•A low N supply limits plant production in most boreal forests, but N-rich spots occur.•The rate of decomposition does not limit the rate of N supply in N-limited forests.•There, tree C allocation to ...mycorrhizal fungi exerts a pivotal control on N cycling.•In N-limited forests mycorrhizal fungi retain much N and transfer little to trees.•The mycorrhizal N sink is weakened by clear-felling, which promotes seedling growth.
The supply of nitrogen commonly limits plant production in boreal forests and also affects species composition and ecosystem functions other than plant growth. These interrelations vary across the landscapes, with the highest N availability, plant growth and plant species richness in ground-water discharge areas (GDAs), typically in toe-slope positions, which receive solutes leaching from the much larger groundwater recharge areas (GRAs) uphill. Plant N sources include not only inorganic N, but, as heightened more recently, also organic N species. In general, also the ratio inorganic N over organic N sources increase down hillslopes. Here, we review recent evidence about the nature of the N limitation and its variations in Fennoscandian boreal forests and discuss its implications for forest ecology and management.
The rate of litter decomposition has traditionally been seen as the determinant of the rate of N supply. However, while N-rich litter decomposes faster than N-poor litter initially, N-rich litter then decomposes more slowly, which means that the relation between N % of litter and its decomposability is complex. Moreover, in the lower part of the mor-layer, where the most superficial mycorrhizal roots first appear, and N availability matters for plants, the ratio of microbial N over total soil N is remarkably constant over the wide range in litter and soil C/N ratios of between 15 and 40 for N-rich and N-poor sites, respectively. Nitrogen-rich and -poor sites thus differ in the sizes of the total N pool and the microbial N pool, but not in the ratio between them. A more important difference is that the soil microbial N pool turns over faster in N-rich systems because the microbes are more limited by C, while microbes in N-poor systems are a stronger sink for available N.
Furthermore, litter decomposition in the most superficial soil horizon (as studied by the so-called litter-bag method) is associated with a dominance of saprotrophic fungi, and absence of mycorrhizal fungi. The focal zone in the context of plant N supply in N-limited forests is further down the soil profile, where ectomycorrhizal (ECM) roots become abundant. Molecular evidence and stable isotope data indicate that in the typical N-poor boreal forests, nitrogen is retained in saprotrophic fungi, likely until they run out of energy (available C-compounds). Then, as heightened by recent research, ECM fungi, which are supplied by photosynthate from the trees, become the superior competitors for N.
In N-poor boreal soils strong N retention by microorganisms keeps levels of available N very low. This is exacerbated by an increase in tree C allocation to mycorrhizal fungi (TCAM) relative to net primary production (NPP) with decreasing soil N supply, which causes ECM fungi to retain much of the available soil N for their own growth and transfer little to their tree hosts. The transfer of N through the ECM fungi, and not the rate of litter decomposition, is likely limiting the rate of tree N supply under such conditions. All but a few stress-tolerant less N-demanding plant species, like the ECM trees themselves and ericaceous dwarf shrubs, are excluded.
With increasing N supply, a weakening of ECM symbiosis caused by the relative decline in TCAM contributes to shifts in soil microbial community composition from fungal dominance to bacterial dominance. Thus, bacteria, which are less C-demanding, but more likely to release N than fungi, take over. This, and the relatively high pH in GDA, allow autotrophic nitrifying bacteria to compete successfully for the NH4+ released by C-limited organisms and causes the N cycle to open up with leaching of nitrate (NO3−) and gaseous N losses through denitrification. These N-rich conditions allow species-rich communities of N-demanding plant species. Meanwhile, ECM fungi have a smaller biomass, are supplied with N in excess of their demand and will export more N to their host trees. Hence, the gradient from low to high N supply is characterized by profound variations in plant and soil microbial physiologies, especially their relations to the C-to-N supply ratio. We propose how interactions among functional groups can be understood and modelled (the plant-microbe carbon-nitrogen model).
With regard to forest management these perspectives explain why the creation of larger tree-free gaps favors the regeneration of tree seedlings under N-limited conditions through reduced belowground competition for N, and why such gaps are less important under high N supply (but when light might be limiting). We also discuss perspectives on the relations between N supply, biodiversity, and eutrophication of boreal forests from N deposition or forest fertilization.
Eucalyptus is a fast-growing genus widely used in the forestry industry; however, in the plant’s early stages, plantations are susceptible to drought conditions and it is common to find high ...mortality rates and loss of productivity. Therefore, this study analyzed the physiological response photosynthesis (An) and predawn leaf water potential (ΨPLWP) and the change in carbon balance (C) in ten Eucalyptus genotypes exposed to different water deficits, with the hypothesis that it is possible to identify and differentiate genotypes with a tolerance to drought. Therefore, ten one-year-old genotypes were placed in greenhouse conditions and soil matric power (Ψs) was regulated in four levels: −0.03 MPa (control), −0.7 Mpa (slight stress), −1.5 Mpa (moderate stress) and −2.5 Mpa (chronic stress); each level was determined from the automated monitoring of soil conditions. The example considered in the experiment was tree stress per genotype × Ψs. The measurements of An and ΨPLWP considered tree measurement per individual (n = 9 per genotype × Ψs); in contrast, the Gross primary productivity (GPP) was estimated with destructive sampling (n = 3 genotype × Ψs). We found a significant relationship between water deficit and physiological response (a major deficit produced a reduction of An and ΨPLWP). E. nitens clones had a minor physiological variation and GPP maintained the same trend and proportionality between aerial and underground production. In contrast, two hybrids of E. nitens × E. globulus showed an immediate physiological change and variation in GPP, with increased underground production and stagnant aerial production. These results suggest that it is possible to differentiate genotypes with a tolerance to water deficit early. This will allow genotype selection according to the climatic conditions of each site, minimizing mortality and optimizing the available water resources.
