I explored the importance of decaying wood to survival and growth of trees in south coastal British Columbia, and the effect of decaying wood on the intensity of podzolization on mesic sites. A field pot study was carried out in both high light and low light conditions using woody and non-woody forest floor materials. After two growing seasons, Pseudotsuga menziesii, Tsuga heterophylla, and Abies amabilis seedlings growing in clearcuts had greater survival and growth in the non-woody substrate; however, in the understory, the effect was much less. The proliferation of western hemlock roots was used as an indicator of the value of decaying wood to trees. In both greenhouse trials (using seed sown on a series of planting pots with each half filled with either a woody substrate or a non-woody substrate), and in field sampling of woody and non-woody substrates in mature stands, the non-woody substrate had a larger density of fine and very fine roots compared to the woody substrates or mineral soil. Ten litres of concentrated solutions of non-woody humus substrate and woody substrates were leached through soil columns. Both the non-woody and woody solutions had similar mean pH but significantly different chemical properties. The non-woody solution leachate had greater net average output of dissolved organic C, Fe, and Mn. The mineral soil treated with the nonwoody solution had significantly greater concentrations of total N and pyrophosphate-extractable Fe. In the field, forest floor and soil samples were compared between pedons having large accumulation of decaying wood and pedons with non-woody humus forms. Despite large and significant differences in chemical properties between the two substrates, there were generally no significant differences between the chemical properties of the soils directly under these substrates. In most cases, the results of (3-analyses showed that the means were not pedologically different. Additionally, 18 pairs of zero tension plate lysimeters were installed under the two substrates. The lysimeter solutions showed no significant differences. I concluded that coarse woody debris appears not to have either a positive effect of increased productivity of trees or a negative effect of increased intensity of podzolization.

Miškų plotas Lietuvoje didėja nuo XX amžiaus vidurio. Mažiausias miškingumas – 19,7% užfiksuotas 1948 metais, 2009 metais siekia 32,9%. Pagal Lietuvos miškingumo didinimo programą per 2004 – 2020 m. laikotarpį bendrą šalies miškingumą planuojama padidinti 3%. Programoje numatytos miško įveisimo apimtys, atsižvelgiant į nenašių ir žemės ūkiui nenaudojamų žemės ūkio naudmenų plotus. Norint efektyviai didinti miškingumą želdinimu arba miško žėlimo skatinimu, būtina atsižvelgti į visą kompleksą aplinkos veiksnių (ekonominių, ekologinių ir socialinių – etnokultūrinių), darančių įtaką miško želdinimui ir žėlimui, želdinių ir žėlinių augimui, būklei ir miško naudojimui mažo našumo, apleistose ir pažeistose žemėse. Planuojant miško plotų didinimą Kauno apskrityje išnagrinėta žemės valstybinės apskaitos duomenys ir išduotų leidimų įveisti mišką žemės ūkio paskirties žemėje apimtys. / The forest area of Lithuania has been increasing from the mid-twentieth century. Minimum Forest area - 19.7% recorded in 1948 and in 2009 increased up to 32.9%. According to the Lithuanian forest improvement program through 2004 - 2020 on period, the total forest country is planned to increase by 3%. The program involves the establishment of forest volume, taking into account the low-performing agriculture and farmland quantity. From 652.7 thousand. ha of agricultural land and non-life area of 163.2 thousand. hectare (30-32 performance ratings) has been proposed temporarily to preserve, and 489.5 thousand. ha of forest produce in the future is appropriate. In order to effectively increase the forest afforestation and forestry promotion Iit should be taken into account a whole range of environmental factors (economic, environmental and social - ethnographic), affecting the forest and afforestation, plantations and Zelin on growth, condition and use of low-productivity forests, abandoned and damaged lands.