Global climate change and tree nutrition: effects of elevated CO2 and temperature

Although tree nutrition has not been the primary focus of large climate change experiments on trees, we are beginning to understand its links to elevated atmospheric CO2 and temperature changes. This review focuses on the major nutrients, namely N and P, and deals with the effects of climate change on the processes that alter their cycling and availability. Current knowledge regarding biotic and abiotic agents of weathering, mobilization and immobilization of these elements will be discussed. To date, controlled environment studies have identified possible effects of climate change on tree nutrition. Only some of these findings, however, were verified in ecosystem scale experiments. Moreover, to be able to predict future effects of climate change on tree nutrition at this scale, we need to progress from studying effects of single factors to analysing interactions between factors such as elevated CO2, temperature or water availability

Effects of climate and forest management on the water and nitrogen status of European beech regeneration and understorey vegetation

Human activities result in climate changes with various impacts on forest ecosystems. An increase in global surface temperature, compared to pre-industrial levels, is already recorded and further elevation is expected. Extreme events, such as hot and dry periods, would increase in frequency and duration in near future. Due to the low adaptive capacity of forest ecosystems to rapid climate changes, high priority is given to the assessment of their responses. Particularly, studies on forests dominated by the drought susceptible European beech, especially when grown on limestone-derived soils with low water storage capacity, being common in Central and Southern Europe, are important. Moreover, climate models emphasize the significance of management practices for the adaptation to the expected changes, since they could contribute to the mitigation of possible adverse effects of climate change. The present study assessed the effects of different climatic conditions on the nitrogen and water status of natural beech regeneration grown in managed (thinned) and not managed (control) stands in a forest in Southern Germany. A SW-exposed site, characterized by low water availability and high temperature and radiation interception, was regarded as representative of the climate conditions expected in the future, whereas a NE-exposed site was used as typical of present climatic conditions...thesi

Ecophysiology of seedlings of three Mediterranean pine species in contrasting light regimes

Seasonal dynamics of net photosynthesis (Anet) in 2-year-old seedlings of Pinus brutia Ten., Pinus pinea L. and Pinus pinaster Ait. were investigated. Seedlings were grown in the field in two light regimes: sun (ambient light) and shade (25% of photosynthetically active radiation (PAR)). Repeated measures analyses over a 12-month period showed that Anet varied significantly among species and from season to season. Maximum Anet in sun-acclimated seedlings was low in winter (yet remained positive) and peaked during summer. Maximum Anet was observed in June in P. pinea (12 μmol m–2 s–1), July in P. pinaster (23 μmol m–2 s–1) and August in P. brutia (20 μmol m–2 s–1). Photosynthetic light response curves saturated at a PAR of 200–300 μmol m–2 s–1 in winter and in shade-acclimated seedlings in summer. Net photosynthesis in sun-acclimated seedlings did not saturate at PAR up to 1900 μmol m–2 s–1 in P. brutia and P. pinaster. Minimum air temperature of the preceding night was apparently one of the main factors controlling Anet during the day. In shade-acclimated seedlings, photosynthetic rates were reduced by 50% in P. brutia and P. pinaster and by 20% in P. pinea compared with those in sun-acclimated seedlings. Stomatal conductance was generally lower in shaded seedlings than in seedlings grown in the sun, except on days with a high vapor pressure deficit. Total chlorophyll concentration per unit leaf area, specific leaf area (SLA) and height significantly increased in P. pinea in response to shade, but not in P. pinaster or P. brutia. In response to shade, P. brutia showed a significant increase in total chlorophyll concentration but not SLA. Photosynthetic and growth data indicate that P. pinaster and P. brutia are more light-demanding than P. pinea

A new hammer to crack an old nut : interspecific competitive resource capture by plants is regulated by nutrient supply, not climate

Peer reviewedPublisher PD

Ecophysiology of seedlings of three Mediterranean pine species in contrasting light regimes

