rhododendron decorum, Rhododendron liliiflorum, and Rhododendron pulchrum). The results showed that the chemical substances in the four rhododendron leaf samples were mainly aldehydes, alcohols, and esters. Among them, the ester content in the leaves of R. simsii is the most abundant, the alcohol content in the R. decorum is the most abundant, and the aldehyde content in the R. liliiflorum is the most abundant. These results are conducive to the protection of the rhododendron ecosystem and laid a scientific foundation for studying the difficulties of natural regeneration of rhododendron communities.
... The desired effects of MSP on neighbouring vegetation are mainly to reduce its competitive pressure as well as its physical effects on the seedlings. It includes removing above-ground and below-ground plant parts, dead plant material and dormant seeds present in the upper soil layers (Dassot and Collet 2015). The desired effects of MSP on the soil are to improve soil structure and to remove potential soil limitations to the tree seedlings. ...
Mechanical site preparation (MSP) is widely used in forestry to improve plantation success. Although it is known to alter soil properties, its direct effects on soil structure have rarely been described. The cultivation profile is a visual soil evaluation (VSE) method developed in agricultural research to analyse the impacts of cultivation practices on soil structure. The objective of the study was to adapt the method to forest plantations in order to analyse the effects of MSP on soil quality. Cultivation profiles were performed in six experimental plantation sites located in Northern France. The method made it possible to compare the impacts on soil structure of three MSP methods. It provided a schematic representation of the soil structural quality and a quantitative estimation of the volume of soil favourable to seedling root growth. It also highlighted unexpected negative effects of some MSP methods on soil structure, such as the creation of small cavities, the presence of compacted soil volumes due to wheel tracks or smeared soil volumes due to tool pass, and the pseudogleisation of soil zones due to changes in water circulation in the soil. The relevance and limitations of VSE methods in the context of forest plantation as well as the expected future development of the methods are discussed.
... Scarification removes vegetation and mix the upper organic layer with the mineral soil to foster seedling establishment (Prévost 1992). Some scarifiers are also able to fracture the soil structure and to remove specific competitive vegetation (Dassot and Collet 2015). Subsoiling is typically used on dry and compacted soils to deeply fracture their structure without mixing horizons and to improve water infiltration (Löf et al. 2012;Szota et al. 2007). ...
Mechanical site preparation (MSP) is often performed prior to planting to improve the growth and survival of planted seedlings. In this study, we compared root development of 5-years-old Quercus petraea and Pinus nigra seedlings planted in plots that had been prepared with different methods, i.e. deep scarification, deep scarification combined with mounding-subsoiling, herbicide and a control without preparation. Seventy-two trees were excavated (36 per species) and their root system was measured by recording points in a three-dimensional space along their roots. The variation of the number of roots with depth and distance to root collar was assessed and analysed, as well as the root projection area. Our results showed that root development was better in the plots with mechanical preparation, for both Q. petraea and P. nigra, when compared to the control. Combining mounding to subsoiling made the roots extending deeper, especially for Q. petraea. A strong relationship was found between root projection area and root collar diameter, indicating the primary effect of lateral root spread on tree growth. The herbicide treatment induced the highest root growth, which raised questions about the potential negative effects of changes in soil properties caused by MSP methods.
... Ce risque environnemental explique pourquoi l'utilisation d'herbicides est considérée par le public comme nocive pour la gestion des écosystèmes au même titre que la coupe à blanc(Löf et al. 2006;McCarthy et al. 2011).I.1.5. Les alternatives mécaniquesDans un contexte de méthodes chimiques interdites(Willoughby et al. 2010;Thiffault et Roy 2011;Dassot et Collet 2015), des méthodes de préparation mécanique des sites (MSP) se sont développées. L'impact des méthodes non chimiques ne semble pas avoir été bien étudié, mais il est généralement admis qu'elles sont moins dommageables que les méthodes chimiques(Willoughby et al. 2010). ...