The article addresses the issues of Douglas-fir (Pseudotsuga menziesii Mirb. Franco) production in the Czech Republic (CR). Our analysis shows that the tree species can occupy 149,616-163,713 ha in ...the CR (with respect to ecological limits set by the Czech legislation). The potential economic effect expressed by the gross yield of forest production might be higher by 27-30 million EUR.yr-1. The results of the analysis support the forest owners' interest to extend Douglas-fir production in the CR, similarly like it has been extended systematically in all European countries where natural conditions allow.
Forests and wood products play a major role in climate change mitigation strategies and the transition from a fossil-based economy to a circular bioeconomy. Accurate estimates of future forest ...productivity are crucial to predict the carbon sequestration and wood provision potential of forests. Since long, forest managers have used empirical yield tables as a cost-effective and reliable way to predict forest growth. However, recent climate change-induced growth shifts raised doubts about the long-term validity of these yield tables. In this study, we propose a methodology to improve available yield tables of 11 tree species in the Netherlands and Flanders, Belgium. The methodology uses scaling functions derived from climate-sensitive process-based modelling (PBM) that reflect state-of-the-art projections of future growth trends. Combining PBM and stand information from the empirical yield tables for the region of Flanders, we found that for the period 1987–2016 stand productivity has on average increased by 13% compared to 1961–1990. Furthermore, simulations indicate that this positive growth trend is most likely to persist in the coming decades, for all considered species, climate or site conditions. Nonetheless, results showed that local site variability is equally important to consider as the in- or exclusion of the CO2 fertilization effect or different climate projections, when assessing the magnitude of forests' response to climate change.
Our projections suggest that incorporating these climate change-related productivity changes lead to a 7% increase in standing stock and a 22% increase in sustainably potentially harvestable woody biomass by 2050. The proposed methodology and resulting estimates of climate-sensitive projections of future woody biomass stocks will facilitate the further incorporation of forests and their products in global and regional strategies for the transition to a climate-smart circular bioeconomy.
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•Climate change positively affects forest biomass production.•Regional variability in growth changes is as large as CO2 fertilization effect.•Developed methodology allows for inclusion of growth changes into yield tables.•Inclusion of climate-induced growth changes can make or break bioeconomy policies.
The correct selection of the species composition of afforestation in relation to the habitat conditions has a decisive impact on the effects of forest reclamation. In most of the reclaimed forestry ...areas in Poland, the stands enter the prelogging period, and it is possible to assess the first economic and production effects of reclamation. The assessment was made based on the analysis of the size of the harvested wood during the intermediate cutting on the heap of the former ‘Piaseczno’ opencast sulphur mine located in southern Poland and managed by the State Forests. At this stage of development,
played a large role in obtaining a good income from the sale of intermediate cutting wood and economic effects. The obtained results may be important in the context of indicating alternative directions for reclamation and afforestation of post-mining areas, e.g., for plantation purposes.
•Climatic water deficit included in basal area modeling is recommended for Brazil.•G & Y system that accounts for water availability displays reduced bias in volume estimation.•The new type of G & Y ...system enables the generation of site-specific curves.•The new type of G & Y system allows for testing environment × genotype interaction.•The new type of G & Y system is simple to use and implement.
Growth and yield (G &Y) model systems aim at forecasting forest productivity. The lack of environmental variables to account for how water availability constrains eucalyptus production in Brazil, however, is argued to be a major drawback of these model systems. Thus, this study aimed to develop a stand-level G & Y model system that accounts for water availability (G & Y with SWD), highlighting its usefulness when applied for clonal eucalypt stands under drier climatic conditions. The dataset is composed of remeasurement information of sixteen research sites that span all climatic regions in Brazil. A total of eleven eucalypt clones were planted in single block plots at each site, and extra replications under the rainfall exclusion system were also installed for these eleven clones in fourteen sites. Linear algebra techniques were used to simultaneously fit a compatible set of prediction and projection basal area equations. A stand-level volume equation was also developed. These equations were validated through the use of an independent dataset composed of the rainfall exclusion plots. Finally, the accuracy and usefulness of a conventional G & Y model system applied to clonal eucalypt stands in Brazil was compared to the new proposed G & Y model system, which accounts for the impact of water availability in eucalyptus productivity. The prediction and projection basal area equations accounting for water availability displayed estimates in the order of 5% more accurate compared to the conventional basal area modeling. Stand-level volume estimates were 40% and 74% less biased through the use of the new G & Y model system. This result highlighted how useful and powerful the newly developed approach is, since the model system was capable to provide accurate estimates through the use of the rainfall exclusion plots. The new G & Y model system is a powerful alternative to estimate forest afforestation yield and is fully capable to accurately update forest inventories. The model system can also be used for projecting how forest growth may be impacted by short-term climate variation.
