Plant Species Composition, Richness, and Diversity in Areas Invaded by Non-Native Plants in the Lower Montane Forest of Kilimanjaro National Park, Tanzania

The present study assessed the impact of invasive alien species on plant species composition, richness, and diversity in the lower montane forest of Kilimanjaro National Park. The study area was categorized into four sites: the first three dominated by non-native species, namely Black Wattle (<i>Acacia mearnsii</i>), Mexican weeping pine (<i>Pinus patula</i>), and Eucalyptus (<i>Eucalyptus</i> spp.), and the fourth zone comprised natural forests. Sixty plots, each measuring 20 m × 50 m, were established at each site for vegetation sampling. A total of 168 plant species representing 135 genera and 64 families were identified and recorded from the study area. The highest plant species diversity was recorded in the natural forest with a mean plant species number of 13.8 ± 1.7, followed by <i>Eucalyptus</i> spp. <i>A. mearnsii</i>, and <i>P. patula</i> with 10.3 ± 1.2, 10.13 ± 1.1, and 7.33 ± 1.1, respectively. The plant species richness was significantly higher in the natural forest than in the areas invaded with non-native plant species (<i>p</i> &lt; .05). Natural forest had the highest tree density of native trees with 774 ± 111 stems/ha and the lowest was observed in the <i>P. patula</i> site with a mean density of 12.7 ± 6.9. The reduction in plant species diversity and density in areas invaded with invasive alien species highlights the negative impact these species have on native plant communities. Sustainable forest management focusing on the protection of natural forests, the control of invasive species, and forest enrichment is highly recommended.

本研究评估了外来入侵物种对乞力马扎罗山国家公园低山地森林植物群落组成、物种丰富度及多样性的影响。本研究将调查区域划分为4个样点：前3个样点以非本土物种为优势种，分别为黑荆树（*Acacia mearnsii*）、墨西哥垂松（*Pinus patula*）以及桉树属（*Eucalyptus* spp.），第四个样点则为天然林。每个样点均设置60个面积为20米×50米的样方用于植被调查采样。本次调查共记录到植物物种168种，隶属于135属、64科。天然林的植物物种多样性最高，其平均物种数为13.8±1.7；其次依次为桉树属样点、黑荆树样点与墨西哥垂松样点，平均物种数分别为10.3±1.2、10.13±1.1与7.33±1.1。天然林的植物物种丰富度显著高于外来植物入侵区域（*p*<0.05）。天然林的本土树木密度最高，达774±111株/公顷；墨西哥垂松样点的树木密度最低，平均密度仅为12.7±6.9株/公顷。外来入侵物种入侵区域内的植物物种多样性与密度均出现下降，这凸显了此类物种对本土植物群落的负面影响。本研究建议应推行以天然林保护、入侵物种防控以及森林物种富集为核心的可持续森林管理策略。