Teak Plantations Research Articles

Biomass Production Assessment in a Protected Area of Dry Tropical forest Ecosystem of India: A Field to Satellite Observation Approach

In recent decades, degradation and loss of the world’s forest ecosystems have been key contributors to biodiversity loss and future climate change. This article analyzes plant diversity, biomass, carbon sequestration potential (CSP), and the net primary productivity (NPP) of four vegetation types viz., Dense mixed forest (DMF); Open mixed forest (OMF); Teak plantation (TP), and Sal mixed forest (SMF) in the dry tropical forest ecosystem of central India through remote sensing techniques together with physical ground observations during 2013–2018. The total C storage in trees varied from 16.02 to 47.15 Mg ha−1 in studied vegetation types with the highest in DMF and lowest in OMF. The total C storage in stem wood, branches, and foliage falls in the range of 52.93–78.30%, 9.49–22.99%, and 3.31–12.89% respectively. The total standing biomass varied from 83.77 to 111.21 Mg ha−1 and these variations are due to different vegetation types, with the highest in DMF followed by TP, SMF while the lowest was estimated in OMF. The net primary productivity (NPP) [aboveground (AG) + belowground (BG)] varied from 7.61 to 9.94 Mg ha−1 yr−1 with mean values of 8.74 Mg ha−1 yr−1 where AG shares a maximum contribution of 77.66%. The total biomass production was distributed from 64.09 to 82.91% in AG and 17.08–35.91% in BG components. The present study outlines that the studied forest ecosystem has the substantial potential of carbon sequestration and a great possibility of mitigating local and global climate change.

PATHOGENIC DISEASE OCCURRENCES IN PLANTATION SITES OF BASTAR DISTRICT, CHHATTISGARH, INDIA

The investigation on “Pathogenic disease occurrence in plantation sites of Bastar district, CG, India” revealed that the several disease of Tectona grandish and Eucalyptus globules trees species in the plantation site maintained by Bastar forest division (C.G.) During the survey of plantation sites, many trees were infected by pathogens. The infected teak species showed leaf spot, leaf blight, leaf gull, leaf brown spot, stem canker, powdery mildew etc. and affecting the growth and form of teak. Whereas in Eucalyptus trees showed stem canker, collar rot, leaf spot, leaf rust, brown leaf spot, disease and affecting the growth and forms of Eucalyptus. The survey was conducted at two plantation sites namely Titrgaon and Bastar in the region and incidence of pathogenic disease commonly found and casual organism/ pathogen were identified prescribed disease management was recorded. Management of immediate removal of infected plants helps to prevent the disease spread. Therefore, the present investigation was carried out for knowing occurrence and abundance of pathogens associated with Teak and Eucalyptus trees plantation in the Bastar district of Chhattisgarh.

Effect of root‐glomalin on soil carbon storage in trees' rhizosphere and interspace of a tropical dry forest

AbstractIncreasing soil organic carbon (SOC) concentration is a desirable aspect of afforestation. Glomalin‐related soil protein (GRSP) is a ubiquitous component of SOC, preferentially produced by arbuscular mycorrhizal fungi (AMF) during symbiotic association with the plant roots. Although the role of AMF in GRSP production is well established, the role of root in GRSP production is not yet clear. Hence, we aimed to assess the glomalin in different tree roots (i.e., glomalin‐related root protein; GRRP) and its influence on GRSP and SOC storage in trees’ rhizosphere and interspace. The experiment was conducted in a tropical dry forest (India) with six native trees (Hardwickia binata, Lagerstroemia parviflora, Diospyros melanoxylon, Terminalia tomentosa, Shorea robusta, and Anogeissus latifolia) and a planted Teak (Tectona grandis). The fine roots (from the rhizosphere) and topsoils (0–15 cm) were collected from the rhizosphere and interspace of each tree. We found GRRP concentration varying between trees, with higher values observed in the roots of native trees than those of Teak. The AMF colonization was positively correlated with GRRP (r2 = 0.88), and GRRP positively correlated with GRSP and SOC. The higher correlation of GRRP was observed with GRSP (r2 = 0.70–0.79) compared with SOC (r2 = 0.56–0.58), while the correlation was much stronger between GRSP and SOC (r2 = 0.91). These results indicate that GRRP influences SOC storage via mediating GRSP concentration. We suggest that GRRP can be used as an indicator for species screening during afforestation with the aim to improve SOC storage on an afforested landscape.