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / With the expansion of cultivated forest in Rio Grande do Sul, there was an increase of the forest plantations, now occupying areas previously used for livestock and agricultural crops. The objective was to generate reccomendations for soil tillage, based on soil quality indicators. The study was conducted in three areas for the cultivation of clonal seedlings of Eucalyptus saligna Smith belonging to Celulose Riograndense in the state of Rio Grande do Sul. The soils are classified as Planossolo Háplico Eutrófico gleissólico (SXe), Nitossolo Vermelho Distrófico típico (NVd) and Neossolo Regolítico Eutroúmbrico típico (RReh). Initially a pilot survey was done to quantify the spatial variability of texture and soil resistance to penetration (RP); subsequently, soil samples were taken at depths of 0-10, 10-20, 20-40 and 40-60 cm. After the characterization and analysis of soil areas different soil tillages (subsoiling to 50 cm depth plus rotary hoe (S50), subsoiling to 50 cm depth with ridge (S50C), and subsoiling to 70 cm depth plusr rotary hoe (S70). Planting of Eucalyptus saligna Smith clones (3.5 x 2.6 m) was carried out. At 6, 12, 18 and 24 months after planting, the dendrometric evaluation of total height and diameter at breast height (dbh 1.30 m). The joint use of factor analysis and spatial variability of RP enabled us to identify locations with different compaction states. The least limiting water range (LLWR) was strongly affected by the penetration resistance and soil aeration in clayey soils. The bulk density values of Argissolos, in the larger states of soil compaction, were above the critical density based on the LLWR. The soil tillage with greater volume of soil disturbed (S50C), in SXe (1267.1 m3 ha- 1) and RReh (836.8 m3 ha-1), favored the initial development of Eucalyptus saligna Smith. In SXe at 24 months-old forest, the height was 10.38 cm and dbh of 9.90, whereas for the RReh the height was 10.15 m and dbh of 10.60 cm. In NVd, the highest growth was observed in the treatment S70, with an average height at 24 months of 9.77 m and dbh of 9.68 cm. The results of this study indicate that the choice of the best tillage depends on the texture, degree of compaction, critical density and penetration resistance of the soil. Thus, for Planossolo Háplico Eutrófico gleissólico and the Neossolo Regolítico Eutroúmbrico típico the best tillage was S50C, while for the Nitossolo Vermelho Distrófico típico was S70. / Com a expansão da produção florestal no Rio Grande do Sul, houve aumento na área dos plantios florestais anteriormente dominadas pela pecuária e pelos cultivos agrícolas. O objetivo foi gerar recomendações adequadas de preparo, com base nos indicadores de qualidade. O estudo foi realizado em três áreas destinadas ao cultivo de mudas clonais de Eucalyptus saligna Smith, pertencentes à empresa Celulose Riograndense, nos municípios de São Gabriel e Vila Nova do Sul, no RS. Os solos das áreas estudadas são classificados como Planossolo Háplico Eutrófico gleissólico (SXe), Nitossolo Vermelho Distrófico típico (NVd) e Neossolo Regolítico Eutroúmbrico típico (RReh). Na área de estudo foi feito, inicialmente, um levantamento piloto para observar a variabilidade espacial da textura e da resistência mecânica do solo à penetração (RP); posteriormente, foram realizadas amostragens do solo, nas camadas de 0-10, 10-20, 20-40 e 40-60 cm. Após a caracterização e análise do solo das áreas, foram aplicados diferentes preparos de solo (subsolagem a 50 cm de profundidade mais enxada rotativa (S50), subsolagem a 50 cm de profundidade mais camalhão (S50C) e subsolagem a 70 cm de profundidade mais enxada rotativa (S70)) e, posteriormente, foi realizado o plantio de clones de Eucalyptus saligna Smith (3,5 x 2,6 m). Aos 6, 12, 18 e 24 meses após o plantio, foram feitas as avaliações dendrométricas de altura total e diâmetro à altura do peito (dap 1,30 m). O uso conjunto da análise fatorial e da variabilidade espacial da RP permitiu identificar, locais com diferentes estados de compactação. O intervalo hídrico ótimo (IHO) foi fortemente limitado pela resistência à penetração e pela aeração do solo, nos solos mais argilosos. Os valores de densidade do solo mais Argissolo, nos maiores estados de compactação, foram superiores à densidade crítica com base no IHO. O preparo do solo com maior volume de solo mobilizado (S50C), no SXe (1267,1 m3 ha-1) e no RReh (836,8 m3 ha-1), favoreceu o melhor desenvolvimento inicial do Eucalyptus saligna Smith. No SXe a altura média aos 24 meses de idade foi de 10,38 m e dap de 9,90 cm e, no RReh, a altura foi de 10,15 m e dap de 10,60 cm. No NVd, o maior crescimento foi observado no tratamento S70, com altura média aos 24 meses de idade de 9,77 m e dap de 9,68 cm. Os resultados deste trabalho indicam que a escolha do melhor preparo de solo depende da textura, grau de compactação, densidade crítica e da resistência à penetração do solo. Assim, para o Planossolo Háplico Eutrófico gleissólico e para o Neossolo Regolítico Eutroúmbrico típico o melhor preparo de solo foi o tratamento S50C e, no Nitossolo Vermelho Distrófico típico, foi o tratamento S70.

