Nuno de Almeida Ribeiro

Introducing the montado, the cork and holm oak agroforestry system of Southern Portugal

The Portuguese montado is an agro-silvo pastoral system quite similar to the dehesa in Spain, and covering in Portugal most of the Southern region of the country, Alentejo. The trees in the montado are cork oh holm oak, and the system is mostly acknowledged due to the cork production, but also due to its singular savanna like land cover pattern, its multiple and complementary productions, the support of a diversity of ecosystems services and its biodiversity. The present special issue covers the diversity of components of the montado and of perspectives required to understand and assess the functioning of the system. This Editorial introduces the montado system, describes its extension and similarities to the dehesa in Spain, and addresses the multiple productions and externalities of the montado. It also refers to the several components of the system. It focus on the uniqueness and values of this system, stressing its potential and threats, and the requirements for integrated knowledge production. In the end of the Editorial, each one of the papers that compose the special issue are presented.

Decline of Mediterranean oak trees and its association with Phytophthora cinnamomi: a review

Mortality events in cork and holm oaks have occurred in the Mediterranean basin since the beginning of the XX century, but severity of decline increased during the 1980s. By that time, the exotic soil borne pathogen Phytophthora cinnamomi was often recovered from declining stands and since then it has been considered the main factor associated with decline. This work analyses data concerning P. cinnamomi surveys in cork and holm oaks trees, pathogenicity tests carried out in controlled experiments, studies about the influence of site characteristics in tree decline and approaches to control the disease. Results of field surveys showed that the pathogen is widespread and pathogenicity tests suggested that host susceptibility to the pathogen is moderate when seedlings are in appropriate watering conditions, particularly cork oaks. Occurrence of decline is also associated with soil characteristics that interfere with root expansion and water retention. We assessed the relative importance of each factor involved in decline and revised the role of P. cinnamomi in cork and holm oak decline.

Leaf-level responses to light in two co-occurring Quercus (Quercus ilex and Quercus suber): leaf structure, chemical composition and photosynthesis

We studied morphological, biochemical and physiological leaf acclimation to incident Photon-Photosynthetic-Flux-Density (PPFD) in Quercus ilex (holm oak) and Quercus suber (cork oak) at Mediterranean evergreen oak woodlands of southern Portugal. Specific leaf area (SLA) decreased exponentially with increasing PPFD in both species. Q. ilex had lower SLA values than Q. suber. Leaf nitrogen, cellulose and lignin concentration (leaf area-based) scaled positively with PPFD. Maximum rate of carboxylation (Vcmax), capacity for maximum photosynthetic electron transport (Jmax), rate of triose-P utilization (VTPU) and the rate of nonphotorespiratory light respiration (Rd) were also positively correlated with PPFD in both Quercus species, when expressed in leaf area but not on leaf mass basis. Q suber showed to have higher photosynthetic potential (Vcmax, Jmaxm and VTPUm) and a higher nitrogen efficient nitrogen use than Q.ilex. Leaf chlorophyll concentration increased with decreasing PPFD, improving apparent quantum use efficiency (Φ) in both Quercus species. We concluded that, in Q.ilex and Q.suber, leaf structural plasticity is a stronger determinant for leaf acclimation to PPFD than biochemical and physiological plasticity.

Integrating differentiated landscape preferences in a decision support model for the multifunctional management of the Montado

A great part of the Alentejo region in Southern Portugal is covered by an agro-silvo pastoral system, the Montado. This traditional land-use system is specific, inter alia, in its ability to join production with favorable conditions for non-production functions. At the present time, as society positively evaluates and even demands cultural and amenity functions from the countryside, the Montado management faces the challenge of integrating production with non-production functions in a way which will result in suitable multifunctionality, and a more sound viability of the whole system. The decision support tool (DST) for the cork oak Montado management, the CORKFITS, based on the single-tree growth model and working at the stand level, is oriented primarily to the management of the production functions, but it is able to integrate also other data that can contribute for a more multifunctionality oriented management. In this exploratory study, the integration in the DST, of the preference distribution, as expressed by landscape users is investigated. The aim was to test a more comprehensive functioning of this tool, where non-production functions are also integrated. The described integration intended to communicate to decision-makers how the change in management practices at tree and under cover level, might alter the satisfaction of expectations of different user groups, as such changes affect the composition of the Montado, at both levels. The users considered are those practicing non-production functions in the Montado. Preferences were assessed through a questionnaire survey applied in the region of Alentejo, in the area of dominance of the cork oak, in the Montado system. The non-production functions are, in this context, related particularly to hunting, aesthetic appreciation related to walking and other leisure activities, to life quality, and to tradition and identity, as well as bee-keeping and mushroom picking. This paper focuses on the description of the specific methodological steps applied for the successful integration of the landscape preferences of different user groups into the DST for the cork oak Montado. Integration has proved to be possible, even if some methodological challenges still need to be faced for a more consistent use of the proposed tool.

