Selective Harvesting Research Articles

Strawberry Detection and Ripeness Classification Using YOLOv8+ Model and Image Processing Method

As strawberries are a widely grown cash crop, the development of strawberry fruit-picking robots for an intelligent harvesting system should match the rapid development of strawberry cultivation technology. Ripeness identification is a key step to realizing selective harvesting by strawberry fruit-picking robots. Therefore, this study proposes combining deep learning and image processing for target detection and classification of ripe strawberries. First, the YOLOv8+ model is proposed for identifying ripe and unripe strawberries and extracting ripe strawberry targets in images. The ECA attention mechanism is added to the backbone network of YOLOv8+ to improve the performance of the model, and Focal-EIOU loss is used in loss function to solve the problem of imbalance between easy- and difficult-to-classify samples. Second, the centerline of the ripe strawberries is extracted, and the red pixels in the centerline of the ripe strawberries are counted according to the H-channel of their hue, saturation, and value (HSV). The percentage of red pixels in the centerline is calculated as a new parameter to quantify ripeness, and the ripe strawberries are classified as either fully ripe strawberries or not fully ripe strawberries. The results show that the improved YOLOv8+ model can accurately and comprehensively identify whether the strawberries are ripe or not, and the mAP50 curve steadily increases and converges to a relatively high value, with an accuracy of 97.81%, a recall of 96.36%, and an F1 score of 97.07. The accuracy of the image processing method for classifying ripe strawberries was 91.91%, FPR was 5.03%, and FNR was 14.28%. This study demonstrates the program’s ability to quickly and accurately identify strawberries at different stages of ripeness in a facility environment, which can provide guidance for selective picking by subsequent fruit-picking robots.

Optimizing Harvesting Efficiency: Development and Assessment of a Pneumatic Air Jet Excitation Nozzle for Delicate Biostructures in Food Processing.

This study presents a new pneumatic air jet excitation nozzle, specifically designed for food processing applications. The device, which uses compressed air equipment and a precision solenoid valve, controls air discharge through a parametric air jet nozzle. Tests showed that the device could achieve shooting frequencies in the 40-45 Hz range, with operational pressures between 5 and 7 bar. A sensor system was used to measure the force generated by the device at different frequencies and pressures. Using the Design of Experiments (DOE) methodology, we identified optimal cavity designs for 5 and 6 bar pressures. These designs outperformed others in generating uniform force and maintaining consistent vibration voltage behavior. This highlights the efficacy of our approach in enhancing device performance under different conditions. The device's practical application in food processing was demonstrated, particularly in delicate tasks such as the selective harvesting of sensitive crops like coffee fruits. The precise vibrations generated by the device could potentially enhance harvesting efficiency while significantly reducing mechanical damage to plants. The results position the device as a compelling proof of concept, offering an alternative method for exciting biostructures in food processing. This device opens up new possibilities in agricultural and biological fields, providing a non-intrusive and practical approach to manipulating and interacting with delicate, contactless structures, with a specific focus on improving food processing efficiency and quality.

Broad-scale acoustic monitoring of koala populations suggests metapopulation stability, but varying bellow rate, in the face of major disturbances and climate extremes.

Population trends are lacking for most threatened species, especially those that are cryptic and difficult to survey. Recent developments in passive acoustics and semi-automated call recognition provide a cost-effective option to systematically monitor populations of vocal species. We assessed recent trends for the koala Phascolarctos cinereus, an iconic marsupial, based on 7 years of acoustic monitoring across 224 forested sites. The study period overlapped with a severe drought and extensive megafires in 2019 followed by 2 years of extremely high rainfall. Dynamic occupancy modelling with a range of covariates at multiple landscape scales found that initial occupancy was related to elevation (-ve), NDVI (+ve) and previous selective harvesting (16-30-year age class; weakly +ve). Extinction probability increased with the extent of high-severity fire. Colonisation probability was related to a range of factors, with the top model showing a decrease with increasing lagged annual rainfall. However, the null model was also supported, suggesting weak associations for colonisation. Using these relationships, koala occupancy was found to be high and stable over the study period. Fire did not influence regional trends because koalas often persisted with low- to moderate-severity fire and because high-severity fire was limited to 11% of their habitat. In contrast, bellow rate varied across years, being initially low and declining immediately after the 2019 fires, with the driver of these changes unclear. Neither timber harvesting nor low-severity fire influenced koala occupancy or bellow rate. Given the extensive area of koala habitat in the region, our results point to the presence of a large population in these public forests, and in recent years, stable occupancy (albeit with site-scale reductions in density with high-severity fire). Ongoing monitoring is crucial for tracking future changes, especially with predictions of more frequent, severe forest fires due to climate change.

