An Overview of the Practices and Management Methods for Enhancing Seed Production in Conifer Plantations for Commercial Use

Flowering, the beginning of the reproductive growth, is a significant stage in the growth and development of plants. Conifers are economically and ecologically important, characterized by straight trunks and a good wood quality and, thus, conifer plantations are widely distributed around the world. In addition, conifer species have a good tolerance to biotic and abiotic stress, and a stronger survival ability. Seeds of some conifer species, such as Pinus koraiensis, are rich in vitamins, amino acids, mineral elements and other nutrients, which are used for food and medicine. Although conifers are the largest (giant sequoia) and oldest living plants (bristlecone pine), their growth cycle is relatively long, and the seed yield is unstable. In the present work, we reviewed selected literature and provide a comprehensive overview on the most influential factors and on the methods and techniques that can be adopted in order to improve flowering and seed production in conifers species. The review revealed that flowering and seed yields in conifers are affected by a variety of factors, such as pollen, temperature, light, water availability, nutrients, etc., and a number of management techniques, including topping off, pruning, fertilization, hormone treatment, supplementary pollination, etc. has been developed for improving cone yields. Furthermore, several flowering-related genes (FT, Flowering locus T and MADS-box, MCMI, AGAMOUS, DEFICIENCES and SRF) that play a crucial role in flowering in coniferous trees were identified. The results of this study can be useful for forest managers and for enhancing seed yields in conifer plantations for commercial use

Gradual transformation of Forest Plantations into Close-to-Nature Forests in NE Vietnam

This research was carried out at Pinus massoniana Lamb. and Acacia auriculiformis Benth plantation sites of between nine to eleven years old in Luc Ngan Distric, Bac Giang Province, Vietnam. Its purpose is to contribute to the knowledge of the dynamics of site conditions beneath the plantation canopy and the growth of indigenous species in local species trials, and to propose silvicultural management options for the gradual transformation of forest plantations into close-to-nature forest. The research indicated that ten years after the establishment of the forest plantation on bare hill, site condition under plantation canopy including soil properties, temperature, humidity, and natural regeneration ability of indigenous species under canopy was significant and positive change. Moreover, the plantation canopy closure varying from 0.4 to 0.6 is the most suitable for the growth and development of indigenous tree species in the first three years after planting. In this study, four species consisting Canarium album, Erythrophleum fordii, Cinnamomum obtusifolium, and Michelia mediocris were selected for planting under plantation canopy

Carbon sequestration in resin-tapped slash pine (Pinus elliottii Engelm.) subtropical plantations

Every year more than 150,000 tons of resin used in a myriad of industrial applications are produced by Brazilian plantations of Pinus elliottii Engelm. (slash pine), which are also used for timber. A pine tree can be tapped for resin over a period of several years. Resin is a complex mixture of terpenes, which are carbon-rich molecules, presumably influencing pine plantation carbon budgets. A total of 270 trees (overall mean DBH of 22.93 ± 0.11 cm) of 14-, 24-, and 26-year-old stands had their C content measured. Three different treatments (intact, wounded panels, and wounded + chemically stimulated panels, 30 trees each) were applied per site. Above- and belowground biomass, as well as resin yield, were quantified for two consecutive years. Data were statistically evaluated using normality distribution tests, analyses of variance, and mean comparison tests (p ≤ 0.05). The highest resin production per tree was recorded in the chemically stimulated 14-year-old stand. Tree dry wood biomass, a major stock of carbon retained in cell wall polysaccharides, ranged from 245.69 ± 11.73 to 349.99 ± 16.73 kg among the plantations. Variations in carbon concentration ranged from 43% to 50% with the lowest percentages in underground biomass. There was no significant difference in lignin concentrations. Soils were acidic (pH 4.3 ± 0.10–5.83 ± 0.06) with low C (from 0.05% to 1.4%). Significantly higher C stock values were recorded in pine biomass compared to those reported for temperate zones. Resin-tapping biomass yielded considerable annual increments in C stocks and should be included as a relevant component in C sequestration assessments of planted pine forests

Demographic strategies of a dominant tree species in response to logging in a degraded subtropical forest in Southeast China

