The trend of ecological thought in Europe has always differed somewhat from that which is at the time in vogue in America. It is peculiarly important, therefore, that American ecologists keep as close an understanding as possible of what is going on across the water. For this purpose the little volume by BRAUN-BLANQUET' is most admirable. His citation of literature is extensive, and extends right up to the date of publication. The very active Scandinavian and Russian ecologists are freely quoted, and much American research is reviewed. The book is a detailed summary of research methods, in fact, together with a critical evaluation of each proposal, and much sound philosophizing. The introductory page points out the difference between studies of the individual organism and studies of communities. Choosing for this volume the second viewpoint, plant sociology is defined as the study of all the phenomena that have to do with the life of plants in social units. Section I discusses commensalism very briefly, and competition at length. Section II, the remainder of the book, presents in order the five principal problems of plant sociology: (i) organization or structure of communities; (2) synecologv, the relation of communities to one another and to the rest of the environment; (3) syngenetics, the origin and decline of plant communities; (4) synchorology, the occurrence and distribution of communities; (5) classification of communities (systematics). The first topic (organization) stands today at the focus of phytosociologic activities. The structure of the community "is the indispensable foundation for an unbiased treatment" of all the related problems. And it is this section that is most needed in American thought and practice. A difficulty arises in finding English equivalents for the terms Assoziation, Einzelbestand, Subassoziation, Fazies, Assoziationsfragment, Siedlung, Vegetationsfleck, Verein, Synusie, and Formation. It is indeed apparent that formation, association, society, as proposed by CLEMENTS and by LIVINGSTON and SHREVE, do not exactly correspond with the categories used by European botanists. It is to be hoped that a clear definition of terms may be decided upon at the forthcoming Cambridge conference. The characteristics of a community are considered under the following heads:

Plant SociologyPflanzensoziologie.J. Braun-Blanquet

Lithobionts (rock-dwelling organisms) have been recognized as agents of aesthetic and physico-chemical deterioration of stonework In consequence, their removal from cultural heritage stone surfaces (CHSS) is widely considered a necessary step in conservation interventions On the other hand, lithobiontic communities, including microbial biofilms ('biological patinas'), can help integrate CHSS with their environmental setting and enhance biodiversity Moreover, in some cases bioprotective effects have been reported and even interpreted as potential biotechnological solutions for conservation This paper reviews the plethora of traditional and innovative methodologies to characterize lithobionts on CHSS in terms of biodiversity, interaction with the stone substrate and impacts on durability In order to develop the best management and conservation strategies for CHSS, such diagnosis should be acquired on a case-by-case basis, as generalized approaches are unlikely to be suitable for all lithobionts, lithologies, environmental and cultural contexts or types of stonework Strategies to control biodeteriogenic lithobionts on CHSS should similarly be based on experimental evaluation of their efficacy, including long-term monitoring of the effects on bioreceptivity, and of their environmental safety This review examines what is known about the efficacy of control methods based on traditional-commercial biocides, as well as those based on innovative application of substances of plant and microbial origin, and physical techniques A framework for providing a balanced scientific assessment of the role of lithobionts on CHSS and integrating this knowledge into management and conservation decision-making is presented

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A review of the nature, role and control of lithobionts on stone cultural heritage: weighing-up and managing biodeterioration and bioprotection.

Cultural heritage sites such as historical or sacred areas provide suitable habitats for plants and play an important role in nature conservation, particularly in human-modified contexts such as urban environments. However, such sites also provide opportunities for the spread of invasive species, whose impact on monuments has been raising growing concerns. The aim of this study was to investigate the patterns of distribution and spread of invasive plants in heritage areas, taking the city of Rome as an example. We focused on woody species as they pose the greatest threat to the conservation of monuments, owing to the detrimental effects of their root system. We analysed changes in the diversity and traits of native and non-native flora growing on the walls of 26 ancient sites that have been surveyed repeatedly since the 1940s. We found that the diversity of the native flora has steadily decreased, while there has been an increase in non-native, larger and more damaging species. The introduced species that have expanded most are ornamental wind- or bird-dispersed trees, which represent a major management problem as their propagules can reach the upper sections of the monuments, where they become more difficult to control. The most widespread and damaging of such species is Ailanthus altissima, which has recently been included among the invasive species of European Union concern (EU Regulation 2019/1262). Our findings show that plant invasion is an emerging challenge for the conservation of heritage sites and needs to be prioritized for management to prevent future expansion.

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Plant invasion as an emerging challenge for the conservation of heritage sites: the spread of ornamental trees on ancient monuments in Rome, Italy

Medium-term field evaluation of several widely used cleaning-restoration techniques applied to algal biofilm formed on a granite-built historical monument

It is well acknowledged that plants in urban areas provide multiple ecosystem services. They contribute improving ambient quality and mitigating negative impacts of human presence, beautifying the anthropic environment, and promoting place identity and cultural heritage. However, the existence of plants in general, and trees in particular, cannot be considered independent on urban activities and infrastructures. Release of plant volatile compounds is profoundly affected in urban environments, in turn modifying plant relationships with other living organisms, both plants and animals, and affecting air chemistry and quality. Plants also interfere with stone artifacts, cultural and historical heritage. Plant-human coexistence requires precise and adequate managing measures, which have often been ignored in cities’ government and planning. Plants and humans (and human’s infrastructures) are frequently considered as independent from each other and plant requirements are often disregarded, thus causing difficult or erroneous management and/or environmental damage. We review some of the most important ecosystem services provided by plants in urban environment, and also focus on possible negative effects of plants that may become relevant if urban vegetation is improperly managed and unintegrated in proper city planning, both of historical centers and of recent or new neighboroughs.

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A Survey of Multiple Interactions Between Plants and the Urban Environment

Archaeological sites can represent a refuge for plant and animal species, protecting them from the pressures of urbanisation. However, sometimes these environmental resources can lead to negative consequences for the monuments. In order to investigate such contrasting effects, we selected the UNESCO World Heritage Site Etruscan necropolis known as “La Banditaccia” (Cerveteri, Italy). We performed floristic and phytosociological analyses, and observations on roots interactions with monuments on several tombs (9 tumuli and 5 cube-shaped tombs) and applied commonly used indices to evaluate damages to the structures. The study revealed rich biodiversity of the site and the presence of rare plants, but also of some invasive species. The analysis of the phytosociological sets showed differences among vegetation types found on the tumuli as a function of the varying degrees of anthropization. Abundant plant colonisation was detected on the top of the tumuli, sometimes causing damages to the structures. The results of the Impact Index analysis showed that the dynamic evolution of vegetation constitutes a significant risk to the archaeological structures. We suggest that careful management of vegetation should achieve equilibrium between the management requirements for the monuments and conservation of naturalistic values. A deeper evaluation of the interactions between plants and monuments is however necessary.

Safeguarding natural and cultural heritage on Etruscan tombs (La Banditaccia, Cerveteri, Italy)

Vegetation management of archaeological sites is a recurrent problem when considering the conservation of historic structures and biodiversity. In the UNESCO site of the Etruscan necropolis...

Fabiola Benelli

Papers

Safeguarding natural and cultural heritage on Etruscan tombs (La Banditaccia, Cerveteri, Italy)

Trends of plant communities growing on the Etruscan tombs (Cerveteri, Italy) related to different management practices