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Author(s): Persaud, Arun; Ludewigt, Bernhard; Ayllon Unzueta, Mauricio; Mixter, William; Poska, Matthew; Croft, Zachary; Brodie, Eoin; Castanha, Cristina; Hicks Pries, Caitlin; Gray, Charles; Brown, Craig

QuestionHow do pollen-based functional and phylogenetic diversity help to explain post-glacial vegetation change in relation to climate and human influence? LocationEstonia and Latvia, NE Europe. MethodsWe used a data set of 1062 pollen samples from 20 sites covering the last 14500yrs to estimate plant richness, evenness, functional and phylogenetic diversity (community-weighted mean and mean pair-wise distance). We adjusted existing functional and phylogenetic diversity measures for the pollen data and tested the methods with a simulation study. The simulations showed that species-based and pollen-based diversity estimates were all significantly positively correlated. ResultsThe Late Glacial (14500-11650cal. yr BP) and the mid-Holocene (8000-4000cal. yr BP) periods showed contrasting values for most of the diversity components, and several diversity estimates were strongly associated with climate. The cold climate during the Late Glacial led to high phylogenetic diversity, and relatively low functional diversity. Climate warming during the transition from the Late Glacial to the Holocene was followed by a decrease in phylogenetic diversity but an increase in functional diversity based on plant height and seed weight. Increasing human impact in the late Holocene was associated with an increase in plant richness and decreases in functional diversity based on plant height and seed weight and in phylogenetic diversity of herbs. ConclusionsPollen-based functional and phylogenetic diversity provide novel insights into post-glacial vegetation change and its drivers. Both functional and phylogenetic diversity were closely related to climatic conditions, suggesting that trait differences play an important role in long-term community response to climate change. Our results indicate that human impact during the last two millennia has influenced functional and phylogenetic diversity negatively by suppressing plants with certain traits (functional convergence) and giving advantage to plants from certain phylogenetic lineages. We see great potential in the further development of functional and phylogenetic diversity methods for pollen data.

From 1778 to 1784, in an attempt to colonise Patagonia, the Spanish Crown transported more than 1,900 peasants from northern Spain to the Rio de la Plata. Based on Enlightenment ideas about economy and society, the Crown used the colonisation scheme to assert control over some of its most marginal subjects. In the hope of transforming these peasants from poverty-stricken burdens on society into filial agents of empire, the Crown invested heavily in the health and wellbeing of the colonising mothers and children, and clearly established the monarchy as a benevolently powerful paternal authority.

Aims Our aim is to reconstruct decadal scale development of historical landscapes during the last 1000 years by means of fossil pollen analysis of annually laminated lake sediments, and detailed historical maps and documents. Location Lake Rouge Tougjarv (Estonia), a small lake with annually laminated lake sediments situated in a dense prehistoric setting. Methods The chronology of the palaeodata is based on the annual laminations supported by AMS 14C and 210Pb dating and 137Cs, 241Am, and spheroidal carbonaceous particle marker horizons. The time-scale and resolution allows fine sampling (the pollen samples generally comprise 3.5 years) and vegetation change reconstruction. Relevant source area of pollen (RSAP) of the lake was estimated, and the statistical zonation, rate of change, palynological richness, and DCA and PCA ordinations were generated on the basis of the pollen data. The historical calibration data set (maps, numerical information on population, domestic stock, farmland division, etc.) is based on archival material preserved in the Estonian Historical Archives. Results The topmost part (0–180 cm) of the sediment column of Lake Rouge Tougjarv, covering the last 1000 years, is visibly laminated carbonaceous gyttja. The varve chronology extends from ad 2000 to ad 1339, with a cumulative ± 9-year error estimate. Beyond this the chronology is extrapolated using the 14C date and varve age–depth estimations. The simulation of the RSAP of Lake Tougjarv shows that the major portion of the pollen loading originating from local vegetation is derived from plants growing within 2000 m of the sampling site. The pollen record divides into five statistically significant subgroups, which fall on the PCA plot into three clusters reflecting the general openness–closedness of the landscape. During the period between ad 1000 and 1200 (RT 1) the Rouge area was generally wooded with birch, spruce and pine forests. The advancement of extensive farming gradually opened up the landscape between ad 1200 and 1650 (RT 2 and RT 3). The maximum openness of the landscape was reached between ad 1650 and 1875 (RT 4), with the most open period in the late eighteenth century. Historical maps from 1684 and 1870–99 and available quantitative data on population, domestic stock, farmland division, etc. show the same trend. The pollen data covering the last 125 years, and maps from 1935 and 1995, show the reduction of arable land in RSAP of the lake under investigation and the reduction of open land to an extent comparable with the end of the seventeenth century. Main conclusions The formation and development of the cultural landscape at Rouge over the last 1000 years is characterized by rapid changes in floristic richness and rates of vegetation change attributed to certain historic processes in the RSAP. Five phases of landscape and social development are clearly distinguished during the last 1000 years. The decadal scale vegetation response to human-induced forcing agrees with historical maps and documents and could be used for past landscapes prior to the period with solid historical data.

Aims and location The potential of pollen records in quantitative climate reconstructions has been widely debated but seldom tested. Our aim is to develop a pollen–climate transfer function for northern Europe and test its performance and inference power by numerical cross-validation with modern climate data. Annual mean temperature (Tann) was assessed as the critical climatic variable because Tann has a distinct south–north gradient (5.5 to )4.7 � C) in the study region with a corresponding zonal vegetation gradient from the hemiboreal zone in the south to the northern boreal zone in the north. Methods We collected 137 pollen surface samples from small- to medium size lakes from southern Estonia to northern Finland. The transfer function for Tann was developed with weighted averaging partial least squares (WA-PLS) regression. All 102 terrestrial pollen and spore types were included in the calculation sum and all 137 surface samples and all 102 taxa were included in the transfer function. The performance of the WA-PLS transfer function was evaluated by leave-oneout cross-validation.