Grandis Forest Research Articles

Variations in plant–microbe–soil C:N:P stoichiometry along a 900-year age gradient in Torreya grandis ‘Merrillii’ plantations in Southeast China

Researches on the ecological stoichiometry of forest vegetation at different growth stages under long-term human management activities and its driving factors will help to clarify how the limited nutrient resources are allocated at different growth stages of forests, providing a basis and suggestions for scientific cultivation of artificial forests. In subtropical China, the C:N:P stoichiometry of an ancient Torreya grandis ‘Merrillii’ community was measured in leaves, twigs, roots, soils, and soil microbes with age gradients of 0–50, 50–100, 100–300, 300–500, and more than 500 years. The results showed that the nutrient use varied with tree ages. The N and P concentrations in the leaves, twigs, and roots of T. grandis had the similar increasing trends with the increasing tree age, and the N concentrations in leaves in 0-50-year-old forests were significantly lower than those forests of other ages. Particularly, the N:P ratio of different organs was always below 10, reflecting limited N supply of plants. The soil C content increased with the increasing T. grandis forest ages while the soil microbe C showed a fluctuated trend. There was a higher correlation among the C, N and P contents and their ratios in leaves, twigs and roots of 0-50-year-old forests than that in soil microbes, but inversely at more than 500-year-old forests. The homeostasis analysis results showed that the roots and soil microbes are more indicative of soil nutrient availability. The results of redundancy analysis showed that acid phosphatase activity had the highest impact on soil microbes in 0–10 and 10–20 cm soil layers, confirming that the decomposition and transformation of P in soils is very active. Moreover, soil enzyme activity mediates the influence of soil microbes on soil N and P limitation. In summary, tree age can effect the plant–microbe–soil C:N:P stoichiometry of T. grandis forests. The growth of T. grandis is mainly restricted by N, and reasonable application of N fertilizer is needed to promote its growth.

Alterations in aggregate characteristics of thermally heated water-repellent soil aggregates under laboratory conditions

Abstract The heat generated during wildfires modifies soil characteristics, including soil water repellency (SWR) and the water stability of aggregates, which are known to be interrelated. SWR lowers the rate of water entry into aggregates, minimizing aggregate disruption and subsequent erosion. This study aimed to examine these aggregate characteristics (SWR, water stability of aggregates) of thermally heated water-repellent soil aggregates under laboratory conditions. Water-repellent aggregates were collected from Eucalyptus grandis forest soil separately from four soil depths (0–5, 5–10, 10–15, and 15–20 cm) with varying initial repellency levels. Using an automated programmable muffle furnace, aggregates were separately exposed to three heating temperatures, T H (150, 200, 250 °C), three rates of heating (speed of rising temperature to reach relevant T H), R H (200, 400, 800 °C h−1), and three durations of exposure to relevant T H, E D (30, 60, 120 min). The molarity of an ethanol droplet test was used to measure the contact angle (contact angle>90°). The water drop penetration time (WDPT) was also measured. The SWR of aggregates declined with the increasing T H and E D. All aggregates were wettable once exposed to 250 °C. At the lowest T H and E D (150 °C, 30 min), the contact angle was <90° only in the least repellent aggregates collected from 10–15 and 15–20 cm depths. Although R H indicated the least influence on the measured parameters, the slowest R H (200 °C h−1) caused a comparatively greater decline in SWR. Water stability of aggregates increased with heating irrespective of decreasing SWR. Further investigations on heat-induced changes in organic compounds at molecular levels would be necessary to understand the theories for the behavior of aggregates.

Understanding the Resilience of Sal and Teak Forests to Climate Variability Using NDVI and EVI Time Series

Abstract This study attempts to understand the climatic resilience of two forest types of central India—that is, Tectona grandis (Teak) forest of Satpura Tiger Reserve and Shorea robusta (Sal) forest of Kanha Tiger Reserve—using normalized difference vegetation index (NDVI), enhanced vegetation index (EVI) extracted from MODIS, and climate variable data sets at highest spatial and temporal scales. Teak and Sal forests within the core area of the selected tiger reserves represent the least anthropogenic disturbances, and therefore, the observed changes in NDVI and EVI over the past 16 years could be analyzed in the context of climate change. The correlation analysis between climatic variables (minimum temperature, maximum temperature, mean temperature, and total annual rainfall) and forest response indicators (NDVI/EVI) at seasonal and annual scales revealed that Teak and Sal forests are more sensitive to change in past temperature as compared with rainfall. Also, the changes in NDVI and EVI of Sal forest are correlated more to minimum temperature, and that of Teak forest to maximum temperature. The analysis of sapling girth class of Sal and Teak further revealed that Sal as compared with Teak is more affected because of the changing climate variables of the recent past. The findings of the study will help manage forests more efficiently in the context of changing climate.

