1 INTRODUCTION

Tropical forests play a crucial role in sequestering carbon, supporting biodiversity and maintaining ecological balance (Bonan, 2008; Pan et al., 2011). Their capacity to fulfil these functions is regulated at least partially by the dynamics of the forest stand that encompasses tree growth, recruitment, mortality and the net change in productivity, which govern both the structure and the ecosystem function of forests (Johnson et al., 2016; McDowell et al., 2018; Sheil, 1995). Both natural and anthropogenic disturbances have remarkable effects on tropical forest function and services (Makana et al., 2011; Matsuo et al., 2021; Poorter et al., 2016). Subsequently, secondary and old-growth forests exhibit variations in stand dynamics due to age, structure, species diversity and environmental conditions (Chazdon, 2003; Chazdon et al., 2016; Letcher & Chazdon, 2009).

In both old-growth and secondary tropical forests, interactions between climate, soil, trees and other plant growth forms, especially lianas, shape forest stand attributes and dynamics (Martin et al., 2004; Norden et al., 2009; Phillips et al., 2002). Forest disturbances create openings in the canopy, allowing more light to reach the forest floor and stimulating the growth of new trees (Schnitzer et al., 2000), while climate factors and the availability of nutrients and water are associated with topography (Körner, 2007; Schnitzer & Bongers, 2011).

Although numerous studies have focused on the abundance of lianas and trees, including in disturbed forests, the impact of lianas on forest succession, biomass recovery and carbon storage has less frequently been examined. Despite lianas being major components of tropical forests (Schnitzer, 2018), only a few studies have rigorously explored and quantified these patterns and their implications for forest dynamics (Finegan, 1996; Lai et al., 2017; Martin et al., 2013; Poorter et al., 2021; Rüger et al., 2020; van der Sande et al., 2023).

Lianas can impede tree growth, recruitment and survival (Estrada-Villegas et al., 2022; Marshall et al., 2017; van der Heijden et al., 2015) by competing for above- and below-ground resources, such as light, water and nutrients (Schnitzer et al., 2005; Toledo-Aceves, 2015). Lianas also cause mechanical damage and increase the risk of tree mortality (Ingwell et al., 2010), leading to an interruption of forest recovery processes (Estrada-Villegas et al., 2020; Lai et al., 2017; Schnitzer & Carson, 2010). Then again, lianas can benefit forest ecosystem function by promoting diversity and canopy connectivity, boosting soil fertility and nutrient cycling through rapid leaf litter turnover (Estrada-Villegas & Schnitzer, 2018; Roeder et al., 2022; Tang et al., 2012), maintaining microclimates (Meunier et al., 2021), and protecting recovering forests from further disturbances (Marshall et al., 2020). Interactions between lianas and trees can be complex and are context-dependent (Schnitzer, 2018), with the feedback of liana competitive success over trees on forest recovery varying based on forest disturbance and other environmental conditions, such as climate and topography (Ngute, Schoeman, et al., 2024).

Elevational gradients, which generally correlate with temperature, moisture, slope, soil fertility and the availability of water, nutrients and light (Körner, 2007), influence tree growth both directly and indirectly (Johnson et al., 2016) and can also be useful predictors of tree stem and biomass recovery (Norden et al., 2009). However, climate change, with altered temperature and precipitation patterns, can significantly impact the number and biomass of tree stems along elevation gradients (Bauman et al., 2022; Bennett et al., 2021). As temperatures increase, tree species that were once limited by cold temperatures could start to colonise higher elevations, potentially leading to an increase in stem number and biomass (Cuni-Sanchez et al., 2024). Additionally, increased temperatures can exacerbate drought conditions, particularly on sunny slopes, which could offset the gains of thermal relief by reducing moisture availability, further complicating predictions of biomass and stem number dynamics (Yin et al., 2023).

The effects of soil, climate and topography on tree recovery are further shaped by forest disturbance legacies (Chazdon, 2003). These impacts are more pronounced in younger (secondary) forests than in old-growth forests (Chazdon, 2008), since tree communities in secondary forests in less fertile soils exhibit slower growth rates (Chazdon et al., 2016).

In view of these complex interactions, our understanding of how forest disturbance, liana abundance and environmental gradients influence the dynamics of tree stems and biomass in tropical forests remains limited. Previous studies have largely focused on individual factors, offering a fragmented view (di Porcia e Brugnera et al., 2019; Laurans et al., 2014). Holistic insights into how these factors interact and shape the number of trees and their biomass over time are crucial for predicting how tropical forests will respond to environmental pressures such as land use change (Marshall et al., 2020) and for understanding whether these factors can have long-lasting effects on forest structure and function (Phillips et al., 2004).

Although previous studies have assessed the recovery of forest trees from disturbances across different environmental gradients and the resilience of tropical forests in the face of global changes, to our knowledge, none have combined forest disturbance, topography, liana dominance—defined as the competitive success of lianas over trees, quantified through liana–tree ratios (LTRs)—as well as soil properties. However, Ngute, Schoeman, et al. (2024) have also recently underscored the importance of considering the influences of disturbance, climatic and topographic factors when examining forest responses to the competitive success of lianas over trees, as they unveiled a global increase in liana dominance catalysed by forest disturbance, climate and topography.

This study aimed to quantify temporal variations in tree stems and above-ground biomass (hereafter, ‘biomass’) across old-growth and secondary tropical forests, taking into account gradients in liana dominance, topography and soil properties. To fulfil this aim, our specific objectives are to: (1) measure and establish temporal variations in tree stem numbers and biomass between old-growth and secondary tropical forests, (2) assess the influence of liana dominance on the dynamics of tree stems and biomass and (3) examine how environmental gradients, especially topography and soil properties, shape patterns in tree stem numbers and their biomass.

