Enrique Andivia

Assessing the effect of late-season fertilization on Holm oak plant quality: insights from morpho–nutritional characterizations and water relations parameters

Forest restoration projects with Holm oak (Quercus ilex) have had limited success, mostly due to water stress after planting and poor plant quality. Recent studies indicated that large and nutrient rich plants perform better in Mediterranean areas, suggesting that late-season fertilization may improve plant quality and field performance. The purpose of this study was to assess the effect of late-season fertilization on the quality of Holm oak seedlings, as determined by morphological, nutritional, and water relations analyses. We grew Holm oak nursery seedlings under 5 different late-season fertilization regimes and then analyzed morphological characteristics, nutritional status, and water relations parameters of the fertilization groups at the end of the nursery period. We also analyzed the effect of fertilization on nutritional status by use of vector nomograms. Our results indicated that late-season NPK fertilization improved shoot and root growth, and the overall nutritional status of seedlings. The lack of late-season fertilization leads to nutrient deficiency in plants, whilst the application of imbalanced fertilization treatments may trigger nutrient luxury consumption and nutrient dilution, pointing out the importance of NPK proportions in the fertilizer. Moreover, late-season fertilization with nitrogen might improve the drought resistance of seedling by enhancing their osmotic adjustment.

Tree species identity mediates mechanisms of top soil carbon sequestration in a Norway spruce and European beech mixed forest

Key messageCombined effects of litterfall and root turnover significantly increase topsoil carbon stocks in Norway spruce and European beech mixed forests, indicating local complementarity effects mediated by tree species mixtures.ContextThe establishment of mixed stands by intermingling individuals of European beech and Norway spruce is an ongoing trend in adaptive forest management strategies. However, our understanding of the potential of these strategies to promote C sequestration remains limited.AimsThis study aims to assess the effect of species composition on SOC stock in a mixed forest of Norway spruce and European beech.MethodsWe studied C stocks in the uppermost soil layers in two stands dominated either by Norway spruce or European beech and in a mixture of both species. We evaluated the effect of litterfall and root turnover on soil organic carbon (SOC) stocks and its spatial distribution by combining structural equation models and geostatistical techniques.ResultsC stocks in the forest floor were highest in Norway spruce, whereas in the mineral soil, the highest values were in the mixed stand. The proportion of Norway spruce litterfall was positively related to C stock in the forest floor across stands. Root turnover was positively related to C stock in the mineral soil of the mixed stand.ConclusionOur results confirm a contrasting role of root turnover and litterfall between soil layers in the studied stands, suggesting that tree species composition can mediate the spatial distribution of SOC stocks in mixed forests.

Forest productivity in southwestern Europe is controlled by coupled North Atlantic and Atlantic Multidecadal Oscillations

The North Atlantic Oscillation (NAO) depicts annual and decadal oscillatory modes of variability responsible for dry spells over the European continent. The NAO therefore holds a great potential to evaluate the role, as carbon sinks, of water-limited forests under climate change. However, uncertainties related to inconsistent responses of long-term forest productivity to NAO have so far hampered firm conclusions on its impacts. We hypothesize that, in part, such inconsistencies might have their origin in periodical sea surface temperature anomalies in the Atlantic Ocean (i.e., Atlantic Multidecadal Oscillation, AMO). Here we show strong empirical evidence in support of this hypothesis using 120 years of periodical inventory data from Iberian pine forests. Our results point to AMO+ NAO+ and AMO−NAO− phases as being critical for forest productivity, likely due to decreased winter water balance and abnormally low winter temperatures, respectively. Our findings could be essential for the evaluation of ecosystem functioning vulnerabilities associated with increased climatic anomalies under unprecedented warming conditions in the Mediterranean.The North Atlantic Oscillation (NAO) drives biological responses in terrestrial ecosystems through oscillatory modes of climatic variability. Here, the authors show how landscape scale productivity responses to NAO are contingent upon the Atlantic Multidecadal Oscillation in southwestern Europe.

Disentangling the relative role of climate change on tree growth in an extreme Mediterranean environment

Climate change can impair ecosystem functions and services in extensive dry forests worldwide. However, attribution of climate change impacts on tree growth and forest productivity is challenging due to multiple inter-annual patterns of climatic variability associated with atmospheric and oceanic circulations. Moreover, growth responses to rising atmospheric CO2, namely carbon fertilization, as well as size ontogenetic changes can obscure the climate change signature as well. Here we apply Structural Equation Models (SEM) to investigate the relative role of climate change on tree growth in an extreme Mediterranean environment (i.e., extreme in terms of the combination of sandy-unconsolidated soils and climatic aridity). Specifically, we analyzed potential direct and indirect pathways by which different sources of climatic variability (i.e. warming and precipitation trends, the North Atlantic Oscillation, [NAO]; the Mediterranean Oscillation, [MOI]; the Atlantic Mediterranean Oscillation, [AMO]) affect aridity through their control on local climate (in terms of mean annual temperature and total annual precipitation), and subsequently tree productivity, in terms of basal area increments (BAI). Our results support the predominant role of Diameter at Breast Height (DHB) as the main growth driver. In terms of climate, NAO and AMO are the most important drivers of tree growth through their control of aridity (via effects of precipitation and temperature, respectively). Furthermore and contrary to current expectations, our findings also support a net positive role of climate warming on growth over the last 50 years and suggest that impacts of climate warming should be evaluated considering multi-annual and multi-decadal periods of local climate defined by atmospheric and oceanic circulation in the North Atlantic.

