By Alan Journet – part 2
In the prior issue of Missouri Sierran Alan reported from a recent meeting of the Missouri Society for Conservation Biology’s conference presentations regarding climate change in Missouri. In that article researchers contemplated how increased temperatures may cause changes in the range of suitable habitat for birds in the state. Part 2 describes impacts on insects, reptiles, and amphibians.
As a perfect follow-up to potential bird consequences, John Landosky then reviewed the possible impacts of climate change on insects, noting that in addition to the temperature effects, it was necessary to consider the direct consequences of increased CO2 concentration.
In terms of the CO2 influence, Landosky pointed out that increasing the gas may reduce the Nitrogen composition and leaf water content of some plants, two factors important to the feeding insect. Reduction in these variables renders plant food less nutritious, thus may have a negative impact on the growth and development of the insect – but may also induce increased feeding which compensates for the poor quality food.
Additionally, elevated CO2 may induce changes in the defensive chemistry and structure of the plant – either to the benefit or cost of the feeding insect – though generally the latter. By causing insects to spend more time feeding, elevated CO2 may also cause them to be more exposed to their natural enemies for longer periods of time, and thus more susceptible to predation and parasitism.
The affect of temperature on insects may primarily occur through the impact on insect growth and behavior since the activity and growth rate of insects are generally enhanced by increased temperatures. In particular it is quite possible that current efforts to contain spreading insect outbreaks such as the Gypsy moth could be negated as higher temperatures promote their growth and spread.
The next contribution was offered by Bethany Williams who discussed the potential impact of climate change on Missouri’s herpetofauna. Williams started by indicating similar potential consequences for herps as may be the case for birds – identifying range shifts, changes in phenology, morphology and behavior, and shifting genetic composition.
Williams pointed out that the primary problems facing amphibians result from their ease of desiccation, their need for damp environments for reproduction, and the dependence of many on ephemeral wetlands. Reptiles, meanwhile, are generally less moisture dependent, having better mechanisms in adult and egg for resisting desiccation. However, for some reptiles, gender is determined by temperature of incubation – so increased temperature potentially may shift the sex ratios in populations. Research suggests that an increase of 4 degrees Celsius could result in the elimination of male offspring in some turtle populations.
In terms of the necessary wetland breeding grounds, Williams noted that early drying out can result in a breeding season with zero recruitment for amphibian populations. For reptiles, climatic changes could induce a shift in nest site selection and phenology. Several recent studies indicate that reduced pond depth increases UV exposure of eggs, thereby increasing amphibian susceptibility to fungal infections. Also, warmer winters can result in increased female mortality, and decreased egg production.
Tim Nigh followed with a discussion of the potential impact of climate change on Missouri’s ecosystems. Placing the future in historical perspective, Nigh pointed out that Missouri has long been in a shifting tension zone broadly between forest to the east and prairie to the west.
Our dominant forest composition has responded to glacial and interglacial periods. As a result of this history, Missouri now incorporates a mix of relicts of the past glacial period and past xeric period.
Looking to the future, Nigh built on the climate history and predictions of Pat Guinan’s presentation to note that the future will potentially present Missouri with greater biomass due to enhanced growth resulting from increased CO2 but also an increased chance of drought and fire.
The climate is likely to reduce the abundance of white oaks, while enhancing post oak distribution, potentially eliminating sugar maple but promoting the distribution of pine-oak woodlands and savannas.
Nigh closed by offering some queries about the future: Will dispersal occur between existing sites or from existing sites onto lands with appropriate physical setting? Are there distance limitations? How will humans influence the ability to disperse? He also wondered if we should be thinking about conserving dispersal corridors between all centers of biological diversity.
The final presentation was authored by Dennis Figg who related climate change considerations to the Missouri Comprehensive Wildlife Strategy. While many of the states included climate change in their state Wildlife Action Plan, most of them merely made mention of the issue, although 13 states (including Missouri) did not mention global climate change at all.
Assessments on the impact of global climate change should not be made on state boundaries, but by an ecological framework Figg presented some preliminary methodology from a national project being developed by the Rocky Mountain Research Station, USFS, which suggests that climate change may well be significant in the Ozarks.
Figg also reminded folks that the Missouri Strategy is built around primary habitat types consistent with The Terrestrial Natural Communities by Paul Nelson. This is important, as the effects of global climate change may have more to do with internal changes to these systems than “shifting” as some people suggest. The internal changes to natural (and domesticated) communities will cause changes in vegetation that will affect animal populations by “reorganizing” them into new and unfamiliar groups.
Although the Missouri Strategy did not address global climate change, it is designed so as be able to respond to climate change information as it becomes available.
The strategy is already organized by ecological units, further subdivided into primary habitat types. Integral to implementing the strategy are working groups, namely the Conservation Opportunity Stakeholder Teams that work on habitat conservation together.
As new information on any threat to habitat quality and quantity, we have a mechanism to respond with conservation action. The loss and degradation of habitat for wildlife is not just by global climate change, and we need to be careful to not lose our emphasis on biodiversity.