Effects of grass competition on tree seedlings growth under different light and nutrient availability conditions in tropical dry forests in India

Abstract

The interactive effects of light, nutrient availability and grass competition on seedlings of four tropical dry forest tree species, namely, Indian jujube (Ziziphus mauritiana), arjun (Terminalia arjuna), gum arabic (Acacia nilotica) and catechu (Acacia catechu), were evaluated in an experimental study at Banaras Hindu University, Varanasi, India. Full‐ and reduced‐ (20% of the full) sunlight, no‐nutrient and nutrient supplementation, and presence of grass and no‐grass conditions were taken in a split‐plot design to observe the effects on the plant growth and leaf nutrient parameters. We observed a significant interaction between light and nutrient availability on total dry weight and relative growth rate for the tree seedlings of all the species. Seedling growth was lower in presence of grass under full sunlight condition with/without nutrient addition, and also under reduced sunlight condition with nutrient addition. However, leaf‐N and ‐P concentration showed slight increase following nutrient addition across the species and light conditions. All the species responded positively to nutrient addition irrespective of light and grass conditions. Our study further indicates that nutrient addition under reduced light condition in tropical dry forests may be a possible strategy to ameliorate the negative impact of grasses on tree seedling growth. Overall, a better understanding of tree seedling establishment in the presence of grasses is of utmost importance for the development of management plans that may improve the diversity of tree species in tropical dry forests.

Cost‐effectiveness of management strategies in a nucleation experiment in a tropical dry forest

“…It is not clear why seedlings in our experiment enjoyed comparatively high survival rates among treatments. It is possible that regular weeding (every 6 months) reduced competition with non‐native grasses particularly for slow‐growing species (Zimmerman et al 2000; Bhadouria et al 2020), and/or the selected species were well adapted to former agricultural field and cattle pasture conditions. The use of hydrogel might have also increased species survival rates (Fajardo et al 2013; Werden et al 2018).…”

Tropical Dry Forest Restoration in an Era of Global Change: Ecological and Social Dimensions

“…This suggests that some physical environmental factors determine TDF gradients of diversity. For example, although it is often cited that TDFs have higher soil fertility than their humid counterparts [9,14,20], the limited available soil data examining how ecosystem function varies along environmental gradients suggests that TDFs are a nutrient-limited ecosystem [21,22]. The pantropical analysis in Rivero-Villar's paper [13] included in this Special Issue addresses an important soil fertility knowledge gap for TDFs.…”

Tree seedling growth allocation of Castanopsis kawakamii is determined by seed-relative positions

“…investments in root biomass at the expense of aboveground tissues to acquire the most available resources and optimize total growth (Hodańǒva, 1981). In addition, the presence of a grass layer also plays a major role in tree seedlings' growth and establishment and competes with the roots of emerged seedlings for available soil resources, thus limiting the rapid seedling growth in this position (Bhadouria et al, 2020). However, litter can also block heat exchange between the soil and the external environment, prevent seedlings from being burned by high light intensities (Donath and Eckstein, 2011), release nutrients by decomposing, as well as reduce the possibility of seed predation (Wellstein, 2015).…”

“…However, litter can also block heat exchange between the soil and the external environment, prevent seedlings from being burned by high light intensities (Donath and Eckstein, 2011), release nutrients by decomposing, as well as reduce the possibility of seed predation (Wellstein, 2015). These interactive effects of light, nutrient availability caused by the litter layer, and the variations of relative positions contribute to seedling survival and recruitment (Bhadouria et al, 2020). When seedlings emerge from seeds positioned beneath or above a moderate litter layer (~40 g of litter), suitable environmental conditions can promote leaf carbon uptake and assimilation and thus facilitate leaf biomass accumulation to increase photosynthesis (de Groot et al, 2003).…”