DOI: 10.5061/dryad.7sqv9s517
title: Data from: Changes of Chinese forest-grassland ecotone in geographical scope and landscape structure from 1990 to 2020

description: Forest-grassland ecotone (FGE) has essential ecological and economic
 value. Unfortunately, it is impacted greatly by environmental changes and
 anthropogenic disturbance, and is considered one of the most severely
 threatened biomes in China. To protect Chinese FGE, identifying its exact
 boundary and exploring its landscape structure dynamic are badly needed,
 especially on nationwide scale at one-year temporal resolution. Here, we
 mapped the annual FGE distribution of China from 1990 to 2020,
 investigated its changing trends of area, location and landscape patterns,
 and revealed the underlying driving factors. Our results showed that FGE
 area over the 31 years totaled 1,011,870 km2, covering about 10.54% of
 China’s land. The FGE area first increased from 1990 and peaked in 1999,
 and then kept decreasing until 2020. The FGE gravity center has moved
 accumulatively 590.15 km over the 31 years, with the net moving distance
 of 228.76 km southwestward. From 1990 to 2020, forest area increased
 continuously while grassland and cropland area decreased, but these three
 landscape types had been dominating the FGE. The increase in forest area
 was largely converted from grassland. The decline in grassland mainly
 resulted from its conversion into cropland and forest. Meanwhile, the
 conversion of cropland to grassland supplemented grassland loss to a
 certain extent. At landscape level, the total area with decreased
 fragmentation is larger than that with increased fragmentation. Returning
 Farmland to Grassland Project and land reclamation were primary drivers
 for changes of fragmentation in the northern and middle part of the FGE,
 while temperature and precipitation were primary drivers in southern part.
 Our results will improve the understanding into the dynamic trends of
 distribution and pattern of FGE at nationwide scale, and thus help to
 optimize the designing of ecological projects and protective schemes for
 FGE as a unique and integral biome.
description: We combined spatial autocorrelation and spatial clustering
 methods to obtain Chinese forest-grassland ecotone(FGE) distribution. We
 mapped the FGE boundary from 1990 to 2020 in the following six steps: i)
 We generated a grid map with a cell size of 1.5km×1.5km in the study
 region and calculated the percentage of forest and grassland in each grid
 cell based on land cover map using ArcGIS10.7; ii) Using local spatial
 autocorrelation in the GeoDa V1.6.7, we produced two maps of spatial
 clustering, i.e., the clustering results of forest and
 grassland that separately include five circumstances including High-High
 (HH), Low-Low (LL), High-Low (HL), Low-High (LH), and Not Significant
 (NS), where “High” and “Low” before and after the short dash represents
 the forest/grassland coverage in the examined grid and its surrounding
 ones respectively, and “Not Significant” represents other circumstances
 than above-mentioned; iii) According to the paired forest and grassland
 clustering results, we obtained four types of landscapes including
 forest-grassland ecotone (FGE), forest zone (FZ), grassland zone (GZ), and
 the other zones (OZ); iv) We extracted FGE distribution of every year
 from 1990 to 2020 (hereafter referred as the original FGE), then merged
 the 31 FGE results to obtain an integrated FGE map, where the FGE covers
 an largest concentrated contiguous patch and many small dissociative
 patches; v) We obtain final FGE distribution map, neglecting the small
 patches that together occupied less than 2% of the total FGE area; vi) We
 obtained final annual FGE distribution by extracting the part of the
 original annual FGE within the final FGE distribution.
description: # Changes of Chinese forest-grassland ecotone in geographical scope and
 landscape structure from 1990 to 2020
 [https://doi.org/10.5061/dryad.7sqv9s517](https://doi.org/10.5061/dryad.7sqv9s517) We have submitted the distribution of Chinese forest-grassland ecotone in 31-years. File naming: the data is stored in Shapefile vector data format. The file named "forest-grassland ecotone" records the extend of Chinese forest-grassland ecotone. The geographic area of forest-grassland ecotone ranges from 88°30′ E to 122°59′ E and from 27°28′ N to 51°05′ N. The total area of forest-grassland ecotone was 1,011,870 km2, covering about 10.54% of China’s land. Data reading method: software or computer language that can read ShapeFile can read the data, such as ArcGIS, envi, IDL, python, MATLAB, etc.