Luigi Portoghesi

Assessing and promoting old-growthness of forest stands: Lessons from research in Italy

Abstract Due to a long-standing history of human impact, it is rare to find in Europe old-growth stands associated to primary forests; the term “old-growthness” is more appropriate to assess old-growth forests in European countries: i.e. the degree to which forest stands, which may or may not have been impacted by humans, express the structural variability commonly found in old-growth forests. The paper focuses on operational methods to assess and promote old-growthness in countries, like Italy, where old-growthness detection is a difficult task because of the scarcity of “relatively old” forest stands. Lessons learnt from research experiences carried out in Italy are reviewed; research findings mostly come from unmanaged tracts of previously managed forest stands that have reached structural and compositional traits typical of the mature stage of forest dynamics. A commentary discussion is provided on the following topics: (i) how to operationally assess old-growthness of forest stands, by coupling remote sensing based approaches and snapshot inventories of structural features; (ii) what forest structural attributes appear to be more strictly related to old-growthness in Mediterranean forests and (iii) how to promote old-growthness in managed forest stands. The paper concludes pointing out open research questions and pragmatic considerations for managing forests for old-growthness.

Italian stone pine forests under Rome’s siege: learning from the past to protect their future

Abstract Italian stone pine is a landmark of Mediterranean coastal areas. Today, pinewoods represent environmental amenity areas at risk, being under siege from intensive urbanisation. We present an emblematic case study in Rome’s coastal strip where urban encroachment around pinewoods is somewhat overlooked by urban planning, which may be threatening for their conservation. We studied: (i) changes in land use intensification in the pinewoods’ surroundings over the past 60 years (1949–2008), by means of a synthetic index of landscape conservation (ILC) ranging from 0 (maximum level of anthropogenic landscape alteration) to 1 (maximum level of landscape naturalness); (ii) influence of different landscape protection level on land use intensification. Findings show that in areas with low levels of landscape protection, the ILC had been decreasing in the first 100-m surrounding pinewoods, and within the 1-km buffer. The ILC had been rather stable within areas with high levels of landscape protection. Lessons learnt have implications for spatial development strategies to protect coastal pinewoods from external pressures due to future (planned) urban densification in their surroundings.

Biodiversity conservation and forest management: The case of the sweet chestnut coppice stands in Central Italy

The ecological and economic relevance of sweet chestnut (Castanea sativa Mill.) has long been related to its widespread geographical distribution and multipurpose product potential. In Central Italy, chestnut management represents a paradigmatic example of the potential conflict between landowner targets and biodiversity conservation: options for preserving stand-scale biodiversity are not fully considered as current management is based on monospecific, even-aged coppice stands and clearcutting on wide areas. Relationships between silvicultural treatment and floristic diversity of chestnut coppices are here investigated focusing the attention on rotation length and on the role of thinning. Seven coppice stands were selected in such a way to be of similar size (about 10 ha) and to cover a wide range of ages and a different number of thinnings. Plot sampling was performed across the stands and their floristic diversity was compared and analyzed by means of indicators in order to assess statistical relationships between floristic data and stand structural attributes. The achieved results suggest alternative suitable options for managing chestnut coppice stands in order to enhance biodiversity while maintaining wood production.

The application of the ecosystem approach through sustainable forest management: an Italian case study.

During the last decades adapting silvicultural systems to a changed society, increasingly aware of the multifunctional role of forests, was a much debated issue in Italy. Stemming from this discussion is the systemic silviculture concept, an adaptive forest management tool aimed at cultivating the forest as a self-organizing system and focusing on sustaining its functional efficiency as the best way to enhance forest multi-functionality. This concept has much connection with the Ecosystem Approach defined by the Convention on Biological Diversity as a strategy for the integrated management of land, water and living resources that promotes conservation and sustainable use in an equitable way. In the following a case study is presented where the principles of systemic silviculture are implemented in the management of private and common forest properties in the Serre mountains of the Calabria Region (Italy); relationships with the Ecosystem Approach principles are analyzed in order to evaluate to what extent systemic silviculture can be regarded as a means to bring the EA to the implementation level.

Inference on diversity from forest inventories: a review

A number of international agreements and commitments emphasize the importance of appropriate monitoring protocols and assessments as prerequisites for sound conservation and management of the world’s forest ecosystems. Mandated periodic surveys, like forest inventories, provide a unique opportunity to identify and properly satisfy natural resource management information needs. Distinctively, there is an increasing need for detecting diversity by means of unambiguous diversity measures. Because all diversity measures are functions of tree species abundances, estimation of tree diversity indices and profiles is inevitably performed by estimating tree species abundances and then estimating indices and profiles as functions of the abundance estimates. This strategy can be readily implemented in the framework of current forest inventory approaches, where tree species abundances are routinely estimated by means of plots placed onto the surveyed area in accordance with probabilistic schemes. The purpose of this paper is to assess the effectiveness of this strategy by reviewing theoretical results from published case studies. Under uniform random sampling (URS), that is when plots are uniformly and independently located on the study region, consistency and asymptotic normality of diversity index estimators follow from standard limit theorems as the sampling effort increases. In addition, variance estimation and bias reduction are achieved using the jackknife method. Despite its theoretical simplicity, URS may lead to uneven coverage of the study region. In order to avoid unbalanced sampling, the use of tessellation stratified sampling (TSS) is suggested. TSS involves covering the study region by a polygonal grid and randomly selecting a plot in each polygon. Under TSS, the diversity index estimators are consistent, asymptotically normal and more precise than those achieved using URS. Variance estimation is possible and there is no need to reduce bias.

Tree Community Ordering by Diversity Profiles: an Application to Chestnut Coppices

The ecological and economical relevance of sweet chestnut (Castanea sativa Mill.) has long been related to its widespread geographical distribution and multipurpose product potential. In Italy, chestnut management represents a paradigmatic example of the potential conflict between landowner targets and tree species diversity conservation. Distinctively, the relationships between silvicultural treatment and tree species diversity of chestnut coppices are here investigated by means of diversity profiles to assess tree diversity of six stands in Central Italy. The stands were purposively selected in such a way to be characterized by the same site conditions but with different silvicultural features (age, number of thinning). Plot sampling was performed across the stands and their tree diversity was compared and ordered by means of intrinsic diversity profiles estimated from the sample data. The achieved results suggest alternative suitable options for managing chestnut coppice stands in order to enhance tree biodiversity while maintaining timber production.