Unravelling the effects of temperature, latitude and local environment on the reproduction of forest herbs

Abstract

Aim : To investigate the effect of temperature, latitude and local environment on the reproductive traits of widespread perennial forest herbs to better understand the potential impacts of rising temperatures on their population dynamics and colonization capacities. Location : Six regions along a latitudinal gradient from France to Sweden. Methods : Within each region, we collected data from three to five populations of up to six species. For each species, several variables were recorded in each region (temperature, latitude) and population (local abiotic and biotic environmental variables), and seed production and germination were estimated. Resource investment in reproduction (RIR) was quantified as seed number x seed mass, while germinable seed output (GSO) was expressed as seed number x germination percentage. We performed linear regression and mixed effect models to investigate the effects of temperature (growing degree hours), latitude and local abiotic and biotic environment on RIR and GSO. Results : Temperature and latitude explained most of the variation in RIR and GSO for early flowering species with a northerly distribution range edge (Anemone nemorosa, Paris quadrifolia and Oxalis acetosella). Reproduction of the more southerly distributed species (Brachypodium sylvaticum, Circaea lutetiana and Primula elatior), in contrast, was independent of temperature/latitude. In the late summer species, B. sylvaticum and C. lutetiana, variation in RIR and GSO was best explained by local environmental variables, while none of the investigated variables appeared to be related to reproduction in P. elatior. Main conclusions : We showed that reproduction of only two early flowering, northerly distributed species was related to temperature. This suggests that the potential reproductive response of forest herbs to climate warming partly depends on their phenology and distribution, but also that the response is to some extent species dependent. These findings should be taken into account when predictions about future shifts in distribution range are made

Impact of land use intensity and temperature on the reproductive performance of Dactylis glomerata populations in the southeastern Alps

“…Several studies have demonstrated different aspects of inter-population variation in seed production and seed mass, including climatic factors (Murray et al 2004;Poncet et al 2009), altitudinal gradients (Totland and Birks 1996;Pluess et al 2005), latitudinal variation (Winn and Gross 1993;Garcia et al 2000;Moles and Westoby 2003;Murray et al 2004;Moles et al 2007;De Frenne et al 2009), soil fertility (Wolfe 1995;Tungate et al 2002) and differences in habitat type (Endels et al 2004;Goulart et al 2006).…”

“…Resource investment in reproduction, i.e. the product of seed number and seed mass, represent an estimate of how many resources are used for sexual reproduction (De Frenne et al 2009). …”

“…An assessment of the relative importance of these factors requires data from a large number of populations and is presently available for very few wild herbaceous species (Totland and Birks 1996;De Frenne et al 2009). Unravelling the effect of temperature on possible future vegetation range shifts compared with other local abiotic and biotic environmental variables is relevant.…”

Combining climate with other influential factors for modelling the impact of climate change on species distribution

“…As Price et al (2004) pointed out, the value of climate change scenarios is not in the forecasts they provide for specific grid cells or geographic locations, but in the possibility of combining the set of continuously varying data that they provide with other spatially referenced factors to produce a rich multidimensional mixture of possible future environments. Given that the species may show differential responses to these factors (De Frene et al 2009), their relative importance for each species should be assessed together with climate before projecting species distribution models to the future. This assessment may be done by producing single-factor models and merging them into combined, and consequently, more balanced models.…”

Herbivory strongly influences among-population variation in reproductive output of Lythrum salicaria in its native range

“…Reproductive output commonly varies among plant populations, and differences in both abiotic conditions (Willson and Price 1980;Ågren 1988;De Frenne et al 2009;Toräng et al 2010) and intensity of biotic interactions (Schemske and Horvitz 1988;Ehrlén 1995;Morris et al 2007;Ågren et al 2008) may contribute to such variation. Determining the processes governing spatial variation in flower and seed production is important not only because of their influence on plant population dynamics and distributions, but also because determining these processes can lead to a greater understanding of among-population variation in selection regimes, and of interactions with pollinators and herbivores that depend on flowers or seeds as a resource.…”