International audienceAbstractKey messageThe demography of pioneer tree species (Pinus massonianaLamb.) is significantly affected by logging in Southeast China. Logging negatively affects the population growth rate ofP. massoniana, which facilitates the growth of individual trees but has no effect on reproduction probability. The survival and growth of seedlings contribute the most to population growth.ContextSubtropical forest degradation caused by unreasonable disturbances is closely related to anthropogenic activities in Southeast China, and the frequent small-scale logging activity by local people was the dominated disturbance regime in forests in this region over the past several decades.AimsThe objective of this study is to evaluate the demographic consequences of logging on Pinus massoniana, a pioneer tree species, at individual level (survival, growth, and fecundity) and population level (the population growth rate and size distribution) over short-term period.MethodsThe size of tree individuals was combined with vital rates using various modeling approaches based on demographic data from three annual censuses. The integral projection model (IPM) was constructed and used to conduct comparative demographic analyses.ResultsLogging negatively affected the population growth rate: from a slight expansion before logging to a moderate decline after logging. This study found a significant reduction in seedling recruitment after logging, and plant growth and mortality were slightly enhanced. The survival of seedlings greatly contributes to population growth rate compared to other life stages for both periods (before and after logging) while its relative importance decreases after logging. Seedling growth is also important to population growth, and its relative importance increased after logging. Shrinkage and fecundity have a minimal contribution effect on the population growth rate.ConclusionGrowing plants in a nursery with a similar demography to P. massoniana could be beneficial for pioneer species regeneration in that this will improve the survival rate and growth of small individuals after logging

Essential Role of Symbiotic Microorganisms Supporting Forests in East Asia under Changing Environment

Regeneration success of forests is strongly dependent on symbiotic microorganisms, that is, arbuscular mycorrhiza (AM) and ectomycorrhiza (ECM). In the northeastern part of Asia, larch and birch are used as timber resources, and in the south, fir, cedar, cypress, and oak are used as timber resources. Planted forests have reached the time of harvesting and/or thinning, and after the forestry practices, it is expected that they will become mixed forests equipped with resistance to weather damage; that is, drought, heat, typhoons, etc. On the other hand, the physical production environment has changed greatly, therefore, we investigated the growth of the major trees and the role of mycorrhizal fungi in the northeastern Asia. Elevated O3 decreased growth, colonization rates of ECM, and the biodiversity; however, elevated CO2 moderated or increased them in larch. Except for disease of rot and damping off, we discuss wise use of symbiotic microbe in far East Asia

Vegetation dynamics and soil characteristics of acacia plantations in Hong Kong.