I explored the importance of decaying wood to survival and growth of trees in south coastal British Columbia, and the effect of decaying wood on the intensity of podzolization on mesic sites. A field pot study was carried out in both high light and low light conditions using woody and non-woody forest floor materials. After two growing seasons, Pseudotsuga menziesii, Tsuga heterophylla, and Abies amabilis seedlings growing in clearcuts had greater survival and growth in the non-woody substrate; however, in the understory, the effect was much less. The proliferation of western hemlock roots was used as an indicator of the value of decaying wood to trees. In both greenhouse trials (using seed sown on a series of planting pots with each half filled with either a woody substrate or a non-woody substrate), and in field sampling of woody and non-woody substrates in mature stands, the non-woody substrate had a larger density of fine and very fine roots compared to the woody substrates or mineral soil. Ten litres of concentrated solutions of non-woody humus substrate and woody substrates were leached through soil columns. Both the non-woody and woody solutions had similar mean pH but significantly different chemical properties. The non-woody solution leachate had greater net average output of dissolved organic C, Fe, and Mn. The mineral soil treated with the nonwoody solution had significantly greater concentrations of total N and pyrophosphate-extractable Fe. In the field, forest floor and soil samples were compared between pedons having large accumulation of decaying wood and pedons with non-woody humus forms. Despite large and significant differences in chemical properties between the two substrates, there were generally no significant differences between the chemical properties of the soils directly under these substrates. In most cases, the results of (3-analyses showed that the means were not pedologically different. Additionally, 18 pairs of zero tension plate lysimeters were installed under the two substrates. The lysimeter solutions showed no significant differences. I concluded that coarse woody debris appears not to have either a positive effect of increased productivity of trees or a negative effect of increased intensity of podzolization. / Forestry, Faculty of / Graduate

O 3-PG (Physiological Principles in Predicting Growth) é o modelo ecofisiológico mais difundido no setor florestal para a predição de crescimento de florestas. Este modelo estima o crescimento florestal com base na radiação fotossinteticamente ativa absorvida pelo dossel, convertida em carboidratos, e alocada nos compartimentos da floresta (folhas, tronco, galhos e raízes), fundamentados na dinâmica dos processos biológicos e suas interações com o clima e solo. No entanto, após quase 15 anos de existência do 3-PG unido a evolução em pesquisa florestal, é possível detectar alguns pontos no modelo com potencialidade para aprimoramento. O objetivo geral desta tese foi aprimorar o modelo 3-PG e aplicá-lo no zoneamento da produtividade em florestas de Eucalyptus plantadas no nordeste do estado de São Paulo. Os objetivos específicos foram: i) aprimorar o modelo para retenção máxima de água no solo; ii) para queda de folhedo; iii) calibrar e validar o modelo 3-PG usando os pares de parcelas gêmeas; iv) determinar o modificador de fertilidade (FR) do 3-PG usando análise química do solo; v) zonear a produtividade real estimada do Eucalyptus no nordeste do estado do São Paulo; vi) determinar os fatores de restrição da produtividade nestas áreas. Para tanto, utilizou-se de dois projetos de pesquisas instalados na empresa International Paper do Brasil: projeto BEPP (Brasil Eucalyptus Produtividade Potencial) e projeto Parcelas Gêmeas de Inventário. O projeto BEPP foi utilizado para o aprimoramento do modelo em relação à retenção de água e queda de folhedo. Para tanto, utilizou-se de dois tratamentos: o tratamento fertilizado irrigado e o tratamento controle (fertilização tradicional sem irrigação). A