Palaeobiogeographical perspectives on pinus pinea, a controversial and enigmatic mediterranean pine

The origins of some species of economic importance occurring over the Mediterranean Basin have been a traditional matter of debate that has important implications for land management. The case of Pinus pinea L. (Stone pine) is probably one of the most controversial, due to its documented long-term interaction with humans and its presence as a symbolic tree in certain areas of the Mediterranean (e.g., southwestern Iberia and Tuscany). Among the rest of the Mediterranean pines, several features make this pine unique (it has a characteristic crown shape, an edible kernel, cones that require three years to mature, and a very depauperate genetic diversity across its range). In addition, its palaeoecological information is rather limited, as the taxonomic precision attained by pollen analysts is insufficient for this tree and macroremains (such as kernels or anatomically well preserved wood) are needed to unequivocally detect the species in the fossil record. Recent findings of macrofossils of Pinus pinea in inland Iberia (Duero Basin) extend the late- Holocene range of the species, but the palaeobiogeographical information and the exhaustive genetic data available still suggest a very limited natural area (but still not sufficiently well defined) and a long and intense history of linkage to humans.

Modelling the spatio-temporal pattern of primary dispersal in stone pine (Pinus pinea L.) stands in the Northern Plateau (Spain)

Natural regeneration in stone pine (Pinus pinea L.) managed forests in the Spanish Northern Plateau is not achieved successfully under current silviculture practices, constituting a main concern for forest managers. We modelled spatio-temporal features of primary dispersal to test whether (a) present low stand densities constrain natural regeneration success and (b) seed release is a climate-controlled process. The present study is based on data collected from a 6 years seed trap experiment considering different regeneration felling intensities. From a spatial perspective, we attempted alternate established kernels under different data distribution assumptions to fit a spatial model able to predict P. pinea seed rain. Due to P. pinea umbrella-like crown, models were adapted to account for crown effect through correction of distances between potential seed arrival locations and seed sources. In addition, individual tree fecundity was assessed independently from existing models, improving parameter estimation stability. Seed rain simulation enabled to calculate seed dispersal indexes for diverse silvicultural regeneration treatments. The selected spatial model of best fit (Weibull, Poisson assumption) predicted a highly clumped dispersal pattern that resulted in a proportion of gaps where no seed arrival is expected (dispersal limitation) between 0.25 and 0.30 for intermediate intensity regeneration fellings and over 0.50 for intense fellings. To describe the temporal pattern, the proportion of seeds released during monthly intervals was modelled as a function of climate variables – rainfall events – through a linear model that considered temporal autocorrelation, whereas cone opening took place over a temperature threshold. Our findings suggest the application of less intensive regeneration fellings, to be carried out after years of successful seedling establishment and, seasonally, subsequent to the main rainfall period (late fall). This schedule would avoid dispersal limitation and would allow for a complete seed release. These modifications in present silviculture practices would produce a more efficient seed shadow in managed stands.

Modelling seed germination in forest tree species through survival analysis. The Pinus pinea L. case study

The direct application of existing models for seed germination may often be inadequate in the context of ecology and forestry germination experiments. This is because basic model assumptions are violated and variables available to forest managers are rarely used. In this paper, we present a method which addresses the aforementioned shortcomings. The approach is illustrated through a case study of Pinus pinea L. Our findings will also shed light on the role of germination in the general failure of natural regeneration in managed forests of this species. The presented technique consists of a mixed regression model based on survival analysis. Climate and stand covariates were tested. Data for fitting the model were gathered from a 5-year germination experiment in a mature, managed P. pinea stand in the Northern Plateau of Spain in which two different stand densities can be found. The model predictions proved to be unbiased and highly accurate when compared with the training data. Germination in P. pinea was controlled through thermal variables at stand level. At microsite level, low densities negatively affected the probability of germination. A time-lag in the response was also detected. Overall, the proposed technique provides a reliable alternative to germination modelling in ecology/forestry studies by using accessible/ suitable variables. The P. pinea case study highlights the importance of producing unbiased predictions. In this species, the occurrence and timing of germination suggest a very different regeneration strategy from that understood by forest managers until now, which may explain the high failure rate of natural regeneration in managed stands. In addition, these findings provide valuable information for the management of P. pinea under climate-change conditions.

