Dynamic changes and driving factors of the forest landscape pattern in Mao'er Mountain Forest Farm in the recent 40 years

This work was designed to study the dynamic evolution of forest landscape patterns in Mao'er Mountain Forest Farm, analyze its changing laws and the driving factors, and further propose reasonable and effective improvement measures which can provide guidance for the sustainable management of forests.

Based on the data of the four forest inventories in 1983,1993, 2004 and 2016, this research used the methods of area transfer matrix, landscape pattern index and structural equation model to analyze the dynamic changes and influencing factors of the forest landscape in Mao'er Mountain Forest Farm.

1) In 2016, the forest land accounted for 86.77% of the whole region, which was the base of the forest farm landscape. The forest land landscape was dominated by soft and hard broad-leaved mixed forest, the forest land landscape generally showed an increasing trend. From 1983 to 1993, the landscape area of forest land decreased by 378.6 hm², and the area increased by 1 730.8 hm² and 499.4 hm² during 1993-2004 and 2004-2016, respectively. Due to the influence of the natural environment and human disturbance, various types of vegetation in the forest land also changed to varying degrees. Compared with 1983, in 2016, the area of soft broad-leaved mixed forest decreased by 1 183.20 hm², the poplar forest area increased by 1 618.89 hm², the hard broad-leaved mixed forest area increased by 1 457.07 hm², and the coniferous broad-leaved mixed forest area increased by 767.87 hm². 2) The increased forest land mainly came from 1 280.84 hm² of cultivated land, 1 050.46 hm² of afforestation land, 779.14 hm² of sparse forest land and 619.30 hm² of unused land, while the proportion of cultivated land was the largest. 3) At the landscape level, the numbers of patch, patch density, patch shape index, Shannon diversity index and Shannon evenness index all decreased, while the patch association index and the maximum patch index increased, which indicated that the landscape fragmentation decreased and the distribution tended to gather. 4) From Phase I to Phase Ⅲ, the overall effects of natural factors (slope, slope position, and elevation) in the structural equation model were 0.319 6, 0.168 5, and 0.109 2, respectively, and the distance factors (distance from roads, rivers and settlements) were 0.271 2, 0.222 6 and 0.201 0, and the management measures were 0.280 0, 0.030 0 and 0.020 0, respectively. The distance factor had a significant and stable influence on stand types, while the natural factors and management measures had a significant impact in the early stage, which was gradually weakened in the latter two periods.

The landscape area of forest land increases steadily. The landscape distribution becomes more concentrated and the landscape diversity decreases. Natural and distance factors have a significant impact on forest types, and human factors promote the positive succession of forests.