Calibrating the data logger…
Investigates how heavy metal pollution from historic mining disturbance affects soil chemistry, plant communities, and pollination of subalpine wildflowers in the Crested Butte area, combining elemental soil analysis with botanical identification and field ecology methods.
The Gunnison Basin of Colorado is a landscape where deep mining history overlaps with some of the richest subalpine wildflower communities in North America. Around Gothic, Crested Butte, and Mount Emmons, abandoned and active mines have left behind soils and stream sediments enriched in heavy metals such as copper, zinc, arsenic, iron, and manganese. Heavy metal pollution — environmental contamination by toxic metals from mining operations — is not just a chemistry problem. Because plants take up whatever is dissolved in the soil around their roots, metals can move from mine waste into plant tissues, and from there potentially into the insects, birds, and mammals that depend on those plants. Some species, called hyperaccumulators, concentrate metals in their leaves and flowers at levels far higher than the surrounding soil, making them especially important to track.
Understanding these effects matters for mountain ecosystems because subalpine plants depend almost entirely on insect pollinators to set seed, and pollinators in turn rely on a diverse, flower-rich landscape. If mine soils make plants shorter, less showy, or chemically unusual, the cascade of consequences can reach pollination, reproduction, and ultimately plant community composition. The Gunnison Basin is also a working landscape where land managers, the Crested Butte Land Trust, and ongoing operations near Mount Emmons must weigh remediation choices against ecological recovery.
To study these questions, researchers rely on a few standard tools. Dichotomous identification keys — tools that use paired either/or statements about leaf shape, flower parts, or fruit characteristics — let field workers reliably tell apart closely related wildflowers such as the many members of the evening primrose family (Onagraceae) found around Gothic. When pollinators are too numerous or too fast-moving to identify to species, researchers use morphotype classification, grouping visitors by body shape and size. Chemical analyses of soils and plant tissues, together with surveys of plant height, flower number, pollinator visits, and seed set, then connect contamination to ecological outcomes.
The earliest research relevant to mine contamination in the basin focused on the physical and chemical fingerprint of mining in local waters. A U.S. Geological Survey study near Mount Emmons established that arsenic, iron, manganese, and zinc concentrations in Coal Creek waters and bottom sediments rose sharply downstream of an old mine discharge, and that the highest arsenic levels appeared in the headwaters above proposed mining activity, providing an early baseline against which later changes could be measured . Around the same era, biosystematic work on alpine wildflower groups such as the Erigeron simplex complex helped clarify which species actually grow in these high-elevation habitats — a prerequisite for any ecological study .
Environmental contamination by toxic metals such as lead, arsenic, nickel, zinc, and cadmium from mining operations
A tool that uses paired statements about morphological characteristics to systematically identify organisms through a series of either/or choices
Grouping of individuals based on body shape rather than species-level identification due to field identification constraints
Environmental contamination by heavy metals from mining activities affecting freshwater ecosystems
A systematic approach to creating identification keys by compiling species lists from authoritative sources, gathering morphological descriptions, and...
Collection of plant specimens from field sites followed by proper labeling and preparation for herbarium storage to create reference collections for t...
Acid digestion of plant and soil samples followed by Inductively Coupled Plasma-Atomic Emission Spectrometry to quantify metal concentrations in tissu...
A consistent story has emerged from work on plants growing on mine spoils in Gunnison County. Plant communities on mine sites are significantly less diverse than nearby uncontaminated sites, and individual plants — including Lupinus argenteus, Thlaspi montanum, and Draba aurea — grow shorter and produce fewer open flowers on contaminated soil (Little, 2008). Tissue analyses confirmed that copper concentrations were significantly higher in plants growing on mine sites than in those from control sites, demonstrating that mine-derived metals are entering the living parts of these wildflowers (Little, 2008). A follow-up thesis broadened the comparison to six paired mine and control sites and reinforced the pattern of stunted, less-floriferous plants and lower-diversity communities on mine spoils, while also showing that metal uptake patterns can be more complicated than a simple "more soil metal equals more plant metal" relationship (Little, 2009).
These physical changes appear to ripple into pollination. For Draba aurea, a small yellow mustard, pollination rates were significantly lower at mine sites across multiple metrics, and fruit set was correspondingly reduced (Little, 2008). Whether this is driven by changes in the pollinator community, by the shorter and less visually attractive plants, or by metals altering nectar and pollen chemistry remains an open mechanistic question, but the reproductive penalty itself is well documented (Little, 2008); (Little, 2009).
Parallel work on the basic reproductive biology of subalpine wildflowers helps interpret these patterns. In Geranium richardsonii, experimental removal of stigma lobes produced a significant decline in seed set, supporting a roughly one-to-one relationship between stigma lobes and ovules, and most naturally pollinated flowers received pollen on all five lobes and set the maximum five seeds (Gomola, 2009). This kind of detailed link between pollen delivery and seed output is exactly what is needed to detect subtler pollination shortfalls on contaminated sites. Companion field botany projects produced working identification keys covering 15 species across 4 genera of Onagraceae in the Gothic area, giving researchers reliable tools to track which species occur where (Bartholomew, 2009); (Gomola, 2009).
Early work in the 1980s established the chemical signature of mine drainage in Gunnison Basin streams (Steele & Coughlin, 1982), while studies clustered in 2008 and 2009 shifted attention from water chemistry to the plants and pollinators living on contaminated soils (Little, 2008); (Little, 2009). The most recent contributions combine GIS mapping of within-site variation in plant traits with tissue chemistry and pollinator observations, moving the field toward a more spatially explicit understanding of how mine effects play out across a single hillside (Little, 2009). At the same time, the Onagraceae key projects and the Geranium richardsonii experiments represent a complementary push to nail down the taxonomy and reproductive biology of the local flora so that future contamination studies can be more precise about which species are responding and why (Bartholomew, 2009); (Gomola, 2009); (Gomola, 2009).
Several major questions remain. First, what is the actual mechanism linking mine soils to lower pollination? Researchers do not yet know whether reduced visits to Draba aurea reflect changes in the pollinator community, simple visual unattractiveness of shorter plants, or chemical effects of metals in nectar and pollen on bee behavior and health (Little, 2008). Second, why do some metals accumulate in plants from mine sites while others appear at lower levels than in control plants, and which native species in the basin behave as hyperaccumulators (Little, 2008); (Little, 2009)? Third, how do downstream sediment patterns of arsenic, zinc, and manganese documented near Mount Emmons translate into effects on streamside plant communities and their pollinators (Steele & Coughlin, 1982)? Addressing these questions over the next decade — by combining tissue chemistry, pollinator identification, long-term monitoring, and experimental manipulations — would let land managers in the Gunnison Basin better predict which mine-affected sites can recover ecologically and which may need active intervention.
Bartholomew (2009). Dichotomous key to the members of the onagraceae family found in the gothic area. →
Gomola (2009). Dichotomous key of the onagraceae family. →
Gomola (2009). Effects of quantity and distribution of pollen on fertilization in the gynodioecious species Geranium richardsonii. →
Little (2008). Effect of Soil Metals on Pollination of Subalpine Wildflowers. →
Little (2009). The effects of mine disturbance and contamination on pollination of subalpine wildflowers. →
Spongberg (1970). Biosystematics and Phytogeography of the Erigeron simplex complex. →
Steele, Coughlin (1982). Bottom sediment chemistry and water quality near Mount Emmons, Colorado. Proceedings of the Exeter Symposium. →