Viktoria Wagner

Low genetic variability and strong differentiation among isolated populations of the rare steppe grass Stipa capillata L. in Central Europe

Stipa capillata L. (Poaceae) is a rare grassland species in Central Europe that is thought to have once been widespread in post-glacial times. Such relict species are expected to show low genetic diversity within populations and high genetic differentiation between populations due to bottlenecks, long-term isolation and ongoing habitat fragmentation. These patterns should be particularly pronounced in selfing species. We analysed patterns of random amplified polymorphic DNA (RAPD) variation in the facultatively cleistogamous S. capillata to examine whether genetic diversity is associated with population size, and to draw initial conclusions on the migration history of this species in Central Europe. We analysed 31 S. capillata populations distributed in northeastern, central and western Germany, Switzerland and Slovakia. Estimates of genetic diversity at the population level were low and not related to population size. Among all populations, extraordinarily high levels of genetic differentiation (amova: phi(ST) = 0.86; Bayesian analysis: theta(B) = 0.758) and isolation-by-distance were detected. Hierarchical amova indicated that most of the variability was partitioned among geographic regions (59%), or among populations between regions when the genetically distinct Slovakian populations were excluded. These findings are supported by results of a multivariate ordination analysis. We also found two different groups in an UPGMA cluster analysis: one that contained the populations from Slovakia, and the other that combined the populations from Germany and Switzerland. Our findings imply that S. capillata is indeed a relict species that experienced strong bottlenecks in Central Europe, enhanced by isolation and selfing. Most likely, populations in Slovakia were not the main genetic source for the post-glacial colonization of Central Europe.

Declining Genetic Diversity and Increasing Genetic Isolation toward the Range Periphery of Stipa pennata, a Eurasian Feather Grass

A common assumption in ecology and evolutionary biology is that genetic diversity declines and differentiation increases toward the edge of a species’ geographic range, where populations tend to be smaller and more isolated. We tested these predictions in a characteristic Eurasian steppe plant, Stipa pennata, by inspecting 230 AFLP bands in 26 populations (345 individuals) along a 3300-km longitudinal gradient from the range core, in Russia, to the range periphery, in central Europe. Overall, our study species showed low genetic diversity within populations (mean proportion of polymorphic ) and moderately high genetic differentiation among them (mean ). As predicted, genetic diversity declined significantly from the range core to the periphery but was not correlated with population size. Pairwise genetic differentiation was significantly higher among peripheral populations than central populations but did not show a pronounced relationship with geographic distance. Our results indicate that peripheral populations may experience higher genetic drift and lower gene flow than their central counterparts, possibly because of smaller population sizes, spatial isolation, and a more complex landscape structure. In addition, historic range fluctuations and the mixed breeding system could have enhanced the observed patterns in our study species.

Can local adaptation research in plants inform selection of native plant materials? An analysis of experimental methodologies.

Local adaptation is used as a criterion to select plant materials that will display high fitness in new environments. A large body of research has explored local adaptation in plants, however, to what extent findings can inform management decisions has not been formally evaluated. We assessed local adaptation literature for six key experimental methodologies that have the greatest effect on the application of research to selecting plant materials for natural resource management: experimental environment, response variables, maternal effects, intraspecific variation, selective agents, and spatial and temporal variability. We found that less than half of experiments used reciprocal transplants or natural field conditions, which are both informative for revegetation and restoration. Population growth rate was rarely (5%) assessed, and most studies measured only single generations (96%) and ran for less than a year. Emergence and establishment are limiting factors in successful revegetation and restoration, but the majority of studies measured later life‐history stages (66%). Additionally, most studies included limited replication at the population and habitat levels and tested response to single abiotic selective factors (66%). Local adaptation research should be cautiously applied to management; future research could use alternative methodologies to allow managers to directly apply findings.

Herbicide usage for invasive non‐native plant management in wildland areas of North America

Summary In North America, herbicides are commonly used to control non-native invasive plants on public wildlands. Little is known about the magnitude, efficacy and financial costs of this practice, although this information is crucial for policymakers, researchers, land managers, pesticide producers and the general public. In Canada and Mexico, herbicide usage data have not been tracked by agencies. In the USA, data archiving has been implemented by federal land managing agencies. However, while area sprayed and amounts of herbicides have been documented to varying degrees, efficacy and financial costs have not been recorded in a standardized and consistent manner and data publication has been insufficient. Based on requested data, we estimate that in the USA, half a million hectares of public wildlands were sprayed with herbicides in 2010, representing 201 tonnes. Although non-selective, glyphosate was the most commonly used active ingredient. Synthesis and applications. Increasing efforts by land management agencies to collect and share herbicide usage data is a key step towards narrowing the knowledge gap on herbicide usage in invasive non-native plant management on public wildlands. Land managers and policymakers in particular would benefit from an enhanced flow of information on efficacy, costs and effects of herbicides.