An integral model for natural regeneration of Pinus pinea L. in the Northern Plateau (Spain) = Modelo integral de regeneración natural para Pinus pinea L. en la Meseta Norte (España)

Natural regeneration is an ecological key-process that makes plant persistence possible and, consequently, it constitutes an essential element of sustainable forest management. In this respect, natural regeneration in even-aged stands of Pinus pinea L. located in the Spanish Northern Plateau has not always been successfully achieved despite over a century of pine nut-based management. As a result, natural regeneration has recently become a major concern for forest managers when we are living a moment of rationalization of investment in silviculture. The present dissertation is addressed to provide answers to forest managers on this topic through the development of an integral regeneration multistage model for P. pinea stands in the region. From this model, recommendations for natural regeneration-based silviculture can be derived under present and future climate scenarios. Also, the model structure makes it possible to detect the likely bottlenecks affecting the process. The integral model consists of five submodels corresponding to each of the subprocesses linking the stages involved in natural regeneration (seed production, seed dispersal, seed germination, seed predation and seedling survival). The outputs of the submodels represent the transitional probabilities between these stages as a function of climatic and stand variables, which in turn are representative of the ecological factors driving regeneration. At subprocess level, the findings of this dissertation should be interpreted as follows. The scheduling of the shelterwood system currently conducted over low density stands leads to situations of dispersal limitation since the initial stages of the regeneration period. Concerning predation, predator activity appears to be only limited by the occurrence of severe summer droughts and masting events, the summer resulting in a favourable period for seed survival. Out of this time interval, predators were found to almost totally deplete seed crops. Given that P. pinea dissemination occurs in summer (i.e. the safe period against predation), the likelihood of a seed to not be destroyed is conditional to germination occurrence prior to the intensification of predator activity. However, the optimal conditions for germination seldom take place, restraining emergence to few days during the fall. Thus, the window to reach the seedling stage is narrow. In addition, the seedling survival submodel predicts extremely high seedling mortality rates and therefore only some individuals from large cohorts will be able to persist. These facts, along with the strong climate-mediated masting habit exhibited by P. pinea, reveal that viii the overall probability of establishment is low. Given this background, current management –low final stand densities resulting from intense thinning and strict felling schedules– conditions the occurrence of enough favourable events to achieve natural regeneration during the current rotation time. Stochastic simulation and optimisation computed through the integral model confirm this circumstance, suggesting that more flexible and progressive regeneration fellings should be conducted. From an ecological standpoint, these results inform a reproductive strategy leading to uneven-aged stand structures, in full accordance with the medium shade-tolerant behaviour of the species. As a final remark, stochastic simulations performed under a climate-change scenario show that regeneration in the species will not be strongly hampered in the future. This resilient behaviour highlights the fundamental ecological role played by P. pinea in demanding areas where other tree species fail to persist.

A silviculture-oriented spatio-temporal model for germination in Pinus pinea L. in the Spanish Northern Plateau based on a direct seeding experiment

Natural regeneration in Pinus pinea stands commonly fails throughout the Spanish Northern Plateau under current intensive regeneration treatments. As a result, extensive direct seeding is commonly conducted to guarantee regeneration occurrence. In a period of rationalization of the resources devoted to forest management, this kind of techniques may become unaffordable. Given that the climatic and stand factors driving germination remain unknown, tools are required to understand the process and temper the use of direct seeding. In this study, the spatio-temporal pattern of germination of P. pinea was modelled with those purposes. The resulting findings will allow us to (1) determine the main ecological variables involved in germination in the species and (2) infer adequate silvicultural alternatives. The modelling approach focuses on covariates which are readily available to forest managers. A two-step nonlinear mixed model was fitted to predict germination occurrence and abundance in P. pinea under varying climatic, environmental and stand conditions, based on a germination data set covering a 5-year period. The results obtained reveal that the process is primarily driven by climate variables. Favourable conditions for germination commonly occur in fall although the optimum window is often narrow and may not occur at all in some years. At spatial level, it would appear that germination is facilitated by high stand densities, suggesting that current felling intensity should be reduced. In accordance with other studies on P. pinea dispersal, it seems that denser stands during the regeneration period will reduce the present dependence on direct seeding.