quantidade máxima de água no solo adotada pelo modelo, antes considerada como um valor constante, passou a variar segundo a dinâmica de crescimento e exploração do sistema radicular. Esta modificação melhorou a estimativa de biomassa do tronco. No aprimoramento do modelo para a queda de folhedo, ajustou-se quatro modelos: linear; logístico; não lineares e modelo combinado. Todos proporcionaram melhores estimativas da taxa de queda de folhedo do que a função atualmente adotado pelo 3-PG com destaque para o modelo combinado, o qual representou duas fases da queda de folhedo: antes e após o fechamento do dossel. Usando os 113 pares de parcelas gêmeas, verificou-se que 63% responderam à fertilização após 48 meses de instalação do experimento, com ganho médio de 12% em produtividade. Com estas parcelas gêmeas foi possível calibrar e validar o modelo 3-PG para a produtividade atingível e real, com adequada precisão. O FR foi correlacionado à somas de bases do solo (Ca, Mg e K), as quais explicaram as maiores respostas à fertilização, sendo possível determinar uma equação para este modificador. Após a calibração e validação e adequações do modelo foi possível zonear a produtividade real do nordeste do estado de São Paulo. O déficit de pressão de vapor e água no solo foram os fatores que mais limitaram o crescimento do Eucalyptus nesta área. / The 3-PG (Physiological Principles in Predicting Growth,) is the most widespread ecophysiological model in the forest sector to predict the forest growth. It is driven by intercepted radiation with the maximum canopy quantum efficiency, which is limited by the temperature, vapour pressure deficit, available soil water, stand age and site fertility, assimilating the carbon into the forest; supported by physical and ecophysiological processes. However, after almost 15 years of development and use, associated by new scientific knowledge in forest research, some improvement in this model can be done, such as: soil water content and litterfall rate. The objectives of this thesis were improve the 3-PG model and zone the real productivity of Eucalyptus plantation in northeast of São Paulo State. The specifics objectives were: i) improve the 3-PG model regarding water soil content; ii) regarding litterfall; iii) calibrate and validate the 3-PG model using the twin-plot experimental design; iv) determine the fertilization modifier (FR) using soil chemical analysis; v) zoning the real productivity for Eucalyptus plantation in northeast of São Paulo State; and vi) determine the main growth constraints. Aiming these objectives, two main research projects were used: BEPP project (Brasil Eucalyptus Produtividade Potencial) and the Twin-plot of inventory. The BEPP was used to improve the 3-PG model for water soil content and litterfall. Two treatments were used: fertilized plus rainfed and extra fertilized plus irrigation. The water soil content had a constant value and was replaced by a dynamic value, changing with root growth and exploratiion depth with the age. This modification improved the stem biomass production estimatives by the model. For the litterfall improvement, 4 functions were fitted (linear, logistic, non linear and mixed). All of those had better performance in estimating the litter fall than the original 3-PG equation, highlighting the mixed model that could represent before and after canopy closure. Using 113 pairs of twin-plots, 63% of those responded the extra fertilization after 48 months, the production gain was 12%. The twin-plots were used to calibrate and validate the 3-PG model for attainable and real productivity resulted in adequated accuracy for stem biomass estimation. The FR could be associated with chemical analysis, and sum of bases (Ca, Mg and K) were used to fit an FR equation. After calibration and valitadation of the 3-PG model, were possible to zone the real productivity in northeast of São Paulo; the two main constraints of productivity for those area were vapour pressure deficit and soil water.

