Changes in foliar carbon isotope composition and seasonal stomatal conductance reveal adaptive traits in Mediterranean coppices affected by drought

We estimated water-use efficiency and potential photosyn- thetic assimilation of Holm oak （Quercus ilex L.） on slopes of NW and SW aspects in a replicated field test examining the effects of intensifying drought in two Mediterranean coppice forests. We used standard tech- niques for quantifying gas exchange and carbon isotopes in leaves and analyzed total chlorophyll, carotenoids and nitrogen in leaves collected from Mediterranean forests managed under the coppice system. We pos- tulated that responses to drought of coppiced trees would lead to differ- ential responses in physiological traits and that these traits could be used by foresters to adapt to predicted warming and drying in the Mediterra- nean area. We observed physiological responses of the eoppiced trees that suggested acclimation in photosynthetic potential and water-use effi- ciency： （1） a significant reduction in stomatal conductance （p〈0.01） wasrecorded as the drought increased at the SW site; （2） foliar 813C increased as drought increased at the SW site （p〈0.01）; （3） variations in levels of carotenoids and foliar nitrogen, and differences in foliar morphology were recorded, and were tentatively attributed to variation in photosyn- thetic assimilation between sites. These findings increase knowledge of the capacity for acclimation of managed forests in the Mediterranean region of Europe.

Carbon concentrations and carbon storage capacity of three old-growth forests in the Sila National Park,Southern Italy

Old-growth forests play a key-role in reducing atmospheric carbon dioxide(CO_(2)) concentrations by storing large CO_(2)amounts in biomass and soil over time.This quantifies the carbon pool into different forest compartments in three Mediterranean old-growth forests of Southern Italy populated by Pinus laricio,Fagus sylvatica and Abies alba.Ecosystem carbon pools have been assessed per compartment,i.e.,living trees,dead wood,litterfall(foliar and woody),roots and 0-20 cm topsoil,combining the whole old-growth forest mass,(i.e.,using tree allometric relationships,deadwood factor conversions,root-to-shoot ratios,litterfall and soil samplings) by the respective organic carbon concentrations.The results show the considerable capacity of these forest ecosystems in storing CO_(2)in biomass and soil,with carbon pool values ranging from 532.2to 596.5 Mg C ha-1.Living trees and 0-20 cm topsoil had larger carbon pool,contributing 53.0 and 22.1%,respectively.In most cases,organic carbon concentration was higher(more than 60%) than the average carbon conversion rate of 50%,especially in living trees,deadwood,and woody litterfall.This study contributes further scientific evidence of the capacity of old-growth forests in storing CO_(2)in their different compartments,with special evidence on tree biomass,litterfall and mineral soil,thereby highlighting the key role of old-growth forests within the challenge of climate change mitigation.

An overview of proven Climate Change Vulnerability Assessment tools for forests and forest-dependent communities across the globe：a literature analysis

Climate Change Vulnerability Assessment（VA） tools for forest ecosystems and forest-dependent communities are important for making decisions and understanding the impact of climate change on both social and natural systems.However,the tools are poorly coordinated,making it difficult for policymakers to carry out VAs properly.The aim of this study was to analyze VA literature worldwide to find representative case studies in terms of methods and tools applied and which have been successful in performing VAs on forests and forest-dependent communities.All successful VA studies analyzed had common characteristics such as significant funding,data availability and technical capacity.An additional characteristic was the development of an integrated approach that considered the vulnerability of both ecosystems and communities by combining qualitative and quantitative methods.Community members and relevant stakeholders were significantly involved in a participatory process that concluded with the identification of adaptation measures.The case studies also revealed how policymakers need to choose suitable methods and tools to undertake efficient assessment of vulnerabilities.They need to consider several aspects of the VA process such as subject matter,availability of resources,time and scale.

Nitrogen Release from Slow-Release Fertilizers in Soils with Different Microbial Activities

Soil microbial activity is recognized as an important factor affecting nitrogen (N) release from slow-release fertilizers. However,studies on the effect of size and activity of soil microflora on fertilizer degradation have provided contrasting results. To date, no clear relationships exist between soil microbial activity and the release of N from slow-release fertilizers. Hence, the aim of this study was to better understand such relationships by determining the release of N from three slow-release fertilizers in soils with different microbial activities. Soils were amended with urea-formaldehyde (UF), isobutylidene diurea (IBDU), and crotonylidene diurea (CDU). Urea, a soluble fertilizer, was used as the control. Fertilized soil samples were placed in a leaching system, and the release of N was determined by measuring ammonium-N and nitrate-N concentrations in leachates during 90 d of incubation. Non-linear regression was used to fit N leaching rate to a first-order model. In all the treated soils, N was released in the order: urea (89%–100%) > IBDU (59%–94%) >UF (46%–73%) > CDU (44%–56%). At the end of incubation, N released from CDU did not differ (P > 0.05) among soils. On the contrary, UF and IBDU released significantly lower (P < 0.05) amounts of N in the soil with higher microbial activity and lower pH.The rate constant (K_0) for UF was lower (P < 0.05) in the soil with lower pH. Taken together, our results indicated that soil microbial size and microbial activity had a marginal effect on fertilizer mineralization.