Modelling Pinus pinea forest management to attain natural regeneration under present and future climatic scenarios

Natural regeneration-based silviculture has been increasingly regarded as a reliable option in sustainable forest management. However, successful natural regeneration is not always easy to achieve. Recently, new concerns have arisen because of changing future climate. To date, regeneration models have proved helpful in decision-making concerning natural regeneration. The implementation of such models into optimization routines is a promising approach in providing forest managers with accurate tools for forest planning. In the present study, we present a stochastic multistage regeneration model for Pinus pinea L. managed woodlands in Central Spain, where regeneration has been historically unsuccessful. The model is able to quantify recruitment under different silviculture alternatives and varying climatic scenarios, with further application to optimize management scheduling. The regeneration process in the species showed high between-year variation, with all subprocesses (seed production, dispersal, germination, predation, and seedling survival) having the potential to become bottlenecks. However, model simulations demonstrate that current intensive management is responsible for regeneration failure in the long term. Specifically, stand densities at rotation age are too low to guarantee adequate dispersal, the optimal density of seed-producing trees being around 150 stems·ha−1. In addition, rotation length needs to be extended up to 120 years to benefit from the higher seed production of older trees. Stochastic optimization confirms these results. Regeneration does not appear to worsen under climate change conditions; the species exhibiting resilience worthy of broader consideration in Mediterranean silviculture.

Climatic factors control rodent seed predation in Pinus pinea L. stands in Central Spain

- Context: Pinus pinea L. presents serious problems of natural regeneration in managed forest of Central Spain. The species exhibits specific traits linked to frugivore activity. Therefore, information on plant–animal interactions may be crucial to understand regeneration failure. - Aims: Determining the spatio-temporal pattern of P. pinea seed predation by Apodemus sylvaticus L. and the factors involved. Exploring the importance of A. sylvaticus L. as a disperser of P. pinea. Identifying other frugivores and their seasonal patterns. - Methods: An intensive 24-month seed predation trial was carried out. The probability of seeds escaping predation was modelled through a zero-inflated binomial mixed model. Experiments on seed dispersal by A. sylvaticus were conducted. Cameras were set up to identify other potential frugivores. - Results: Decreasing rodent population in summer and masting enhances seed survival. Seeds were exploited more rapidly nearby parent trees and shelters. A. sylvaticus dispersal activity was found to be scarce. Corvids marginally preyed upon P. pinea seeds. - Conclusions: Survival of P. pinea seeds is climate-controlled through the timing of the dry period together with masting occurrence. Should germination not take place during the survival period, establishment may be limited. A. sylvaticus mediated dispersal does not modify the seed shadow. Seasonality of corvid activity points to a role of corvids in dispersal.

Epigenetic variability in the genetically uniform forest tree species Pinus pinea L

There is an increasing interest in understanding the role of epigenetic variability in forest species and how it may contribute to their rapid adaptation to changing environments. In this study we have conducted a genome-wide analysis of cytosine methylation pattern in Pinus pinea, a species characterized by very low levels of genetic variation and a remarkable degree of phenotypic plasticity. DNA methylation profiles of different vegetatively propagated trees from representative natural Spanish populations of P. pinea were analyzed with the Methylation Sensitive Amplified Polymorphism (MSAP) technique. A high degree of cytosine methylation was detected (64.36% of all scored DNA fragments). Furthermore, high levels of epigenetic variation were observed among the studied individuals. This high epigenetic variation found in P. pinea contrasted with the lack of genetic variation based on Amplified Fragment Length Polymorphism (AFLP) data. In this manner, variable epigenetic markers clearly discriminate individuals and differentiates two well represented populations while the lack of genetic variation revealed with the AFLP markers fail to differentiate at both, individual or population levels. In addition, the use of different replicated trees allowed identifying common polymorphic methylation sensitive MSAP markers among replicates of a given propagated tree. This set of MSAPs allowed discrimination of the 70% of the analyzed trees.