La plantation est un outil intéressant pour mettre en œuvre des stratégies de gestion forestière et constitue également une étape critique du cycle de gestion forestière. Durant cette période, la préparation du site est très souvent employée pour assurer le succès de la plantation en l’allégeant de contraintes telles que la compétition exercée par la végétation accompagnatrice.Les modèles de croissance sont largement utilisés depuis de nombreuses années et sont des outils efficaces pour simuler l’impact des opérations sylvicoles et de la compétition. Toutefois, il n’existe actuellement en France aucun modèle de croissance des arbres permettant d'évaluer ou de comparer les opérations sylvicoles réalisées au cours des jeunes stades, même pour des essences commerciales cultivées couramment. La plupart d'entre eux sont des modèles phénoménologiques décrivant les variables dendrométriques en fonction des caractéristiques techniques des opérations sylvicoles réalisées. Ces modèles produisent généralement des prédictions robustes mais difficilement extrapolable en dehors de leurs conditions d’application. D’autres modèles, dit fonctionnels, se basent sur les processus écophysiologique afin d'estimer la croissance des semis mais nécessitent cependant d’un nombre de paramètres qui peuvent être difficiles à obtenir et, en outre, produisent des prévisions de croissance des arbres qui ne sont pas toujours solides. Des modèles hybrides qui mêlent méthodes de mensuration et méthodes écophysiologique sont une approche prometteuse qui permet d'utiliser des relations fonctionnelles exprimant la croissance des arbres tout en obtenant une prédiction robuste de la croissance.La fougère aigle (Pteridium aquilinum L. Kuhn) est l'une des espèces problématiques pour le succès des jeunes plantations. Elle réagit rapidement à l’ouverture de la canopée et se révèle très compétitrice pour les ressources du milieu (notamment l'eau et lumière), pouvant ainsi retarder le développement des jeunes arbres pendant plusieurs années.
... herbicide treatments or different degrees of mechanicals soil scarification from light harrowing to deep ploughing (e.g. Dassot & Collet, 2015;Löf et al., 1998). These studies, however, after applying their preparation treatment, allowed competing vegetation to invade the seedlings' surrounding again. ...
The unwanted development of dense understorey vegetation composed of resource‐acquisitive, tall plant species competing strongly with tree regeneration can pose formidable problems for managers attempting to regenerate temperate forests. Despite many studies on the effects of understorey removal, no comprehensive review has summarised and quantified its effects on subsequent life stages of tree regeneration in temperate forests.
We synthesised data from 32 experimental studies from temperate forest regions. We used meta‐analytic techniques to find general patterns in terms of the characteristics of the understorey, overstorey and characteristics of the regenerating tree species, which are most responsible for possible positive understorey removal effects on early life stages of tree regeneration, i.e. emergence, survival and growth.
Both seedling survival and growth increased in response to understorey removal; emergence did not show a clear pattern. Seedlings growing free from competition mainly increased their biomass growth (total and above‐ground), whereas diameter and height growth responded less. These positive effects were largest when removing denser understorey vegetation and under more open overstorey conditions. Multiple management options influenced the regeneration responses to understorey removal. For instance, growth of older, planted seedlings responded less to removal, whereas protection against large browsers increased growth responses.
Tree species with differing strategies responded differently to understorey removal. Growth and survival responses of early‐successional species responded more strongly to understorey removal than mid‐ or late‐successional tree species.
Synthesis and applications. Our study showed that understorey removal can have strong positive effects on tree regeneration across temperate forest contexts. The magnitude of these effects depended on overstorey and understorey conditions, but also on the type of tree species that is regenerated. Our results can support forest managers in their decision‐making and help assess under what conditions understorey removal will be most justified.
... herbicide treatments or different degrees of mechanicals soil scarification from light harrowing to deep ploughing (e.g. Dassot & Collet, 2015;Löf et al., 1998). These studies, however, after applying their preparation treatment, allowed competing vegetation to invade the seedlings' surrounding again. ...
... The amount, phenology and the composition (foliar, seed and wood) of litterfall from the trees are under the influence of the mean stand age and height (Atay, 1971), canopy closure (Lopez et al., 2008) and LAI (Liu and Jin, 2017) besides the features of tree species and climate characteristics. The forest practitioners use these data in order to estimate and evaluate the amount, timing and extent of seed cover (Dassot and Collet, 2015) as well as the process of nutrient flow (Magalhães et al, 2014) and carbon sequestration (McGovern and Pasher, 2016) within a stand structure . ...