Population Growth Models of Forest Trees for Conservation Management: Case of Teak (Tectona Grandis) Forest in Begal, East Java, Indonesia

Based on 2010 FAO report, teak forest and plantation in Indonesia covers 1,269 million hectares or 7 per mill of total area of Indonesia. It can be found dominantly in Central and East Java. PT Perhutani, Indonesia has responsible for management of the government owned forests in the islands of Java and Madura. Based on 2007 data, the teak wood production is 517,627 m3 and the highest percentage, which is 37% of total production, is coming from East Java. In this paper, we develop growth population models using Leslie Matrix and Markov Chain in order to predict the future condition based on the current condition. The models are implemented into data from Teak Forest in Begal, East Java, that covers 2,052.8 hectares and consists of 114 sites. The result from the first model using Leslie Matrix shows that it needs 16 years from year 2011 that the sustainable condition of the forest can be achieved. The result from the implementation of the second model using Markov Chain into the existing data shows that the condition of the teak forest can be classified as quite critical because the good condition part based on its density of the early age group (0 - 4 years) has potential to become the worst condition before its harvest time.

ESTIMATION OF BIOMASS AND CARBON POOL IN BARKOT FOREST RANGE, UK USING GEOSPATIAL TOOLS

Abstract. The forest ecosystem is an important carbon sink and source containing majority of the aboveground terrestrial organic carbon. Carbon management in forests is the global concern to mitigate the increased concentration of green house gases in the atmosphere. The present study estimated vegetation carbon pool and biophysical spectral modelling to correlate biomass with reflectance/ derivatives in Barkot Forest Range, Uttarakhand. The study was carried out using Cartosat-1, IRS-P6 LISS-IV MX, IRS LISS-III, Landsat 7 ETM satellite data and ground data collected from stratified random sampling. Forest type and forest crown density was mapped using resolution merged Cartosat-1 and LISS-IV imagery. Growing stock, biomass and carbon was calculated for the individual sample plots using inventory-based biomass assessment technique. Field-inventoried data was correlated with the surface reflectance and derivatives of it. Among the four vegetation types, viz. Shorea robusta, S. robusta mixed, S. robusta Tectona grandis mixed, T. grandis plantation, mixed plantation, Grassland and Agriculture/ orchard, the S.robusta was found to be the dominant vegetation in the area, covering 55.86 km2 of the total area. The study revealed that the S.robusta with high density had the highest aboveground biomass (AGB) (t/ha) was found in S.robusta > 70% (530 t ha−1), followed by S.robusta 40–70% (486 t ha−1) and minimum was found in mixed plantation < 10% (101 ha−1). The general trend showed the decrease in AGB with decrease of forest density in each forest type category. The average AGB of S. robusta T. grandis forest was found (308 t ha−1–458 t ha−1) due to the dominancy of S. robusta trees. The study highlighted the invaluable role of geospatial technology and field inventory for growing stock, biomass and carbon assessment.

Aboveground biomass estimation using multi-sensor data synergy and machine learning algorithms in a dense tropical forest

Forest aboveground biomass (AGB) is an important factor for tracking global carbon cycle to tackle the impact of climate change. Among all available remote sensing data and methods, Synthetic Aperture Radar (SAR) data in combination with decision tree based machine learning algorithms has produced favourable results in estimating higher biomass values. Suitability of this method for dense tropical forests has not been properly checked with an adequate number of studies. In this study, aboveground biomass was estimated for two major tree species, Shorea robusta, and Tectona grandis, of Katerniaghat Wildlife Sanctuary, a tropical forest situated in northern India. Aboveground biomass was estimated by combining C-band SAR data from Sentinel-1A satellite, texture images generated from Sentinel-1A data, vegetation indices produced using Sentinel-2A data and ground inventory plots. Decision tree-based machine learning algorithms were used in place of parametric regression models for establishing a relationship between fields measured values and remotely sensed parameters. Using random forest model with a combination of vegetation indices with SAR backscatter as predictor variables shows the best result for S. robusta forest, with a coefficient of determination value of 0.71 and an RMSE value of 105.027 t/ha. In T. grandis forest best result can be found in the same combination but for stochastic gradient boosted model with a coefficient of determination value of 0.6 and an RMSE value of 79.45 t/ha. This study shows that Sentinel series satellite data has exceptional capabilities in estimating dense forest AGB and machine learning algorithms can be very helpful to do so.

