Growth characteristics of multipurpose tree species, crop productivity and soil properties in agroforestry systems under subtropical humid climate in India

摘要

在印地安具有亚热带潮湿气候特点的东北地区，本文对几种多种用途的树种进行研究。选择12种多用途树种种植在农林系统中，耳果相思(Acacia auriculiformis)，种植间距为2m × 2m(2500 个·hm~(-2))，有很大的生长潜力。在10年期的短期轮伐中，每年有很高的产量(635m~3·hm~(-2))，平均每年增涨量为2.54 × 10~2 m~3·tree~(-1) ·a~(-1)，可以满足薪碳材的需要。所以，耳果相思(Acacia auriculiformis)是一种短期轮伐树种，适合种植在潮湿亚热带气候地区。另一方面，16年树龄的桉树(Eucalyptus hybrid)和黄兰(Michelia champaca)种植间距为3m × 3m(1111个·hm~(-2))，分别有较高的生长量(315m~3·hm~(-2)和165m~3·hm~(-2))，平均每年每棵树增长量分别为1.77 × 10~(-2)m~3和0.92 × 10~(-2)m~3。16年树龄的印度石梓(Gmelina arborea)木材产量为147m~3·hm~(-2)，每年每树的增长量是1.47 × 10~(-2)m~3。其次为Samania saman(140 m~3·hm~(-2))和柚木(Tectona gandis(“(79m~3·hm~(-2))，平均每年每树的增长量分别是1.40，1.13和0.78 × 10~(-2)m~3。%Multipurpose tree species (MPTs) were studied in an agroforestry arboretum under subtropical humid climate in Northeast India. Out of 12 MPTs planted under agroforestry systems, Acacia auriculiformis in spacing of 2m × 2m (2500 stems·hm~(-2)) could have the potentiality to meet the timber/fuelwood requirement due to its high wood production of 635 m~3·hm~(-2) with mean annual increment (MAI) of 2.54 × 10~(-2)·m~3·tree~1·a~(-1) in a short rotation period of 10 years. Thus, A. auriculiformis is a short rotation forest tree species suitable to grow in subtropical humid climate. On the other hand, at 16 years of age, Eucalyptus hybrid and Michelia champaca in spacing of 3m × 3 m (1111 stems·hm~(-2)) produced appreciably high timber volume of 315m~3·hm~(-2) and 165m~3·hm~(-2) with MAI of 1.77 × 10~(-2) m~3·tree~(-1)·a~(-1) and 0.92 × 10~(-2) m~3·tree~(-1)·a~(-1), respectively. At 16 years of age, Gmelina arborea produced a timber volume of 147 m~3·hm~(-2) with MAI of 1.47 × 10~(-2) m~3·tree~(-1)·a~(-1) followed by Samania saman (140m~3·hm~(-2)), Albizzia procera (113m~3·hm~(-2)) and Tectona grandis (79m~3·hm~(-2)) with MAI of 1.40, 1.13 and 0.78 × 10~(-2) m~3·tree~(-1)·a~(-1), respectively in 4m × 4 m spacing (625 stems·hm~(-2)). Gliricidia maculata and Leucaena leucocephala could be used as live fences around the farm boundary to supply their N-rich leaves for mulch as well as manure to crops. In agroforestry arboretum, direct seeded upland rice (Oryza sativa - variety, AR-11), groundnut (Arachis hypogaea - variety, JL-24) and sesamum (Sesamum indicum - variety, B-67) were grown during the initial period upto 8 years of tree establishment. Under other MPTs, there was a reduction in crop productivity as compared to open space. After 8 years of tree establishment, horti-silvi and silvi-pastoral systems were developed and pineapple (Ananas comosus - variety Queen), turmeric (Curcuma longa -variety RCT -1) and cowpea (Vigna sinensis - variety Pusa Barsati) as forage crop were raised. The productivity of pineapple, turmeric and cowpea was comparatively high under Azadirachta indica. The productivity of horticultural and forage crops in association with trees such as G. arborea, A. procera, S. saman, T. grandis and M. champaca of high timber value could be harnessed as viable agroforestry systems. Changes in soil properties were also monitored. Amelioration of soil acidity, increase in soil organic carbon, and enhanced humification of soil humus, high nutrient availability, low soil erodibility and high surface soil (0-15 cm) moisture availability were noted in soils under MPTs.