PERBAIKAN PENDAPATAN PETERNAK SAPI PENGGEMUKAN MELALUI PEMANFAATAN LAMTORO TARAMBA DI KECAMATAN UNTER IWIS, KABUPATEN SUMBAWA, NTB

This community service activity in addition to aiming to increase the income of farmers by utilizing Lamtoro Taramba as feed for fattening cattle is also aimed at saving the environment from the influence of erosion due to massive land deforestation that has occurred recently, including in Unter Iwis District, Sumbawa Regency. Apart from receiving short training on seed selection procedures, seeding patterns, harvesting and techniques for using Lamtoro taramba, farmers are also given input on economic calculations regarding the results of fattening cattle using Lamtoro taramba compared to using other feed crops.. The results of the service show that lamtoro taramba is trusted by breeders as a plant that has many benefits in the process of fattening cattle, and is no longer considered a pest that destroys land and the environment. The consolidation of breeders into groups makes it easier for the Sumbawa District Government to provide guidance on feed and the environment.

Relationship between Height and Exposure in Multispectral Vegetation Index Response and Product Characteristics in a Traditional Olive Orchard.

The present research had two aims. The first was to evaluate the effect of height and exposure on the vegetative response of olive canopies' vertical axis studied through a multispectral sensor and on the qualitative and quantitative product characteristics. The second was to examine the relationship between multispectral data and productive characteristics. Six olive plants were sampled, and their canopy's vertical axis was subdivided into four sectors based on two heights (Top and Low) and two exposures (West and East). A ground-vehicle-mounted multispectral proximal sensor (OptRx from AgLeader®) was used to investigate the different behaviours of the olive canopy vegetation index (VI) responses in each sector. A selective harvest was performed, in which each plant and sector were harvested separately. Product characterisation was conducted to investigate the response of the products (both olives and oils) in each sector. The results of Tukey's test (p > 0.05) showed a significant effect of height for the VI responses, with the Low sector obtaining higher values than the Top sector. The olive product showed some height and exposure effect, particularly for the olives' dimension and resistance to detachment, which was statistically higher in the upper part of the canopies. The regression studies highlighted some relationships between the VIs and product characteristics, particularly for resistance to detachments (R2 = 0.44-0.63), which can affect harvest management. In conclusion, the results showed the complexity of the olive canopies' response to multispectral data collection, highlighting the need to study the vertical axis to assess the variability of the canopy itself. The relationship between multispectral data and product characteristics must be further investigated.

Signature of logging in the Brazilian Amazon still detected after 17 years

Selective logging in the Amazon Biome holds significant importance economically and environmentally. Due to its potential for forest degradation, monitoring these areas is of utmost importance. We assessed canopy openness in sustainably logged forest areas in Eastern Amazonia using hemispherical photos taken in areas that were logged in different years (2004, 2007, 2017, 2019, and 2021), along with one unlogged control area to evaluate the time period over which the effects of logging remained detectable. Timeframes of detectability varied across logging features considered (e.g. log landings, logging roads and skid trails). Canopy openness of log landings used to store logs was still greater than that of unlogged forests controls >17 years after logging had ceased while the impacts of logging roads and skid trails were still detectable at least 5 years after cessation of logging. The detection of the impacts of selective tree harvesting on the forest several years after the end of operations provides confidence for larger-scale quantification of historical low-intensity logging over Amazonia through high-resolution imagery. More generally, the study also highlighted the importance of monitoring selective tree extraction areas to understand their influence on forest disturbance and the occurrence of regeneration processes.

