Sérgio Godinho

Chapter 4 Changing Agriculture – Changing Landscapes: What is Going on in the High Valued Montado

The Portuguese montado is a particular land use system, characterized by the combination, in the same area, of the forestry and the grazing components interrelating with each other, in large-scale farm units. Mostly, this system is acknowledged due to its specific landscape character, in a savanna-like phisionomy, with changing densities along a continuous tree cover of holm and cork oaks and grazing in the under cover. The montado is a production system, and its extensive character and particular pattern makes it possible to support a multitude of ecosystem goods and services nowadays valued by society. Nevertheless the system is threatened and the resulting landscape is under strong reduction in the last decades. This paper shows the dimension of the ongoing reduction, for the whole region of Alentejo, since 1960 and up to now. And furthermore, based on a survey to land managers of montado in a Natura 2000 site, it shows how the land management options for the most are still focusing on production and productivist ideals, even when keeping a multifunctional system. These orientations do not result in a radical replacement of the system, and therefore the illusion is kept that the multifunctionality is mantained – but progressively the system loses its balance and the tree cover decays in such a way that the montado disappears. This unique landscape is thus under severe threat. The paper ends with a discussion on the urgent need for integrated policy goals and tools for the montado as a system, and for much more colaboration with the land managers in order to strength the multifunctionalty relevance and support a novel attitude replacing the productivist concept of farming, misleading in the context of this system.

Is the Nature 2000 Network associated with small-game bag results?

Small-game hunting is of great economic importance in Portugal. Game managers claim that game management restrictions regarding shoots inside the Nature 2000 Network negatively influence small-game bags, particularly of hare, wild rabbit and red-legged partridge. We analyse whether different habitat and game management practices are associated with game bags of those species in Alentejo (Portugal). Game bag records from five hunting seasons referring to shoots both inside and outside Nature 2000 sites were analysed. Significant differences concerning habitat and game management descriptors were found between shoots inside and outside Nature 2000 sites. However, this ecological network does not seem to correlate with hare and red-legged partridge game bags, whilst it may negatively influence wild rabbit hunting results. Considering that habitat quality for wild rabbit is rather poor inside the studied Nature 2000 sites, further investigation is needed of the possible negative influence of this ecological network on the species’ game bag. Hare game bags increase with extensive non-irrigated agricultural fields and orchards. Besides these two habitats, red-legged partridge game bags are also favoured by cork oak montado where predators are controlled. The game bags of the three small-game species studied increase with hunting effort. Further, our results suggest that there is a positive relation between hunting effort and small-game population abundance.

Measuring β-diversity by remote sensing: a challenge for biodiversity monitoring

Biodiversity includes multiscalar and multitemporal structures and processes, with different levels of functional organization, from genetic to ecosystemic levels. One of the mostly used methods to infer biodiversity is based on taxonomic approaches and community ecology theories. However, gathering extensive data in the field is difficult due to logistic problems, overall when aiming at modelling biodiversity changes in space and time, which assumes statistically sound sampling schemes. In this view, airborne or satellite remote sensing allow to gather information over wide areas in a reasonable time. Most of the biodiversity maps obtained from remote sensing have been based on the inference of species richness by regression analysis. On the contrary, estimating compositional turnover (beta-diversity) might add crucial information related to relative abundance of different species instead of just richness. Presently, few studies have addressed the measurement of species compositional turnover from space. Extending on previous work, in this manuscript we propose novel techniques to measure beta-diversity from airborne or satellite remote sensing, mainly based on: i) multivariate statistical analysis, ii) the spectral species concept, iii) self-organizing feature maps, iv) multi- dimensional distance matrices, and the v) Raos Q diversity. Each of these measures allow to solve one or several issues related to turnover measurement. This manuscript is the first methodological example encompassing (and enhancing) most of the available methods for estimating beta-diversity from remotely sensed imagery and potentially relate them to species diversity in the field.

Estimating tree canopy cover percentage in a mediterranean silvopastoral systems using Sentinel-2A imagery and the stochastic gradient boosting algorithm

