Alexander Helen M, Collins Cathy D, Reed Aaron W, Kettle W Dean, Collis Daniel A, Christiana Lucy D, Salisbury Vaughn B
Department of Ecology and Evolutionary Biology University of Kansas Lawrence Kansas.
Biology Program Bard College Annondale-on-Hudson New York.
Ecol Evol. 2018 Nov 11;8(23):11975-11986. doi: 10.1002/ece3.4654. eCollection 2018 Dec.
Worldwide, grasslands are becoming shrublands/forests. In North America, eastern red cedar () often colonizes prairies. Habitat management can focus on woody removal, but we often lack long-term data on whether removal leads to population recovery of herbaceous plants without seeding. We undertook a long-term study (17 years) of numbers of the rare annual plant in a gridwork of 100 m plots in adjacent prairie and oldfield sites in Kansas, USA. We collected data before and after removal of at the prairie. Plant population sizes were highly variable at both sites and over time. High numbers of plants in a plot 1 year were often followed by low numbers the following year, suggesting negative density-dependence. Plant numbers were lowest with extensive woody cover and with low precipitation. After woody plant removal, increased dramatically in abundance and occupancy in most years; increases were also seen at the oldfield, suggesting later survey years were overall more favorable. : Removal of woody plants led to increased numbers of a rare annual prairie plant, without seeding. Multiple years of data were essential for interpretation given extreme temporal variability in numbers. The largest prairie population was 7 years following tree removal, showing that positive effects of management can last this long. This species also fared well in oldfield habitat, suggesting restoration opportunities. Given that land managers are busy, time-efficient field methods and data analysis approaches such as ours offer advantages. In addition to general linear models, we suggest Rank Occupancy-Abundance Profiles (ROAPs), a simple-to-use data visualization and analysis method. Creation of ROAPs for sites before and after habitat management helps reveal the degree to which plant populations are responding to management with changes in local density, changes in occupancy, or both.
在全球范围内，草原正在变成灌木丛/森林。在北美，东部红雪松（）常常侵入草原。栖息地管理可以侧重于去除木本植物，但我们往往缺乏关于去除木本植物后不进行播种草本植物种群是否恢复的长期数据。我们在美国堪萨斯州相邻的草原和旧耕地的100米样地网格中，对一种稀有的一年生植物的数量进行了为期17年的长期研究。我们在草原去除木本植物前后收集了数据。两个地点的植物种群数量在不同时间都高度可变。某一年样地中植物数量多，次年往往就少，这表明存在负密度依赖性。在木本植物覆盖广泛且降水量低的情况下，植物数量最少。去除木本植物后，大多数年份该植物的丰度和占有率都大幅增加；在旧耕地上也出现了增加，这表明后期调查年份总体上更有利。结论：去除木本植物导致一种稀有的一年生草原植物数量增加，且无需播种。鉴于数量存在极大的时间变异性，多年的数据对于解读至关重要。去除树木后7年，该草原种群数量达到最大，这表明管理的积极效果可以持续这么长时间。该物种在旧耕地栖息地也表现良好，这表明存在恢复机会。鉴于土地管理者很忙，像我们这样省时的野外方法和数据分析方法具有优势。除了一般线性模型外，我们还建议使用等级占有率 - 丰度剖面图（ROAPs），这是一种易于使用的数据可视化和分析方法。为栖息地管理前后的地点创建ROAPs有助于揭示植物种群在当地密度变化、占有率变化或两者兼有的情况下对管理的响应程度。
