Increase In Forest Growth Research Articles

Past and Future of Temperate Forests State under Climate Change Effects in the Romanian Southern Carpathians

Research Highlights: Carpathian forests hold high ecological and economic value while generating conservation concerns, with some of these forests being among the few remaining temperate virgin forests in Europe. Carpathian forests partially lost their original integrity due to their management. Climate change has also gradually contributed to forest changes due to its modification of the environmental conditions. Background and Objectives: Understanding trees’ responses to past climates and forms of management is critical in foreseeing the responses of forests to future conditions. This study aims (1) to determine the sensitivity of Carpathian forests to past climates using dendrochronological records and (2) to describe the effects that climate change and management will have on the attributes of Carpathian forests, with a particular focus on the different response of pure and mixed forests. Materials and Methods: To this end, we first analysed the past climate-induced growth change in a dendrochronological reference series generated for virgin forests in the Romanian Curvature Carpathians and then used the obtained information to calibrate spatially explicit forest Landis-II models for the same region. The model was used to project forest change under four climate change scenarios, from mild to extreme. Results: The dendrochronological analysis revealed a climate-driven increase in forest growth over time. Landis-II model simulations also indicate that the amount of aboveground forest biomass will tend to increase with climate change. Conclusions: There are differences in the response of pure and mixed forests. Therefore, suitable forest management is required when forests change with the climate.

长江流域生态系统格局演变及驱动力

PDF HTML阅读 XML下载 导出引用 引用提醒 长江流域生态系统格局演变及驱动力 DOI: 10.5846/stxb201712052191 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 中国科学院科技服务网络计划项目（KFJ-STS-ZDTP-010） Driving forces behind ecosystem spatial changes in the Yangtze River Basin Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:长江流域生态系统格局复杂，多种社会经济、政策和自然因素对土地利用变化的影响使得生态环境发生变化。分析了2000年至2015年长江流域生态系统格局和演变特征，及主要驱动力对生态系统变化的贡献。15年间，共有约6.4万km2的生态系统类型发生变化，城镇增长67.5%，农田缩减7.5%，森林增加2.1%，剧烈的生态系统变化集中于下游，以及中上游的大城市，城镇聚集区以及退耕还林区。生态系统景观破碎化程度和景观多样性提高。上、中、下游生态系统格局、构成差异较大，15年间，上游和下游森林显著增加，下游城镇显著扩张、农田和湿地显著缩减，上游湿地增加最为显著。城镇化是生态系统格局演变的首要驱动力，对生态系统变化的贡献率达48.0%，长江下游城镇化的贡献率高达64.5%。生态保护与恢复工程是第二驱动力，对生态系统变化的贡献率为32.8%，在上游高达47.8%。水资源开发和农业开发贡献率分别为8.5%和9.9%，此外，气候变化促使高原湖泊面积增大。为保护长江流域生态系统的可持续发展，需划定生态保护红线，合理规划城市化进程中的土地利用，保护优质耕地，禁止重要湿地的开发。 Abstract:There are obvious differences among the upper, middle, and lower reaches in the natural environment in the Yangtze River Basin. The regional topography and climatic conditions are significantly distinct, and economic development is unbalanced. The impacts of various socioeconomic factors, policies, and natural factors on land use stimulate changes in the ecological environment. Therefore, knowledge of the ecosystem's patterns, characteristics, and driving forces is the basis for studying the ecosystem services, ecological environmental problems, and ecological risk assessments. The ecosystem patterns, changing characteristics, and primary driving forces were analyzed from 2000 to 2015 in the Yangtze River Basin. During the 15-year period, about 6.4×104 km2 of the ecosystem changed, including a 67.5% increase in urban land, 2.1% increase in forest growth, and 7.5% reduction in croplands. These dramatic changes were concentrated in the lower reaches, big cities in the upper and the middle reaches, urban agglomerations, and reforested cropland areas. Ecosystem patterns and compositions in the upper, middle, and lower reaches were different. Forests and wetlands in the upper reach and urban land in the lower reach increased significantly, whereas croplands and wetlands in the lower reach decreased substantially. Through the analysis of landscape patterns, the degree of landscape fragmentation, as well as landscape diversity, increased. Between the years 2000 and 2015, the change in ecosystem patterns in the Yangtze River Basin was influenced by urbanization, ecological conservation and restoration, water resource development, agricultural development, geological hazards, and climate change. The contributions of the primary driving forces to ecosystem changes varied for the upper, middle, and lower reaches. The first important driving force was urbanization, with a contribution rate of 48.0% and up to 64.5% in the lower reach. The second important driving force was ecological conservation projects, with a contribution rate of 32.8% and up to 47.8% in the upper reach. Water resource development and agricultural development contributed 8.5% and 9.9%, respectively. In addition, the area of plateau lakes increased due to climate change. To sustainably protect the ecosystem in the Yangtze River Basin, the design of the ecological conservation redlines, reasonable land use planning in urbanization, conservation of high quality cropland, and the prohibition of development on important wetlands are necessary. 参考文献 相似文献 引证文献

