Data from: Brewing trouble: coffee invasion in relation to edges and forest structure in tropical rainforest fragments of the Western Ghats, India

While the conservation impacts of inva- sive plant species on tropical biodiversity is widely recognised, little is known of the potential for cultivated crops turning invasive in tropical forest regions. In the Western Ghats biodiversity hotspot, India, fragmented rainforests often adjoin coffee plantations. This study in the Anamalai hills assessed the effects of distance from edges and forest structure on the occurrence and abundance of shade-tolerant coffee (Arabica Coffea arabica and Robusta C. canephora) in four fragments (32–200 ha) using replicate line transects laid from the edges into the interiors. The coffee species cultivated in adjoining plantations was more abundant than the other coffee species inside study fragments, showing a clear decline in stem density from edge (0 m) to interior (250 m), suggesting the influence of propagule pressure of adjoining plantations, coupled with edge effects and seed dispersal by animals. Significant positive correlations of coffee density with canopy cover indicate the potential threat of coffee invasion even in closed canopy rainforests. Stem density of Coffea arabica (150–1,825 stems/ha) was higher in more disturbed fragments, whereas Coffea canephora had spread in disturbed and undisturbed sites achieving much higher densities (6.3–11,486 stems/ha). In addition, a negative relationship between C. cane- phora and native shrub density indicates its potential detrimental effects on native plants.

尽管入侵植物物种对热带生物多样性的保护影响已得到广泛认可，但人们对栽培作物在热带森林区域演变为入侵物种的潜在可能性却知之甚少。在印度西高止山脉（Western Ghats）这一生物多样性热点地区，碎片化雨林常与咖啡种植园毗邻。本研究在阿纳马莱丘陵（Anamalai hills）开展，通过布设从林缘向林内延伸的重复样线样带，对4处面积介于32至200公顷的雨林片段展开调查，评估了距离林缘的距离以及森林结构对耐阴咖啡——小粒咖啡（Coffea arabica）与中粒咖啡（C. canephora）——的出现概率与种群丰度的影响。研究区域毗邻种植园所栽培的咖啡物种，在样地内部的茎密度高于其他咖啡物种；且茎密度从林缘（0米）到林内250米处呈现显著下降趋势，这表明毗邻种植园的繁殖体压力，结合边缘效应与动物介导的种子传播，共同塑造了这一分布格局。咖啡种群密度与冠层盖度之间存在显著正相关关系，这表明即便在封闭冠层的雨林中，咖啡入侵也存在潜在威胁。小粒咖啡的茎密度为150–1,825株/公顷，在受干扰程度更高的雨林片段中密度更高；而中粒咖啡则在受干扰与未受干扰的样地中均已成功扩散，其茎密度可达更高水平（6.3–11,486株/公顷）。此外，中粒咖啡的茎密度与本土灌木密度之间存在负相关关系，这暗示其可能对本土植物群落产生潜在的不利影响。