中文翻译：

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原生林和次生林的树干和生物量沿藤本植物优势度、海拔和土壤梯度的动态

 1 简介

热带森林在固碳、支持生物多样性和维持生态平衡方面发挥着至关重要的作用（Bonan，2008；Pan 等，2011）。它们履行这些功能的能力至少部分受到林分动态的调节，包括树木生长、补充、死亡率和生产力的净变化，这些动态控制着森林的结构和生态系统功能（Johnson等人， 2016；麦克道尔等人，2018；谢尔，1995）。自然和人为干扰都对热带森林功能和服务产生显着影响（Makana 等，2011；Matsuo 等，2021；Poorter 等，2016）。随后，由于年龄、结构、物种多样性和环境条件，次生林和老年林表现出林分动态变化（Chazdon，2003；Chazdon 等人，2016；Letcher 和 Chazdon，2009）。

在古老的热带森林和次生热带森林中，气候、土壤、树木和其他植物生长形式（尤其是藤本植物）之间的相互作用，塑造森林林分属性和动态（Martin 等，2004 年；Norden 等，2009 年；Phillips 等） .，2002）。森林扰动在树冠上形成开口，让更多的光线到达森林地面并刺激新树的生长（Schnitzer等人，2000年），而气候因素以及养分和水的可用性与地形有关（Körner，2007年）施尼策和邦格斯，2011）。

尽管许多研究都集中在藤本植物和树木的丰富度上，包括在受干扰的森林中，但藤本植物对森林演替、生物量恢复和碳储存的影响却很少被研究。尽管藤本植物是热带森林的主要组成部分（Schnitzer，2018），但只有少数研究严格探索和量化了这些模式及其对森林动态的影响（Finegan，1996；Lai 等，2017；Martin 等，2013； Poorter 等人，2021；Rüger 等人，2020；van der Sande 等人，2023）。

藤本植物会通过争夺地上和地下资源（例如光、水和营养物质（Schnitzer 等人，2005 年；Toledo-Aceves，2015 年）。藤本植物还会造成机械损伤并增加树木死亡的风险（Ingwell 等，2010），导致森林恢复过程中断（Estrada-Villegas 等，2020；Lai 等，2017；Schnitzer 和 Carson， 2010）。另一方面，藤本植物可以通过促进多样性和冠层连通性、通过快速落叶周转来提高土壤肥力和养分循环来有益于森林生态系统功能（Estrada-Villegas & Schnitzer，2018；Roeder 等，2022；Tang 等，2012） ，维持小气候（Meunier 等，2021），并保护正在恢复的森林免受进一步干扰（Marshall 等，2020）。藤本植物和树木之间的相互作用可能很复杂，并且取决于环境（Schnitzer，2018），藤本植物在森林恢复方面相对于树木的竞争成功的反馈因森林干扰和其他环境条件（例如气候和地形）而异（Ngute，Schoeman）等，2024）。

海拔梯度通常与温度、湿度、坡度、土壤肥力以及水、养分和光照的可用性相关（Körner，2007），直接和间接影响树木生长（Johnson 等，2016），并且也很有用树干和生物量恢复的预测因子（Norden 等，2009）。然而，气候变化以及温度和降水模式的改变，会显着影响沿海拔梯度的树干数量和生物量（Bauman 等人，2022 年；Bennett 等人，2021 年）。随着气温升高，曾经受到寒冷温度限制的树种可能开始在更高的海拔地区定居，可能导致茎数量和生物量增加（Cuni-Sanchez 等，2024）。此外，气温升高会加剧干旱，特别是在向阳的山坡上，这可能会通过减少可用水分来抵消热量缓解的收益，从而使生物量和茎数量动态的预测进一步复杂化（Yin等人，2023）。

土壤、气候和地形对树木恢复的影响进一步受到森林干扰遗产的影响（Chazdon，2003）。这些影响在年轻（次生）森林中比在古老森林中更为明显（Chazdon，2008），因为土壤不太肥沃的次生林中的树木群落表现出较慢的生长速度（Chazdon 等人，2016）。

鉴于这些复杂的相互作用，我们对森林干扰、藤本植物丰度和环境梯度如何影响热带森林中树干和生物量动态的理解仍然有限。先前的研究主要集中在个体因素上，提供了碎片化的观点（di Porcia e Brugnera 等人，2019 年；Laurans 等人，2014 年）。随着时间的推移，全面了解这些因素如何相互作用并影响树木的数量及其生物量，对于预测热带森林将如何应对土地利用变化等环境压力至关重要（Marshall 等人，2020），并了解这些因素是否可以对森林结构和功能具有长期持续的影响（Phillips et al., 2004）。

尽管之前的研究评估了森林树木在不同环境梯度干扰下的恢复情况以及热带森林面对全球变化的恢复能力，但据我们所知，没有一项研究将森林干扰、地形、藤本植物优势（定义为竞争成功）结合起来。树木上的藤本植物，通过藤本植物与树木的比率（LTR）以及土壤特性进行量化。然而，Ngute、Schoeman 等人。 （2024）最近还强调了在研究森林对藤本植物相对于树木的竞争成功的反应时考虑干扰、气候和地形因素的影响的重要性，因为他们揭示了森林干扰、气候和地形催化了藤本植物在全球范围内的优势地位的增加。

本研究旨在量化古老和次生热带森林的树干和地上生物量（以下简称“生物量”）的时间变化，同时考虑藤本植物优势、地形和土壤特性的梯度。为了实现这一目标，我们的具体目标是：(1) 测量和建立古老和次生热带森林之间树干数量和生物量的时间变化，(2) 评估藤本植物优势对树干动态的影响，以及(3) 研究环境梯度，特别是地形和土壤特性，如何影响树干数量及其生物量的模式。