Acid rain mitigation experiment shifts a forested watershed from a net sink to a net source of nitrogen

Decades of acid rain have acidified forest soils and freshwaters throughout montane forests of the northeastern United States; the resulting loss of soil base cations is hypothesized to be responsible for limiting rates of forest growth throughout the region. In 1999, an experiment was conducted that reversed the long-term trend of soil base cation depletion and tested the hypothesis that calcium limits forest growth in acidified soils. Researchers added 1,189 kg Ca(2+) ha(-1) as the pelletized mineral wollastonite (CaSiO3) to a 12-ha forested watershed within the Hubbard Brook Experimental Forest in the White Mountains of New Hampshire. Significant increases in the pH and acid-neutralizing capacity of soils and streamwater resulted, and the predicted increase in forest growth occurred. An unanticipated consequence of this acidification mitigation experiment began to emerge a decade later, with marked increases in dissolved inorganic nitrogen (DIN) exports in streamwater from the treated watershed. By 2013, 30-times greater DIN was exported from this base-treated watershed than from adjacent reference watersheds, and DIN exports resulting from this experiment match or exceed earlier reports of inorganic N losses after severe ice-storm damage within the study watershed. The discovery that CaSiO3 enrichment can convert a watershed from a sink to a source of N suggests that numerous potential mechanisms drive watershed N dynamics and provides new insights into the influence of acid deposition mitigation strategies for both carbon cycling and watershed N export.

Predicting the activity of Heterobasidion parviporum on Norway spruce in warming climate from its respiration rate at different temperatures

SummaryWe studied the effect of climate warming on Heterobasidion root rot in boreal forests by measuring respiration activity of pure cultures of Heterobasidion parviporum in Norway spruce (Picea abies) sawdust and by linking these data to temperature data obtained from three spruce forests located along a north‐south transect stretching from northern Germany to northern Finland. The pure cultures applied in this investigation were homokaryotic, but in a separate investigation, we found no significant difference between the activity of homo‐ and heterokaryotic isolates. We also found that the temperature response curves of growth and respiration rates of this fungus were similar and propose that respiration reflects the general activity of H. parviporum. The respiration data were scaled up to annual cumulative respiration activity using daily temperature measurements from soil and air in the spruce forest sites. The annual respiration activity of H. parviporum showed a linear relationship with the average annual air temperature. An increase in the annual air temperature by 5°C would raise the annual activity of H. parviporum in spruce roots in northern Finland, southern Finland and northern Germany by 91%, 53% and 40%, respectively. This increase remains below the predicted increase in forest growth in northern Finland but exceeds considerably the predictions for southern Finland. According to the previous literature, a number of other decay fungi show a similar activity response to temperature as H. parviporum, suggesting that this result can be generalized to decay fungi with similar ecological habits.

Effects of stump extraction on the carbon sequestration inNorway spruce forest ecosystems under varying thinning regimes with implications for fossil fuel substitution

AbstractThe overall aim of this work was to assess the effects of stump and root extraction on the long‐term carbon sequestration and average carbon storage in the integrated production of energy biomass and stemwood (pulpwood and sawlogs) under different thinning options (unthinned, current thinning and 30% increased thinning thresholds from current thresholds). The growth and development of Norway spruce (Picea abiesL. Karst.) stands on a fertile site (Oxalis‐myrtillus) in central Finland (Joensuu region: 62˚39΄N, 29˚37΄E) was simulated for two consecutive rotation periods (80 + 80 years/160 years). Stemwood and energy biomass production, carbon sequestration, and average storage and emission dynamics related to the entire production process of biomass were assessed. The assessment was done by employing a life cycle assessment tool, which combines simulation outputs from an ecosystem model and the related technosystem emissions. It was found that stump and root harvesting constituted 21–36% of the total biomass production (energy biomass and stemwood) depending on the thinning regimes and rotation period. No considerable effect was found in stemwood production when stump and root extraction was compared to the regime in which stumps and roots were left at the site. Stump and root extraction did not affect carbon sequestration on the following rotation and, in fact, an increase in forest growth was found for the unthinned and 30% increased thresholds compared to the first rotation. The results also showed that if current thinning threshold is increased, win‐win situations are possible, especially when climate change mitigation is the main concern. The substitution of coal with energy biomass is possible without reducing carbon storage in the forest ecosystem. The utilization of energy biomass, including stumps and roots, instead of coal could reduce up to 33% of emissions over two rotation periods depending on the thinning regimes. Even if stumps and roots were excluded, a maximum of 19% carbon emissions could be reduced by using only logging residues.