Effects of Topography, Soil Organic Matter, and Chemical Properties on the Growth of Teak (<i>Tectona grandis</i>) Plantations in Northeast Thailand

Effects of Topography, Soil Organic Matter, and Chemical Properties on the Growth of Teak (<i>Tectona grandis</i>) Plantations in Northeast Thailand

PROPERTIES OF TEAK WOOD INFECTED BY Ceratocystis fimbriata

In Brazil, the growth of Tectona grandis (teak) plantations is accompanied by an increased incidence of Ceratocystis wilt, a fungal disease that colonizes the vascular system of such tree. The objective of this work was to evaluate the properties of teak wood infected with Ceratocystis fimbriata at different radial positions. Ten 17-year-old trees (five infected and five healthy) were collected. A disk was removed from the base of each tree to determine Janka hardness, basic density, anatomical analysis, colorimetric parameters in the CIEL*a*b* system and sodium hydroxide solubility (NaOH). There were no significant differences for radial position and health for basic density and Janka hardness of the wood, with mean values of 0.488 g.cm3 and 58.66 MPa, respectively. The deposition of dark compounds was observed inside the parenchyma cells and fibers, as well as the formation of tyloses in the sapwood. Yellow pigment was predominant in the color formation of teak wood, which was influenced by radial position, with the sapwood being lighter. Regarding C. fimbriata infection, the color change was more evident in sapwood. Conversely, the NaOH solubility was lower for the sapwood attacked by the fungus. In conclusion, the changes in teak wood infected by C. fimbriata are visual and the anatomical structures do not deteriorate.

Chitin metabolism as a potential target for RNAi-based control of the forestry pest Hyblaea puera Cramer (Lepidoptera: Hyblaeidae).

Hyblaea puera, commonly known as the teak defoliator, is a serious pest in teak plantations. Despite the availability of control measures, this pest causes losses in yield and quality of timber through voracious feeding. RNA interference (RNAi) is a promising strategy for the control of this pest. Chitin metabolism, which is vital for the growth and development of arthropods, is a potential target for developing RNAi-based insecticides. To assess the effects of chitin metabolism inhibition, H. puera larvae were treated with a chitin synthesis inhibitor, diflubenzuron (DFB). DFB treatment caused pupal deformities and disrupted eclosion. Partial gene sequences for three key genes of H. puera chitin metabolism were cloned and sequenced: chitin synthase 1 (HpCHS1), chitinase-h (HpChi-h) and ecdysone receptor (HpEcR). Feeding dsRNA cognate for these three target genes to the first instar of H. puera resulted in mortality and reduction in the corresponding transcript levels as assessed through qRT-PCR. This is the first report of RNAi in this forestry pest. The highest mortality was 45.9%, in response to dsHpEcR treatment; HpChi-h transcripts were the most down-regulated in response to dsHpEcR feeding. DsHpEcR RNAi resulted in growth inhibition and molting arrest. The mortalities were 29.7% and 32.4% for dsHpCHS1 and dsHpChi-h feeding, respectively. Chitin metabolism could be a potential target for RNAi-based control of H. puera, and HpCHS1, HpChi-h and HpEcR could be suitable target genes. However, the RNAi efficacy needs to be improved through formulations that improve stability and uptake, and employing better delivery strategies. © 2021 Society of Chemical Industry.

Enhancing Teak (Tectona grandis) Seedling Growth by Rhizosphere Microbes: A Sustainable Way to Optimize Agroforestry.