A novel lightweight model HGCA-YOLO: Application to recognition of invisible spears for white asparagus robotic harvesting

Timely harvesting white asparagus depend on the detection of two forms: the emerging unearthed spear tips and the soil leaks raised by earthed spears. Accurate detection of the small spear tips and the invisible spears in the complex backgrounds of field ridges remains a challenge, especially the soil leaks with pattern similarity to the drought-induced cracks. In this paper, a novel lightweight model named HGCA-YOLO (Hyperparameter evolution-Ghost module-Coordinate Attention mechanism You Only Look Once algorithm) is proposed for accurate detection of two forms of targets. Firstly, the baseline network is determined by adopting the hyperparameter evolution to converge the network faster and obtain better parameters for spear detection. Then, the Ghost module and coordinate attention mechanism are introduced in the baseline network to decrease the complexity of the model as well as to enhance the sensitivity to the target location. In addition, the TTA (Test Time Augmentation) is introduced to the network inference to handle the targets in strongly varying environment. Finally, a dataset covered spear tips and soil leaks acquired from natural ridge is constructed, and the detection test and field experiments are conducted. The experimental results show that the accuracy of the proposed method achieved mAP 0.952 and mF1 0.924. Compared to the baseline network, this method reduced the parameters, GFLOPs and model size by 46.2%, 48.4% and 44.7%. In particular, the success rate of detection achieved 87% in the field test. This lightweight model effectively extracted the features of the cracking pattern of invisible asparagus and the small spear tips, which improved the accuracy of spear detection for selective robotic harvesting of white asparagus.

Non-smooth dynamics of a fishery model with a two-threshold harvesting policy

The non-linear dynamical systems theory helps implement regulatory measures to control the growth and evolution of various populations. While invasion by alien fish species is an emerging threat to native fish species in marine ecosystems, a suitable fishery management protocol needs to be incorporated in marine protected areas (MPAs) to mitigate the problem. We propose a policy of selective harvesting whenever the density of a species crosses a predefined threshold. An ecosystem with such a harvesting policy is modelled by a piece-wise smooth prey-predator type fishery model, where a control function defined by two thresholds evokes signals to cease or commence harvesting. This work reports the dynamics and bifurcations of a Filippov system, including the possibility of sliding mode dynamics. We show that the variations in the growth rate and the harvesting rate of the invasive fish species can lead to hysteresis through saddle–node and transcritical bifurcations and the appearance of a stable homoclinic orbit. We obtain the conditions for sliding domains, regular or virtual equilibria, boundary equilibria, pseudo-equilibria, and tangent points. Depending on the parameter choice, the system can stabilize at a regular equilibrium, a pseudo-equilibrium, or a pseudo-attractor, exhibiting multistability. We report the occurrence of regular or virtual equilibrium bifurcation, boundary node bifurcation and pseudo-saddle–node bifurcation. Our findings indicate that proper harvesting strategies can prevent the proliferation of invasive fish species in MPAs.

A novel perception and semantic mapping method for robot autonomy in orchards

Agricultural robots must navigate challenging dynamic and semi-structured environments. Recently, environmental modelling using LiDAR-based SLAM has shown promise in providing highly accurate geometry. However, how this chaotic environmental information can be used to achieve effective robot automation in the agricultural sector remains unexplored. In this study, we propose a novel semantic mapping and navigation framework for achieving robotic autonomy in orchards. It consists of two main components: a semantic processing module and a navigation module. First, we present a novel 3D detection network architecture, 3D-ODN, which can accurately process object instance information from point clouds. Second, we develop a framework to construct the visibility map by incorporating semantic information and terrain analysis. By combining these two critical components, our framework is evaluated in a number of key horticultural production scenarios, including a robotic system for in-situ phenotyping and daily monitoring, and a selective harvesting system in apple orchards. The experimental results show that our method can ensure high accuracy in understanding the environment and enable reliable robot autonomy in agricultural environments.

Tree marking guidelines for northern hardwoods: a review of criteria for assessing vigour and quality

Recent studies have highlighted the need to update hardwood tree marking guides by changing the criteria used to assess vigour and quality, and thus the priority for deciding which trees to remove and retain during selection harvests. However, these studies have recommended different criteria, so it remains uncertain which should be included in the classification systems used to assess vigour and quality. We review these studies with the aim of reducing this uncertainty and identifying potential improvements to the provincial tree marking guides for northern hardwood forests in Canada, particularly the Ontario Tree Marking Guide. We review the differences in methodologies and summarize which defects have been shown to affect vigour and/or quality. The defects that should be used to assess vigour are canopy dieback, cankers, and fungi. Decaying wounds, wounds without decay, canopy density, and bark condition could also be used as secondary criteria for borderline cases in which the primary criteria are not decisive. The defects that should be used to assess quality are cankers, fungi, cracks, cavities, and decay (including black bark and wounds with moisture or soft wood). We present a new classification system based on these results and identify potential challenges to its implementation.