Modeling the future distribution of Mediterranean Pinus species

The potential future distribution of four Mediterranean pines was aimed to be modeled supported by EUFORGEN digital area database (distribution maps), ESRI ArcGIS 10 software’s Spatial Analyst module (modeling environment), PAST (calibration of the model with statistical method), and REMO regional climate model (climatic data). The studied species were Pinus brutia, Pinus halepensis, Pinus pinaster, and Pinus pinea. The climate data were available in a 25 km resolution grid for the reference period (1961-90) and two future periods (2011-40, 2041-70). The climate model was based on the IPCC SRES A1B scenario. The model results show explicit shift of the distributions to the north in case of three of the four studied species. The future (2041-70) climate of Western Hungary seems to be suitable for Pinus pinaster.

Pine wilt disease: global issues, trade and economic impact

Pine wilt disease (PWD) is perhaps the most serious threat to pine forests worldwide. Since it´s discovery in the early XXth century by Japanese forest researchers, and the relationship with its causative agent, the pinewood nematode (PWN) Bursaphelenchus xylophilus, in the 1970s, PWD has wreaked havoc wherever it appears. Firstly in the Far East (Japan, China and Korea) and now, more recently in 1999, in the EU (Portugal). The forest sector in Portugal plays a major role in the Portuguese economy with a 12% contribution to the industrial gross domestic product, 3.2% of the gross domestic product, 10% of foreign trade and 5% of national employment. Maritime pine (Pinus pinaster) is one of the most important pine productions, and industrial activity, such as the production of wood and resin, as well as coastal protection associated with sand dunes. Also, stone pine (Pinus pinea) plays an important role in the economy with a share derived from the exports of high-quality pineon seed. Thus, the tremendous economical and ecological impact of the introduction of a pest and pathogen such as the PWN, although as far as is known, the only species susceptible to the nematode is maritime pine. Immediately following detection, the research team involved (Univ. Évora, INIAP) informed the national plant quarantine and forest authorities, which relayed the information to Brussels and the appropriate EU authorities. A task force (GANP), followed by a national program (PROLUNP) was established. Since then, national surveys have been taking place, involving MADRP (Ministry of Agriculture), the University of Évora and several private corporations (e.g. UNAC). Forest growers in the area are particularly interested and involved since the area owned by the growers organizations totals 700 000 ha, largely affected by PWD. Detection of the disease has led to serious consequences and restrictions regarding exploration and commercialization of wood. A precautionary phytosanitary strip, 3 km-wide, has been recently (2007) established surrounding the affected area. The Portuguese government, through its national program PROLUNP, has been deeply involved since 1999, and in conjunction with the EU (Permanent Phytosanitary Committee, and FVO) and committed to controlling this nematode and the potential spread to the rest of the country and to the rest of the EU. The global impact of the presence of Bursaphelenchus xylophilus or the threat of its introduction and the resulting pine wilt disease in forested areas in different parts of the world is of increasing concern economically. The concern is exacerbated by the prevailing debate on climate change and the putative impact this could have on the vulnerability of the world’s pine forests to this disease. The scientific and regulatory approach taken in different jurisdictions to the threat of pine wilt disease varies from country to country depending on the perceived vulnerability of their pine forests to the disease and/or to the economic cost due to lost trade in wood products. Much of the research surrounding pine wilt disease has been located in the northern hemisphere, especially in southern Europe and in the warmer, coastal, Asian countries. However, there is an increased focus on this problem also in those countries in the southern hemisphere where plantations of susceptible pine have been established over the years. The forestry sector in Australia and New Zealand are on “high alert” for this disease and are practicing strict quarantine procedures at all ports of entry for wood products. As well, there is heightened awareness, as there is worldwide, for the need to monitor wood packaging materials for all imported goods. In carrying out the necessary monitoring and assessment of products for B. xylophilus and its vectors substantial costs are incurred especially when decisions