With its premium wood quality and resistance to pests, teak is a valuable tree species remarkably required for timber trading and agroforestry. The nursery stage of teak plantation needs critical care to warrant its long-term productivity. This study aimed to search for beneficial teak rhizosphere microbes and assess their teak-growth-promoting potentials during nursery stock preparation. Three teak rhizosphere/root-associated microbes, including two teak rhizobacteria (a nitrogen-fixing teak root endophyte-Agrobacterium sp. CGC-5 and a teak rhizosphere actinobacterium-Kitasatospora sp. TCM1-050) and an arbuscular mycorrhizal fungus (Claroideoglomus sp. PBT03), were isolated and used in this study. Both teak rhizobacteria could produce in vitro phytohormones (auxins) and catalase. With the pot-scale assessments, applying these rhizosphere microbes in the form of consortia offered better teak-growth-promoting activities than the individual applications, supported by significantly increased teak seedling biomass. Moreover, teak-growth-promoting roles of the arbuscular mycorrhizal fungus were highly dependent upon the support by other teak rhizobacteria. Based on our findings, establishing the synergistic interactions between beneficial rhizosphere microbes and teak roots was a promising sustainable strategy to enhance teak growth and development at the nursery stage and reduce chemical inputs in agroforestry.

Synergistic effects of habitat configuration and land-use intensity shape the structure of bird assemblages in human-modified landscapes across three major neotropical biomes

Maximizing biodiversity persistence in heterogeneous human-modified landscapes is hindered by the complex interactions between habitat quality and configuration of native and non-native habitats. Here we examined these complex interactions considering avian diversity across 26 sampling sites, each of which comprised of three sampling points located across a gradient of disturbance: core native habitat fragment, fragment edge, and non-native adjacent matrix. The 78 sampling points were further nested within three neotropical biomes—Amazonia, Cerrado and Pantanal—in central-western Brazil. Matrix type consisted of cattle pastures in the Amazon and teak plantations in the Pantanal and Cerrado. We considered the interactive effects of (1) disturbance-context: fragment core, edge and adjacent matrix, (2) matrix type: tree plantation or cattle pastures, both subject to varying land-use intensity, and (3) native habitat configuration (fragment size, shape and isolation) on bird species richness, abundance and composition. Based on point-count surveys, we recorded 210 bird species. Bird species richness and abundance declined across the disturbance gradient, while genus composition only differed within the adjacent matrix, particularly cattle-pastures. The effect of native habitat area was positive but only detected at fragment edges. Overall bird diversity increased at sites characterized by higher availability of either relict trees within pasture landscapes or old-growth trees within teak plantation landscapes. The core of native fragments played a primary role in ensuring the persistence of bird diversity, regardless of fragment size. In contrast to pastures, tree plantations likely harbour a higher proportion of forest-dependent species while bird diversity can be further enhanced by reduced management intensity in both matrix types. Strategies to maximize avian persistence should not only include retaining native habitats, but also maximizing the size of core native habitats. Likewise, more structurally complex matrix types should be encouraged while maintaining low levels of land-use intensity.

Comparison of terrestrial vertebrates between natural and teak plantation forest in Peninsular Malaysia: A case study in Perlis State Park and Mata Ayer Field Center, FRIM

Species compositions are influenced by the habitat types and methods used in a study. The objectives of this study are to document species diversity in teak plantation in Mata Ayer Research Station, FRIM and to compare differences in species diversity and composition between plantation and natural forest of Perlis State Park. Different types of traps and methods were used to survey four targeted groups of vertebrates (small mammal, bird, reptile and amphibian), including mist net, harp trap, collapsible trap, and active search. A total of 252 individuals were captured, representing 117 species of 53 families of vertebrates. Alpha diversity analysis shows that natural forest has higher species diversity than a teak plantation. Shannon-Weiner Index show higher result in natural forest (3.768) than teak plantation (3.439) while evenness of species distribution is higher in teak plantation (0.8419) than the natural forest (0.4755). Sorenson dissimilarity index indicates that 90.4% significant difference between sites thus; both sites have different species composition of vertebrates. Taxonomic distinctness however reflects different significant variation responses of both areas. Natural forest shows more species compared to plantation forest as it provides more food resources, suitable home and higher rate of reproduction while teak plantation shows a similar habitable environment with structural and conditions more similar to natural forest. So, both natural forest and plantation should be protected, manage and use suitable planning in order to sustain the biodiversity for future generation.