Leaching of carbon from native and non-native leaf litter of subtropical riparian forests

We evaluated the leaching of dissolved organic and inorganic carbon (DOC and DIC, respectively) from leaf litter of plant species of the native Atlantic Forest and of Pinus elliottii (Engelm.) and Eucalyptus grandis (Hill ex Maiden) forests. We carried out experiments in which leaves from each forest system (native, E. grandis, and P. elliottii) were placed in reactors with sterile water. After 1/4 h, 1 h, 4 h, 12 h, 24 h, and 48 h of incubation, we quantified the concentrations of DIC and DOC of each leachate. The greatest quantity of DIC was leached in the native forest system, whereas the greatest quantity of DOC was leached in the E. grandis forest system. With respect to the period of year, the greatest quantity of DIC was leached in autumn, whereas that of DOC was leached in the summer. Our results demonstrated that the replacement of native species in riparian zones, by non-native forest monocultures, could alter the chemical composition of the water. Finally, the results presented in this paper reinforce the need for a more careful look at ecological processes.

Modelling forest canopy gaps using LiDAR-derived variables

Remote sensing has revolutionized forest management and has been widely employed to model canopy gaps. In this study, a canopy height model (CHM) and an intensity raster (IR) derived from light detection and ranging (LiDAR) data were used to model canopy gaps within a four-year-old Eucalyptus grandis forest using an object-based image analysis (OBIA) approach. Model thematic accuracies using the CHM, intensity raster and combined data set (CHM and IR) were all above 90%, with KHAT values ranging from 0.88 to 0.96. Independent test thematic accuracies were also above 90%, with KHAT values ranging from 0.82 to 0.91. A comparative area-based assessment yielded accuracies ranging from 70 to 90%, with the highest accuracies achieved using the combined data set. The results of this study show that using a CHM and intensity raster, and an OBIA approach, provides a viable framework to accurately detect and delineate canopy gaps within a commercial forest environment.

Optimal rotation length for carbon sequestration in Eucalyptus plantations in subtropical China

Most Eucalyptus plantations are intensively managed as short-rotation plantations and carbon (C) storage in plants and soils in stands older than 10 years is not well understood. We examined the changes in plant biomass C and soil organic C (SOC) storage across a chronosequence of E. urophylla × E. grandis forests (4-, 7-, 10-, 13-, and 21-year-old) in subtropical China. Biomass C stock significantly increased with stand age. SOC storage increased initially after afforestation, peaking in 10-year-old stands, and declined gradually. Ecosystem C pools in the five development stages were 111.76, 167.66, 234.04, 281.00, and 299.29 Mg ha−1, respectively. Trees and soils were the dominant C pools across all stand ages with the contribution of tree biomass C storage significantly increasing and SOC storage decreasing with age. Eucalyptus plantations are still in vigorous growth phase and have great potential for C sequestration at the end of the current rotation length (within 7 years). Considering the sharp decrease of annual biomass C increment rate and the gradual loss of SOC storage in stands older than 13 years, we recommend the optimal length for one full Eucalyptus plantation cycle should be 12–15 years in subtropical China to maximize land-use value and carbon sink value.

English

English

Above-ground biomass and carbon estimates of Shorea robusta and Tectona grandis forests using QuadPOL ALOS PALSAR data

Mechanisms to mitigate climate change in tropical countries such as India require information on forest structural components i.e., biomass and carbon for conservation steps to be implemented successfully. The present study focuses on investigating the potential use of a one time, QuadPOL ALOS PALSAR L-band 25m data to estimate above-ground biomass (AGB) using a water cloud model (WCM) in a wildlife sanctuary in India. A significant correlation was obtained between the SAR-derived backscatter coefficient (σ°) and the field measured AGB, with the maximum coefficient of determination for cross-polarized (HV) σ° for Shorea robusta, and the weakest correlation was observed with co-polarized (HH) σ° for Tectona grandis forests. The biomass of S. robusta and that of T. grandis were estimated on the basis of field-measured data at 444.7±170.4Mg/ha and 451±179.4Mg/ha respectively. The mean biomass values estimated using the WCM varied between 562 and 660Mg/ha for S. robusta; between 590 and 710Mg/ha for T. grandis using various polarized data. Our results highlighted the efficacy of one time, fully polarized PALSAR data for biomass and carbon estimate in a dense forest.