Financial Comparison of Continuous-Cover Forestry, Rotational Forest Management and Permanent Carbon Forest Regimes for Redwood within New Zealand

Continuous-cover forestry (CCF), which maintains a relatively intact forest cover through selective harvesting, has emerged over the last few decades as a popular alternative to rotational forest management (RFM). Coast redwood, which is native to the western United States, grows rapidly in New Zealand and is well suited to CCF as it has high shade tolerance, an ability to coppice from the cut stem, and resistance to pests, diseases, wind and fire. A forest estate model was used to compare the carbon sequestration, timber production and profitability of redwood CCF, RFM and permanent carbon forestry (PCF) regimes at a regional level within New Zealand. Through linear programming, this model optimised carbon accumulation and harvesting decisions across a large forest to meet a series of constraints associated with each regime. All three regimes represented good investment decisions, but CCF had the highest soil expectation value (SEV) within most North Island regions while PCF had a slightly higher SEV within the South Island regions. Under the transitional CCF (CCFt), revenue from carbon initially increased before levelling out at 40 years, after which time a sustainable harvest of high-value timber commenced in perpetuity without additional revenue from carbon. The CCFt regime transitioned to a steady-state condition, with a uniform age class distribution from year 150 onwards (CCFs), after which time a very high SEV was attained that exceeded that of CCFt by four-fold in the North Island (NZD 136,126/ha vs. NZD 34,430/ha) and seven-fold (NZD 44,714 vs. NZD 6267/ha) in the South Island. This study highlights the profitability of managing redwood under CCF and how initial carbon revenue can be used to finance the transition of the forest to a steady-state condition that produces a stream of valuable timber with a very high rate of return.

Discrete-Time Model of an Exploited Population with Age and Sex Structures: Instability and the Hydra Effect

This study proposes a discrete-time mathematical model to investigate the impact of selective harvesting on the dynamics of a population with age and sex structures. The model assumes that the birth rate depends on the sex ratio of the population and the number of breeding pairs. The growth rate is regulated by limiting juvenile survival, where an increase in population size decreases the survival of immature individuals. We consider the following selective proportional exploitation: harvesting of juveniles and harvesting of mature males. Depending on the values of population parameters, selective harvesting can lead to the stabilization of population dynamics by dampening oscillations or the emergence and amplification of fluctuations in population size. The model reveals multistability domains in which different dynamic modes coexist, and variations in initial conditions can lead to changes in dynamic modes. Depending on the values of the population parameters, the proposed models with harvest reveal the hydra effect, indicating an increase in the equilibrium abundance of the exploited group after reproduction but before harvesting, with an increase in the harvesting rate. Selective harvesting, resulting in the hydra effect, increases the remaining population size due to reproduction and the number of harvested individuals.

Avocado (Persea americana cv. ‘Hass’) Fruit Mineral Composition at Canopy Level towards Sustainable Quality