by Au Pui Sze.Thesis submitted in: December 2000.Thesis (M.Phil.)--Chinese University of Hong Kong, 2001.Includes bibliographical references (leaves 135-150).Abstracts in English and Chinese.Abstract --- p.iAbstract (in Chinese) --- p.iiiAcknowledgement --- p.ivTable of contents --- p.viList of tables --- p.xList of figures --- p.xiList of appendices --- p.xiiChapter Chapter one --- IntroductionChapter 1.1 --- The role of plantations in ecosystem rehabilitation --- p.1Chapter 1.2 --- Reforestation history in Hong Kong --- p.2Chapter 1.3 --- Conceptual framework of the study --- p.5Chapter 1.4 --- Objectives of the study --- p.15Chapter 1.5 --- Scope and significance of the study --- p.16Chapter 1.6 --- Organisation of the thesis --- p.17Chapter Chapter two --- The Study AreaChapter 2.1 --- Geographical setting of Hong Kong --- p.18Chapter 2.1.1 --- Climate --- p.18Chapter 2.1.2 --- Geology --- p.20Chapter 2.1.3 --- Soils --- p.20Chapter 2.1.4 --- Vegetation --- p.21Chapter 2.2 --- Site selection --- p.23Chapter 2.3 --- Site description --- p.26Chapter 2.4 --- Nature and extent of disturbance prior to planting --- p.30Chapter 2.5 --- Planting techniques and post-planting maintenance --- p.31Chapter Chapter Three --- Stand Characteristics of Acacia PlantationsChapter 3.1 --- Introduction --- p.33Chapter 3.2 --- Methodology --- p.37Chapter 3.2.1 --- Sampling plots design --- p.37Chapter 3.2.2 --- Tree density --- p.37Chapter 3.2.3 --- Tree growth parameters --- p.38Chapter 3.2.4 --- Data processing and statistical analysis --- p.38Chapter 3.3 --- Results and discussion --- p.39Chapter 3.3.1 --- Growth dynamics of acacias --- p.39Chapter 3.3.2 --- Growth characteristics of the reforested species --- p.44Chapter 3.3.3 --- Sustained growth and natural regeneration of acacia plantations --- p.48Chapter 3.3.4 --- Rehabilitation of degraded lands by exotic species plantations --- p.52Chapter 3.4 --- Conclusion --- p.54Chapter Chapter Four --- Cover Soil Characteristics of Acacia PlantationsChapter 4.1 --- Introduction --- p.56Chapter 4.2 --- Methodology --- p.60Chapter 4.2.1 --- Soil sampling --- p.60Chapter 4.2.2 --- Laboratory analysis --- p.61Chapter 4.2.3 --- Texture --- p.61Chapter 4.2.4 --- Soil pH --- p.61Chapter 4.2.5 --- Organic carbon --- p.62Chapter 4.2.6 --- Total Kjeldahl nitrogen --- p.62Chapter 4.2.7 --- Carbon : nitrogen ratio --- p.63Chapter 4.2.8 --- Mineral nitrogen (NH4-N and N03-N) --- p.63Chapter 4.2.9 --- Available phosphorus --- p.64Chapter 4.2.10 --- Exchangeable cations --- p.64Chapter 4.3 --- Data processing and statistical analysis --- p.64Chapter 4.4 --- Results and discussion --- p.65Chapter 4.4.1 --- Effect of acacias on soil texture and pH --- p.65Chapter 4.4.2 --- "Effect of acacias on SOM, TKN and mineral N" --- p.69Chapter 4.4.3 --- Effect of acacias on the available P and exchangeable cations… --- p.77Chapter 4.4.4 --- Soil nutrient status of the plantations --- p.82Chapter 4.5 --- Conclusion --- p.90Chapter Chapter Five --- Understorey Vegetation of Acacia PlantationsChapter 5.1 --- Introduction --- p.92Chapter 5.2 --- Methodology --- p.96Chapter 5.2.1 --- Understorey plant sampling --- p.96Chapter 5.2.2 --- Species identification and nomenclature --- p.98Chapter 5.2.3 --- Plant growth parameters --- p.98Chapter 5.2.4 --- Data processing and statistical analysis --- p.99Chapter 5.3 --- Results and discussion --- p.100Chapter 5.3.1 --- Floristic composition of the acacia plantations --- p.100Chapter 5.3.2 --- "Species richness, diversity and woody abundance of the understories" --- p.101Chapter 5.3.3 --- Species composition and structure of the understories --- p.106Chapter 5.3.4 --- Mechanisms and pathway of succession in the exotic plantations --- p.115Chapter 5.4 --- Conclusion --- p.116Chapter Chapter Six --- ConclusionChapter 6.1 --- Summary of findings --- p.118Chapter 6.2 --- Implications of the study --- p.122Chapter 6.2.1 --- Ecological value of exotic plantations in Hong Kong --- p.122Chapter 6.2.2 --- Restoration strategies for borrow areas --- p.125Chapter 6.2.3 --- Enrichment planting after fire --- p.128Chapter 6.3 --- Limitations of the study --- p.131Chapter 6.4 --- Suggestion for future study --- p.132References --- p.135Appendices --- p.15

Vegetation dynamics and soil characteristics of lophostemon confertus plantations in Hong Kong.

