This study was conducted to investigate growth inhibitory or stimulating effects of leaf residues derived from a globally recognized invasive alien weed Ageratina adenophora on two dominant tree species viz. Banj oak (Quercus oblongata) and Chir pine (Pinus roxburghii) of Kumaun Himalaya, India. Leaves of different life cycle stages (fresh leaves and dry-senesced leaves) were cumulated from the A. adenophora population flourishing in the vicinity of D.S.B. Campus, Nainital and compost was prepared from collected fresh leaves following the standard methods. Fresh, dry-senesced and composted leaf materials were added separately to 1 kg of soil pots in different concentrations, i.e. C₁ (10 g leaves/kg of soil), C₂ (20 g/kg), C₃ (40 g/kg) and C₄ (80 g/kg) representing the variation in the degree of invasion while control (C₀) without leaf residues was used representing un-invaded regions to compare the results. Seed germination was recorded on daily basis and seedling growth parameters were recorded in first month, sixth month and twelfth month of time durations. The entire experiment was performed for 1 year of time duration excluding composted period. Our results showed that both the tree species responded differently to different leaf treatments. Fresh and composted leaf treatments showed positive effects on Pine, while Oak responded positively only to composted leaves in concentration dependent manner. Dry-senesced leaf treatments inhibited all the studied traits of both the tested species and were highly suppressive among all the leaf residue types. As the seed germination is the foremost and most crucial phase in population recruitment of any region, this weed suppressed germination parameters of both the native trees. The negative response of Pine and Oak to A. adenophora leaf residues indicated the inhibitory activity of this weed that enabled A. adenophora to form monospecies stands in these forests. Therefore, proper management, and utilization of A. adenophora in the form of compost for growth of other species could help in eradication of this species and mantainance of dominant forest systems of Kumaun Himalayan region.

Graphical Abstract

中文翻译：

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不同浓度紫茎泽兰叶渣对印度库马恩喜马拉雅山两种乡土树种种子萌发及生长行为的影响

本研究旨在调查全球公认的外来入侵杂草紫茎泽兰叶残留物对两种优势树种（即紫茎泽兰）的生长抑制或刺激作用。印度库马恩喜马拉雅山的班吉橡树（Quercus oblongata）和赤松（Pinus roxburghii ）。不同生命周期阶段的叶子（新鲜叶子和干枯叶子）是从DSB 校园附近繁盛的紫茎泽兰种群中收集的，奈尼塔尔并按照标准方法从收集的新鲜叶子中制备堆肥。将新鲜、干枯和堆肥的叶料分别按不同浓度添加到1kg土盆中，即C ₁（10 g 叶子/kg 土壤）、C ₂ (20 g/kg)、C ₃ (40 g/kg) 和 C ₄ (80 g/kg) 代表对照（C ₀）没有叶残留物被用来代表未入侵的区域来比较结果。每天记录种子发芽情况，并记录第一个月、第六个月和第十二个月的幼苗生长参数。整个实验持续1年，不包括堆肥期。我们的结果表明，这两种树种对不同的叶子处理的反应不同。新鲜和堆肥的叶子处理对松树表现出积极的影响，而橡树仅对堆肥叶子以浓度依赖性方式产生积极的反应。干枯叶处理抑制了两个测试物种的所有研究性状，并且对所有叶残留物类型均具有高度抑制作用。由于种子发芽是任何地区人口招募中最重要和最关键的阶段，这种杂草抑制了两种本土树木的发芽参数。松树和橡树的负面反应紫茎泽兰叶子残留物表明了这种杂草的抑制活性，使得紫茎泽兰能够在这些森林中形成单一种林。因此，正确管理并以堆肥形式利用紫茎泽兰来促进其他物种的生长，有助于消灭该物种并维护库马恩喜马拉雅地区的主要森林系统。

图形概要