Duyar: The relationships between the litterfall and the canopy closure of Uludağ fir (Abies nordmanniana (Stev.) subsp. bornmulleriana (Matff.)) forests-2357-APPLIED ECOLOGY AND ENVIRONMENTAL RESEARCH 17(2):2357-2372. Abstract. The litter is the organic layer on the forest ground and has a variety of ecological functions. The litterfall is the main source of litter. The structure of forest canopy affects most ecologic processes such as the net primary production and litterfall in forest ecosystems. This research study focused on the exploration of the changes of litterfall based upon canopy closure of Uludağ fir forests. The study area was selected from Bolu Aladağ forests. Ten litterfall traps were systematically emplaced under the stand. The litterfall accumulated in each trap was collected monthly. The hemisphere photographs of the canopy closures above the stands were analysed with Gap Light Analyzer (GLA) software. The canopy closures were calculated separately for each hemisphere photographs with angles expanded in the multiples of 10° angle of view. The highest correlation coefficient (r = 0.359) was found between the amount of total litterfall (333.5 g•m⁻²•y⁻¹) and the canopy closure at 20° angle of view. The canopy closure values observed at 20° angle of view varied between 6.4% and 83.3%. Different mathematical models were developed to estimate the amount of litterfall fractions based on the canopy closure values at 20° angle of view. The coefficients of determination (R²) for the models developed as part of this study are 0.93 for foliar, 0.82 for seed and 0.83 for wood fraction. Practitioners can estimate the amounts of litterfall components, spreading distances and the accumulating amounts based on the distance by using the mathematical models developed in this study.
... Ces composés racinaires peuvent avoir une influence directe sur la germination des graines et la croissance des semis (Bertin et al. 2003 ;Huang et al. 2000 ;Reigosa et González 2003 (Clark et al. 1999 ;Klein et al. 2013, cité dans Dassot et Collet 2015. Dans ces écosystèmes forestiers, il est avéré que la structure du couvert est un facteur clé pour la réussite de la régénération naturelle (Dassot et Collet 2015). ...
En marge arrière d’aire de répartition, les espèces persistent ou disparaissent en réponse aux changements climatiques et autres facteurs globaux. Les refuges climatiques ont joué un rôle majeur dans la persistance de la biodiversité au cours des périodes de transitions climatiques majeures et une compréhension mécaniste claire de leur fonctionnement est primordiale pour la conservation des populations de marge arrière. En limite géographique sud-ouest de son aire de distribution, des fragments de hêtre (Fagus sylvatica) persistent dans des micro-refuges en raison de facteurs locaux. Connue pour sa biodiversité remarquable, la vallée du Ciron offre un laboratoire naturel idéal pour l'étude des refuges climatiques et la prédiction de leur évolution dans un climat régional de plus en plus chaud et sec. Cette thèse interdisciplinaire est centrée sur l’étude des populations de hêtres et des communautés associées par des approches in situ et ex situ combinant écologie des communautés et physique de l’environnement. Nos résultats mettent en évidence une forte originalité floristique des communautés du sous-bois des populations à hêtre de marge chaude, ainsi que l’existence de variations microclimatiques à fine échelle, fonction notamment de la topographie, de la présence de la rivière et de la localisation dans le paysage. Nous montrons que la régénération du hêtre dépend du microclimat et qu’elle est modulée par des interactions allélopathiques. De plus, notre étude met en avant le rôle facilitateur de la canopée forestière ainsi que l’importance du rayonnement solaire, au moins dans des conditions où ce dernier impacte peu la disponibilité en eau. L’ensemble des résultats suggèrent la persistance probable du hêtre dans la vallée du Ciron ainsi qu’une potentialité de présence plus importante dans le Bassin aquitain.
... The cover crops vary from monocultures (e.g. Kristensson 1991;Paris 1995;Hànninen 1998;Willoughby et al. 2004) to rich mixtures (Willoughby and McConald 1999;Dassot and Collet 2015). ...
... Other cover crops have been mixtures of wild flowers motivated by the increased conservation value (e.g. Willoughby and McConald 1999;Dassot and Collet 2015) or ornamental species (Willoughby et al. 2004) not traditionally used as cover crops. ...
... However, wild flower mixtures are also frequently mentioned as an option and have also been tested. For example, Dassot and Collet (2015) successfully used 'a natural community' as a cover crop. Acknowledging that the empirically substantiated knowledge base is still very limited, the contemporary discourse on ecosystem services and the political and societal awareness about using local species to avoid biotic homogenisation are likely to encourage more tests on local wild flower mixtures as cover crops. ...
This report summarises empirically substantiated findings regarding the use of herbaceous cover crops as a weed management technique when establishing woody plantings. Based on this, practical recommendations are given for the green sector in southern Sweden, Denmark and other temperate and hemi-boreal vegetation zones of southern Scandinavia and neighbouring countries. The most common cover crop species used successfully to control resident weeds when establishing woody plantings are also described. In Denmark, cover crops are generally called ‘dækafgrøde’ and in Sweden ‘täckgröda’. The report is written in English to make it accessible beyond the main target group.