Space Planting, Competition, and Productivity of a Seven-Year-Old Clonal Teak Plantation in the East Java Monsoon Forest Area

Tree breeding of teak results in selected clones with high growth. Intensive silviculture is required to support a large-scale clonal teak plantation. Appropriate spacing is one of the methods to increase forest plantation productivity. Research of teak clone spacing was conducted on a seven-year-old clonal teak plantation with randomized completely block design. The treatments tested in this study were four plant spacing distances, namely, 3 m × 3 m, 6 m × 2 m, 8 m × 2 m, and 10 m × 2 m. Results show that spacing had significantly different effects on diameter, height, bole height, branch angle, crown area, crown projections, volume, and competition index. However, the height growth did not exhibit any significant differences. The 10 m × 2 m spacing produced the best diameter growth, crown area, and competition index, but has a low volume per hectare and the lowest height of free branch and branch angle. Meanwhile, the 3 m × 3 m spacing will increase bole height and stand volume per hectare. This result suggests that spacing could improve the growth of teak clone but must be followed by intensification of proper maintenance to reduce branch angle and increase bole height.

The use of near infrared spectroscopy to predict foliar nutrient levels of hydroponically grown teak seedlings

Due to a combination of durability, strength, and aesthetically pleasing color, teak ( Tectona grandis L.f.) is globally regarded as a premier timber species. High value, in combination with comprehensive harvesting restrictions from natural populations, has resulted in extensive teak plantation establishment throughout the tropics and subtropics. Plantations directly depend on the production of healthy seedlings. In order to assist growers in efficiently diagnosing teak seedling nutrient issues, a hydroponic nutrient study was conducted at North Carolina State University. The ability to accurately diagnose nutrient disorders prior to the onset of visual symptoms through the use of near infrared (NIR) technology will allow growers to potentially remedy seedling issues before irreversible damage is done. This research utilized two different near infrared (NIR) spectrometers to develop predictive foliar nutrient models for 13 nutrients and then compared the accuracy of the models between the devices. Destructive leaf sampling and laboratory grade NIR spectroscopy scanning was compared to nondestructive sampling coupled with a handheld NIR device used in a greenhouse. Using traditional wet lab foliar analysis results for calibration, nutrient prediction models for nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), sulfur (S), copper (Cu), molybdenum (Mo), magnesium (Mg), boron (B), calcium (Ca), manganese (Mn), iron (Fe), sodium (Na), and zinc (Z) were developed using both NIR devices. Models developed using both techniques were good for N, P, and K (R2 > 0.80), while the B model was adequate only with the destructive sampling procedure. Models for the remaining nutrients were not suitable. Although destructive sampling and desktop scanning procedure generally produced models with higher correlations they required work and time for sample preparation that might reduce the value of this NIR approach. The results suggest that both destructive and nondestructive sampling NIR calibrations can be useful to monitor macro nutrient status of teak plants grown in a nursery environment.

Composition of native and alien invasive species in soil seed banks of five different physiognomies in Akure Forest Reserve, Ondo State, Nigeria

