Shifting agriculture system (locally known as Jhum) is the main driver of deforestation and forest degradation in north eastern region. This system has been extensively practiced to sustain the livelihood in rural areas of Mizoram which possesses serious threats to forest ecosystem and soil fertility. The course of vegetation development in secondary forest in abandoned fallow is a major concern to understand the process of succession in different fallow length. This study was undertaken in Aizawl and Mamit districts, Mizoram with the objectives to determine the tree species diversity, richness and abundance in different fallow periods. Fallow ages of 2–5 years (F₅), 6–10 years (F₁₀), 11–20 years (F₂₀) and 21–30 years (F₃₀) were selected with a total number of 37 sites and two circular plots of 12.6 m were laid in each site to carry out extensive enumeration and analysis of tree species. A total number of 91 tree species and 38 families were recorded. The number of trees increased by 47% from F₅ to F₁₀ but the same was decreased by 35% from F₁₀ to F₃₀. Ecological indices indicate high diversity and species richness in F₁₀ and F₃₀ compared to F₅ and F₂₀. The basal area significantly increased with the length of fallow period. The average girth at breast height (GBH) in F₅ was 30 cm but in F₃₀, the GBH increased to 130 cm. The dominant species changed as fallow period increased e.g. F₅ was dominated by Castanopsis tribuloides, F₁₀—Rhus chinensis, F₂₀—Macaranga denticulata and F₃₀—Albizia chinensis. The changes in dominant species with respect to fallow ages in the present study could be due to large anthropogenic disturbance on the pioneer species as well as greater establishment ability of the climax species in relation to its environment, altitude and soil condition.

中文翻译：

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印度东北米佐拉姆邦废弃的朱姆土地上树木的种类组成和多样性

不断变化的农业系统（当地称为Jhum）是东北地区森林砍伐和森林退化的主要驱动力。该系统已得到广泛实践，以维持米佐拉姆邦农村地区的生计，这严重威胁着森林生态系统和土壤肥力。废弃休耕地次生林的植被发育历程是了解不同休耕长度下演替过程的主要关注点。这项研究是在米佐拉姆邦的Aizawl和Mamit地区进行的，目的是确定不同休耕期的树木物种多样性，丰富度和丰度。休假年龄2-5岁（F ₅），6-10岁（F ₁₀），11-20岁（F ₂₀）和21-30岁（F选择了₃₀个，总共37个站点，并在每个站点中放置了两个12.6 m的圆形图，以对树木进行广泛的枚举和分析。总共记录了91个树种和38个科。从F ₅到F ₁₀，树木数量增加了47％，但是从F ₁₀到F ₃₀，树木数量减少了35％。生态指数表明，与F ₅和F ₂₀相比，F ₁₀和F ₃₀具有较高的多样性和物种丰富性。随着休耕期的延长，基础面积显着增加。F _5的胸高（GBH）的平均围长为30 cm，而F ₃₀，GBH增加到130厘米。优势种改变休耕期增加例如F ₅是由主导栲tribuloides，F ₁₀ -盐肤木，F ₂₀ -血北球和F ₃₀ -楹树。在本研究中，优势物种相对于休耕年龄的变化可能是由于对先驱物种的人为干扰较大，以及与环境，海拔和土壤条件有关的高潮物种的建立能力增强。