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效应已得到广泛认可，但学界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仍知之甚少。 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，选取4块面积为32~200公顷的雨林片段，采用从边缘向内部布设的重复样线法，评估了边缘距离与森林结构对耐阴咖啡（阿拉比卡咖啡Coffea arabica，即小粒种咖啡；罗布斯塔咖啡C. canephora，即中粒种咖啡）的出现率与种群丰度的影响。 毗邻种植园中栽培的咖啡物种在研究片段内的丰度高于其他咖啡类群，其茎密度从边缘（0米）向内部（250米）呈现显著下降趋势，这表明毗邻种植园的繁殖体压力，连同边缘效应与动物介导的种子传播共同发挥了调控作用。 咖啡种群密度与冠层覆盖度呈显著正相关，这表明即便在密闭冠层的雨林中，咖啡入侵也存在潜在威胁。 阿拉比卡咖啡的茎密度（150~1825株/公顷）在受干扰程度更高的片段中更高；而罗布斯塔咖啡则在受干扰与未受干扰的样地中均已扩散，种群密度可达更高水平（6.3~11486株/公顷）。 此外，罗布斯塔咖啡与本土灌木密度呈负相关关系，这表明其可能对本土植物产生潜在的不利影响。