Kong Hoi-Yeung.Thesis submitted in: November 2003.Thesis (M.Phil.)--Chinese University of Hong Kong, 2004.Includes bibliographical references (leaves 132-146).Abstracts in English and Chinese.Abstract --- p.iAbstract (in Chinese) --- p.ivAcknowledgement --- p.vTable of contents --- p.viiList of tables --- p.xList of figures --- p.xiList of plates --- p.xiiList of appendices --- p.xiiChapter Chapter one --- IntroductionChapter 1.1 --- Introduction --- p.1Chapter 1.2 --- Afforestation in Hong Kong --- p.2Chapter 1.3 --- Conceptual framework of the study --- p.6Chapter 1.4 --- Objectives of the study --- p.13Chapter 1.5 --- Scope and significance of the study --- p.14Chapter 1.6 --- Organization of the thesis --- p.15Chapter Chapter Two --- The Study AreaChapter 2.1 --- Geographical setting of Hong Kong --- p.17Chapter 2.1.1 --- Climate --- p.17Chapter 2.1.2 --- Geology --- p.19Chapter 2.1.3 --- Soils --- p.20Chapter 2.1.4 --- Vegetation --- p.21Chapter 2.1.5 --- Characteristics of Lophostemon confertus --- p.23Chapter 2.2 --- Site selection --- p.24Chapter Chapter Three --- Stand Characteristics of Lophostemon confertus PlantationsChapter 3.1 --- Introduction --- p.31Chapter 3.2 --- Methodology --- p.35Chapter 3.2.1 --- Sample plots design --- p.35Chapter 3.2.2 --- Tree density --- p.35Chapter 3.2.3 --- Tree growth parameters --- p.35Chapter 3.2.4 --- Data processing and statistical analysis --- p.36Chapter 3.3 --- Results and discussion --- p.37Chapter 3.3.1 --- Tree density and mortality rate --- p.37Chapter 3.3.2 --- Growth performance of Lophostemon confertus --- p.39Chapter 3.3.3 --- Growth rate of Lophostemon confertus in the plantations --- p.41Chapter 3.4 --- Conclusion --- p.44Chapter Chapter Four --- Soil Characteristics of Lophostemon confertus PlantationsChapter 4.1 --- Introduction --- p.47Chapter 4.2 --- Methodology --- p.51Chapter 4.2.1 --- Soil sampling --- p.51Chapter 4.2.2 --- Laboratory analysis --- p.52Chapter 4.2.3 --- Texture --- p.52Chapter 4.2.4 --- Soil pH --- p.53Chapter 4.2.5 --- Organic carbon --- p.53Chapter 4.2.6 --- Total Kjeldahl Nitrogen (TKN) --- p.53Chapter 4.2.7 --- Carbon: Nitrogen ratio --- p.54Chapter 4.2.8 --- Mineral nitrogen (NH4-H and N03-N) --- p.54Chapter 4.2.9 --- Available phosphorus --- p.55Chapter 4.2.10 --- Exchangeable cations --- p.55Chapter 4.3 --- Data processing and statistical analysis --- p.55Chapter 4.4 --- Results and discussion --- p.56Chapter 4.4.1 --- Soil texture --- p.56Chapter 4.4.2 --- Effects of Lophostemon confertus plantations on reaction pH --- p.58Chapter 4.4.3 --- "Effects of Lophostemon confertus plantations on SOM, TKN and mineral nitrogen" --- p.59Chapter 4.4.4 --- Effects of Lophostemon confertus plantations on available P and exchangeable cations --- p.69Chapter 4.4.5 --- Effects of Lophostemon confertus plantations on nutrient status of the soils --- p.73Chapter 4.5 --- Conclusion --- p.79Chapter Chapter Five --- Understorey Vegetation of Lophostemon confertus PlantationsChapter 5.1 --- Introduction --- p.81Chapter 5.2 --- Methodology --- p.85Chapter 5.2.1 --- Understorey plant sampling --- p.85Chapter 5.2.2 --- Species identification and nomenclature --- p.86Chapter 5.2.3 --- Plant growth parameters --- p.87Chapter 5.2.4 --- Data processing and statistical analysis --- p.87Chapter 5.3 --- Results and discussion --- p.89Chapter 5.3.1 --- Floristic composition of the Lophostemon confertus plantations --- p.89Chapter 5.3.2 --- "Species richness, diversity and woody abundance of the understorey" --- p.93Chapter 5.3.3 --- Species composition and structure of understories --- p.99Chapter 5.3.4 --- Dynamics of species establishment in the understorey --- p.109Chapter 5.4 --- Conclusion --- p.112Chapter Chapter Six --- ConclusionChapter 6.1 --- Summary of findings --- p.114Chapter 6.2 --- Implications of the study --- p.118Chapter 6.2.1 --- Ecological value of Lophostemon confertus plantations in Hong Kong --- p.118Chapter 6.2.2 --- Rehabilitation of badland derived from granite --- p.124Chapter 6.2.3 --- Management of the existing plantations --- p.126Chapter 6.3 --- Limitations of the study --- p.129Chapter 6.4 --- Suggestions for future study --- p.130References --- p.132Appendices --- p.14

Carbon Sequestration in Resin-Tapped Slash Pine (Pinus elliottii Engelm.) Subtropical Plantations.

