阳春砂仁(Amomum villosum)种植对热带湿性季节雨林的影响十分显著，对次生林的影响不大。为保护热带雨林，改变现有阳春砂仁栽培模式，探讨雨林下种阳春砂仁改为次生林下种植阳春砂仁的可行性，比较研究了热带雨林和次生林下阳春砂仁的生长状况和产量。次生林和雨林林下阳春砂仁壮株密度和生物量均明显高于其它株型，同类型林下阳春砂仁笋、苗和衰老株密度差异不显著，但衰老株生物量显著高于笋和苗。次生林和雨林下阳春砂仁笋和苗的密度之和分别为衰老株的1.45和2.18倍，远多于衰老株数量。表明阳春砂仁种群能够维持稳定。值得注意的是阳春砂仁产量很低，茎生物量比很高（0.58以上），果实生物量比极低（约0.01），增产潜力较大。在水分较充足的一块次生林样地阳春砂仁果实产量高达211.149 0 kg•hm-2，远高于其它样地。阳春砂仁喜湿可能与其较低的根生物量比和浅根系有关。阳春砂仁叶面积指数、壮株和全部植株生物量与果实产量呈极显著的正相关。次生林和雨林林下阳春砂仁生物量、产量叶面积指数和各株型密度差异均不显著。研究结果表明次生林下可以种植阳春砂仁。
Amomum villosum is a perennial herb that occurs in the understory of tropical and subtropical forests and is an important medicinal plant. A. villosum, native to Guangdong Province, was introduced intentionally to Xishuangbanna, Yunnan in 1963 and was planted under tropical rainforests. Farmers often thin out some of the canopy trees (5%-85%) when they grow this plant for commercial purposes in these primary forests, resulting in a loss of biodiversity in these forests. A. villosum fruit yield is low and varies greatly among fields and years due to the crude cultivation method. The area of primary rainforest is much smaller than secondary forests in Xishuangbanna. The influence of A. villosum cultivation on rainforest biodiversity, biomass, and net productivity was significant, but the influence on secondary forests was negligible. To improve A. villosum yield and to protect rainforest biodiversity, we explored the possibility of cultivating A. villosum in secondary forests. Plant density, biomass, biomass allocation, and fruit yield were measured in A. villosum cultivated in tropical wet seasonal rainforests and secondary forests in Xishuangbanna. The density and biomass of vigorous plants were 72.60% and 85.29% of the total plants in the secondary forest and 71.27% and 86.69% in the rainforest and was significantly higher than those of other plant types. The density of shoots, seedlings, and senescent plants were not significantly different within the same forest types, but the biomass of senescent plants was significantly higher than that of shoots and seedlings. The sum of shoots and seedlings in secondary forest and rainforest were 1.45 and 2.18 times of senescent plants, respectively, indicating that A. villosum populations could be maintained. In the rainforest, many A. villosum seedlings were old and most of them grew poorly and could not develop into normal, healthy and vigorous plants. It is worthwhile to note that the A. villosum yield was very low, stem biomass ratio was very high (above 0.58), and fruit biomass ratio was extremely low (about 0.01). This suggests that increasing the yield potential of A. villosum could be achieved by improving biomass partitioning between the fruit and stem. In one of the experimental plots in the secondary forest, soil water conditions were improved by a rivulet, and fruit yield production was 211.149 0 kg•hm-2, much higher than that of other fields. Apparently, A. villosum cannot tolerate dry conditions and moderate dry periods might influence A. villosum yield. These yields were related to its low root biomass ratio and shallow root system. Leaf area index, biomass of both vigorous plants and other plants were significantly and positively correlated with fruit yield in A. villosum. Fruit yield and leaf area index were 105.034 5 kg•hm-2 and 2.908 2 in the secondary forest, and 60.931 9 kg•hm-2 and 2.560 0 in the rainforest, respectively. The density and biomass of the same plant types were not significantly different between the secondary forest and the rainforest. These results suggest that A. villosum can be cultivated in secondary forests.