have to be made rapidly and regardless of whether the outcome is positive or negative. Australia’s response recently to the appearance of some dying pines in a plantation illustrated the high sensitivity of some countries to this disease. Some $200,000 was spent on the assessment in order to save a potential loss of millions of dollars to the disease. This rapid, co-ordinated response to the report was for naught, because once identified it was found not to be B. xylophilus. This illustrates the particular importance of taking the responsibility at all levels of management to secure the site and the need of a rapid, reliable diagnostic method for small nematode samples for use in the field. Australia is particularly concerned about the vulnerability of its 1million hectares of planted forests, 80% of which are Pinus species, to attack from incursions of one or more species of the insect vector. Monochamus alternatus incursions in wood pallets have been reported from Brisbane, Queensland. The climate of this part of Australia is such that the Pinus plantations are particularly vulnerable to the potential outcome of such incursions, and the state of Queensland is developing a risk management strategy and a proactive breeding programme in response to this putative threat. New Zealand has 1.6 million hectares of planted forests and 89% of the commercial forest is Pinus radiata. Although the climate where these forests are located tends to be somewhat cooler than that in Australia the potential for establishment and development of the disease in that country is believed to be high. The passage alone of 200,000 m³/year of wood packaging through New Zealand ports is itself sufficient to require response. The potential incursion of insect vectors of pinewood nematode through the port system is regarded as high and is monitored carefully. The enormous expansion of global trade and the continued use of unprocessed/inadequately-processed wood for packaging purposes is a challenge for all trading nations as such wood packaging material often harbours disease or pest species. The extent of this problem is readily illustrated by the expanding economies and exports of countries in south-east Asia. China. Japan and Korea have significant areas of forestland infested with B. xylophilus. These countries too are among the largest exporting countries of manufactured goods. Despite the attempts of authorities to ensure that only properly treated wood is used in the crating and packaging of goods B. xylophilus and/or its insect vector infested materials is being recorded at ports worldwide. This reminds us, therefore, of the ease with which this nematode pest can gain access to forest lands in new geographic locations through inappropriate use, treatment or monitoring of wood products. It especially highlights the necessity to find an alternative to using low-grade lumber for packaging purposes. Lest we should believe that all wood products are always carriers of B. xylophilus and its vectors, it should be remembered that international trade of all kinds has occurred for thousands of years and that lumber-born pests and diseases do not have worldwide distribution. Other physico-biological factors have a significant role in the occurrence, establishment and sustainability of a disease. The question is often raised as to why the whole of southern Europe doesn’t already have B. xylophilus and pine wilt disease. European countries have traded with countries that are infested with B. xylophilus for hundreds of years. Turkey is an example of a country that appears to be highly vulnerable to pine wilt disease due to its extensive forests in the warm, southern region where the vector, Monochamus galloprovincialis, occurs. However, there is no record of the presence of B. xylophilus occurring there despite the importation of substantial quantities of wood from several countries In many respects, Portugal illustrates both the challenge and the dilemma. In recent times B. xylophilus was discovered there in the warm coastal region. The research, administrative and quarantine authorities responded rapidly and B. xylophilus appears to have been confined to the region in which it was found. The rapid response would seem to have “saved the day” for Portugal. Nevertheless, it raises again the long-standing questions, how long had B. xylophilus been in Portugal before it was found? If Lisbon was the port of entry, which seems very likely, why had B. xylophilus not entered Lisbon many years earlier and established populations and the pine wilt disease? Will the infestation in Portugal be sustainable and will it spread or will it die out within a few years? We still do not have sufficient understanding of the biology of this pest to know the answers to these questions.