•New information on the frost prediction for forest.•Frost forecasting from spatial data.•Machine learning algorithms to classify frost risk probability.•High prediction performance using Random ...Forest classifier.•Transferability of the predictive approach for other agricultural plantations.
Brazil is one of the leading timber producers in the world. However, in South Brazil, frost events frequently cause damage and reduce yield in forest plantations, a situation predicted to become more common under global change scenarios. This raises the need for low cost and efficient tools, such as machine learning algorithms to improve forecasting of frost risk. This study used machine learning algorithms to create zoning classifications forecasting frost risk for forest plantations located in the south-central region of Rio Grande do Sul State, Brazil. For this, we gathered and processed data from a local geodatabase (i.e. high-spatial-resolution contour lines, hydrography, and forest stands limits) comprising 30 management units with consistent historical data of frost occurrence. Then, we generated possible local-scale predictors of frost occurrence, which included longitude, latitude, elevation, relative altitude, relief orientation, and Euclidean distance from hydrography. We carried out tests of three machine learning classifiers (Random Forest – RF; Support Vector Machine-SVM and Multi-layer Perceptron-MLP) in order to determine which would most accurately predict frost occurrence. We found that RF provided the highest accuracy (> 90%), as well as the smallest percentages of class-specific errors (i.e. commission and omission errors), when compared to SVM and MLP. Latitude was the most important predictor of frost occurrence when using RF. Conversely, MLP performed worst, especially for classifying frost occurrence versus non-occurrence, and therefore had the highest percentage of class-specific errors. Our findings lead us to conclude that RF is the most proficient algorithm for forecasting frost occurrence from local-scale geomorphological data, without the need for high-cost investment in micro-meteorological sensors to monitor climate frost events linking temperature to plant damage. With increasing global climate extreme events, accurate risk zoning is essential for planning strategies of plantation at the landscape scale.
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The objective of this work was to analyze the legal arrangements on a very complex theme in the forest sector: the use of a species threatened with extinction, araucaria. After years of intense ...deforestation, linked to the country's economic growth, after 1960 decade, it was edited an array of regulations aimed to control the forest use through strict laws and expansion of the environmental bureaucracy. In 2014, MMA Decree 443, araucaria was included in the danger category, restricting any timber use, including the ones gathered under forest management. The justification for this inclusion comes from the population reduction, deforestation and logging. Regarding the justification of its inclusion, it is important to note the non-disclosure of official data, an obligation of the State, on the remaining area and number of individuals. Decree 443 collides with the Brazilian forest low removing rights, as forest management, not established by Law number 12.651 of 2012. It also defies the Complementary Law 140 which establishes reports and technical-scientific studies for framing the listed species. Nor does it comply with the steps required in article 5º MMA Decree 43, which precedes Decree 443. By analyzing the regulations regarding the araucaria and its commercial use: there is no law prohibiting the use, through management and planting; what exists are Decrees and resolutions. Whoever is in the messianic right to forbid the cutting of the species, subsidizes itself in Decrees and resolutions. Moreover, who believes they have the right to cut it, is not aware of the legislation.
Abstract
With the trend of trade globalization, developing countries have an indispensable role in the global value chain. In China, production and trade of forest products appear to be considerably ...sensitive in balancing industry development and ecological conservation. Simultaneously, increased trade in non-timber forest products (NTFPs) has merged as a new direction for sustainable forestry development. This study explores the effect of the NTFP trade globalization process on NTFP producer capital input using a dataset of 976 oolong tea producers in Wuyishan City, China, from 2008 to 2020. We ran pooled- ordinary least square regression and the results show that the trade globalization process of tea products is a driving force in oolong tea producer capital inputs in Wuyishan City, which increases with forest resources and producer scale. Additionally, our findings reveal that the local government implemented a fiscal policy to promote a sustainable composite model (SCM) in tea production, which includes terrace protection, organic fertilizers, tea-broadleaf symbiosis, and ecological water systems. Given structural growth in demand for tea products driven by trade globalization, the SCM promotion policy enhanced the quantity and quality of oolong tea products based on a harmonious coexistence with nature resulting in a mutually beneficial outcome for the government and producers.
Study Implications: Results of our study provide evidence that NTFP trade globalization and diversification can promote the NTFP industry by increasing productive capital inputs by producers and innovatively summarize an environmentally benign solution for the adjustment of the production model of NTFPs. The scarcity of forestland and the social uses of forest resources require embedding sustainable governance into the development of the NTFP industry. With government support, the new model of sustainable NTFP production can serve the long-term planning of rational forest resource use.
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