Supporting data for increasing fire activity reinforces shrub conversion in Southwestern US forests

Fire-exclusion in historically frequent-fire forests of the southwestern United States has altered forest structure and increased the probability of high-severity fire. Warmer and drier conditions, coupled with dispersal distance limitations are limiting tree seedling establishment and survival following high-severity fire. Post-fire conversion to non-forest vegetation can be reinforced by subsequent fire events. We sought to determine the influence of fire probability on post-fire vegetation development in a severely burned landscape in New Mexico, USA. We used LANDIS-II to simulate three fire probability scenarios—contemporary mean fire return interval (CMFRI), and 1.5 times and 2 times CMFRI—with contemporary climate. As fire probability increased, the mean size of the largest fires and the mean landscape fire severity increased. These changes in fire characteristics resulted in a net decrease in total above ground biomass and photosynthetic capacity on the landscape. Additionally, t..., These data are outputs of a set of simulations using the LANDIS-II (v6.2) model with the PnET Succession extension (v.2.1.1) and the Dynamica Fuels and Fire System (v2.1)
extension. We used current climate data from Daymet and atmospheric CO2 data from the Mauna Loa observatory. We ran the model with three fire ignition probability scenarios; these are labelled 'Low or LO', 'Medium or MED', and 'High or HI'. Our study objective was to examine differences in post-fire vegetation recovery under
variable fire regimes. Our simulation area was the footprint of the 2011 Las Conchas fire in New Mexico, USA.

We ran 30 replicate simluations for each scenario; the length of each was 50 years. We summarized most data by calculating the mean and standard deviation of the 30 replicates. Mean and standard deviation for fire severity data were calculated for all years/replicates together. We present the data sets (raw and final) and code for creating figures in Keyser et al.

The parameter file..., The data is organized as follows:

The directory includes folders for 1) Fire Size and Severity, 2) Resprouter Probability,
3) Vegetation Distribution, and 4) Photosynthesis.  The directory also includes a folder with the parameter files for the PnET succession and Dynamic Fire and Fuels extensions.

Within each directory is R code for creating figures and the data used to create each figure.

1) Area Burned and Fire Size Distributions:
Files
'CAB_allScen.csv'       contains summarized data for cumulative area burned for all
                        scenarios. (Figure 1)

'bigFireLO2.csv'        contains a subset of the summary log records for the Low fire
                        scenario. The subset is the top 25% of fires by size. The field
                        TotalSitesBurned is the number of 1ha pixels that burned in the
                        fire event. The logAB field is the log of area burned.

'bigFireMED2.csv'       contains the same as above, but for th...

美国西南部历史上属于高频火干扰的森林，因长期防火措施改变了林分结构，提升了高强度林火（high-severity fire）发生的概率。气候暖干化叠加种子传播距离受限，使得高强度林火过后的树木幼苗定植与存活受到抑制。后续发生的林火会进一步加剧火烧后植被向非林植被类型的转变。

本研究旨在明确美国新墨西哥州某重度火烧区域内，火灾发生概率对火烧后植被演替的影响。本研究采用LANDIS-II模型，结合当前气候条件，模拟了三种火灾发生概率情景：当代平均火轮回期（contemporary mean fire return interval, CMFRI）、1.5倍CMFRI以及2倍CMFRI。随着火灾发生概率提升，最大火灾的平均规模与区域平均火烧烈度均有所上升。火行为特征的上述变化使得区域内总地上生物量与光合能力整体呈下降趋势。

此外，本数据集为采用LANDIS-II（v6.2）模型及其PnET演替扩展模块（PnET Succession extension, v.2.1.1）、动态可燃物与林火系统扩展模块（Dynamica Fuels and Fire System, v2.1）开展的一系列模拟结果。本研究使用的当前气候数据来自Daymet数据集，大气CO₂数据取自莫纳罗亚天文台（Mauna Loa observatory）。模型共设置三种火点源发生概率情景，分别标记为「低（Low, LO）」、「中（Medium, MED）」与「高（High, HI）」。

本研究的核心目标为探究不同火干扰制度下，火烧后植被恢复过程的差异。模拟区域为美国新墨西哥州2011年拉斯孔查斯（Las Conchas）火灾的过火范围。每种情景均开展30次重复模拟，单次模拟时长为50年。本研究对多数数据通过计算30次重复模拟的均值与标准差进行汇总；火烧烈度数据则整合所有年份与重复模拟结果后计算均值与标准差。本数据集包含原始数据与最终处理数据，以及用于生成图表的代码，相关内容见于Keyser等人的研究。

数据集组织形式如下：
数据目录包含以下4个子文件夹：1）火灾规模与烈度（Fire Size and Severity）、2）萌蘖概率（Resprouter Probability）、3）植被分布（Vegetation Distribution）以及4）光合能力（Photosynthesis）；此外目录中还包含一个用于存放PnET演替模块与动态火可燃物系统扩展模块参数文件的子文件夹。每个子文件夹中均包含用于生成对应图表的R代码与绘图所需数据。

1）过火面积与火灾规模分布：
文件'CAB_allScen.csv'包含所有情景下的累计过火面积汇总数据（对应图1）。
文件'bigFireLO2.csv'包含低火情景下的部分汇总日志记录，该子集为按火灾规模排序的前25%火灾数据。其中TotalSitesBurned字段代表火灾事件中过火的1公顷像元数量，logAB字段为过火面积的对数值。
文件'bigFireMED2.csv'与上述文件内容一致，但对应中火情景，原文此处存在截断。