Effects of Microtopography on Neighborhood Diversity and Competition in Subtropical Forests

Forests are complex systems in which subtle variations in terrain can reveal much about plant community structure and interspecific interactions. Despite a wealth of studies focusing on broad-scale environmental gradients, the role of fine-scale topographic nuances often remains underappreciated, pa...

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Main Authors: Jianing Xu, Haonan Zhang, Yajun Qiao, Huanhuan Yuan, Wanggu Xu, Xin Xia
Format: Article
Language:English
Published: MDPI AG 2025-03-01
Series:Plants
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Online Access:https://www.mdpi.com/2223-7747/14/6/870
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author Jianing Xu
Haonan Zhang
Yajun Qiao
Huanhuan Yuan
Wanggu Xu
Xin Xia
author_facet Jianing Xu
Haonan Zhang
Yajun Qiao
Huanhuan Yuan
Wanggu Xu
Xin Xia
author_sort Jianing Xu
collection DOAJ
description Forests are complex systems in which subtle variations in terrain can reveal much about plant community structure and interspecific interactions. Despite a wealth of studies focusing on broad-scale environmental gradients, the role of fine-scale topographic nuances often remains underappreciated, particularly in subtropical settings. In our study, we explore how minute differences in microtopography—encompassing local elevation, slope, aspect, terrain position index (TPI), terrain ruggedness index (TRI), and flow direction—affect neighborhood-scale interactions among plants. We established an 11.56-hectare dynamic plot in a subtropical forest at the northern margin of China’s subtropical zone, where both microtopographic factors and neighborhood indices (density, competition, diversity) were systematically measured using 5 m × 5 m quadrats. Parameter estimation and mixed-effects models were employed to examine how microtopography influences plant spatial patterns, growth, and competitive dynamics across various life stages. Our findings demonstrate that aspect and TPI act as key drivers, redistributing light and moisture to shape conspecific clustering, heterospecific competition, and tree growth. Remarkably, sun-facing slopes promoted sapling aggregation yet intensified competitive interactions, while shaded slopes maintained stable moisture conditions that benefited mature tree survival. Moreover, in contrast to broader-scale observations, fine-scale TRI was associated with reduced species richness, highlighting scale-dependent heterogeneity effects. The intensification of plant responses with life stage indicates shifting resource demands, where light is critical during early growth, and water becomes increasingly important for later survival. This study thus advances our multiscale understanding of forest dynamics and underscores the need to integrate fine-scale abiotic and biotic interactions into conservation strategies under global change conditions.
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spelling doaj-art-7632f11dd0454d128ea0d84516d217ed2025-08-20T02:42:28ZengMDPI AGPlants2223-77472025-03-0114687010.3390/plants14060870Effects of Microtopography on Neighborhood Diversity and Competition in Subtropical ForestsJianing Xu0Haonan Zhang1Yajun Qiao2Huanhuan Yuan3Wanggu Xu4Xin Xia5Innovative Research Team for Forest Restoration Mechanisms, Chishui National Ecological Quality Comprehensive Monitoring Stations, Research Laboratory for Protected Area Survey and Monitoring, Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment (MEE), Nanjing 210042, ChinaInnovative Research Team for Forest Restoration Mechanisms, Chishui National Ecological Quality Comprehensive Monitoring Stations, Research Laboratory for Protected Area Survey and Monitoring, Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment (MEE), Nanjing 210042, ChinaInnovative Research Team for Forest Restoration Mechanisms, Chishui National Ecological Quality Comprehensive Monitoring Stations, Research Laboratory for Protected Area Survey and Monitoring, Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment (MEE), Nanjing 210042, ChinaInnovative Research Team for Forest Restoration Mechanisms, Chishui National Ecological Quality Comprehensive Monitoring Stations, Research Laboratory for Protected Area Survey and Monitoring, Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment (MEE), Nanjing 210042, ChinaInnovative Research Team for Forest Restoration Mechanisms, Chishui National Ecological Quality Comprehensive Monitoring Stations, Research Laboratory for Protected Area Survey and Monitoring, Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment (MEE), Nanjing 210042, ChinaInnovative Research Team for Forest Restoration Mechanisms, Chishui National Ecological Quality Comprehensive Monitoring Stations, Research Laboratory for Protected Area Survey and Monitoring, Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment (MEE), Nanjing 210042, ChinaForests are complex systems in which subtle variations in terrain can reveal much about plant community structure and interspecific interactions. Despite a wealth of studies focusing on broad-scale environmental gradients, the role of fine-scale topographic nuances often remains underappreciated, particularly in subtropical settings. In our study, we explore how minute differences in microtopography—encompassing local elevation, slope, aspect, terrain position index (TPI), terrain ruggedness index (TRI), and flow direction—affect neighborhood-scale interactions among plants. We established an 11.56-hectare dynamic plot in a subtropical forest at the northern margin of China’s subtropical zone, where both microtopographic factors and neighborhood indices (density, competition, diversity) were systematically measured using 5 m × 5 m quadrats. Parameter estimation and mixed-effects models were employed to examine how microtopography influences plant spatial patterns, growth, and competitive dynamics across various life stages. Our findings demonstrate that aspect and TPI act as key drivers, redistributing light and moisture to shape conspecific clustering, heterospecific competition, and tree growth. Remarkably, sun-facing slopes promoted sapling aggregation yet intensified competitive interactions, while shaded slopes maintained stable moisture conditions that benefited mature tree survival. Moreover, in contrast to broader-scale observations, fine-scale TRI was associated with reduced species richness, highlighting scale-dependent heterogeneity effects. The intensification of plant responses with life stage indicates shifting resource demands, where light is critical during early growth, and water becomes increasingly important for later survival. This study thus advances our multiscale understanding of forest dynamics and underscores the need to integrate fine-scale abiotic and biotic interactions into conservation strategies under global change conditions.https://www.mdpi.com/2223-7747/14/6/870neighbor scaleneighborhood diversitycompetition indexmicrotopographicsubtropical forest
spellingShingle Jianing Xu
Haonan Zhang
Yajun Qiao
Huanhuan Yuan
Wanggu Xu
Xin Xia
Effects of Microtopography on Neighborhood Diversity and Competition in Subtropical Forests
Plants
neighbor scale
neighborhood diversity
competition index
microtopographic
subtropical forest
title Effects of Microtopography on Neighborhood Diversity and Competition in Subtropical Forests
title_full Effects of Microtopography on Neighborhood Diversity and Competition in Subtropical Forests
title_fullStr Effects of Microtopography on Neighborhood Diversity and Competition in Subtropical Forests
title_full_unstemmed Effects of Microtopography on Neighborhood Diversity and Competition in Subtropical Forests
title_short Effects of Microtopography on Neighborhood Diversity and Competition in Subtropical Forests
title_sort effects of microtopography on neighborhood diversity and competition in subtropical forests
topic neighbor scale
neighborhood diversity
competition index
microtopographic
subtropical forest
url https://www.mdpi.com/2223-7747/14/6/870
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