Les processus physiologiques déterminant la productivité forestière and l’allocation du carbone (C) entre les différents organes de l’arbre restent mal connus. La croissance forestière a longtemps été considérée comme limitée par le C, à travers un lien causal entre photosynthèse et croissance (contrôle de la croissance par la source de C). Ce paradigme C-centré est à l’origine des règles gouvernant l’allocation du C dans la plupart des modèles à base de processus (MBP). Cependant, le contrôle de la croissance forestière par la source de C a été remis en cause par un certain nombre d’études mettant en lumière que l’activité des méristèmes est plus sensible aux stress environnementaux (stress hydrique, température basse) que ne l’est l’assimilation du C (contrôle de la croissance par l’activité du puits). De plus, l’effet de la gestion, qui influe fortement sur le fonctionnement de la forêt and sa croissance, n’est pas pris en compte dans la plupart des MBP utilisés pour projeter le futur puits de C terrestre. Notre objectif principal dans cette thèse est d’améliorer notre connaissance des contraintes qui affectent - ou affecteront- la productivité ligneuse des forêts européennes, depuis l’époque actuelle jusqu’à la fin du 21ème siècle. Nous avons abordé cet objectif à travers l’amélioration du modèle CASTANEA, sur la base d’une analyse détaillée des déterminants de la productivité ligneuse annuelle des forêts françaises sur les 30 dernières années. Les espèces étudiées sont Fagus sylvatica, Quercus ilex, Quercus petraea, Quercus robur et Picea abies. Nos résultats suggèrent que la croissance annuelle des espèces étudiées est soumise à un contrôle complexe, impliquant des limitations par la source de C et par l’activité du puits. La variabilité inter-site de la fraction de C allouée à la croissance est principalement expliquée par un déclin lié à l’âge. La croissance annuelle à l’échelle de l’arbre est bien prédite par la taille des individus. Nous avons montré que l’asymétrie de la croissance, i.e., l’avantage des gros arbres dans la compétition pour les ressources, augmente avec la productivité, aux échelles inter-site et inter-annuelle. Sur la base de ces résultats, nous avons développé un nouveau schéma d’allocation du C dans le modèle CASTANEA. Le nouveau modèle a été capable de reproduire de manière satisfaisante la variabilité inter-annuelle et inter-site dans la croissance ligneuse aérienne le long de gradients environnementaux à l’échelle nationale. Le modèle a également été validé en utilisant une méta-analyse de mesure de réserves carbonées et des estimations satellitaires d’indices foliaires. Nos résultats indiquent que la représentation du contrôle de la croissance par l’activité du puits n’affecte pas les prédictions qualitatives de l’évolution de la productivité forestière européenne précédemment obtenues par les MBP C-centrés. Cependant, les MBP C-centrés sous-estiment certainement l’hétérogénéité spatiale des effets du changement climatique.Nous avons enfin utilisé notre nouvelle connaissance des déterminants de la croissance ligneuse annuelle à l’échelle de l’arbre (i.e., les règles empiriques de la compétition) pour calibrer un module simulant la croissance individuelle dans CASTANEA. Le modèle couplé a été utilisé pour évaluer l’effet potentiel de la gestion sur le fonctionnement des forêts et la croissance ligneuse à l’échelle de la France. Nous avons identifié les zones où la gestion pourrait être intensifiée pour réduire l’impact du changement climatique sur la productivité forestière nationale. Environ un quart des forêts françaises en hêtre et chênes tempérés sont en zone de forte vulnérabilité, zone dans laquelle la gestion pourrait donc être utilisée à profit pour limiter l’impact du changement climatique sur la récolte de bois. / The processes that underlie forest productivity and C allocation dynamics in trees are still poorly understood. Forest growth has for long been thought to be C limited, through a hypothesized causal link between C supply and growth (source control). This C-centric paradigm underlies most of the C allocation rules formalized in process-based models (PBMs). However, the source limitation of growth has been questioned by several authors, arguing that meristem activities are more sensitive than C assimilation to environmental stresses (e.g., water deficit and low temperatures). Moreover, the effect of management, which strongly affects forest functioning and wood growth, is not accounted for in most of the PBMs used to project the future terrestrial C sink. Our main objective in this thesis was to move forward into our understanding of the constraints that affect - or will affect - the wood productivity in European forests, from present to the end of the 21 st century. We addressed this objective through the improvement of the representation of the forest productivity and C allocation in the CASTANEA PBM, building on a detailed analysis of the key drivers of annual wood productivity in French forests over the last 30 years (the species studied are Fagus sylvatica, Quercus ilex, Quercus petraea, Quercus robur and Picea abies). Our results supported the premise that the annual wood growth of the studied species is under a complex control including both source and sink limitations. The inter-site variability in the fraction of C allocatedto stand wood growth was predominantly driven by an age-related decline. At the tree level, we showed that annual wood growth was well predicted by the individual size. The size-asymmetry of growth, i.e., the advantage of big trees in the competition for resources, increased consistently with the whole stand productivity at both inter-site and inter-annual scales. On the basis of our findings, we developed a new C allocation scheme in the CASTANEA PBM, which integrate a combined source-sink limitation of wood growth. The new calibrated model captured both the inter-annual and inter-site changes in stand wood growth that was observed across national environmental gradients. The model was also successfully evaluated against a meta-analysis of carbohydrate reserve pools in trees and satellite-derived leaf area index estimates. Our results indicated that the representation of the environmental control of sink activity does not affect the qualitative predictions of the future of the European forest productivity previously obtained from source-driven PBMs. However, the current, source-driven generation of PBMs probably underestimates the spatial heterogeneity of the effects of climate change on forest growth that arise from sink limitations.Further, we successfully used our findings regarding the dependences of annual wood growth at tree level (i.e., empirical rules of tree growth competition) to calibrate a module for the simulation of the individual growth of trees in the CASTANEA model. The coupled model was used to assess the potential effects of management on forest functioning and wood growth across France. We identified the areas where management efforts may be concentrated in order to mitigate near-future drought impact on national forest productivity. Around a quarter of the French temperate oak and beech forests are currently in zones of high vulnerability, where management could thus mitigate the influence of climate change on forest yield.

