Abstract

Herbaceous vegetation is of great ecological importance and responds quickly to environmental changes. The present study was aimed to understand the variation in herbaceous species composition, biomass and soil physico-chemical properties in the naturally formed gap and the understory of semi-arid forests in the Aravalli hills. Four permanent plots consisting of the gap as well as the understory were established. To study herbs phytosociological attributes and biomass, 10 quadrats of 0.5 × 0.5 m size were laid in each plot. For soil physico-chemical properties, 5 soil samples were collected randomly at 0–10 cm depth from each plot. Relationships among biodiversity indices, herbaceous biomass and soil physico-chemical properties were determined using Redundancy Analysis (RDA) and correlation analysis. Across the sites, Poaceae was the dominant family. All species showed a contagious distribution pattern. In the understory, Importance Value Index (IVI) was the recorded highest for Oplismenus burmannii, ranging from 138 to 230.5 while in the gap, it was the highest for Achyranthes aspera (56.15) followed by Eragrostis ciliaris (53.1). Both sites included, herbaceous community biomass in the gap ranging from 700 to 900 g m⁻² while in the understory it ranged from 30 to 70 g m⁻². Cenchrus ciliaris (597.97 g m⁻²) and Chrysopogon sp. (391.2 g m⁻²) contributed a major proportion of herbaceous community biomass in the gap. Oplismenus burmannii (52.2 g m⁻²), Dipteracanthus prostratus (16.6 g m⁻²) and Cynodon dactylon (9.6 g m⁻²) contributed a major proportion of herbaceous community biomass in the understory. The understory soil had significantly (p < 0.05) higher soil moisture (%), electrical conductivity (EC), soil organic carbon (SOC) and soil total nitrogen (TN) compared to the gap. Even though canopy had positive effects on soil physico-chemical properties, it has negatively influenced herbaceous species composition, diversity and biomass, due to significant reduction in solar radiation reaching the ground.

摘要

草本植物具有重要的生态意义，对环境变化反应迅速。本研究旨在了解阿拉瓦利山自然形成的间隙和半干旱森林下层草本物种组成、生物量和土壤理化性质的变化。建立了由间隙和林下层组成的四个永久地块。为了研究草药的植物社会学属性和生物量，在每个地块中放置了 10 个 0.5 × 0.5 m 大小的样方。对于土壤理化性质，在每个小区的0-10 cm深度处随机收集5个土壤样品。使用冗余分析（RDA）和相关分析确定生物多样性指数、草本生物量和土壤理化性质之间的关系。在各个网站上，禾本科是主要科。所有物种均呈现出传染性分布格局。在林下，重要性价值指数 (IVI) 是记录的最高值Oplismenus burmannii，介于 138 至 230.5 之间，而在差距中，牛膝（56.15）最高，其次是纤毛画笔（53.1）。两个地点都包括，间隙中的草本群落生物量范围为 700 至 900 gm ^-2，而在林下其范围为 30 至 70 gm ^-2。Cenchrus ciliaris (597.97 gm ^-2 ) 和Chrysopogon sp. （391.2 gm ^-2）在间隙中贡献了大部分草本群落生物量。Oplismenus burmannii (52.2 gm ^-2 )、Dipteracanthus prostratus (16.6 gm ^-2 ) 和Cynodon dactylon (9.6 gm ^-2 ) 贡献了林下草本群落生物量的主要比例。与间隙相比，林下土壤的 土壤水分（%）、电导率（EC）、土壤有机碳（SOC）和土壤全氮（TN）显着升高（ p < 0.05）。尽管冠层对土壤理化性质有积极影响，但由于到达地面的太阳辐射显着减少，它对草本物种组成、多样性和生物量产生了负面影响。