Effect of Harding Grass Land Management on Native and Non-Native Plant Diversity in Coastal Grasslands

<b>Meta-Data</b> <b>Methods</b>: This experiment was performed at two grassland locations in Cambria, California that were subject to two different management strategies. At the first location, Rancho Marino Reserve, two different transects were set up – one with no history of tilling or planting*(35.52895, -121.07758) and one that had been previously tilled and planted (35.53932, -121.09002). At the second location, Fiscalini Ranch Preserve, two transects were set up - both with no history of tilling or planting (35.54976, -121.10072 and 35.5508, -121.10195). All four transects were 100 meters long with 25 quadrats (0.5m x 0.5m) randomly placed along them. Plant community structure and composition were assessed in one census per transect over a three-day period. We observed abundance through species diversity, percent coverage, density, and flower count. Species diversity was measured through direct count of the number of different species found in each quadrat. Percent coverage was assessed visually and flower count was counted directly. The density was calculated by counting the number of individual plant stems in four circular rings (20.27 cm2) placed in the center of each quarter of the quadrat and then dividing by the total surface area of the rings (81.07cm2). These measurements were taken separately for <i>Phalaris aquatica</i>, native species, and non-native species. Co-variants and soil moisture levels were also considered to control for any confounding variables. *“Planting” refers to the intentional introduction of <i>Phalaris aquatica</i> <b>Data</b>: The column site has two values: RM refers to Rancho Marino Reserve and FR refers to Fiscalini Ranch Preserve. Management indicates the historical management strategies of both sites and whether there was an introduction of <i>Phalaris aquatica </i>(Harding grass). Each location has two sampling sites on 100-meter-long transects and the column rep.day refers to the quadrat sample number at each transect. Harding cover, exotic plant cover, and bare cover refer to the percentage of ground covered by each. Animal sign indicates any animal presence found within the quadrats including scat, holes, trails, and/or individuals. Abundance is a calculation derived by adding the diversity value for Harding grass, exotic plants and native plants. Diversity is a count of all different species of plant present in each quadrat. Sampling time and rate per hour are irrelevant to this experiment. Harding density, native density, and exotic density refer to the number of relevant individuals that occur in the quadrat. The density value was calculated by adding the number of individual plant stems in four surface area samples and dividing the resulting value by the total surface area sampled. This value was then multiplied by 100 to extrapolate for the entire quadrat. Native flowers and exotic flowers is a direct count of the number of flowers found within the quadrat. Soil moisture is a measure of the water content of the soil in the quadrat taken with a digital soil moisture meter - all results indicated the soil was “too dry.” **Authors are all equal contributors listed in alphabetical order.

**元数据与实验方法**：本实验于美国加利福尼亚州坎布里亚的两处草原样地开展，两处样地采用两种不同的管理策略。第一处样地为马里诺牧场保护区（Rancho Marino Reserve），设置两条样带（transect）——一条无翻耕或种植历史（坐标：35.52895, -121.07758），另一条曾被翻耕并种植过植物（坐标：35.53932, -121.09002）。第二处样地为菲斯卡利尼牧场保护区（Fiscalini Ranch Preserve），同样设置两条样带，均无翻耕或种植历史（坐标分别为35.54976, -121.10072与35.5508, -121.10195）。四条样带均长100米，沿样带随机布设25个样方（quadrat，0.5m×0.5m）。在为期三天的单次植物普查中，对每条样带的植物群落结构与组成进行评估。

我们通过物种多样性、植被盖度、植株密度及花数来量化植物丰度。物种多样性通过统计每个样方内发现的不同植物物种数量直接计算得到。植被盖度采用目视估测法，花数则直接计数。植株密度的计算方式为：在每个样方的四个象限中心分别放置4个圆形取样环（单环面积20.27 cm²），统计每个环内的植物茎秆数量，将总茎秆数除以取样环总表面积（81.07 cm²）得到基础密度值。上述测量分别针对球茎虉草（*Phalaris aquatica*）、本土植物与外来植物开展。同时还记录了协变量（covariate）与土壤含水率，以控制混杂变量。*注：此处“种植”指有意引入球茎虉草（*Phalaris aquatica*）。

**数据说明**：数据列中，`site`字段包含两个取值：RM代表马里诺牧场保护区（Rancho Marino Reserve），FR代表菲斯卡利尼牧场保护区（Fiscalini Ranch Preserve）。`management`字段用于标识两处样地的历史管理策略，以及是否引入过球茎虉草（Harding grass）。每个样地均设有两条100米长的样带采样点，`rep.day`字段代表每条样带上的样方采样编号。`Harding cover`、`exotic plant cover`与`bare cover`分别指代对应植被或裸地所占的地面百分比。`animal sign`字段指代在样方内发现的所有动物活动痕迹，包括粪便、洞穴、小径以及活体个体。

丰度（abundance）为球茎虉草、外来植物与本土植物的物种丰富度数值之和。物种丰富度（diversity）为每个样方内存在的所有植物物种的总数。采样时间与每小时采样速率与本实验无关。`Harding density`、`native density`与`exotic density`分别指代样方内对应类群的个体数量：密度值的计算方式为，将4个表面积取样环内的植物茎秆总数除以总取样表面积，再乘以100以外推得到整个样方的密度值。`native flowers`与`exotic flowers`为样方内发现的对应类群花朵数量的直接计数结果。`soil moisture`为使用数字土壤湿度计测得的样方内土壤含水量，所有测试结果均显示土壤处于“过干”状态。

**所有作者均为同等贡献者，按字母顺序排列。**