Semi-Dry Grassland Restoration in the Se Alpine Foreland of Austria – A Study of Early Spontaneous Colonisation Patterns

Abstract We investigated early spontaneous colonisation patterns during semi-dry grassland restoration at two sites in SE Austria. The sites were left to regenerate passively without addition of plant propagules on a former arable field and an apple orchard. The sites were prepared only by ploughing (arable field) or clear cutting (apple orchard) and subsequently mowed annually. We studied whether, four years after project initiation, target species from adjacent semi-dry grasslands had established at the restored sites. We asked: 1) Does passive restoration lead to the establishment of target species? 2) Do abiotic parameters or distance to reference sites explain early colonisation patterns? 3) Do plant traits predict the colonisation success of different species? At each site, we collected data in 4 m × 4 m plots, in which we sampled the vegetation, analysed abiotic parameters (soil potassium- and phosphorus-content, soil-pH, slope) and recorded the minimum distance to the reference site. We tested for correlations between abiotic variables, plant traits and colonisation success. Colonisation patterns were not driven by abiotic soil conditions but rather by nearest distance to the reference sites. In addition, the vegetation developed differently in the former arable field and the apple orchard. Competitive species of the Arrhenatherion and thermophilic ruderal associations dominated the early restoration stage at both sites. Passive restoration of semi-dry grasslands on former agricultural land is unlikely to succeed unless complemented by initial ploughing, nutrient stripping and addition of propagules of rare species. Izvleček Preučevali smo vzorce zgodnje naselitve vrst med obnovo polsuhih travišč na dveh lokacijah v jugovzhodni Avstriji. Travišča smo prepustili pasivni obnovi brez vnosa propagul na nekdanjo obdelano površino in sadovnjak jablan. Obe površini smo predhodno obdelali tako, da smo polje preorali, sadovnjak pa posekali in nato kosili vsako leto. Po štirih letih od začetka projekta smo spremljali, ali se na obnovljenih površinah pojavljajo tarčne vrste s sosednjih polsuhih travišč. Zanimalo nas je: 1) Ali pasivna obnova omogoča naselitev tarčnih vrst? 2) Ali lahko z abiotskimi dejavniki ali oddaljenostjo ciljnega travišča razložimo vzorce zgodnje naselitve? 3) Ali lahko z rastlinskimi znaki napovemo uspešnost naselitve različnih vrst? Na vsaki lokaciji smo postavili poskusne ploskve 4 m × 4 m, kjer smo vzorčili vegetacijo, abiotske dejavnike (vsebost kalija in fosforja v tleh, pH tal, naklon) in izmerili minimalno oddaljenost od ciljnega travišča. Testirali smo korelacijo med abiotskimi dejavniki, rastlinskimi znaki in uspešnostjo naselitve vrst. Vzorci kolonizacije so bolj odvisni od bližine ciljnega travišča kot pa od abiotskih dejavnikov tal, poleg tega se je vegetacija razvijala drugače na nekdanji njivi kot v sadovnjaku. Na obeh rastiščih so v zgodnjih fazah obnove prevladovale konkurenčno uspešnejše vrste zveze Arrhenatherion in termofilnih ruderalnih združb. Pasivna obnova polsuhih travišč na nekdanjih obdelovanih površinah bo verjetno neuspešna brez predhodnega oranja, odstranjevanja hranil in dodajanja propagul redkih vrst

Strong indirect herbicide effects on mycorrhizal associations through plant community shifts and secondary invasions

Million of acres of U.S. wildlands are sprayed with herbicides to control invasive species, but relatively little is known about non-target effects of herbicide use. We combined greenhouse, field, and laboratory experiments involving the invasive forb spotted knapweed (Centaurea stoebe) and native bunchgrasses to assess direct and indirect effects of the forb-specific herbicide picloram on arbuscular mycorrhizal fungi (AMF), which are beneficial soil fungi that colonize most plants. Picloram had no effect on bunchgrass viability and their associated AMF in the greenhouse, but killed spotted knapweed and reduced AMF colonization of a subsequent host grown. Results were similar in the field where AMF abundance in bunchgrass-dominated plots was unaffected by herbicides one year after spraying based on 16:1ω5 phospholipid fatty acid (PLFA) and neutral lipid fatty acid (NLFA) concentrations. In spotted-knapweed-dominated plots, however, picloram application shifted dominance from spotted knapweed, a good AMF host, to bulbous bluegrass (Poa bulbosa), a poor AMF host. This coincided with a 63% reduction in soil 16:1ω5 NLFA concentrations but no reduction of 16:1ω5 PLFA. Because 16:1ω5 NLFA quantifies AMF storage lipids and 16:1ω5 PLFA occurs in AMF membrane lipids, we speculate that the herbicide-mediated reduction in host quality reduced fungal carbon storage, but not necessarily fungal abundance after one year in the field. Overall, in greenhouse and field experiments, AMF were only affected when picloram altered host quantity and quality. This apparent lack of direct effect was supported by our in-vitro trial where picloram applied to AMF mycelia did not reduce fungal biomass and viability. We show that the herbicide picloram can have profound, indirect effects on AMF within one year. Depending on herbicide-mediated shifts in host quality, rapid interventions may be necessary post herbicide applications to prevent loss of AMF abundance. Future research should assess consequences of these potential shifts for the restoration of native plants that differ in mycorrhizal dependency.