Landscape change caused by humans, including tropical deforestation, can set off complex degradation processes. This research examines how the fragmentation of a tropical forest can affect an insect, with significant consequences for the plants and animals, in addition to the livelihoods of local people. Large areas of evergreen montane oak forest in northeastern Mexico have been converted for grazing. Present-day forests reside in a patchy matrix of pasture and more intensive agricultural land uses. Observed increases in the densities of an endemic scale insect in these forests are hypothesized to be a consequence of this anthropogenic fragmentation. As fragmentation has proceeded over the past decades, temperatures may have warmed, promoting greater fecundity in this insect and higher infestation levels. This research examines whether greater abundances of these insects has had large impacts on the growth and reproduction of the trees upon which it feeds, and consequently, on the potential regeneration of these forest fragments. Tree ring analyses will be used to reconstruct the timing of forest fragmentation and insect infestation, given that these events leave distinct patterns in the tree ring record. By comparing the timing of tree ring growth and release events among trees with varying densities of scale insects, the synergisms among initial fragmentation, insect infestation, and the potential for forest regeneration can be examined. This scale insect also produces honeydew, a rich source of carbohydrates for insects and birds that might ordinarily feed directly on plant nectar. Greater abundances of honeydew may initiate changes in bird diversity and in the types and numbers of other insects attracted to this food resource. Avian and insect surveys on trees with high and low levels of honeydew will convey how fragmentation may also have an unanticipated engineering effect on trophic organization and biodiversity. Field vegetation sampling and satellite remote sensing will be used to map the distribution of scale insect infestation within individual forest patches and across different elevations and slope aspects. This will facilitate insight into how local forest patch microclimates and larger scale climatic controls shape insect densities and future forest dynamics.
The scale insect in this study can be conceptualized as an ecosystem engineer, a species that creates, modifies or maintains habitats. This study steers away from ecosystem engineering's emphasis on balance and predictability toward a perspective that incorporates non-linear dynamics and tradeoffs for the engineer. If fragmentation has catalyzed current scale insect infestation levels, and if infestation is detrimental to forest recovery, forest state can be characterized as a "lock-in" whereby decline is canalized once fragmentation begins. Recent studies suggest that synergisms among forest fragmentation, disturbance, and species interactions may magnify the initial impacts of fragmentation. Thus this research seeks to inform the sustainable use and conservation of these forests by developing more contextual, field-based evidence of how forest fragmentation unfolds. Honeydew beekeeping will also be introduced to a community neighboring the study area. Honeydew from scale insects can be used as forage for honeybees. Some of the foremost honeys in the world (New Zealand, Germany) come from scale insects. By setting up a hive, this project also hopes to catalyze interest in a livelihood that could lessen dependence upon livestock grazing, the primary contributor to forest fragmentation.