Ecosystem-specific forest management requires comprehension of tree species productivity in managed settings, and how this productivity varies with the ecological determinants of site quality, i.e., the environmental factors that directly affect the growth of plants: light, heat, soil moisture, soil nutrients, and soil aeration. A good understanding of this variation is necessary for making species- and site-specific silvicultural decisions to maximize productivity. Productivity of a given species is usually measured by site index (tree height at 50 years at breast height age). Quantitative relationships between site index and these measures of site quality provide predictive models for estimating site index. Pacific silver fir (Abies amabilis (Dougl. ex Loud.) Forbes) is an important timber crop species in the coastal forests of British Columbia. In relation to climate, its range in southwestern British Columbia extends from sea level to almost timberline, and from the hypermaritime region on western Vancouver Island to the subcontinental region on the leeward side of the Coast Mountains. In relation to soils, its range extends from slightly dry to wet sites and from very poor to very rich sites. In view of this relatively wide climatic amplitude, a large variability in productivity can be expected. It is particularly important to consider the growth performance of Pacific silver fir when decisions are made regarding whether or not to cut stands on high-elevation sites. In the study summarized here, relationships between Pacific silver fir site index and selected ecological measures of site quality were examined, and site index models using these measures as predictors were developed.

Central to the issue of harvest feasibility on the outer BC coast (CWHvh) is the question of whether sites, once harvested, can be regenerated, and whether the time period for replacement and subsequent growth is economically and environmentally acceptable. Since low productivity sites have not been harvested in the past, there is a lack of data to answer this question. We tried to provide an answer by assessing regeneration following natural disturbances. Small scale gap disturbances are the norm within old-growth stands. If regeneration is not a problem in gaps, then we have some evidence that regeneration should not be a problem upon implementation of our management practices. The objectives of this study were: (1) to develop baseline information on the mechanisms and the patterns of regeneration across a sequence of forest types; (2) to assess regeneration success with respect to productivity; and (3) to estimate future growth and productivity.

Knowledge of ecological characteristics of trees, sites and tree growth on different sites is fundamental for silvicultural decision-making and planning. With the biogeoclimatic ecosystem classification in place, silvicultural management in British Columbia has been given an ecological foundation; however, relationships between growth and site have not yet been fully investigated. The purpose of this study was to determine how height growth of Douglas-fir within the drier portion of the CWH zone varies with site. We adopted site index (m @ 50 yr bh) as a species-specific measure of forest productivity, recognizing that it indicates height growth performance at a selected point in time. If forest productivity is correlated with ecological measures of site quality, what site factors should be used to quantify the relationships? Because of compensating effects, the numerous site factors can be reduced to four primary (synoptic) factors that directly affect plant establishment and growth: climate (light and temperature), soil moisture, soil nutrients, and soil aeration (not used in this study).

Knowledge of ecological site characteristics and tree growth on different sites is fundamental for silvicultural decisionmaking and planning. With biogeoclimatic ecosystem classification in place in British Columbia, silvicultural management has been given an ecological foundation; however, relationships between growth and site quality have not yet been fully investigated. The purpose of this study was to determine how site conditions within the SBS zone affect the height growth of lodgepole pine (Pl) and interior spruce (Sx).