Metodologias de Sistemas de Informação Geográfica em sistemas de produção florestal : uma aplicação geoestatística

As florestas são uma fonte importante de recursos naturais, desempenhando um papel fulcral na sustentabilidade ambiental. A sua gestão quer territorial quer económica, conduz a uma maximização da produção, sem alteração da qualidade da matéria-prima. Portugal apresenta mais de um terço do seu território coberto por floresta, apresentando uma possibilidade de aplicação de sistemas de gestão, territorial e económica que maximizem a sua produção. Os Sistemas de Informação Geográfica (SIG) são modelos da realidade em que é possível integrar toda a informação disponível sobre um assunto tendo por base um campo comum a todos as variáveis, a localização geográfica. Os SIG podem contribuir de diversas formas para um maior desenvolvimento das rotinas e ferramentas de planeamento e gestão florestal. A sua integração com modelos quantitativos para planeamento e gestão de florestas é uma mais-valia nesta área. Nesta dissertação apresentam-se modelos geoestatísticos, com recurso a Sistemas de Informação Geográfica, de apoio e suporte à produção de pinha em Pinheiro-manso (Pinus pinea L.). Procurando estimar as áreas com melhor propensão à produção, a partir de dados amostrais. Estes foram previamente estudados tendo sido selecionadas quatro variáveis: largura da copa, área basal, altura da árvore e produção de pinha. A geoestatística aplicada, inclui modelos de correlação espacial: kriging, onde são atribuídos pesos às amostras a partir de uma análise espacial baseada no variograma experimental. Foi utilizada a extensão Geostatistical Analyst do ArcGis da ESRI, para realizar 96 krigings para as quatro variáveis em estudo, com diferentes parametrizações, destes foram selecionados 8 krigings. Com base nos critérios de adequação dos modelos e da análise de resultados da predição dos erros - cross validation. O resultado deste estudo é apresentado através de mapas de previsão para a produção de pinha em Pinheiro manso, em que foram analisadas áreas com maior e menor probabilidade de produção tendo-se realizado análises de comparação de variáveis. Através da interseção de todas as variáveis com a produção, podemos concluir que os concelhos com maiores áreas de probabilidade de produção de pinha em Pinheiro manso, da área de estudo, são Alcácer do Sal, Montemor-o-Novo, Vendas Novas, Coruche e Chamusca. Com a realização de um cruzamento de dados entre os resultados obtidos dos krigings, e a Carta de Uso e Ocupação do Solo de Portugal Continental para 2007 (COS2007), realizaram-se mapas de previsão para a expansão do Pinheiro manso. Nas áreas de expansão conseguimos atingir aumentos mínimos na ordem dos 11% e máximo na ordem dos 61%. No total consegue-se atingir aproximadamente 128 mil ha para área de expansão do Pinheiro manso. Superando, os valores esperados pelos Planos Regionais de Ordenamento Florestal, abrangidos pela área da amostra em estudo, em que é esperado um incremento de cerca de 130 mil hectares de área de Pinheiro manso para 2030.

Uso sostenibile dei suoli forestali di ambiente costiero in relazione ai fattori di pressione esistenti