ABSTRACT The availability of accurate and updated spatial information of tree cover in semi-arid and arid silvopastoral systems (SPSs) is crucial to understand their spatial patterns and trends. Although remote-sensing techniques have been proved useful in estimating tree canopy cover in general, more research is required to investigate the capabilities of new high spectral and spatial resolution satellites, such as Sentinel-2A, in predicting tree canopy cover in semi-arid environments. The objective of this study was to explore the capabilities of Sentinel-2A multispectral data, in combination with a stochastic modelling technique, for mapping montado tree canopy cover percentage (CCP) at pixel level. The stochastic gradient boosting algorithm was used to predict tree CCP using Sentinel-2A spectral data, vegetation indices, and textural information as predictor variables. The results of the study showed that the combination of multispectral bands with the selected vegetation indices and grey-level co-occurrence matrix (GLCM) texture features performs well, presenting a coefficient of determination (R2) of 82.8% and an error prediction of 8.68%. The analysis also showed that normalized difference vegetation index (NDVI) and Plant Senescence Reflectance Index (PSRI), as well as homogeneity texture feature, were the most important predictor variables to undertake the complex montado tree canopy cover estimation. In addition, this study demonstrated the usefulness of narrow spectral bands provided by the Sentinel-2A sensor for accurately estimating tree CCP (e.g. Red Edge1 – B5 – for PSRI and NIR2 – B8a – for NDVI computation). The modelling procedure used here emphasizes the effectiveness of stochastic models for predicting tree canopy cover from a complex semi-arid silvopastoral system by using Sentinel-2A multispectral data.

The impact of abandoned/disused marble quarries on avifauna in the anticline of Estremoz, Portugal: does quarrying add to landscape biodiversity?

Abstract Although the extractive operations of quarrying are often considered environmental threats, there is some evidence that abandoned quarries may have a significant positive impact on biodiversity by enhancing habitat quality for several species. In Estremoz Anticlinal, SE Portugal, many of the existing marble quarries have been inactive for decades and were abandoned without any restoration project in progress. The impact of quarry abandonment on avifauna diversity was assessed relative to reference conditions using adjacent rural fields as control areas. No significant differences were found in within-community diversity (alpha diversity) between abandoned quarries and reference sites. However, several dissimilarity indices showed a clear divergence in species composition between abandoned quarries and reference sites. Furthermore, statistically significant differences in species compositions were found between quarries abandoned for different periods. Over time, species composition becomes more similar to that observed in reference sites, reflecting ecological succession and landscape resilience to quarrying. Nevertheless, the studied quarrying landscape exhibited higher gamma and beta diversity than the former traditional landscape; thus, our results suggest that abandoned quarries, rather than damaging and destroying niches, can promote new ecological niches and significantly diversify rural landscapes.

Assessment of landscape composition and configuration via spatial metrics combination: conceptual framework proposal and method improvement

Abstract Landscape transformations have been a central topic in landscape ecology due to their influence on ecosystem services and biodiversity conservation. Landscape dynamics can be very complex and one of the most difficult issues to analyse is the contribution and the effects of landscape composition and configuration changes to the overall impact. We enhanced an existing approach designed to assess landscape transformation via metrics combination. Based on the area and the number of patches, we defined a Landscape Dynamics Typology (LDT) with eight different dynamics. The agro-forestry areas dynamics between 1990 and 2006, in Portugal, is presented as a practical example to show the implementation steps and the outputs obtained. A diagnostic tree is provided to help identify which dynamics are present. This new method provides detailed results concerning the location of the different dynamics within a landscape. The LDT is a versatile tool and is able to accommodate upgrades.

Advances in remote-sensing applications in silvo-pastoral systems

Detailed studies of silvo-pastoral systems (SPS), including studies of changes in degradation patterns, as well as the causes and impacts of degradation, for example, on biogeophysical mechanisms, productivity, and resilience, are crucial for building a broad understanding of the overall process of SPS land-use change and to support policymakers in making informed decisions. Timely and accurate data on the main SPS components, such as tree and herbaceous layer cover fraction, and on the spatio-temporal patterns of SPS are therefore critical for such studies. Free access to remote-sensing data sets obtained from spaceborne sensors, along with imagery from airborne sensors and unmanned aerial vehicles (UAVs), supplemented by data from ground-based instruments, allows researchers to ask new scientific questions and address relevant issues, including monitoring and assessing the spatio-temporal trends of SPS land-use changes. Given the presence of a markedly dry season in SPS systems, and also the spatial fuzziness caused by its tree density variability, the spectral characteristics of these landscapes constitute one of the most challenging aspects for remote sensing. Despite the great progress, especially in recent years, the remote sensing of SPS is still evolving due to the growing availability of high-quality remote-sensing-based products able to effectively address the complexity, diversity, and dynamics of these ecosystems. This special issue addresses these and other challenges, as well as focusing on recent advances in remote sensing of SPS. The special issue includes manuscripts originally presented at the ‘World Congress Silvo-Pastoral Systems 2016: SilvoPastoral Systems in a changing world: functions, management and people’, held 27–30 September 2016 at Évora, Portugal. The articles can be divided into four groups according to the type of platform used to produce remote and proximal sensing data and derived products, namely spaceborne (satellite), airborne, UAVs, ground instruments, and multi-platform (multi-source applications).