Sustaining avocado fruit quality is crucial to maintain customer satisfaction and confidence. Among fruit qualities, mineral nutrient composition is an important contributor to postharvest robustness. Towards better understanding and addressing variability within the plant canopy, ‘Hass’ fruit from across seven orchard blocks were individually characterised. From five representative trees in each block, five fruit were harvested (one from each of five positions: top (sun-exposed), bottom (shaded), middle (shaded), East (sun-exposed), and West (sun-exposed)). Fruit dry matter was significantly higher (p ≤ 0.001) in fruit from the top, East, and West sun-exposed positions. No significant (p > 0.05) effect of position was discerned for fruit weight at harvest or for either stem end rot (SER) or body rot (BR) incidence at eating soft. Shaded fruit had significantly higher (p ≤ 0.05) [N], [K], [Mg], N:Ca, K:Ca, and K + Mg:Ca in their flesh. Significant negative linear correlations (p ≤ 0.001) were obtained between fruit DM and flesh [N] (r = −0.75), [K] (r = −0.67), and N:Ca (r = −0.57). SER and BR incidence were significantly positively correlated (p ≤ 0.01) with flesh and skin mineral ratios of N:Ca, K:Ca, Mg:Ca, and K + Mg:Ca. Skin and flesh [Ca] were significantly negatively correlated with SER (r = −0.51, p ≤ 0.01) and BR (r = −0.74, p ≤ 0.001) incidences. Soil cation (Ca, Mg, K) availability (%base saturation of cation exchange capacity (CEC)) was not (p > 0.05) correlated with skin or flesh mineral concentrations or ratios. Considered collectively, results suggest that selective harvest of sun-exposed fruit with inherently lower mineral nutrient ratios yields relatively robust fruit. Such fruit lots should better tolerate the rigours of harvest and postharvest treatment and handling. In this context, they should better maintain quality upon passage through long, in terms of accumulated time-temperature increments, export supply chains. In contrast, shaded fruit could be directed into shorter domestic supply chains. As a harvest strategy, segregating fruit lots from harvest could underpin the quality offered to consumers at the end of ‘short’ and ‘long’ supply chains.

Economic Evaluation of Precise Intelligent Cauliflower Harvester: A Comparative Study with Manual Harvesting

Aim: The traditional harvesting of cauliflower has been done by hand using labor-intensive, expensive, and time-consuming techniques that frequently lead to significant yield losses because immature curds are harvested without selection. A rising number of people are interested in creating selective cauliflower harvesters that can precisely detect and gather healthy, mature heads while reducing damage, waste, and labor-intensive operations in response to these difficulties. The purpose of this research article is to present a thorough analysis of the ownership and operating costs related to this kind of selective harvesting technology.
 Methodology: Through accurate cost insights, farmers can make well-informed decisions on the purchase of new machinery, the maintenance, and upkeep of current equipment, or the investigation of alternative approaches to improve farm productivity and financial results. The economic assessment was conducted through the computation of operating costs utilizing the straight-line method, coupled with breakeven point analysis and determination of the payback period.
 Results: The developed selective harvester's ownership and running costs are calculated to be 58.41 and 75.5 rupees per hour, respectively. The selective harvester has several advantages over typical manual harvesting techniques, as demonstrated by a comparative analysis. In particular, the selective harvester shows a remarkable 24.6% cost reduction in addition to saving an astounding 60.6% of the necessary time.
 Conclusion: These results highlight the efficiency and financial gains that come with using selective cauliflower harvesting technologies. This analysis is further utilized by farmers for decision-making.

FILIPPOV TYPE PREY–PREDATOR SYSTEM FOR SELECTIVE HARVESTING OF PREY

In this paper, the dynamics of a Filippov system with logistically growing prey and Holling Type II predation is explored. The selective nonlinear harvesting of prey is carried out when the ratio of prey to predator is above a specified threshold value. In order to prevent the extinction of both the species and sustainable economic gains, no harvesting is allowed when the ratio is below a threshold value. The equilibrium states and their stability for the individual smooth are analyzed. Filippov convex method is applied to determine the dynamics on the boundary. The sliding mode dynamics is scrutinized, and it is observed that there is no escaping region. The existence of boundary points, tangent points and pseudo-equilibrium points are established. The conditions are obtained for the visibility of the tangent points. The complex behavior within the sliding region is studied by experimenting with different initial conditions. The increase in harvesting effort may lead to extinction of both the species through the sliding region of the boundary. The change in the stability behavior of both the interior equilibrium states is investigated with respect to model parameters. Border cross bifurcates with threshold value as the bifurcation parameter is shown for both the interior equilibrium states.

