江西和福建省植被覆盖时空特征及其地形梯度效应

Spatiotemporal Characteristics of Vegetation Coverage and Its Terrain Gradient Effect in Jiangxi and Fujian Provinces in South China

[目的]探讨华南地区植被覆盖时空特征,为生态系统调查与保护提供参考。[方法]以江西和福建省为例,将1998年、2005年、2010年、2015年、2019年5年的植被覆盖由低到极高划分为6个等级,使用土地利用研究中的动态度、转移等思路分析植被覆盖时空特征,并探讨其地形梯度效应。[结果](1)江西和福建植被覆盖以高和极高覆盖为主(78.47%~89.8%),尤其是在内陆山地丘陵区,而沿江、沿海等人口密集的城市区相对较低、面积较小;1998—2019年该区植被覆盖较好且变化的整体趋势仍是增加;最显著变化发生在2010—2015年由高覆盖转移为极高覆盖。(2)地形梯度指数显示,中等植被覆盖及以下主要分布在海拔低于200 m、坡度小于6°、地形位小于0.48的1~2级地形梯度区;较高覆盖及以上较为分散的分布在各地形梯度内,且随着覆盖度增加有向海拔高于200 m、坡度大于6°、地形位大于0.48的3~5级地形梯度区分布趋势。(3)在植被覆盖不变或改善类中,低覆盖转移主要发生在1级地形梯度,较低覆盖和中等覆盖转移主要发生在1~3级地形梯度区,较高覆盖及以上的转移在5类地形梯度均有发生且相对分散;在植被覆盖恶化类中,中等覆盖及以下的转移多发生在1~3级地形梯度区,较高覆盖及以上的转移在5类地形梯度区多有发生且相对分散;转移等级跨度较大的情况多发生在较低等级的地形梯度区。[结论]研究区植被覆盖率较高,植被覆盖变化存在时空差异,生态系统调查与保护需要考虑不同地形梯度下的影响因素。

[Objective]Exploration of the spatiotemporal characteristics of vegetation coverage in the South China region serves as a reference for ecosystem investigation and conservation.[Methods]Taking Jiangxi and Fujian provinces as examples,the vegetation cover of five years,including 1998,2005,2010,2015,and 2019,was divided into six levels from low to high levels.The spatiotemporal characteristics of vegetation coverage were analyzed using concepts such as dynamic degree and transfer in land use research,and its topographic gradient effect was discussed.[Results](1)The vegetation coverage in Jiangxi and Fujian was mainly high and extremely high(78.47%~89.8%),especially in the inland mountainous and hilly areas,while the densely populated urban areas along the river and coastal areas were relatively low coverage and small area;the vegetation coverage in this area was good and the overall trend of change was still increasing from 1998 to 2019.The most significant change occurred in 2010—2015 from high to very high coverage.(2)The terrain gradient index showed that the moderate vegetation coverage and below mainly distributed in grade 1~2 terrain gradient areas with an altitude of less than 200 m,a slope of less than 6°and a terrain position of less than 0.48.High vegetation coverage and above scattered in each terrain gradients,and with the increase of coverage,they tended to distribute in the terrain gradient areas of grade 3~5 with altitude higher than 200 m,slope higher than 6°and terrain level higher than 0.48.(3)In the category of unchanged or improved vegetation coverage change,the low coverage transfer mainly occurred in the grade 1 terrain gradient,the low and medium coverage transfer mainly occurred in the grade 1~3 terrain gradient area,and the transfer of high coverage and above occurred in the five types of terrain gradient and is relatively scattered.In the category of vegetation coverage change as deterioration,the transfer of medium coverage and below mostly occurred in the terrain gradient area of grade 1~3,while the transfer of high coverage and above mostly occurred and relatively scattered in the terrain gradient area of grade 5.The large span of transfer level usually occurred in the lower grade terrain gradient area.[Conclusion]The vegetation coverage in the research area is relatively high,and there are spatial-temporal differences in vegetation coverage changes.Ecological system investigation and protection need to consider the influencing factors under different terrain gradients.