Empirical realised niche models for British higher and lower plants - development and preliminary testing

Abstract

Question: Can useful realised niche models be constructed for British plant species using climate, canopy height and mean Ellenberg indices as explanatory variables? Location: Great Britain. Methods: Generalised linear models were constructed using occurrence data covering all major natural and semi‐natural vegetation types (n=40 683 quadrat samples). Paired species and soil records were only available for 4% of the training data (n=1033) so modelling was carried out in two stages. First, multiple regression was used to express mean Ellenberg values for moisture, pH and fertility, in terms of direct soil measurements. Next, species presence/absence was modelled using mean indicator scores, cover‐weighted canopy height, three climate variables and interactions between these factors, but correcting for the presence of each target species in training plots to avoid circularity. Results: Eight hundred and three higher plants and 327 bryophytes were modelled. Thirteen per cent of the niche models for higher plants were tested against an independent survey dataset not used to build the models. Models performed better when predictions were based only on indices derived from the species composition of each plot rather than measured soil variables. This reflects the high variation in vegetation indices that was not explained by the measured soil variables. Conclusions: The models should be used to estimate expected habitat suitability rather than to predict species presence. Least uncertainty also attaches to their use as risk assessment and monitoring tools on nature reserves because they can be solved using mean environmental indicators calculated from the existing species composition, with or without climate data.

How will the semi-natural vegetation of the UK have changed by 2030 given likely changes in nitrogen deposition?

“…The habitat suitability (HS) for individual species was modelled using MultiMOVE (Butler and Smart, 2009;Smart et al, 2010). MultiMOVE is a small ensemble of plant species niche models that predict the suitability of conditions for a plant species under a particular environmental conditions.…”

“…An alternative approach to these simple doseeresponse calculations has been the use of dynamic soil-vegetation model chains combining models such as ForSAFE-VEG, MAGIC, NTM, MOVE and GBMOVE Smart et al, 2010;Sverdrup et al, 2007;Wamelink et al, 2009). In these approaches a dynamic soil model predicts change in the soil environment in response to changing deposition which feeds into a statistical or process-based model of vegetation response to changing soil conditions.…”

Strengths and Weaknesses of Quantitative Climate Reconstructions Based on Late-Quaternary Biological Proxies

“…optimum) of the realised Grinellian niche or the regeneration niche today (e.g. Smart et al 2010). In the past, the realised niches of taxa may have been different for a variety of ecological, environmental, and historical reasons (Jackson & Overpeck 2000;Jackson & Williams 2004) and thus assumption 3 of calibration functions and other climate reconstruction approaches, namely that the ecological responses of taxa today have not changed over the time represented by the fossil assemblages, may not be valid.…”

Pedo-climatic and land use preferences of Gentiana lutea subsp. lutea in central Italy

“…DCA results on the data matrices ("plot-by-G. lutea and herb cover %" matrix and "plot-by-G. lutea individualvariables" matrix) showed short gradients (0.529 S.D., 0.630 S.D., respectively), suggesting that an ordination technique based on the linear model, such as Redundancy analysis, could be used (ter Braak 1995).…”

“…Moreover, considering the altitude distribution range, and especially its lower boundary (1280 m), joint to our results and the rainfall features of the study area (Amici & Spina 2002), we can in-fer that the species thrives when the annual rainfall exceeds 1000-1100 mm, with not less than 250-260 mm in summer, while, as highlighted in figure 1, the AWC should be higher than 50-55, and the summer water deficit should not exceed 28-30 mm yr -1 . These water deficit values may be considered as a threshold value for summer drought stress, which in turn could be useful for calibrating the realised niche breadth (Lawesson & Oksanen 2002, Smart et al 2010) and land suitability for this species.…”