Tree patch distribution drives spatial heterogeneity of soil traits in cork oak woodlands

Key messageSpatial heterogeneity of soil resources is linked to tree patch distribution in Mediterranean cork oak woodlands. Tree patch distribution modifies soil traits by varying litterfall inputs due to different tree covers.ContextThe spatial heterogeneity of soil resources affects the structure and functioning of the different plant communities on ecosystems. In Mediterranean oak woodlands, the scattered trees play a key role in this spatial heterogeneity and might strongly influence ecosystem functioning and its productivity.AimsTo assess the influence of the spatial pattern of trees and litter nutrient content on the spatial heterogeneity of soil properties.MethodsWe used a combination of geostatistical techniques and a linear mixed model to evaluate the spatial heterogeneity of soil and the seasonal and spatial variability of litter nutrient content, respectively.ResultsSoil parameters showed a high spatial heterogeneity. Tree cover was positively related with soil pH, and the organic matter, N, K, and Ca soil content. The return of nutrients to the soil via leaf fall had a marked seasonality and a high spatial variability, but this spatial variability had no effect on the spatial pattern of soil resources.ConclusionThe spatial heterogeneity of soil in cork oak woodlands is mainly driven by tree patches distribution. The importance of the spatial heterogeneity of soil resources and the spatial pattern of trees on the functioning of the dehesa ecosystem makes it necessary to include them in plant nutrition studies and modeling approaches in these ecosystems.

How can my research paper be useful for future meta-analyses on forest restoration plantations?

Statistical meta-analysis is a powerful and useful tool to quantitatively synthesize the information conveyed in published studies on a particular topic. It allows identifying and quantifying overall patterns and exploring causes of variation. The inclusion of published works in meta-analyses requires, however, a minimum quality standard of the reported data and information on the methodology used. Our experience with conducting a meta-analysis on the relationship between seedling quality and field performance is that nearly one third of the apparently relevant publications had to be discarded because essential data, usually statistical dispersion parameters, were not properly reported. In addition, we encountered substantial difficulty to explore the effect of covariates due to the poor description of nursery cultivation methods, plantation location, and management in a significant proportion of the selected primary studies. Thus, we present guidelines for improving methodology detail and data presentation so that future forest restoration-oriented research can be more readily incorporated into meta-analyses. In general, research studies should report data on means, sample size, and any measure of variation even if they are not statistically significant. The online availability of raw data is the best practice to facilitate the inclusion of primary research on meta-analyses. Providing full information about the production of nursery seedlings, such as plant material and experimental conditions, is essential to test whether these procedures might have an effect on seedling quality. In addition, detailed information about field trials such as site climate, soil preparation techniques, previous land use, or post-plantation management, is needed to elucidate whether seedling quality is context-dependent. Thus, we provide a detailed checklist of important information that should be included when reporting forest restoration research involving the use of nursery-produced seedlings. All this will help to quantitatively synthetize current state-of-knowledge and thus contribute to the advancement of the forest restoration discipline.

Estudio, gestión, conservación y restauración de ecosistemas ante el cambio global: 1º Jornadas FORECO en la Universidad de Alcalá

Bonache, J., de Mingo-Sancho, G., Serrada, J., Amengual, P., Perales, J., Martinez, R., Rodado, S., Albornos, E. 2016. Long-term monitoring and evaluation in Spanish National Parks Network. Ecosistemas 25(1): 31-48. Doi.: 10.7818/ECOS.2016.25-1.05 The Spanish National Parks Network, consisting of a selection of natural spaces containing a representative sample of the main existing natural systems in Spain, is a very appropriate setting for research and long-term monitoring, in which the rules protects and promotes the improvement of knowledge and its application to management. In this regard, the National Parks Agency develops, in collaboration with the Autonomous Communities and with specific Scientific advise, a Research Program and a Monitoring and Evaluation Plan of the National Parks Network, latter having programs of ecological, sociological monitoring and functional. The article briefly explains the various monitoring initiatives underway, with examples of outcomes in each: mapping of natural systems, productivity monitoring through remote sensing, monitoring plant health, common bird monitoring, studies of social perception etc. Future prospects and areas for improvement of long-term monitoring in the National Parks Network are explained taking into account the synergies with the LTER Network, which is useful for monitoring in National Parks, especially concerning the application of comparable protocols and information management.