Every year more than 150,000 tons of resin used in a myriad of industrial applications are produced by Brazilian plantations of Pinus elliottii Engelm. (slash pine), which are also used for timber. A pine tree can be tapped for resin over a period of several years. Resin is a complex mixture of terpenes, which are carbon-rich molecules, presumably influencing pine plantation carbon budgets. A total of 270 trees (overall mean DBH of 22.93 ± 0.11 cm) of 14-, 24-, and 26-year-old stands had their C content measured. Three different treatments (intact, wounded panels, and wounded + chemically stimulated panels, 30 trees each) were applied per site. Above- and belowground biomass, as well as resin yield, were quantified for two consecutive years. Data were statistically evaluated using normality distribution tests, analyses of variance, and mean comparison tests (p ≤ 0.05). The highest resin production per tree was recorded in the chemically stimulated 14-year-old stand. Tree dry wood biomass, a major stock of carbon retained in cell wall polysaccharides, ranged from 245.69 ± 11.73 to 349.99 ± 16.73 kg among the plantations. Variations in carbon concentration ranged from 43% to 50% with the lowest percentages in underground biomass. There was no significant difference in lignin concentrations. Soils were acidic (pH 4.3 ± 0.10?5.83 ± 0.06) with low C (from 0.05% to 1.4%). Significantly higher C stock values were recorded in pine biomass compared to those reported for temperate zones. Resin-tapping biomass yielded considerable annual increments in C stocks and should be included as a relevant component in C sequestration assessments of planted pine forests

Thinning partially mitigates the Impact of atlantic forest replacement by pine monocultures on the soil microbiome

Forest replacement by exotic plantations drive important changes at the level of the overstory, understory and forest floor. In the Atlantic Forest of northern Argentina, large areas have been replaced by loblolly pine (Pinus taeda L.) monocultures. Plant and litter transformation, together with harvesting operations, change microclimatic conditions and edaphic properties. Management practices such as thinning promote the development of native understory vegetation and could counterbalance negative effects of forest replacement on soil. Here, the effects of pine plantations and thinning on physical, chemical and microbiological soil properties were assessed. Bacterial, archaeal, and fungal community structure were analyzed using a metabarcoding approach targeting ribosomal markers. Forest replacement and, to a lesser extent, thinning practices in the pine plantations induced significant changes in soil physico-chemical properties and associated shifts in bacterial and fungal communities. Most measured physical and chemical properties were altered due to forest replacement, but a few of these properties reached values similar to natural forests under the thinning operation. Fungal alpha diversity decreased in pine plantations, whereas bacterial alpha diversity tended to increase but with little statistical support. Shifts in community composition were observed for both fungal and bacterial domains, and were mostly related to changes in plant understory composition, soil carbon, organic matter, water content, pH and bulk density. Among several other changes, highly abundant phyla such as Proteobacteria (driven by many genera) and Mortierellomycota (mainly driven by Mortierella) decreased in relative abundance in the plantations, whereas Acidobacteria (mainly driven by Acidothermus and Candidatus Koribacter) and Basidiomycota (mainly driven by the ectomycorrhiza Russula) showed the opposite response. Taken together, these results provide insights into the effects of forest replacement on belowground properties and elucidate the potentially beneficial effect of thinning practices in intensive plantation systems through promoting the understory development. Although thinning did not entirely counterbalance the effects of forest replacement on physical, chemical and biological soil properties, the strategy helped mitigating the effects and might promote resilience of these properties by the end of the rotation cycle, if subsequent management practices compatible with the development of a native understory vegetation are applied.Fil: Trentini, Carolina Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú; ArgentinaFil: Campanello, Paula Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Villagra, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú; ArgentinaFil: Ferreras, Julian Alberto. Universidad Nacional de Misiones. Facultad de Ciencias Exactas, Químicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú; ArgentinaFil: Hartmann, Martin. Institute of Agricultural Sciences; Suiz