Design and experiment on mechanized batch harvesting of Shiitake mushrooms

Shiitake mushroom must be harvested in time or its commercial value will be reduced. At present, manual harvesting is time-consuming and labor-intensive, and the robotic selective harvesting is far from mature and marketable. Based on the analysis of manual harvesting, a mechanized batch-based harvesting method for the stick cultivation of shiitake mushrooms is proposed as an alternative harvest method in the scenario of large-scale factory production. The feasibility of the simplified picking method was verified by a data acquisition system with integrated force sensor and inertial measurement unit, and the picking force and picking action during manual picking were measured. A mechanized harvesting scheme by picking rings with forward forces to the mushroom stalk was proposed, and its finite element analysis concluded that the mushroom could be picked without damaging the mushroom by using a 5/10 size latex tube. A new mushroom Batch Harvesting Picker (BHP) was designed, including a pushing mechanism, a guiding mechanism, and a harvesting mechanism. By analyzing the causes of harvesting failure and mushroom damage, the stick surface profiling unit were improved by multi-body dynamics simulation. The simulation results show that when the preload force of the reset spring of the harvesting mechanism is set to 30 N, the least pressure on the mushroom stick is 8.97 N, and the picking ring working closer along the surface of stick. The experiment of BHP showed that the harvesting success rate is 98.93 %, the harvesting damage rate is 3.31 %, and the average harvesting time of a single mushroom stick is 9.8 s, which improved the harvesting efficiency of single stick by 2.2–6.6 times compared with the manual harvesting process, which proved the feasibility and efficiency of this batch harvesting scheme in large-scale factory production of shiitake mushrooms.

Influences of earthworm activity and mucus on Cd phytoremediation based on harvesting different leaf types of tall fescue (Festuca arundinacea).

To explore cost-effective and efficient phytoremediation strategies, this study investigated the distinct roles of earthworm activity and mucus in enhancing Cd phytoextraction from soils contaminated by Festuca arundinacea, focusing on the comparative advantages of selective leaf harvesting versus traditional whole-plant harvesting methods. Our study employed a horticultural trial to explore how earthworm activity and mucus affect Festuca arundinacea' s Cd phytoremediation in soils using control, earthworm, and mucus treatments to examine their respective effects on plant growth and Cd distribution. Earthworm activity increased the dry weight of leaves by 13.5% and significantly increased the dry weights of declining and senescent leaves, surpassing that of the control by more than 40%. Earthworm mucus had a similar, albeit less pronounced, effect on plant growth than earthworm activity. This study not only validated the significant role of earthworm activity in enhancing Cd phytoextraction by Festuca arundinacea, with earthworm activity leading to over 85% of Cd being allocated to senescent tissues that comprise only approximately 20% of the plant biomass, but also highlighted a sustainable and cost-effective approach to phytoremediation by emphasizing selective leaf harvesting supported by earthworm activity. By demonstrating that earthworm mucus alone can redistribute Cd with less efficiency compared to live earthworms, our findings offer practical insights into optimizing phytoremediation strategies and underscore the need for further research into the synergistic effects of biological agents in soil remediation processes.

АНАЛИЗ СТРУКТУРЫ ПРОМЫСЛА И ДИНАМИКИ РОСТА СТАДА СЕВЕРНОГО МОРСКОГО КОТИКА (CALLORHINUS URSINUS) ОСТРОВА ТЮЛЕНИЙ В ПЕРИОД ЭКСПЛУАТАЦИИ И ПОСЛЕ ЕЁ ЗАВЕРШЕНИЯ

Based on a long time series providing biological monitoring data of the Northern fur seal population on Tyuleny Island and detailed information on the harvesting characteristics of this population, we have analyzed trends in its growth. The research results of changes in the average reproductive success of bulls and the age structure of Northern fur seal males on Tyuleny Island are presented as indicators of harvesting impact on the reproductive potential of the population. Evidence has shown that selective harvesting was practiced, where most productive bulls were removed from the population. This led to a significant change in the age structure of the population and a significant reduction in the population growth. Despite a slight increase in the natural survival of almost all age groups, the population growth slowed down sharply. The proximity of the growth potential indicator to the critical unitary value revealed in recent years leads to a bleak forecast. Further growth in the Northern fur seal population, if any, will not be rapid. To accelerate it, it is necessary to provide a new natural restructuring of the population structure, improving its qualitative composition and increasing the proportion of males with high reproductive success.

