Influence of native shade tree canopies on the clump and culm growth of Pseudoxytenanthera stocksii (Munro) T.G.Nguyen in the Western Ghats, India

Abstract

Tree canopies create shaded microhabitats in the understorey by reducing light availability for plants growing beneath them. Medium-sized tropical sympodial bamboos, such as Pseudoxytenanthera stocksii, typically exhibit shade tolerance, particularly during early developmental stages, but may adopt light-demanding growth strategies in response to resource competition. P. stocksii is traditionally cultivated by local farmers in the central Western Ghats, often in association with native shade trees. This study investigated the effects of varying tree canopy cover viz. full shade (70–80 % canopy cover), partial shade (30–50 %), and open conditions, on clump and culm growth of P. stocksii. Clump-level traits assessed included clump diameter, total number of standing culms, the relationship between mother and daughter culms, average distance between them, and culm density. Culm-level traits included total height, number of nodes, basal diameter and height of the first branch above ground. Results indicated that the total number of standing culms was primarily determined by clump size rather than shading effect of tree canopies. However, open conditions supported relatively higher culm density per unit area. The relationship between mother and daughter culm numbers was consistently strong across treatments, suggesting minimal influence of canopy cover. A decrease in canopy cover was associated with a reduced average distance between mother and daughter culms. Shaded conditions significantly enhanced culm growth traits, including greater height, basal diameter and node number, along with an increased height of the first branch from the ground. Strong positive correlations were observed among culm height, basal diameter and node number, indicating these traits are interrelated and likely regulated by similar environmental factors. Overall, the study highlights the beneficial role of native shade trees in bamboo-based agroforestry systems, emphasizing that their retention, rather than replacement with monoculture bamboo plantations, fosters a synergistic, climate-resilient land-use model that supports both biodiversity conservation and sustainable rural livelihoods.