不同林药复合经营模式对杉木生态公益林土壤理化性质的改良效果

为筛选适宜的林药模式，促进杉木Cunninghamia lanceolata生态公益林改造和林下经济的健康发展，研究了杉木与药用植物复合经营对退化林地土壤理化性质的影响。采用完全随机区组试验设计在杉木生态公益林内构建8种复合经营模式。在模式内分层取土测定6个物理指标和9个化学指标，并采用灰色关联法对各模式的改良效果进行综合评价。结果表明:8种药用植物均能显著（P < 0.05）改善土壤物理性质和养分质量分数，尤其是对表层土壤，其中土壤含水量、田间持水量、总孔隙度以杉木+胆木Nauclea officinalis模式改良效果为佳，分别比杉木纯林模式提高50.5%，75.1%和36.9%；非毛管孔隙度以杉木+石笔木Tutcheria championi模式最佳，是纯林的1.1倍；土壤容重以杉木+梅叶冬青Ilex asprella模式最低，比纯林降低了22.3%。土壤有机质、有效氮、速效钾、全钾和全磷质量分数以杉木+草豆蔻Alpinia katsumadai最高，分别比纯林提高了41.8%，35.0%，108.1%，42.4%和37.0%；土壤有效磷质量分数以杉木+裸花紫珠Callicarpa nudiflora最高，是杉木纯林的2.1倍；土壤全氮和阳离子交换量分别以杉木+胆木和杉木+金花茶Camellia nitidissima模式最高，分别比杉木纯林提高32.1%和52.0%。20~40 cm土层中，土壤物理性质亦有不同程度的提高，而养分大多差异不显著。灰色关联分析表明:8种林药模式对杉木生态公益林土壤理化性质改良效果关联度大小排序为:杉木+草豆蔻>杉木+胆木>杉木+梅叶冬青>杉木+红豆杉Taxus chinensis >杉木+石笔木>杉木+裸花紫珠>杉木+土沉香Aquilaria sinensis >杉木+金花茶>杉木纯林。杉木+草豆蔻模式是本研究中改良杉木生态公益林林地土壤理化性质最佳的复合模式，可考虑推广应用。

Physical and chemical properties of ecological forest soils using different agroforestry patterns of Chinese fir with medicinal plants

The objective of this research was to screen out appropriate forest and medicinal plant agroforestry patterns of Chinese fir (Cunninghamia lanceolata) with medicinal plants and determine the effect on soil physical and chemical properties so as to promote the reconstruction of an ecological forest and healthy development of an understory-forest economy. A completely randomized block experimental design was used to establish eight agroforestry patterns including [SD (Chinese fir (Cf) + Nauclea officinalis), SS (Cf + Tutcheria championi), SM (Cf + Ilex asprella), SC (Cf + Alpinia katsumadai), SL (Cf + Callicarpa nudiflora), SJ (Cf + Camellia nitidissima), SH (Cf + Taxus chinensis), and ST (Cf + Aquilaria sinensis)] and a control of Chinese fir with six physical and nine chemical indexes at 0-20 cm and 20-40 cm soil layers having three replications. The grey correlation method was used to evaluate the improvement effect. Results showed that eight patterns significantly (P < 0.05) improved the surface soil physical properties and nutrient content. SD had the best improvement with higher soil quality water content (50.5%), field water holding capacity (75.1%), and total capillary porosity (36.9%) than the control; whereas, non-capillary porosity in SS was 1.1 times the control. The minimum soil bulk density was reduced 22.3% in SM compared to the control. The highest contents of soil organic matter (41.8%), available N (35.0%), available K (108.1%), total K (35.0%), and total P (108.1%) compared to the control all appeared in SC with soil available P highest in SL. Soil total N reached maximum in SD with cation exchange capacity in SD (32.1%) and SJ (52.0%) higher than the control. The rank of improvement on soil physical and chemical properties for the eight patterns and the control was as SC >SD >SM >SH >SS >SL >ST >SJ >control. So Chinese fir and medicinal plant agroforestry patterns improved soil quality with the best pattern being SC (Alpinia katsumadai with Chinese fir) which was suitable for popularization and application.