Trees as Indicators of the Urban Heat Island

“Bäume als Indikatoren f<e:1> r die urbane Wärmeinsel （BIWi）”（树木作为城市热岛的指示器）项目包括一项试点研究，用于生成和分析不同树木年轮参数（树木年轮宽度、指针年份目录、木材解剖特征）的年表。将采用树木气候学方法在柏林12个不同的城市生态地点获取数据。柏林是德国城市热岛效应最严重的城市。该项目的目的是调查可归因于热岛效应的增长特征的质量和确定性的大小。将根据树木年代学和时间序列分析的既定测量方法和数据处理技术，例如相关和回归分析、主成分分析和极端年份统计，制订一套城市地区的方法。通过这种方法，我们的目标是确定和优先考虑不同地点的平均气候和极端天气条件（旱季、热浪、烟雾）的生长因素。为此目的，树木年轮年表以及处理极端生长反应和木材解剖特征（冰冻圈、密度波动等）的目录将在大约50年的时间内生成。150棵树分布在12个城市生态不同的地点。通过与柏林以外农村地区的站点进行比较，热岛效应最终将与一般气候生长条件分开。除了分析特定的城市树种（平、枫、小叶椴树和类似树种）外，分化过程还特别需要分析橡树、山毛榉或松树等基本森林树种，以防止已识别的城乡多样性被物种特异性差异所模糊。试点研究取得的结果将在两篇硕士论文中进行评估和解释，并在国际知名的同行评审期刊上发表。目前的研究成功地利用树木气候学来分析城市树木的生长。biwi项目中的创新是基于应用城市树木和树木气候学技术来分析城市气候影响，特别关注城市热岛的演变。如果成功，这项初步研究将为后续项目的开展服务。其目标是开发一种通用程序，利用树木气候学数据调查UHIs的空间分布和时空演变。从长远来看，这有助于根据不断变化的气候、人口和城市规划发展，为大学卫生系统的演变提供回顾性和预测证据。

The project "Bäume als Indikatoren für die urbane Wärmeinsel (BIWi)" (trees as indicators of the urban heat island) comprises a pilot study for generating and analyzing chronologies of different tree ring parameters (tree-ring width, pointer year catalogs, wood anatomical features). Dendroclimatological methods to acquire data at 12 urban-ecologically different sites in Berlin will be applied. Berlin is the City in Germany with the largest urban heat island (UHI) effect. The objective of the project is to investigate the magnitude of quality and certainty of growth features that can be attributed to UHI effect. Based on established methods of measurement and data processing techniques in dendrochronology and time series analysis such as correlation and regression analysis, principal component analysis and statistics of extreme years a set of methods for urban areas are to be developed. With this approach we aim at determining and prioritizing the growth factors for mean climatic and extreme weather conditions (dry seasons, heat waves, smog) at different sites in a combination of methods. For this purpose, tree-ring chronologies as well as catalogs addressing extreme growth reactions and wood anatomical features (freeze circles, density fluctuations, etc.) will be generated for approx. 150 trees at 12 urban-ecologically different sites. The UHI effects will finally be separated from general climatic growth conditions by comparison with sites from rural sites outside of Berlin. In addition to the analysis of specific urban tree species (plane, maple, littleleaf linden and similar species) the differentiating process particularly also requires the analysis of basic forest tree species such as oak, beech or pine to prevent the identified urban-rural diversities from being blurred by species specific differences. The results achieved by the pilot study will be evaluated and interpreted within two master theses and additionally be published in an internationally established peer-reviewed journal. Current studies use dendroclimatology successfully to analyze the growth of urban trees. The innovation within the BIWi-project is based on the application of urban trees and dendroclimatological techniques for the analysis of urban climatological effects with particular focus on the evolution of the UHI. In case of success, this pilot study will serve for pursuing a subsequent project. Its goal will be the development of a general procedure investigating the spatial distribution and spatio-temporal evolution of UHIs using dendroclimatological data. Perspectively, this can contribute to giving retrospective and projective evidence for the evolution of UHIs in the light of changing climatic, demographic and urban planning developments.