Seasonal dynamics of net photosynthesis (Anet) in 2-year-old seedlings of Pinus brutia Ten., Pinus pinea L. and Pinus pinaster Ait. were investigated. Seedlings were grown in the field in two light regimes: sun (ambient light) and shade (25% of photosynthetically active radiation (PAR)). Repeated measures analyses over a 12-month period showed that Anet varied significantly among species and from season to season. Maximum Anet in sun-acclimated seedlings was low in winter (yet remained positive) and peaked during summer. Maximum Anet was observed in June in P. pinea (12 μmol m–2 s–1), July in P. pinaster (23 μmol m–2 s–1) and August in P. brutia (20 μmol m–2 s–1). Photosynthetic light response curves saturated at a PAR of 200–300 μmol m–2 s–1 in winter and in shade-acclimated seedlings in summer. Net photosynthesis in sun-acclimated seedlings did not saturate at PAR up to 1900 μmol m–2 s–1 in P. brutia and P. pinaster. Minimum air temperature of the preceding night was apparently one of the main factors controlling Anet during the day. In shade-acclimated seedlings, photosynthetic rates were reduced by 50% in P. brutia and P. pinaster and by 20% in P. pinea compared with those in sun-acclimated seedlings. Stomatal conductance was generally lower in shaded seedlings than in seedlings grown in the sun, except on days with a high vapor pressure deficit. Total chlorophyll concentration per unit leaf area, specific leaf area (SLA) and height significantly increased in P. pinea in response to shade, but not in P. pinaster or P. brutia. In response to shade, P. brutia showed a significant increase in total chlorophyll concentration but not SLA. Photosynthetic and growth data indicate that P. pinaster and P. brutia are more light-demanding than P. pinea

Landscape transformations at the dawn of agriculture in southern Syria (10.7–9.9 ka cal. BP): plant-specific responses to the impact of human activities and climate change

In southwest Asia, the accelerated impact of human activities on the landscape has often been linked to the development of fully agricultural societies during the middle and late Pre-Pottery Neolithic B (PPNB) period (around 10.2–7.9 ka cal. BP). This work contributes to the debate on the environmental impact of the so-called Neolitisation process by identifying the climatic and anthropogenic factors that contributed to change local and regional vegetation at the time when domesticated plants appeared and developed in southern Syria (around 10.7–9.9 ka cal. BP). In this work a multidisciplinary analysis of plant microremains (pollen and phytoliths) and macroremains (wood charcoal) is carried out along with stable carbon isotope discrimination of wood charcoals in an early PPNB site (Tell Qarassa North, west of the Jabal al-Arab area). Prior to 10.5 ka cal. BP, the results indicate a dynamic equilibrium in the local and regional vegetation, which comprised woodland-steppe, Mediterranean evergreen oak-woodlands, wetland vegetation and coniferous forests. Around 10.5–9.9 ka cal. BP, the elements that regulated the vegetation system changed, resulting in reduced proportions of arboreal cover and the spread of cold-tolerant and wetlands species. Our data show that reinforcing interaction between the elements of the anthropogenic (e.g. herding, fire-related activities) and climatic systems (e.g. temperature, rainfall) contributed to the transformation of early Holocene vegetation during the emergence of fully agricultural societies in southern Syria

Building synergies among ground-based forest inventorying and monitoring networks to meet scientific, political and societal needs

