Dynamics of biomass and nutrient accumulation in rubber (Hevea brasiliensis) plantations established on two soil types: Implications for nutrient management over the immature phase

Abstract

Rubber trees are the main source of natural rubber (NR). The area occupied by rubber plantations rose from 3.9 million ha in 1961 to 12.5 million ha in 2018. Both the expansion of rubber plantations in marginal zones (prone to biotic and abiotic stress), and long-term rubber tree cultivation in traditional areas, raise questions about the sustainability of NR production in a context of climate change. Our study set out to gain insights into the biogeochemical cycles in rubber plantations, for a better matching of fertilizer inputs to the dynamics of nutrient demand throughout rubber tree growth. Nutrient accumulation in tree biomass is a major component of the biological cycle in tree plantations. We studied the dynamics of biomass and nutrient accumulation in two chronosequences covering the whole lifespan of a plantation in Ivory Coast managed on a sandy soil at the SAPH site, and one on a clayey soil at the SOGB site. In total, 56 trees were destructively sampled in 2-, 5-, 20-and roughly 40-year-old stands. While the use of allometric relationships is common for estimating nutrient stocks in planted forests, this study was the first to provide allometric equations predicting nutrient stocks in rubber tree components. Allometric models were applied to the inventory of 4 commercial stands, for each age at each site, to estimate stand biomass and nutrient stocks. The current annual increments of nutrient stocks in tree biomass peaked between 2 and 5 years after planting. They reached 80 kg ha-1 yr-1 for N, 14 kg ha-1 yr-1 for P and 34 kg ha-1 yr-1 for K at SAPH (53, 7, and 39 kg ha-1 yr-1 respectively at SOGB), which highlighted the importance of an appropriate fertilization schedule for young rubber trees. At the clear-cut age (38-40 years), the amounts of nutrients accumulated in tree biomass were 970 kg N ha-1 , 188 kg P ha-1 , 366 kg K ha-1 , 941 kg Ca ha-1 and 255 kg Mg ha-1 on the sandy soil at SAPH (907,118, 629 1499, and 375 kg ha-1 respectively on the clayey soil at SOGB). Contrasting soil properties and management practices at the two sites had a much greater effect on the amounts of P, K, Ca and Mg accumulated in the trees than on N accumulation. Logging practices in rubber plantations can lead to considerable nutrient exports on poor tropical soils. Harvest residues should be distributed uniformly in the plots so that the roots of young trees can quickly gain access to the nutrients released during decomposition.

Implementing a New Rubber Plant Functional Type in the Community Land Model (CLM5) Improves Accuracy of Carbon and Water Flux Estimation

“…Secondly, the defoliation (leaf offset), also referred to as "wintering", is usually seen in rubber trees once they are matured, that is, once they are greater than 4 years old [50][51][52]. In the Northern Hemisphere, specifically in mainland Asia (e.g., Cambodia and Thailand), rubber plantations have been observed to be in dormancy (LAI = 0) for about three weeks in January [11].…”

Rubber, rubber and rubber: How 75 years of successive rubber plantation rotations affect topsoil quality?

“…Wood biomass removal is known to be detrimental to soil quality (Hardiyanto & Sadanandan Nambiar, 2014; Perron, Kouakou, et al, 2021). According to Perron, Mareschal, et al (2021), exporting biomass may lead to a critical lack of nutrients in rubber plantations. Fertilization practices may overcome this loss for the second rotation but may not be sufficient to restore overall soil characteristics.…”

Temporal changes in soil nematode communities in rubber plantations in Ivory Coast in response to logging residue management

“…Planting cover crops, typically legumes, can improve soil physical and chemical properties, leading to an improvement in soil function and crop yield in tropical regions (Snapp et al 2005;Gao et al 2017). Perron et al (2021) suggested that a potential alternative for restoring soil functions is to leave logging residues due to the large amounts of nutrients and carbon they contain. Logging residues play important ecological roles in maintaining plantation fertility in various soil and climate systems, such as reducing chemical fertilizer use, increasing soil carbon sequestration, promoting soil nitrogen cycling (Arcand et al 2014) and preventing environmental pollution from burning (Ibrahim et al 2015).…”