No evidence that chronic nitrogen additions increase photosynthesis in mature sugar maple forests

Atmospheric nitrogen (N) deposition can increase forest growth. Because N deposition commonly increases foliar N concentrations, it is thought that this increase in forest growth is a consequence of enhanced leaf-level photosynthesis. However, tests of this mechanism have been infrequent, and increases in photosynthesis have not been consistently observed in mature forests subject to chronic N deposition. In four mature northern hardwood forests in the north-central United States, chronic N additions (30 kg N ha(-1) yr(-1) as NaNO3 for 14 years) have increased aboveground growth but have not affected canopy leaf biomass or leaf area index. In order to understand the mechanism behind the increases in growth, we hypothesized that the NO3(-) additions increased foliar N concentrations and leaf-level photosynthesis in the dominant species in these forests (sugar maple, Acer saccharum). The NO3(-) additions significantly increased foliar N. However, there was no significant difference between the ambient and +NO3(-) treatments in two seasons (2006-2007) of instantaneous measurements of photosynthesis from either canopy towers or excised branches. In measurements on excised branches, photosynthetic nitrogen use efficiency (micromol CO2 s(-1) g(-1) N) was significantly decreased (-13%) by NO3(-) additions. Furthermore, we found no consistent NO3(-) effect across all sites in either current foliage or leaf litter collected annually throughout the study (1993-2007) and analyzed for delta 13C and delta 18O, isotopes that can be used together to integrate changes in photosynthesis over time. We observed a small but significant NO3(-) effect on the average area and mass of individual leaves from the excised branches, but these differences varied by site and were countered by changes in leaf number. These photosynthesis and leaf area data together suggest that NO3(-) additions have not stimulated photosynthesis. There is no evidence that nutrient deficiencies have developed at these sites, so unlike other studies of photosynthesis in N-saturated forests, we cannot attribute the lack of a stimulation of photosynthesis to nutrient limitations. Rather than increases in C assimilation, the observed increases in aboveground growth at our study sites are more likely due to shifts in C allocation.

Aumento della produttività negli ecosistemi forestali: nuove evidenze dalle foreste temperate

Abstract: A paper recently published on PNAS provides a new evidence for an increase in forest growth in temperate forests. The possible causes of this process are discussed. The results show a relation between this change in tree growth with the increase in atmospheric CO2 concentration, temperature, and length of growth season. A better understanding of the specific mechanisms involved and the assessment of the consequences on the current and future global changes are needed.

Aumento della produttività negli ecosistemi forestali: nuove evidenze dalle foreste temperate

Aumento della produttività negli ecosistemi forestali: nuove evidenze dalle foreste temperate

Evidence for a recent increase in forest growth is questionable

In a recent article, McMahon et al. (1) examined forest-plot biomass accumulation across a range of stands in the mid-Atlantic United States and suggest that climate change and trends in atmospheric CO2 explain an increase in forest growth. To show this increase, they fit a simple model to live above-ground forest biomass (AGB) as a function of stand age, and then propose that the derivative of this model is the expected rate of ensemble biomass change (). They conclude that biomass changes within census plots that exceed the ensemble expectation constitute recent increases in growth rates.

Evidence for a recent increase in forest growth.

Forests and their soils contain the majority of the earth's terrestrial carbon stocks. Changes in patterns of tree growth can have a huge impact on atmospheric cycles, biogeochemical cycles, climate change, and biodiversity. Recent studies have shown increases in biomass across many forest types. This increase has been attributed to climate change. However, without knowing the disturbance history of a forest, growth could also be caused by normal recovery from unknown disturbances. Using a unique dataset of tree biomass collected over the past 22 years from 55 temperate forest plots with known land-use histories and stand ages ranging from 5 to 250 years, we found that recent biomass accumulation greatly exceeded the expected growth caused by natural recovery. We have also collected over 100 years of local weather measurements and 17 years of on-site atmospheric CO(2) measurements that show consistent increases in line with globally observed climate-change patterns. Combined, these observations show that changes in temperature and CO(2) that have been observed worldwide can fundamentally alter the rate of critical natural processes, which is predicted by biogeochemical models. Identifying this rate change is important to research on the current state of carbon stocks and the fluxes that influence how carbon moves between storage and the atmosphere. These results signal a pressing need to better understand the changes in growth rates in forest systems, which influence current and future states of the atmosphere and biosphere.

Nitrogen deposition and carbon sequestration

Nadelhoffer et al.1 use 15N-tracer studies in nine northern forests to argue that increasing inputs of combined nitrogen from the atmosphere are unlikely to cause the increase in forest growth that has been postulated as the ‘missing sink’ for atmospheric CO2. Only about 20% of the tracer ended up in the trees and about 70% remained in the organic and mineral layers of the soil. If only 20% of the nitrogen input from the atmosphere were available for tree growth, then not enough combined nitrogen would be coming into the northern forests each year to explain the missing carbon sink.