Societal Impact Statement: Ground-based Inventorying and Monitoring programs are crucial for documenting long-term forest responses to global change pressures, though there is limited coordination among them. We call for building synergies between different Inventorying and Monitoring programs, as well as community science and stakeholder engagement, to expand the temporal and spatial scale of forest monitoring and better integrate ground-based monitoring, remote sensing and modelling for timely detection of changes in forest conditions and functioning. This will be beneficial for the Proposal for a Monitoring Framework for Resilient European Forests and other not forestry-related European Union policies and strategies. Summary: There are high expectations from policymakers and society about the role of forests in contributing to climate change mitigation and biodiversity conservation goals, while also supporting a sustainable forest-based bioeconomy. Yet, multiple global change drivers are undermining forest health and functioning, resulting in great uncertainties around the future of the ecological, economic and social benefits that humanity relies on from forests. Consequently, there is a pressing need to document the state of forests, which is traditionally accomplished through long-term ground-based inventorying and monitoring. There are several Inventorying and Monitoring networks in Europe, each with a specific scope, resulting in their independent development and limited interactions. There is now a growing need for a stronger integration across networks, both conceptually and operationally, to achieve an in-depth assessment of changes in forest status, underlying mechanisms and drivers, to support the development of pan-European Earth Observation products and the European Union strategies. Here we briefly summarize the forest ground-based Inventorying and Monitoring networks in Europe, identifying their role, strengths and areas for improvement. We suggest actions that can favour a transition towards a new, co-operative and effective era in forest monitoring, which can support research, policy and societal needs in a timely manner.</p

Carbon sequestration and soil nitrogen enrichment in Robinia pseudoacacia L. post-mining restoration plantations

Robinia pseudoacacia L. (black locust) has been extensively used for restoring degraded lands, following anthropogenic interventions like coal mining. Here we have addressed the contribution of black locust restoration plantations, established on overburden post-mining material, to carbon storage and to soil nitrogen enrichment at the largest lignite center in Greece. Carbon stocks and fluxes in all pools of the ecosystem, as well as the foliar nitrogen resorption efficiency and soil N stocks were quantified and the effect of plantations’ age was tested. The young age of the plantations (4–24 years) resulted in a relatively low total ecosystem C stock (56.7 t ha−1), which was partitioned among the different pools in the following order: above-ground biomass (50%) &gt; black locust-derived SOC (24%) &gt; coarse roots (14%) &gt; deadwood (6%) &gt; forest floor (5%) &gt; fine roots (less than 1%). Litterfall started early in the growing season and together with fine roots that had a turnover rate of 0.62 yr−1, fueled soil organic carbon. SOC accrual, referring to the accumulation of SOC derived by black locust, declined with age. However, further SOC accumulation is expected, based on the potential SOC storage capacity of soil at the area. C stocks in above- and below-ground biomass increased linearly with age. The same response was observed for soil N stock and NRE, indicating that despite the N2-fixing capacity of black locust, there was still a poor pedospheric N supply and a need for efficient N cycling. Overall, the studied restoration plantations have a considerable contribution to C and N accumulation at the degraded post-mining sites. These positive effects are expected to further increase at least until the plantations reach maturity

Highest drought sensitivity and lowest resistance to growth suppression are found in the range core of the tree Fagus sylvatica L. not the equatorial range edge

Biogeographical and ecological theory suggests that species distributions should be driven to higher altitudes and latitudes as global temperatures rise. Such changes occur as growth improves at the poleward edge of a species distribution and declines at the range edge in the opposite or equatorial direction, mirrored by changes in the establishment of new individuals. A substantial body of evidence demonstrates that such processes are underway for a wide variety of species. Case studies from populations at the equatorial range edge of a variety of woody species have led us to understand that widespread growth decline and distributional shifts are underway. However, in apparent contrast, other studies report high productivity and reproduction in some range edge populations. We sought to assess temporal trends in the growth of the widespread European beech tree (Fagus sylvatica) across its latitudinal range. We explored the stability of populations to major drought events and the implications for predicted widespread growth decline at its equatorial range edge. In contrast to expectations, we found greatest sensitivity and low resistance to drought in the core of the species range, while dry range edge populations showed particularly high resistance to drought and little evidence of drought-linked growth decline. We hypothesise that this high range-edge resistance to drought is driven primarily by local environmental factors that allow relict populations to persist despite regionally unfavourable climate. The persistence of such populations demonstrates that range edge decline is not ubiquitous and is likely to be driven by declining population density at the landscape scale rather than sudden and widespread range retraction