Oggetto di studio del dottorato sono stati i suoli forestali in ambiente litoraneo della Regione Emilia-Romagna. In particolare sono state considerate quattro zone di studio in Provincia di Ravenna: Pineta di San Vitale, aree boscate di Bellocchio, Pineta di Classe e Pineta di Pinarella di Cervia. Lo studio in una prima fase si è articolato nella definizione dello stato del sistema suolo, mediante la caratterizzazione pedologica delle zone di studio. A tale scopo è stata messa a punto un’adeguata metodologia d’indagine costituita da un’indagine ambientale e successivamente da un’indagine pedologica. L’indagine ambientale, mediante fotointerpretazione ed elaborazione di livelli informativi in ambito GIS, ha permesso di individuare ambiti pedogenetici omogenei. L’indagine pedologica in campo ha messo in luce l’elevata variabilità spaziale di alcuni fattori della pedogenesi, in particolar modo l’andamento microtopografico tipico dei sistemi dunali costieri e la profondità della falda freatica del piano campagna. Complessivamente sono stati aperti descritti e campionati 40 profili pedologici. Sugli orizzonti diagnostici di questi sono state eseguite le seguenti analisi: tessitura, pH, calcare totale, carbonio organico, azoto kjeldahl, conduttività elettrica (CE), capacità di scambio cationico (CSC) e calcare attivo. I suoli presentano, ad eccezione della tessitura (generalmente grossolana), un’elevata variabilità delle proprietà chimico fisiche in funzione della morfologia, della profondità e della vicinanza della falda freatica. Sono state riscontrate diverse correlazioni, tra le più significative quelle tra carbonio organico e calcare totale (coeff. di correlazione R = -0.805 per Pineta di Classe) e tra calcare totale e pH (R = 0.736), dalle quali si è compreso in che misura l’effetto della decarbonatazione agisce nei diversi ambiti pedogenetici e tra suoli con diversa età di formazione. Il calcare totale varia da 0 a oltre 400 g.kg-1 e aumenta dalla superficie in profondità, dall’entroterra verso la costa e da nord verso sud. Il carbonio organico, estremamente variabile (0.1 - 107 g.kg-1), è concentrato soprattutto nel primo orizzonte superficiale. Il rapporto C/N (>10 in superficie e molto variabile in profondità) evidenzia una efficienza di umificazione non sempre ottimale specialmente negli orizzonti prossimi alla falda freatica. I tipi di suoli presenti, classificati secondo la Soil Taxonomy, sono risultati essere Mollic/Sodic/Typic Psammaquents nelle zone interdunali, Typic Ustipsamments sulle sommità dunali e Oxiaquic/Aquic Ustipsamments negli ambienti morfologici intermedi. Come sintesi della caratterizzazione pedologica sono state prodotte due carte dei suoli, rispettivamente per Pineta di San Vitale (scala 1:20000) e per le aree boscate di Bellocchio (scala 1:10000), rappresentanti la distribuzione dei pedotipi osservati. In una seconda fase si è focalizzata l’attenzione sugli impatti che le principali pressioni naturali ed antropiche, possono esercitare sul suolo, condizionandone la qualità in virtù delle esigenze del soprasuolo forestale. Si è scelta la zona sud di Pineta San Vitale come area campione per monitorarne mensilmente, su quattro siti rappresentativi, le principali caratteristiche chimico-fisiche dei suoli e delle acque di falda, onde evidenziare possibili correlazioni. Le principali determinazioni svolte sia nel suolo in pasta satura che nelle acque di falda hanno riguardato CE, Ca2+, Mg2+, K+, Na+, Cl-, SO4 2-, HCO3 - e SAR (Sodium Adsorption Ratio). Per ogni sito indagato sono emersi andamenti diversi dei vari parametri lungo i profili, correlabili in diversa misura tra di loro. Si sono osservati forti trend di aumento di CE e degli ioni solubili verso gli orizzonti profondi in profili con acqua di falda più salina (19 – 28 dS.m-1) e profonda (1 – 1.6 m dalla superficie), mentre molto significativi sono apparsi gli accumuli di sali in superficie nei mesi estivi (CE in pasta satura da 17.6 a 28.2 dS.m-1) nei profili con falda a meno di 50 cm dalla superficie. Si è messo successivamente in relazione la CE nel suolo con diversi parametri ambientali più facilmente monitorabili quali profondità e CE di falda, temperatura e precipitazioni, onde trovarne una relazione statistica. Dai dati di tre dei quattro siti monitorati è stato possibile definire tali relazioni con equazioni di regressione lineare a più variabili. Si è cercato poi di estendere l’estrapolabilità della CE del suolo per tutte le altre casistiche possibili di Pineta San Vitale mediante la formulazione di un modello empirico. I dati relativi alla CE nel suolo sia reali che estrapolati dal modello, sono stati messi in relazione con le esigenze di alcune specie forestali presenti nelle zone di studio e con diverso grado di tolleranza alla salinità ed al livello di umidità nel suolo. Da tali confronti è emerso che per alcune specie moderatamente tolleranti la salinità (Pinus pinea, Pinus pinaster e Juniperus communis) le condizioni critiche allo sviluppo e alla sopravvivenza sono da ricondursi, per la maggior parte dei casi, alla falda non abbastanza profonda e non tanto alla salinità che essa trasmette sull’intero profilo del suolo. Per altre specie quali Quercus robur, Populus alba, Fraxinus oxycarpa e Ulmus minor moderatamente sensibili alla salinità, ma abituate a vivere in suoli più umidi, la salinità di una falda troppo prossima alla superficie può ripercuotersi su tutto il profilo e generare condizioni critiche di sviluppo. Nei suoli di Pineta San Vitale sono stati inoltre studiati gli aspetti relativi all’inquinamento da accumulo di alcuni microtossici nei suoli quali Ag, Cd, Ni e Pb. In alcuni punti di rilievo sono stati osservati moderati fattori di arricchimento superficiale per Pb e Cd riconducibili all’attività antropica, mentre le aliquote biodisponibili risultano maggiori in superficie, ma all’interno dei valori medi dei suoli italiani. Lo studio svolto ha permesso di meglio conoscere gli impatti sul suolo, causati dalle principali pressioni esistenti, in un contesto dinamico. In particolare, si è constatato come i suoli delle zone studiate abbiano un effetto tampone piuttosto ridotto sulla mitigazione degli effetti indotti dalle pressioni esterne prese in esame (salinizzazione, sodicizzazione e innalzamento della falda freatica). Questo è dovuto principalmente alla ridotta presenza di scambiatori sulla matrice solida atti a mantenere un equilibrio dinamico con le frazioni solubili. Infine le variabili ambientali considerate sono state inserite in un modello concettuale DPSIR (Driving forces, Pressures, States, Impacts, Responces) dove sono stati prospettati, in via qualitativa, alcuni scenari in funzione di possibili risposte gestionali verosimilmente attuabili, al fine di modificare le pressioni che insistono sul sistema suolo-vegetazione delle pinete ravennati.