The study investigated the composition of native and alien invasive species in soil seed banks of five different vegetation physiognomies in Akure Forest Reserve Ondo State, Nigeria. This was done with a view to determining and providing an insight into the population dynamics of alien, invasive species for subsequent prediction of potential plant population of the extant population. Five distinct sites (Natural forest, Teak plantation, Taungya system, Taungya + Teak + Gmelina and Teak + Gmelina + Pinus Plantation) designated as A, B, C, D and E were selected in the Forest Reserve. Two plots 25 m x 25 m each were selected for sampling in each of the five distinct physiognomies. Five replicates soil samples were randomly collected at 0-15 cm soil depth in dry and rainy seasons in each site and they were subjected to seedlings emergence for six months to determine the density and species composition (natives or aliens and percentage contribution) of the seed bank. The results of the seedling emergence revealed that the seed bank was dominated by herbaceous stems and also the proportion of aliens to natives was low. Analysis of variance revealed that there was no significant difference (P>0.05) in the density of both the aliens and native species in sites A, B and C indicating similarities in the seed bank density of the aliens and natives in the three sites while in sites D and E, there was a significant difference (P<0.05) indicating dissimilarity in the seed bank density of the aliens and natives in the two sites.Keywords: Plant Ecology, Forest, Seedling Emergence, Seed Bank, Alien Species, Conservation.

Growth and profitability of smallholder sengon and teak plantations in the Pati district, Indonesia

Despite the ambitious target to establish 12.7 million ha of social forestry across Indonesia and various government support for smallholder private forests, implementation has been slow and financial returns for smallholders from timber production have been variable. For most smallholders, any motivation to plant trees competes with their interest in planting short term food or cash crops to support their family's livelihood. Moreover, lack of market knowledge and monetary need often sees smallholders sell their trees at below market prices, rather than at the optimum time for financial returns. Also, a limited understanding of silvicultural options to improve log quality further undermines the financial returns from timber production for smallholders. There are few studies from Indonesia that provide sufficient detail to be able to replicate the financial analysis and benchmark the results against key input variables (e.g., unit costs of production, timber yields by product and log size class, discount rate). Another deficiency is the lack of empirical data on the growth performance of existing smallholder plantations in Indonesia. This article reports on research to fill these knowledge gaps by using inventory data from smallholder plantations in Pati (Central Java) together with other data to develop silvicultural systems that were used to assess the profitability for smallholders of growing sengon (Paraserianthes falcataria) and teak (Tectona grandis) for timber. The results indicated that growing sengon on a 6-year rotation was profitable with an estimated net present value (NPV) of USD 1015 ha−1 (Rp 14,218,000 ha−1) at a real discount rate of 8%, with an internal rate of return (IRR) of 20%. Growing teak on a 20-year rotation was also profitable with an NPV of USD 2815 ha−1 at a real discount rate of 8%, and an IRR of 15%. Although the NPV for teak was nearly three times that for sengon, in the long term (i.e., over perpetual rotations), the returns from sengon and teak were closer. Our results support the view that the best opportunity for enhancing smallholder returns from forestry lies in improving the common approach to silviculture, particularly the lack of effective pruning and thinning, to realise the financial potential of timber production.

Effects of Thinning Intensity on Soil Quality and Growth of Teak Plantation

Effects of Thinning Intensity on Soil Quality and Growth of Teak Plantation

Soil carbon stock in different land-use systems in the hilly terrain of Mizoram, Northeast India

Soil carbon is one of the most affected variables to land-use change in tropics. The soil carbon flux plays a major role in regulating microbial activities and nutrient distribution in soil. This study aimed to evaluate the soil carbon stock in various land uses at different depths in the hilly terrain of Mizoram, Northeast India. Soil samples at 0-10 cm, 10-20 cm and 20-30 cm soil depths were collected from Rubber plantation (RP), Oil palm plantation (OPP), Teak plantation (TP), Bamboo Forest (BF), 5 years fallow (5YF), 10 years fallow (10YF), Tephrosia candida plantation (TCP), Horticulture garden (HORT), Homegarden (HG) and Natural forest (NF). Soil carbon stock varied significantly (p <0.05) across the land uses and depths. The soil under Tephrosia candida stand had significantly (p <0.05) higher values of C stock (73.66 Mg ha-1) which may be due to high biomass, dense vegetative cover and high C in root exudates. The minimum C stock estimated in Horticulture garden (43.28 Mg ha-1) is probably due to reduced soil organic matter. Soil carbon stock in Homegarden, Teak plantation, Bamboo forest and Rubber plantation ranged from 46.82 Mg ha-1 to 59.34 Mg ha-1 whereas 5 years and 10 years fallow land, Natural forest and Oil palm plantation ranged from 61.35 Mg ha-1 to 73.35 Mg ha-1. The study indicated that the land use change in the mountainous region significantly affected the carbon stock in the soil. A proper land use management strategies to increase the soil organic matter is recommended to enhance the carbon stock in this region.

