Climate change will substantially alter native forest ecosystem dynamics. Increased storm frequencies and severities and longer summer droughts are major threats for the provision of ecosystem goods and services (EG&S) from forests. To adapt forests stands to climate change, two silvicultural measures have been proposed: (i) the promotion of mixed stands and (ii) the integration of exotic tree species that are expected to be adapted to future climatic conditions (in particular from areas with a drier and warmer climate). Non-native tree species as well as mixed stands may be better suited for the expected future climate due to a higher resistance and resilience against disturbances. The combination of mixed stands that consist of native and non-native tree species, may present a suitable compromise between the desired effects on growth and vitality of forests and potential undesired effects on the composition of native species associations and ecosystem processes such as nutrient cycling. Despite high potential benefits of mixed stands, planted forests around the globe are mainly monocultures. To foster the provision of EG&S, more knowledge about the mechanistic functioning of mixtures as well as trade-offs between the provision of different EG&S from mixed and pure stands is necessary. Interdisciplinary research projects are necessary that address effects of mixtures consisting of native and non-native tree species on the composition of various taxonomic groups, ecosystem processes and their consequences for the provision of EG&S. The interdisciplinary research training group 'RTG2300: Enrichment of European beech forests with conifers' addresses this knowledge gap by studying the mechanistic and supplying ecosystem functioning of forest stands of native European beech (Fagus sylvatica L.), Norway spruce (Picea abies L. KARST) and non-native Douglas-fir (Pseudotsuga menziesii MIRB. FRANCO) in Northern Germany. The stand types in this project include pure stands of all three species and mixed beech/spruce and beech/Douglas-fir stands. Each stand type is represented at eight locations resulting in a total of forty study plots. Twenty out of the forty research plots of 0.25 ha size are located in the southern part of the study area in the Solling and Harz mountain ranges, whereas the other twenty plots were selected in the northern part of the study area in the North German plain. The southern plots are located at higher altitudes with lower mean annual temperatures and a higher annual precipitation than those in the north. The stands on the northern plots have less favorable growing conditions than those on the southern plots, in particular due to less precipitation. Here, we provide basic datasets that were collected by the RTG2300. This includes data about location, topography and climate of the research plots, data of the tree inventories and data about the density and spatial structure of the stands that were derived from the tree inventory data.
This dataset provides information about the study design, topography, geographic location and climatic conditions of the research plots of the interdisciplinary research training group 'RTG2300: Enrichment of European beech forests with conifers'. In each of forty forest stands, plots of 0.25 ha in size (called regular measurement plots, RMPs) were established in fall 2017 across the federal state of Lower Saxony, northwest Germany. The plots are grouped in eight so-called 'quintets'. Each quintet comprises five plots representing different forest stand types: three pure plots (European beech (Fagus sylvatica), Douglas-fir (Pseudotsuga menziesii), Norway spruce (Picea abies)) and two beech-conifer mixtures (beech-Douglas-fir and beech-Norway spruce). Four of the eight quintets are located in the southern part of the study area in the Solling and Harz mountain ranges. The other four quintets are located in the northern part of the study area in the North German plain. The southern plots are located in higher altitudes with lower mean annual temperatures and a higher annual precipitation. Growing conditions on the northern plots are less favorable than on the southern sites, in particular with respect to precipitation. On a subset of twenty out of the forty plots, intensive surveys such as root growth measurements, nitrogen retention analyses, or experiments on regeneration dynamics are carried out, besides the regular measurements on all plots. These intensive measurement plots (IMPs) comprise two southern and two northern quintets. Permanent, highly intensive measurements are conducted on special measurement plots (SMPs) that are a subset of 10 out of the 20 IMPs.
This dataset contains information from a tree census on the plots of the interdisciplinary research training group 'RTG2300: Enrichment of European beech forests with conifers'. The tree cesus was carried out during winter 2017/2018 using a Field-Map system (software Version 5x; IFER - Monitoring and Mapping Solutions, Ltd.; Prague; Czech Republic). All living and dead trees with a diameter greater or equal than 7.0 cm were recorded in the 0.25 ha plots (https://doi.pangaea.de/10.1594/PANGAEA.923125) and in a ten meter buffer zone surrounding the plot border. Tree coordinates relative to the plot center were recorded with a laser range finder with an integrated electronic compass (TruPulse Laser 360 R, Laser Technology Inc, Centennial, USA). Tree diameters were measured with a diameter tape preferentially at 1.3 m height. If a diameter measurement at 1.3 m was not possible, the alternative height of the diameter measurement was recorded. Tree species, tree vitality (dead or alive) and tree condition ('normal', 'snag', 'hung_up', 'sloping', 'thrown', 'stump') of each tree and heights of snags were recorded.