Barriers against wear affect the spatial distribution of tree saplings in urban woodlands

http://www.elsevier.com/locate/issn/16188667In order to maintain indigenous, self-regenerating tree populations in urban woodlands, it is essential to identify factors affecting the survival of tree seedlings and saplings. In densely populated areas, intensive recreational use may cause considerable wear of the vegetation and soil, and decrease the total number of saplings. At the same time trees, high stones and other structural elements in a woodland patch can act as natural barriers and give shelter against wear. Hence, we hypothesised that with an increasing amount of wear, a greater proportion of tree saplings survive, and is thus found, close to these natural barriers. We tested this hypothesis with observational data, and described the microhabitat associations of different sapling species in detail to define the most favourable or unfavourable microhabitats. We recorded the microhabitats of saplings and randomly chosen points in 30 medium-fertile Picea abies dominant woodlands in Helsinki and the surroundings, Finland. The description included location in relation to physical objects (stones, trees, topography, etc.), other saplings, vegetation and canopy. We then compared the sapling microhabitats to those available (the random points). Our results suggest that the microhabitat associations of saplings change with increasing wear: Sorbus aucuparia, Populus tremula, Rhamnus frangula, Picea abies and Acer platanoides saplings grew more often close to natural barriers (obstacles X30 cm high excluding other saplings), the first three showing a statistically significant response to wear in logistic regression models. The saplings were able to grow in a variety of microhabitats, but the species also differed in their microhabitat associations. In general, saplings grew in groups, and in worn sites the grouping was more pronounced. With increasing wear the saplings associated more positively with trees, canopy cover and lush vegetation

Coming to Terms with the Concept of Moving Species Threatened by Climate Change - A Systematic Review of the Terminology and Definitions

Intentional moving of species threatened by climate change is actively being discussed as a conservation approach. The debate, empirical studies, and policy development, however, are impeded by an inconsistent articulation of the idea. The discrepancy is demonstrated by the varying use of terms, such as assisted migration, assisted colonisation, or managed relocation, and their multiple definitions. Since this conservation approach is novel, and may for instance lead to legislative changes, it is important to aim for terminological consistency. The objective of this study is to analyse the suitability of terms and definitions used when discussing the moving of organisms as a response to climate change. An extensive literature search and review of the material (868 scientific publications) was conducted for finding hitherto used terms (N = 40) and definitions (N = 75), and these were analysed for their suitability. Based on the findings, it is argued that an appropriate term for a conservation approach relating to aiding the movement of organisms harmed by climate change is assisted migration defined as follows: Assisted migration means safeguarding biological diversity through the translocation of representatives of a species or population harmed by climate change to an area outside the indigenous range of that unit where it would be predicted to move as climate changes, were it not for anthropogenic dispersal barriers or lack of time. The differences between assisted migration and other conservation translocations are also discussed. A wide adoption of the clear and distinctive term and definition provided would allow more focused research on the topic and enable consistent implementation as practitioners could have the same understanding of the concept.Peer reviewe

Global environmental change: local perceptions, understandings, and explanations.

Global environmental change (GEC) is an increasingly discussed phenomenon in the scientific literature as evidence of its presence and impacts continues to grow. Yet, while the documentation of GEC is becoming more readily available, local perceptions of GEC- particularly in small-scale societies-and preferences about how to deal with it, are still largely overlooked. Local knowledge and perceptions of GEC are important in that agents make decisions (including on natural resource management) based on individual perceptions. We carried out a systematic literature review that aims to provide an exhaustive state-of-the-art of the degree to and manner in which the study of local perceptions of change are being addressed in GEC research. We reviewed 126 articles found in peer-reviewed journals (between 1998 and 2014) that address local perceptions of GEC. We used three particular lenses of analysis that are known to influence local perceptions, namely (i) cognition, (ii) culture and knowledge, and (iii) possibilities for adaptation.We present our findings on the geographical distribution of the current research, the most common changes reported, perceived drivers and impacts of change, and local explanations and evaluations of change and impacts. Overall, we found the studies to be geographically biased, lacking methodological reporting, mostly theory based with little primary data, and lacking of indepth analysis of the psychological and ontological influences in perception and implications for adaptation. We provide recommendations for future GEC research and propose the development of a "meta-language" around adaptation, perception, and mediation to encourage a greater appreciation and understanding of the diversity around these phenomena across multiple scales, and improved codesign and facilitation of locally relevant adaptation and mitigation strategies

Terms used in three or more publications.

<p>Other terms (used in one or two publications) are: adaptation assisted migration, assisted afforestation, assisted ecosystem migration, assisted population migration, assisted range expansion, assisted reintroduction, assisted species relocation, facilitated translocation, forestry assisted migration, human aided translocation, human assistance of dispersal, human assisted colonisation, human assisted establishment, human assisted migration management, human assisted relocation, managed migration, migration management, managed reintroduction, planned invasions process, plant refuge translocation, species rescue assisted migration, and trans situ conservation.</p

Number of times the three most common terms were used.

<p>Number of times the three most common terms denoting a conservation measure entailing intentional human-mediated dispersal of organisms in response to climate change were used as compared to other terms. AM  =  assisted migration; AC  =  assisted colonization; MR  =  managed relocation; Other  =  all other terms found in the literature search (N = 39; see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0102979#pone-0102979-t001" target="_blank">Table 1</a>).</p

Number of publications mentioning a term for the measure.

<p>Number of publications per year (1994–2012) in which a term was mentioned for the measure entailing intentional human-mediated dispersal of organisms. The total number of publications mentioning a term was 868.</p

Definitions and a model of translocation concepts.

<p>According to the IUCN <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0102979#pone.0102979-IUCN2" target="_blank">[45]</a>, <i>translocation</i> is defined as the movement of living organisms from one area with free release in another.</p