Forest property insurance: an application to Portuguese woodlands

Fire is the biggest forest hazard, especially in Mediterranean climate countries, leading to desertification and collapse (Naveh, 2007). Wildfire is among the most dramatic threats to forests (Goldammer, 2004). In many countries, it is not easy to find companies that want to insure forests stands. This can be explained by the following reasons. Firstly, in many countries, forest insurance is not mandatory; so many farmers do not make it. Secondly, insurance companies need to have models based on desegregated and reliable data to estimate the probability of fire occurrences. Finally, it is very difficult for the insurer to estimate the real value of the stands because their values vary with the species, the stand age and market prices. The main objective of this paper is to present simple models that help to estimate ‘fair’ insurance risk premiums, contributing, in this way, to make forest business more appealing and sustainable.

Importance of automatic threshold for image segmentation for accurate measurement of fine roots of woody plants / Význam automatického prahovania na obrazovú segmentáciu pre presné merania jemných koreňov drevín

Abstract The fine roots are considered the key organs for plant survival, growth and productivity. Measurement of fine roots variables is easily and conveniently achieved by means of digital image. The descriptive variables like root area, surface, total length and diameter distribution may be obtained from the image. Analysis of digital image consists from several steps, each of them represents potential source of the error. In this article we want to evaluate the automatic thresholding and its impact on principal variables obtainable from digital scans of the fine roots. We compare 16 different thresholding methods and compare them with the human processed binary images of roots of cork oak (Quercus suber L.). We found some of the thresholding methods perform significantly better than others in the estimation of total projected area however the length estimation error points out a little different order of accuracy Abstrakt Jemné korene sú považované za kľúčové orgány zabezpečujúce prežitie rastliny, jej rast a produkciu. Merania jemných koreňov sú ľahko a pohodlne vykonávateľné pomocou digitálneho obrazu. Popisné veličiny ako plocha koreňov, ich povrch, celková dĺžka či hrúbková štruktúra sa dajú získať z digitálneho obrazu. Analýza digitálneho obrazu pozostáva z niekoľkých krokov, z ktorých každý predstavuje potenciálny zdroj chyby merania. V tomto článku sa zameriavame na automatickú segmentáciu prahovaním a jej vplyv na veličiny získavané z digitálnych skenov jemných koreňov korkového duba (Quercus suber L.). Porovnávame 16 rôznych prahovacích metód a ich správnosť v porovnaní s binárnymi obrazmi vytvorenými ľudským hodnotiteľom. Zistili sme, že niektoré prahovacie metódy dávajú lepšie výsledky ako ostatné v odhade plochy koreňov, ale pred odhad dĺžky koreňov je poradie metód podľa ich správnosti len mierne odlišné

Method for evaluation of coarse cork oak root system by means of digital imaging

Digital imaging is becoming a powerful tool for data storage and information retrieval. Image comparison and similarity evaluation has become part of the information market and it is today a common part of, for example, web search engines. The cork oak tree (Quercus suber L.), the dominant species of the ‘montado’ woodland system is, due to its cultural and socio-economic value, protected by law that prevents extensive destructive studies on an essential part of the tree—the root. Especially in the Mediterranean zone, where the water is the limiting growth factor, the root development studies are of significant interest. In this work we present a method of using digital images for cork oak coarse root systems-evaluation by means of digital imaging. Acquired images of structural roots are processed automatically to prevent subjective decisions by the human observer. The performance of the method, its potential for semantic retrieval and similarity assessment is demonstrated, having as example eight young cork oak root systems, and critical issues for evaluation and conclusion-making, are discussed.

Multi Level Monitoring System for Cork Oak (Quercus Suber L.) Stands in Portugal

Cork oak stands occupy about 22% (750000 ha) of the Portuguese forest area with a relevant economic importance. They are managed in agro-silvo-pasture systems whose sustainability depends on balanced relations between their components. An integrated multilevel monitoring procedure was created in order to understand the system dynamics, with the following components: (i) aerial photography: crown cover diachronic studies, single tree spatial structure modelling; (i) stand: stand dendrometrics, soil and climate monitoring; (iii) tree: growth modelling in mature and young trees, with individual spatial information. The monitoring components as well as the available results are presented.

ESTIMATION OF CORK PRODUCTION USINGAERIAL IMAGERY1

Inventory and prediction of cork harvest over time and space is important to forest managers who must plan and organize harvest logistics (transport, storage, etc.). Common field inventory methods including the stem density, diameter and height structure are costly and generally point (plot) based. Furthermore, the irregular horizontal structure of cork oak stands makes it difficult, if not impossible, to interpolate between points. We propose a new method to estimate cork production using digital multispectral aerial imagery. We study the spectral response of individual trees in visible and near infrared spectra and then correlate that response with cork production prior to harvest. We use ground measurements of individual trees production to evaluate the model’s predictive capacity. We propose 14 candidate variables to predict cork production based on crown size in combination with different NDVI index derivates. We use Akaike Information Criteria to choose the best among them. The best model is composed of combinations of different NDVI derivates that include red, green, and blue channels. The proposed model is 15% more accurate than a model that includes only a crown projection without any spectral information.