The study on the complex nature of a predator-prey model with fractional-order derivatives incorporating refuge and nonlinear prey harvesting

<abstract> <p>The main objective of our research was to explore and develop a fractional-order derivative within the predator-prey framework. The framework includes prey refuge and selective nonlinear harvesting, where the harvesting progressively approaches a threshold value as the density of the harvested population advances. For memory effect, a non-integer order derivative is better than an integer-order derivative. The solutions to the fractional framework were shown to be existence, uniqueness, non-negativity, and boundedness. Matignon's condition was used for analysing local stability, and a suitable Lyapunov function provided global stability. While discussing the Hopf bifurcation's existence condition, we explored derivative order and refuge as bifurcation parameters. We aimed at redefining the predator-prey framework to incorporate fractional order, refuge, and harvesting. This kind of nonlinear harvesting is more realistic and reasonable than the model with constant yield harvesting and constant effort harvesting. The Adams-Bashforth-Moulton PECE algorithm in MATLAB software was used to simulate the proposed outcomes, investigate the impact on various factors, and analyse harvesting's effect on non-integer order predator-prey interactions.</p> </abstract>

Restoring forest structure, biodiversity and ecosystem function in the West African humid tropics: secondary versus plantation forests

Deforestation and forest degradation in the tropics has resulted in the depletion of vital forest resources and services, the near eradication of suitable habitats for forest fauna and flora, and the impoverishment of human populations reliant on forest ecosystems. The rapid and concerning pace of deforestation in tropical regions calls for urgent and pragmatic steps to tackle the root causes and rehabilitate or restore degraded and deforested landscapes. The aim of the study was to evaluate the effectiveness of old, unmanaged forest plantations compared to similar-aged secondary forests in restoring forest stand structure, floristics and diversity of vascular plants, and important ecological functions with reference to neighbouring primary forests. In addition, timber value was estimated and compared among the three forest types. The research was conducted across 11 sites within Ghana's moist and wet climatic/forest zones. Systematic random sampling of 93 plots each measuring 20m × 20m with nested subplots measuring 5m x 5m for saplings and 2m x 2m for ground vegetation was undertaken. Forty-two years after establishment and/or abandonment, both the plantation and secondary forests showed structural attributes comparable to those of the primary forests. Nevertheless, the plantation recorded much higher bole volume and basal area compared to the secondary forests. The secondary, plantation and primary forests exhibited considerable overlap in terms of floral composition, with the presence of several rare and restricted-range species. A significant proportion of primary forest vascular plant species, namely 60% and 77%, were identified in the secondary and plantation forests, respectively. The diversity of plant species, as quantified by the Shannon-Wiener Diversity Index (H') and Simpson Index (S), showed no significant variation between primary (H'=3.07, S = 0.91) and secondary (H'=2.95, S = 0.87) or plantation (H'=2.85, S = 0.87) forests. Generally, the primary and secondary forests exhibited higher species richness than the plantations. The mean above-ground carbon stocks of the plantations (159.7 ± 14.3 Mg ha-1 ) was found to be similar to that of the primary forests (173.0 ± 25.1 Mg ha-1 ), but both were much higher than the secondary forests (103.4 ± 12.0 Mg ha-1 ). Soil pH levels in the wet sites were much lower, ranging from 4.2 to 4.6, compared to moist sites, which had pH levels ranging from 4.6 to 5.4. Soil physicochemical properties, carbon stocks, fertility, microbial activity, and litter decomposition measurements across the different forest types within the climatic zones were similar. Nevertheless, significant differences were observed between climatic zones. Contrary to results of earlier tropical studies, we observed higher litter decomposition rates in the moist compared to the wet zone, which experiences higher annual rainfall, especially for the recalcitrant carbon fraction of the litter. Relatedly, soil microbial biomass and microbial population were significantly greater in the moist compared to the wet zone. Mean soil carbon stocks (0 - 50 cm) was significantly higher in the wet (106.8 Mg ha-1 ) compared to the moist (56.9 Mg ha-1 ), with mean site values ranging from 51.16 Mg ha-1 to 122.84 Mg ha-1 . The mean timber stumpage value of plantations was $8577 per hectare, compared to primary and secondary forests, which were $3112 and $1870 per hectare, respectively. Tropical forest plantations established on long rotations under low-intensity management regimes, and secondary forests can evolve into forest systems that exhibit structural complexity, floristic diversity, ecological functionality, and self-sustainability, akin to primary forests. Such forest plantations and secondary forests constitute viable pathways for the restoration of deforested landscapes and climate change mitigation, while potentially providing landowners with moderate financial returns through selective timber harvesting.