Comportamiento de coníferas bajo riego : Mendoza, Argentina

La provincia de Mendoza, ubicada en el centro-oeste de la Argentina, tiene una extensión de 150 830 km2. Prácticamente todas las actividades agropecuarias y forestales están concentradas en el 3 % de su territorio que es posible irrigar. Al oeste, en el límite con Chile, está la cadena montañosa que forma parte de la región fitogeográfica del Desierto Andino que se extiende por más de 500 km, con un ancho promedio de 100 km. El objetivo del trabajo fue introducir algunas especies de coníferas y evaluar su comportamiento en dicha región fitogeográfica, con la finalidad de lograr un aprovechamiento forestal, proteger el suelo contra la erosión hídrica y/o eólica, modificar el paisaje y desarrollar áreas de explotación turística. Las especies seleccionadas en esta primera etapa fueron: Cedrus deodara, Cupressus arizonica, Cupressus macrocarpa, Juniperus virginiana, Pinus griffithii, Pinus halepensis, Pinus nigra, Pinus pinaster, Pinus pinea y Pinus radiata. Las experiencias se llevaron a cabo en dossitios, separados por más de 150 km, y situados a 1 050 y 2 000 msnm, respectivamente. Se tomaron datos de supervivencia, altura y diámetro de los individuos, y se efectuaron observaciones sobre su hábito de crecimiento y condiciones fitosanitarias. Las principales conclusiones fueron las siguientes: 1. Todas las especies mostraron buen estado fitosanitario sin haberse detectado ninguna plaga o enfermedad de importancia. 2. El hábito de crecimiento fue el correspondiente a cada especie; sólo hubo fustes bifurcados en algunos individuos de Pinus pinea. 3. Las especies que evidenciaron mayor aptitud fueron: Juniperus virginiana, Cupressus arizonica, Pinus pinea, Pinus pinaster y Cupressus macrocarpa.

Comportamiento de coníferas bajo riego en Dique Yaucha : Mendoza, Argentina

La provincia de Mendoza, que se ubica en el Centro-Oeste de la República Argentina, posee una extensión de 150.830 km2. Prácticamente todas las actividades agropecuarias y forestales están concentradas en el 3% de su territorio que es posible irrigar. Al oeste, en el límite con la República de Chile, está la cadena montañosa que forma parte de la región fitogeográfica del Desierto Andino que se extiende por más de 500 km, con un ancho promedio de 100 km. El objetivo de este trabajo fue evaluar la supervivencia y el comportamiento de distintas especies de coníferas en zonas del piedemonte mendocino. Para ello se instaló una parcela experimental en el Dique Yaucha, ubicado en el Departamento de San Carlos a 34°00' S y 69°07' O, a una altura de 1213 msnm. Las especies del ensayo fueron: Pinus pinea L., Pinus halepensis Mill. y Cupressus arizonica Greene. Se llevaron plantas de aproximadamente 0,70 m de altura, que se instalaron a una distancia de plantación definitiva de 3 x 3 m y se regaron superficialmente por surcos. Se tomaron periódicamente datos dasométricos de diámetro altura de pecho (DAP) de todas las plantas, altura total de los árboles promedio de cada especie, registrándose además las fallas producidas y el estado sanitario. Los resultados obtenidos a la edad de 17 años son: Pinus pinea: diámetro promedio 17 cm, altura 6,60 m y 22,5% de fallas; Pinus halepensis: diámetro promedio 16 cm, altura 8,60 m y 12,2% de fallas; Cupressus arizonica: diámetro promedio 20 cm, altura 7,75 m y 18,1% de fallas. Es de destacar que P. pinea presenta el 6% de fustes bifurcados a baja altura. Todas las especies tienen un buen estado sanitario, no registrándose hasta la fecha plagas o enfermedades que hayan afectado el desarrollo del ensayo.