Tree regeneration after fire: Delta 1994 burn surveys, general site data

Data for this study were collected in 2001 and 2002 by Jill Johnstone (University of Alaska Fairbanks) and Eric Kasischke (University of Maryland). Sites were located within the perimeter of the 1994 burn southeast of Delta Junction Alaska, USA, bordering the Alaska Highway to the North and the Gerstle River to the West. Sites were selected from satellite classifications prepared by Eric Kasischke to represent different levels of burn severity and post-fire vegetation canopy greenness (NDVI). Site selection was constrained by road access, and only areas where all trees had been killed by the fire were selected. At each site, a central point was located in an area of visually homogeneous vegetation. Five parallel transects, each 50 m long, were laid out as follows: 1) the first transect started at the central point and followed a randomly-selected compass direction, 2) two additional transects were established parallel to the first, but at a random distance from the central transect up to 25 m distant. Vegetation was sampled in a 2-m wide belt centered on each transect, and soil samples were made at intervals along the transect line. Vegetation measurements included: a) basal diameters of all pre-fire trees greater than 1.3 m in height, b) counts of all post-fire tree seedlings, and c) basal diameters of tree seedlings and willows, measured in a randomly chosen 5x2 m portion of each transect. General notes were made on visual percent cover of different vegetation growth forms at the site. Destructive measurements of tree seedlings and willows made in 2001 were used to develop allometric equations to predict dry biomass from basal diameter. Measurements of soil organic layer depth were made at 5 m intervals with the use of a spade to excavate small chunks of sod. At one randomly-selected sample point per transect, a 10x10 cm sample of the organic layer was collected for bulk density measurements. Bulk density samples were dried in a 60degC oven for 48 hours and then weighed. Information on the soil profile to 50-100 cm depth was collected from a single soil pit at the site. The purpose of the study was to document variations in post-fire tree establishment and woody biomass accumulation that could be related to variations in fire severity or pre-fire vegetation characteristics. Data from the study have not yet been published as of 2003. Presents general site data, including a description of pre- and post-fire vegetation cover, site locations, and a soil profile description. Data in columns.本研究所用数据由阿拉斯加费尔班克斯大学的吉尔·约翰斯通（Jill Johnstone）与马里兰大学的埃里克·卡基施克（Eric Kasischke）于2001至2002年间采集。采样点坐落于美国阿拉斯加州德尔塔章克申东南侧1994年森林火灾的过火边界范围内，北侧毗邻阿拉斯加公路，西侧紧邻格斯特尔河。采样点由埃里克·卡基施克基于卫星分类结果选取，以覆盖不同火烧烈度及火灾后植被冠层绿度（归一化差异植被指数，NDVI）等级。采样点选取受道路通行条件限制，且仅纳入所有树木均被火灾致死的区域。 每个样地的中心点设于植被外观均一的区域。共布设5条平行样带，每条长度为50m，布设规则如下： 1) 第一条样带从中心点出发，沿随机选定的罗盘方位延伸； 2) 另外两条样带与第一条平行，与中心样带的随机间距不超过25m。 沿每条样带以2m宽的带状区域开展植被采样，并沿样带线按固定间隔采集土壤样品。植被测量指标包含： a) 所有高度大于1.3m的火前树木的基径； b) 火后树木幼苗的个体数量； c) 在每条样带随机选取的5m×2m区域内，测量树木幼苗及柳树的基径。 对样地内不同植被生长型的目视盖度进行记录。2001年开展的树木幼苗及柳树破坏性测量数据，用于构建异速生长方程，以通过基径推算植株干生物量。按5m间隔测量土壤有机层厚度，使用铁锹挖掘小型草皮块完成测量。在每条样带随机选取的一个采样点处，采集10cm×10cm的有机层样品用于容重测定。容重样品置于60℃烘箱中烘干48小时后称重。在样地内的单个土壤剖面坑中，采集0至50-100cm深度的土壤剖面信息。 本研究旨在记录火后树木定植与木本生物量积累的变化特征，该变化可能与火烧烈度或火前植被特征的差异相关。截至2003年，本研究的数据尚未正式发表。 本数据集提供样地基础数据，包括火前与火后植被盖度描述、样地位置信息及土壤剖面描述。数据以列项形式组织呈现。