Shifted Baselines: Quantifying Past Human Influences on Andean Landscapes

就生态系统而言，了解什么是自然的，而不是简单地接受看起来是自然的东西，对于所有对自然过程的研究都很重要。在海洋生物学中，这一概念被概括为“不断变化的基线”，即每一代人都接受环境的退化，并认为它是“自然的”。碳储量、生长速度、植被演替和潜在的生物多样性都是人类活动改变的生态系统服务的重要组成部分。有时，社会变化以牺牲另一个进程为代价，加强了一个进程。从历史上看，在安第斯高地这样的干旱地区，保水可能是最重要的，但当面临全球气候变化时，碳储存可能会变得更加紧迫。政策制定者为应对气候变化和生物多样性丧失所做的努力，增加了对景观变化轨迹的更深入了解和对什么是自然的更清晰识别的需要。这项研究项目将调查秘鲁安第斯山脉一个生物多样性非常高的地区，在那里，人们正在努力保护安第斯山脉的栖息地，以促进生物多样性和碳固存，这一景观已经被人类操纵了数千年。提出在Polyepis周围建立高海拔碳汇中心的计划，Polyepis是一种可以在比其他任何树都高的海拔生长的树。这种树的林地是特有物种的重要栖息地。虽然扩大森林的努力是由波利普人曾经比现在丰富得多的信念推动的，但这一假设尚未得到检验。研究人员将为不同海拔范围的生态系统定义“自然基线”，确定林线的自然高度(对地面碳储存很重要)，以及过去11,000年来与气候变化相关的景观变化轨迹。研究人员将分析来自10个湖泊和200个土壤岩心的沉积物岩芯，以提供建立这些自然基线的历史数据，他们将调查气候变化如何与人类活动相互作用，导致火灾制度、作物使用和森林覆盖发生变化。古生态学可以通过分析从土壤和湖泊沉积物中发现的化石花粉和木炭，提供有关系统如何变化的详细信息。全新世早期气候(从大约。(距今11,000年至9,000年前)与今天非常相似，但安第斯山脉的人口非常少。因此，这一时期提供了在没有人类活动的情况下对安第斯生态系统的洞察。制定关于当地土地使用甚至全球碳预算的区域保护政策需要了解人类对生态系统影响的轨迹。该项目将提供关于人类引起的安第斯地貌变化的时间、范围和性质的新数据，并提供与正在进行的通过固碳来限制气候变化影响、同时保护生物多样性的努力相关的基线数据。与互补学科(土壤科学、植物生理学、生态学和遥感)的科学家合作，将使项目成果能够纳入对安第斯山脉保护和试图减少安第斯生态系统内碳排放的适当政策的更大预测中。

Knowing what is natural in terms of an ecosystem, rather than simply accepting what appears to be natural, is important for all investigation of natural processes. In marine biology this concept has been summarized as "shifting baselines" in which each generation accepts a degradation of the environment and perceives it to be "natural." Carbon storage, rates of growth, vegetation succession, and potential biodiversity all are important components of ecosystem services modified by human actions. Sometimes societal changes enhance one process at the cost of another. Historically, water retention may have been paramount in a dry setting like the high Andes, but when faced with global climate change, carbon storage may become more pressing. Efforts by policy makers to grapple with climate change and loss of biodiversity increases the need for deeper understand of the trajectory of landscape change and for clearer identification of what is natural. This research project will investigate an area of very high biodiversity in the Peruvian Andes, where efforts to conserve Andean habitats to promote both biodiversity and carbon sequestration are being undertaken in a landscape that has been manipulated for millennia by humans. Present plans for high elevation carbon sequestration center around Polylepis, a tree that can grow at higher altitudes than any other. Woodlands of this tree are important habitat for endemic species. While efforts to expand forests are fueled by the belief that Polylepis was once much more abundant than present, this hypothesis has not been tested. The investigators will define "natural baselines" for ecosystems across a range of elevations, determine the natural height of tree line (important for above-ground carbon storage), and the trajectory of landscape change relative to climate change for the last 11,000 years. The researchers will analyze sediment cores from ten lakes and 200 soil cores to provide the historical data to establish these natural baselines, and they will investigate how climate change interacted with human activity to produce altered fire regimes, crop use, and forest cover. Paleoecology can, through analysis of fossil pollen and charcoal recovered from soils and lake sediments, provide detailed information about how systems have changed. The early Holocene climate (from roughly. 11,000 years to 9,000 years before the present) was quite similar to that of today, but human populations in the Andes were very low. This period therefore offers insights into the Andean ecosystem without human activity.Forming regional conservation policy with regard to local land use or even global carbon budgets requires an understanding of the trajectory of human influence on ecosystems. This project will provide new data on the timing, extent, and nature of human-induced change in Andean landscapes and provide baseline data relevant to ongoing efforts to constrain the effects of climate change through carbon sequestration while conserving biodiversity. Collaborations with scientists in complimentary disciplines (soil science, plant physiology, ecology, and remote sensing) will permit project results to be integrated into a larger prediction of appropriate policy for Andean conservation and for attempts to mitigate carbon release within Andean ecosystems.