Developing taper equations for planted teak (Tectona grandis L.f.) trees of central lowland Nepal

Foresters rely on taper models to estimate total and merchantable volume for commercial species. While there is an abundance of literature in taper modeling for many softwood and hardwood species, little is known of teak tree stem form. Taper modeling is in early stage for the forestry sector in Nepal. Currently, no publicly available taper equations exist for teak trees in Nepal. Therefore, the main goal of this study was to develop a taper equation for valuable teak trees of lowland Nepal. Destructive sampling was carried out in teak plantations in the Sagarnath Forestry Development Project. Five common taper equations (simple, segmented, and variable exponent types) from the literature as well as one dynamic taper equation were considered as candidate models. Our results showed that the nonlinear dynamic taper equation performed best in terms of fit and cross-validation statistics with least error and bias. This new taper model can be considered as a step forward for hardwood forest management in Nepal. It is expected that this equation will assist forest managers to predict stem volume and diameters to any merchantable limit for teak growing in similar site conditions.

Herpetofaunal diversity of West Bali National Park, Indonesia with identification of indicator species for long-term monitoring

We report on the results of a survey of the herpetofauna of West Bali National Park (Taman Nasional Bali Barat in Indonesian, hereafter TNBB) that was carried out in 2015. The survey also included other taxa and the motivation for it was to identify a species or group of species that could be used as indicators of management success for Protected Area Credits (PAC) under the Rainforest Standards (RFS™) system. Four major ecosystems, moist forest, deciduous monsoon forest, savanna and an abandoned Teak plantation, were sampled over a period of 10 days, using belt transects and pitfall traps. We measured species richness, abundance and density, herpetofaunal diversity (Simpson’s Index of Dominance and the Shannon Weiner Index) and community similarity. We also estimated the indicator value to determine which species, if any, might be suitable as indicators of environmental conditions. The survey yielded 30 species, 12 frogs and toads, 7 snakes and 11 lizards. Out of them there is an endangered gecko, Cyrtodactylus jatnai, a vulnerable frog, Microhyla orientalis, and a vulnerable tree-skink, Cryptoblepharus baliensis. Diversity was highest in the moist forest, followed closely by both the deciduous forest and the savanna. The greatest abundance was found in the savanna, followed by the moist forest and then the deciduous forest. Both diversity and abundance were extremely low in the abandoned teak plantation. Eleven species were identified as potential indicators of environmental deterioration if their numbers were to decrease. Frogs and toads were the best indicators in the moist forest, while lizards were the most suitable indicators for savanna and deciduous forest. No snakes were identified as indicators. It is concluded that herpetofauna can be useful and cost-effective indicators of environmental change.

Effects of tree density and size symmetry of competition on diameter growth in the early stages of growth in planted teak (Tectona grandis) trees in northern Thailand

ABSTRACT Teak (Tectona grandis) is among the most valuable tropical hardwoods, but silvicultural guidelines are needed to improve the growth and quality of trees in teak plantations, particularly those owned by smallholders in Asia. We analyzed the diameter growth of individual trees to determine the effects of density control in the early stages of growth in a teak plantation in northern Thailand. Site water conditions estimated using the topographic index (TI) affected initial tree size at 10 years after planting, before the first thinning was conducted. Thinning comprised three levels: high, low, and none (control). Five years after thinning, we assessed the effects of thinning, diameter at thinning, TI, and neighborhood competition on tree diameter growth using generalized linear mixed models. We found two significant factors on diameter growth: negative effect of neighborhood competition and positive effect of initial diameter at thinning. We used two indices of neighborhood competition: size-asymmetric (one-sided) and symmetric (two-sided) competition. The two-sided competition model predicted diameter growth more accurately. The results indicate that inter-tree competition in even-aged teak plantations is size-symmetric or two-sided. In addition, the presence of size-symmetric competition implies that teak trees compete not only for light but also for below-ground resources, such as water and nutrients.

