Biology subjects

Kuebbing, S. E.

Publications and source records attributed to Kuebbing, S. E..

3 recordsLinked to original sources

bioRxiv2023

Evaluating the definition and distribution of spring ephemeral wildflowers in eastern North America

The herbaceous layer accounts for the majority of plant biodiversity in eastern North American forests, encompassing substantial variation in life history strategy and function. One group of early season herbaceous understory species, colloquially referred to as "spring ephemeral wildflowers," are of particular ecological and cultural importance. Despite this, little is known about the prevalence and biogeographic patterns of the spring ephemeral strategy. Here, we used georeferenced and dated observations from the Global Biodiversity Information Facility (GBIF) to define the phenological strategies of 559 herbaceous, vascular, understory plant species in eastern North America from a composite species list encompassing 16 site-level species lists ranging from Georgia to southern Canada. Specifically, we estimated activity periods from regional observations (primarily consisting of citizen scientist iNaturalist observations) and classified species as ephemeral if they completed all aboveground activity (including leafing, flowering, fruiting, and senescence) prior to an estimated date of canopy closure derived from remote-sensed data. We then evaluated the richness of these species at the landscape scale using estimates of biogeographic and environmental drivers aggregated for 100 km x 100 km grid cells. Importantly, our spatially-explicit approach defines each species spring ephemerality along a continuous scale (which we call the Ephemerality Index, EI) based on the proportion of its range in which it senesces before canopy closure (with EI = 0 indicating a species that is never ephemeral and EI = 1 indicating a species that is always ephemeral). We found that 18.4% (103 species) of understory wildflowers exhibited spring ephemerality in at least part of their range, with only 3.4% of all species exhibiting ephemeral behavior in all parts of their range. Ephemeral species had higher overall richness and composed a higher proportion of understory biodiversity in low-elevation areas with intermediate spring temperatures and elevated spring precipitation. Spring ephemerals peaked in both absolute species richness and relative proportion at mid latitudes. These biogeographic patterns deserve further study in other regions of the world and to uncover mechanisms behind these patterns. Using our new metric, our results demonstrate that the spring ephemeral strategy is not a discrete category, but rather a continuum that can vary across species ranges.

ecology↗

bioRxiv2022

Wildflower phenological escape differs by continent and spring temperature

Temperate understory plant species are at risk from climate change and anthropogenic threats that include increased deer herbivory, habitat loss, pollinator declines and mismatch, and nutrient pollution. Recent work suggests that spring ephemeral wildflowers may be at additional risk due to phenological mismatch with deciduous canopy trees. The study of this dynamic, commonly referred to as "phenological escape", and its sensitivity to spring temperature is limited to eastern North America. Here, we use herbarium specimens to show that phenological sensitivity to spring temperature is remarkably conserved for understory wildflowers across North America, Europe, and Asia, but that canopy trees in North America are significantly more sensitive to spring temperature compared to in Asia and Europe. We predict that advancing tree phenology will lead to decreasing spring light windows in North America while spring light windows will be maintained or even increase in Asia and Europe in response to projected climate warming.

ecology↗

bioRxiv2019

The scaling of genome size and cell size limits maximum rates of photosynthesis with implications for ecological strategies

A central challenge in plant ecology is to define the major axes of plant functional variation with direct consequences for fitness. Central to the three main components of plant fitness (growth, survival, and reproduction) is the rate of metabolic conversion of CO2 into carbon that can be allocated to various structures and functions. Here we (1) argue that a primary constraint on the maximum rate of photosynthesis per unit leaf area is the size and packing density of cells and (2) show that variation in genome size is a strong predictor of cell sizes, packing densities, and the maximum rate of photosynthesis across terrestrial vascular plants. Regardless of the genic content associated with variation in genome size, the simple biophysical constraints of encapsulating the genome define the lower limit of cell size and the upper limit of cell packing densities, as well as the range of possible cell sizes and densities. Genome size, therefore, acts as a first-order constraint on carbon gain and is predicted to define the upper limits of allocation to growth, reproduction, and defense. The strong effects of genome size on metabolism, therefore, have broad implications for plant biogeography and for other theories of plant ecology, and suggest that selection on metabolism may have a role in genome size evolution.

ecology↗