Background: Theory predicts that plants can reduce their fitness in the presence of neighbours by allocating resources to root growth, in order to pre-empt resource capture. A number of studies that have tested this idea have done so by using experiments where neighbour presence is confounded with soil volume. Aims: To avoid confounding effects of neighbour presence and soil volume we adjusted these variables independently from one another. Methods: We grew Andropogon gerardii with and without neighbours, holding soil volume available to each plant constant, and compared plant performance with a treatment where both neighbour presence and soil volume were varied. We also grew plants with a quarter of the soil volume but four times the nutrient concentration to determine if changes in plant growth in response to soil volume are caused by access different levels of soil resources. Results: We found no evidence that plants adjust root growth to the presence of neighbour roots alone. We did, however, find a significant reduction in plant growth when soil volume was reduced. The reduction was overcome by increasing nutrient concentrations in the growth media. Conclusions: Our results suggest the effects of soil volume on plant growth are mainly due to changes in nutrient availability.

Understanding the natural revegetation of forests disturbed by the dumping of mine wastes is vital for the success of reclamation strategies. The Gunnar gold mine tailings pond in southeast Manitoba has remained largely unvegetated since the mine was closed in 1942, with limited vegetation developed on one side of the pond. We examined the natural Picea mariana/Larix laricina forest that has developed on the pond to determine how the plant community develops and what changes in the tailings are associated with this development. Vegetation sampled along transects showed a consistent pattern of succession from Equisetum palustre to Salix spp., and Populus balsamifera, to Larix laricina and finally to P. mariana. Larix laricina and P. mariana are moving into the site at the rate of 1.5 m per year with L. laricina invading 4 years ahead of P. mariana. Both tree species show a similar pattern of annual growth, showing positive correlations with spring precipitation, a pattern also occurring on L. laricina growing on a nearby site. The establishment of E. palustre was accompanied by initially rapid decreases in compaction and conductivity of the tailings, and an increase in inorganic nitrogen. Surface organic matter depth, coarse organic matter mass, and soil organic carbon increased at a constant rate, whereas subsurface coarse organic matter had an initial rapid increase followed by a gradual increase. As fern allies (and specifically members of the Equisetaceae family) have a number of properties that facilitate succession on mine wastes, their use should be explored further.

Local ecological knowledge of culturally important plants informed food choices by Indigenous peoples across North America. Recovery of such knowledge through ecological and genetic studies of contemporary populations increases understanding of variation in seasonal availability and economic value, potentially enhancing interpretation of the archaeobotanical record. We compared habitat, seed yield, and nutritional value of seed in up to ten wild populations of net-seed goosefoot (Chenopodium berlandieri) from four survey regions in Manitoba, North Dakota, Missouri, and Ohio with evidence of pre-contact cultivation and domestication of C. berlandieri. We assessed cultivation impacts and variation in seasonal timing by growing seed from three Manitoban populations in two common gardens. Population density, plant size, and seed yield increased sixfold from north (Manitoba) to south (Ohio) in wild populations, with genetic differences between Manitoban populations remaining evident in gardens. However, cultivation (e.g., watering, weeding) in well-worked soil extended timing of seed harvest and increased seed yield beyond the range of wild populations. Nutritional profiles from five populations were similar across the survey regions but differed from domesticated quinoa in their higher fiber and slightly lower energy content. Our results suggest that both plasticity and genetic factors influence productivity of C. berlandieri populations as a seed source. Genetic variation in seasonal timing would have provided choice between populations and flexibility in incorporating C. berlandieri into a seasonal subsistence strategy. Simple cultivation techniques would have substantially increased yield, thereby enhancing reliability and economic returns.

Chenopodium berlandieri (pitseed goosefoot) is a widespread native North American plant, which was cultivated and consumed by indigenous peoples prior to the arrival of European colonists. Chenopodium berlandieri is closely related to, and freely hybridizes with the domesticated South American food crop C. quinoa. As such it is a potential source of wild germplasm for breeding with C. quinoa, for improved quinoa production in North America. The C. berlandieri genome sequence could also be a useful source of information for improving quinoa adaptation. To this end, we first optimized barcode markers in two chloroplast genes, rbcL and matK. Together these markers can distinguish C. berlandieri from the morphologically similar Eurasian invasive C. album (lamb’s quarters). Second, we performed whole genome sequencing and preliminary assembly of a C. berlandieri accession collected in Manitoba, Canada. Our assembly, while fragmented, is consistent with the expected allotetraploid structure containing diploid Chenopodium sub-genomes A and B. The genome of our accession is highly homozygous, with only one variant site per 3–4000 bases in non-repetitive sequences. This is consistent with predominant self-fertilization. As previously reported for the genome of a partly domesticated Mexican accession of C. berlandieri, our genome assembly is similar to that of C. quinoa. Somewhat unexpectedly, the genome of our accession had almost as many variant sites when compared to the Mexican C. berlandieri, as compared to C. quinoa. Despite the overall similarity of our genome sequence to that of C. quinoa, there are differences in genes known to be involved in the domestication or genetics of other food crops. In one example, our genome assembly appears to lack one functional copy of the SOS1 (salt overly sensitive 1) gene. SOS1 is involved in soil salinity tolerance, and by extension may be relevant to the adaptation of C. berlandieri to the wet climate of the Canadian region where it was collected. Our genome assembly will be a useful tool for the improved cultivation of quinoa in North America.