东北平原典型玉米种植区农业景观植物多样性研究——以昌图县为例

非耕作生境是农业景观中的重要组成部分,为生物提供食物和栖息地,对生物多样性保护具有重要意义。本文以辽宁省昌图县为例,选取了20个非耕作生境比例为0~50%的网格(1 km?1 km)为样区,采用典型样地法对调查区域内农业景观中的林地、田间路、草地、沟渠、果园5类主要非耕作生境中的植物群落进行调查,探讨不同非耕作生境类型和比例中植物多样性及其与景观异质性之间的关系。研究结果表明,随着非耕作生境比例增加,植物物种多样性和均匀度先增加后减小,在20%~30%时达到峰值;非耕作生境比例在0~40%范围内时,植物物种丰富度同样呈现先增加后减小,且在20%~30%时达到峰值;非耕作生境比例高于40%时,植物物种丰富度再次出现峰值且高于20%~30%。随着非耕作生境比例的增加,农业景观香浓多样性、香浓均匀度指数和景观斑块形状复杂程度逐渐增加,蔓延度恰好相反。不同生境中重要值最高的均为禾本科植物,但植物种不同;优势种优势度为果园沟渠草地田间路林地。果园、草地和沟渠的物种多样性和均匀度指数显著高于林地和田间路,丰富度指数为草地林地沟渠果园田间路,且草地、果园和田间路的不同调查区域间植物群落指数存在较大的变异性。草地、果园、沟渠、田间路和林地中景观异质性与物种多样性相关性顺次降低。研究结论表明,东北平原典型玉米种植区农业景观中,最适宜非耕作生境比例为20%~30%;非耕作生境中林地、沟渠对物种多样性维持、湿生植物多样性保护具有积极作用;不同生境干扰类型和方式不同,景观异质性与植物物种多样性相关性程度也不同。在今后农业景观生物多样性保护中应综合考虑非耕作生境的类型和比例,干扰的类型和方式等多种因素对生物多样性、生态服务及农业产量的影响。

The plant diversity of agro-landscapes in typical maize planting areas in the Northeast Plain, China-A case study of Changtu County

Non-cropped habitats in agricultural landscapes constitute an important landscape for biodiversity preservation. Such habitats in agro-ecosystems can support both food production and biodiversity. In order to explore the relationship between plant species diversity and heterogeneity of agricultural landscape, and furthermore, to probe the suitable proportion of non-cropped habitats in agricultural landscape, we investigated plant diversity in Changtu County in the Northeast Plain, China. A total of 20 sampling plots (1 km×1 km) were selected for area proportions 0-50% of non-cropped habitats, and were divided into five groups according to area proportion of non-cropped habitats, which were 0-10%, 10%-20%, 20%-30%, 30%-40% and 40%-50%. The plant species in non-cropped habitats were investigated using the Braun-Blanquet method. The surveyed non-cropped habitats included woodland, grassland, ditch, orchard and field road. The heterogeneity indexes of agricultural landscape with different proportions of non-cropper habitats were calculated. The results showed that plant species diversity and evenness of agricultural landscapes gradually increased initially and later decreased with increasing area proportion of non-cropped habitats. Peak plant species diversity and evenness were in landscapes with 20%-30% area of non-cropped habitats. Meanwhile, plant species richness gradually increased initially and decreased later when area proportion of non-cropped habitats was 0-40%. However, peak plant species richness was in agricultural landscape with 40%-50% area of non-cropped habitats. The Shannon diversity index, Shannon evenness index of agricultural landscape increased with increasing of area proportion of non-cropped habitats, while landscape contagion metrics showed contrary tendency, indicating that lower area proportion of non-cropped habitats induced higher landscape dominance. The plant species with highest important values in different non-cropped habitats was Gramineae plants, but the species were different. The order of dominant degree of dominant species was orchard, ditch, grassland, field road and woodland. Species diversity and evenness in orchard, grassland and ditch were significantly higher than those in woodland and field road. Species richness (from high to low) was grassland, woodland, ditch, orchard and field road. There were obvious variation in plant community diversity among orchards, grasslands and ditches. The correlation between landscape heterogeneity and species diversity decreased from grassland to orchard, ditch, field road and to woodland. Thus the optimum area proportion of non-cropped habitats was 20%-30% within agricultural landscapes in typical maize planting areas in the Northeast Plains, China. Woodland and ditch had a positive effect on species diversity and on maintenance and conservation of hygrophytes. Different non-cropped habitats disturbances resulted in different correlation coefficients between landscape heterogeneity and plant species diversity. Thus future research should concentrate on comprehensive analysis of various factors such as area proportion of non-cropped habitats and habitat disturbances that influenced biodiversity, ecosystem services and agricultural production.