Doctoral Dissertation Research: Engineering Effects of Scale Insects on Forest Dynamics in Fragmented Tropical Montane Oak Forests of Veracruz, Mexico

博士论文研究：介壳虫对墨西哥韦拉克鲁斯破碎化热带山地橡树林森林动态的工程影响

• 批准号: 0802589
• 负责人: Jon Stallins
• 金额: $ 1.19万
• 依托单位: Florida State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-04-15 至 2010-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0802589&HistoricalAwards=false
• 关键词: Doctoral; Dissertation; Research; Engineering; Effects

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.

人类造成的景观变化，包括热带森林砍伐，可能引发复杂的退化过程。这项研究探讨了热带森林的破碎化如何影响昆虫，除了对当地人民的生计之外，还对动植物产生重大影响。墨西哥东北部大片常绿山地橡树林已转变为放牧地。当今的森林存在于一片片片牧场和更加集约化的农业用地矩阵之中。观察到的这些森林中特有介壳虫密度的增加被推测是这种人为破坏的结果。随着过去几十年碎片化的进行，温度可能会变暖，从而促进这种昆虫的繁殖力增加和侵染水平更高。这项研究探讨了这些昆虫的大量存在是否对其所食树木的生长和繁殖产生了重大影响，从而对这些森林碎片的潜在再生产生了重大影响。鉴于这些事件在树木年轮记录中留下了不同的模式，树木年轮分析将用于重建森林破碎和昆虫侵扰的时间。通过比较具有不同介壳虫密度的树木的树木年轮生长和释放事件的时间，可以检查初始破碎、昆虫侵扰和森林再生潜力之间的协同作用。这种介壳虫还产生蜜露，蜜露是昆虫和鸟类的丰富碳水化合物来源，这些昆虫和鸟类通常直接以植物花蜜为食。大量的蜜露可能会引发鸟类多样性以及被这种食物资源吸引的其他昆虫的类型和数量的变化。对蜜露含量高低的树木进行的鸟类和昆虫调查将表明，破碎化也可能对营养组织和生物多样性产生意想不到的工程影响。将利用野外植被采样和卫星遥感来绘制各个森林斑块内以及不同海拔和坡度范围内介壳虫侵染的分布情况。这将有助于深入了解当地森林斑块的微气候和更大规模的气候控制如何影响昆虫密度和未来的森林动态。本研究中的介壳虫可以被概念化为生态系统工程师，即创造、改变或维持栖息地的物种。这项研究偏离了生态系统工程对平衡和可预测性的强调，转向了工程师的非线性动力学和权衡的观点。如果破碎化已经促进了目前介壳虫侵扰的水平，并且如果侵扰对森林恢复有害，则森林状态可以被描述为“锁定”，一旦破碎化开始，森林状况就会被疏导。 最近的研究表明，森林破碎化、干扰和物种相互作用之间的协同作用可能会放大破碎化的最初影响。因此，本研究旨在通过开发有关森林破碎化如何展开的更多背景、实地证据，为这些森林的可持续利用和保护提供信息。蜜露养蜂业也将被引入研究区域附近的社区。介壳虫的蜜露可用作蜜蜂的饲料。世界上一些最重要的蜂蜜（新西兰、德国）来自介壳虫。通过建立蜂巢，该项目还希望激发人们对生计的兴趣，从而减少对牲畜放牧的依赖，而放牧是森林破碎化的主要原因。