Carbon and nutrient cycling in tree plantations vs. natural forests: implication for an efficient cocoa agroforestry system in West Africa

Nutrient cycling has been widely studied in tree plantations. However, studies on the observed negative changes relative to natural vegetations and how these could be capitalized toward setting up ecofriendly agroecosystems are rare. This study was conducted in Central-West Cote d’Ivoire to establish the changes in carbon and macronutrient cycling occurring in full-sun cocoa (Theobroma cacao L.) and Teak (Tectona grandis) relative to primary forest and subsequently make cocoa agroforestry-based recommendations. Leaf litterfall and associated carbon and macronutrient inputs, rates of leaf litter decomposition, and macronutrient release were assessed. In addition, soil (0–10 cm depth) chemical and microbial parameters were evaluated. Litterfall yields were 10.6 ± 2.0, 9.3 ± 0.8, and 10.1 ± 0.4 Mg dry mass ha−1 year−1 in forest, cocoa, and teak, respectively. Compared to the forest, the cocoa plantation supplied lower inputs of C (−736 kg ha−1 year−1 or −15.5%) and N (−75 kg ha−1 year−1 or −27%), similar P, but greater K. Similar quantities of C and N were recorded in the teak plantations and the forest. However, the teak plantation supplied lower K but higher P inputs than the forest. Cocoa leaf litters decomposed at the same rate as those of the forest (k = 0.3 month−1) but faster than the teak’s, the initial leaf litter N:P ratio being the most influencing factor. Except for P, the macronutrient release from cocoa and forest litters exhibited similar patterns and rates, which were significantly different from those observed in the teak leaf litter. Soil C mineralization rate and mineral N concentration drastically declined in both tree plantations, the greatest gap occurring in cocoa (Cmin: −40%, mineral N: –54.2%) due to lower litter Ca input and soil acidity. Teak appears to be a good candidate for shade as it may compensate for the deficit in litter C (and N, to a lesser extent) supply exhibited by cocoa relative to the forest. The trends in microbial activity underscore the need to grow cocoa in association with trees that provide quality litter materials, for improved cocoa nutrient availability and faster C storage in soil. In line with this, some suggestions were made and discussed. This study can be used in support of developing an efficient cocoa agroforestry system in West Africa.

Impact of thinning and pruning on tree growth, stress wave velocity, and pilodyn penetration response of clonal teak (Tectona grandis) plantation

The objective of this research was to examine the impact of different thinning and pruning intensities on the growth characteristics and wood properties of clonal teak. A 14-year-old clonal teak plantation was used in the study. The first thinning and pruning were established 5 years after planting. Three different levels of thinning (un-thinned, moderate, and heavy) and pruning (low, medium, high) were tested. Growth characteristics, pilodyn penetration, and stress wave velocity were examined. Results showed that different thinning intensities significantly affected the mean annual diameter increment (F = 37.67; p < 0.01). The standing stock estimations of the thinning intensity regimes also significantly differed between different thinning intensities (F = 4.16; p = 0.035). Moreover, pilodyn penetration significantly varied with the thinning treatment (F = 23.53; p < 0.01). The stress wave velocity, however, did not significantly vary with the thinning treatment (F = 2.54; p = 0.11). Meanwhile, the effect of pruning treatment was not observed under all parameters. Heavy thinning treatment promoted all parameters except height and stress wave velocity. A strong positive correlation was observed between pilodyn penetration and DBH. This result suggested that thinning and pruning promoted positive DBH growth and an increase in the economic value of the stand, but it did not affect the wood properties of clonal teak wood.