Biodiversity of nematodes in “Tectona grandis” of Adilabad district forest

Nematode population was studied in Tectona grandis (Teak) forest plants in Adilabad district. Plant parasitic nematodes were identified based on morphology and is often difficult as the characters, nematodes associated with Tectona grandis (Teak). Xiphinema, Hemicycliophora, Hoplolaimus, Paralongidorus, Longidorus, while Tectonia grandis, Emblica officinalis, Syzygium cuminii, and Careya arborea had most nematodes in the rhizosphere. Soil samples are collected from 3 locations in Adilabad forest district by symptoms caused by these nematodes are somewhat similar to nutrient deficiency symptoms, such as stunting and yellowing of plants and cause galling of roots. At the site of infection of Hoplolaimus species many lateral roots may emerge giving the root system a ‘bushy’ appearance. White females of cyst nematodes can be seen as small, white, pearl-like bodies on the roots. Environmental factors such as soil type, temperature, moisture and nutrient level play a major role in the expression of nematode-induced symptoms. Teak lumber comes from a tropical tree “ Tectona grandis ”, which grow in the Southeast part of Asia. However, one can find this kind of wood growing in many places around the world but Burma is the main exporter of Teak lumber. It was used especially in the manufacture of the outdoor furniture and boat decks construction. Uses of Tectona grandis is the source of a high quality general purpose hardwood known as teak. The timber is used for ship decking, flooring, furniture and construction. It is particularly recommended for construction in seaside environments (such as bridges and docks) because it is resistant to shipworm, a wood-boring sea mollusc ( Teredo spp., Teredinidae). Quinones in the sawdust inhibit the growth of several species of the fungi that cause wood rot. Plant parasitic nematodes are microscopic, identification of nematode species based of morphological is often difficult as the characters, below are the nematodes associated with Tectona grandis .

Phosphorus limits Eucalyptus grandis seedling growth in an unburnt rain forest soil.

Although rain forest is characterized as pyrophobic, pyrophilic giant eucalypts grow as rain forest emergents in both temperate and tropical Australia. In temperate Australia, such eucalypts depend on extensive, infrequent fires to produce conditions suitable for seedling growth. Little is known, however, about constraints on seedlings of tropical giant eucalypts. We tested whether seedlings of Eucalyptus grandis experience edaphic constraints similar to their temperate counterparts. We hypothesized that phosphorous addition would alleviate edaphic constraints. We grew seedlings in a factorial experiment combining fumigation (to simulate nutrient release and soil pasteurization by fire), soil type (E. grandis forest versus rain forest soil) and phosphorus addition as factors. We found that phosphorus was the principal factor limiting E. grandis seedling survival and growth in rain forest soil, and that fumigation enhanced survival of seedlings in both E. grandis forest and rain forest soil. We conclude that similar to edaphic constraints on temperate giant eucalypts, mineral nutrient and biotic attributes of a tropical rain forest soil may hamper E. grandis seedling establishment. In rain forest soil, E. grandis seedlings benefited from conditions akin to a fire-generated ashbed (i.e., an “ashbed effect”).

Response of soil mite abundance and diversity to a monospecific timber Tectona grandis plantation in Ivory Coast

Abstract This study aims to assess the impact of monospecific Tectona grandis forest plantation on the soil mite abundance and diversity. To achieve these objectives, two sites situated in Ivory Coast were investigated. The first, a primary forest was characterized by a very weak human activities whereas the second, a teak plantation was characterized by a high disturbance performed during the planting. After extracting, sorted and description, 116 mite species were described in the two sites. Mite densities were lower in teak plantation and also higher in the litter and decreased to the depth in both sites. Species richness recorded in teak plantation (52 species) was significantly lower compared to primary forest (98 species). The same trend was observed for Oribatida but not for Gamasida. The lower Oribatida (5 vs. 17) and higher Oribatida (24 vs. 41) were recorded respectively in teak plantation and primary forest. Mite Shannon index and evenness were significantly different between sites. High Jaccard index values and the appearance of exclusive species in both habitats showed that the sites are very distinct. Total number of species recorded corresponded to 58%–63% of the total number of species estimated by ACE and Chao 1&2 estimators, indicating that the sampling effort was not sufficient. Mite abundance and diversity varied depending on the characteristics of habitats. Chemical element (Corg, Ctot, Ntot, and SOM) values were lower in teak plantation (disturbed habitat) and significantly different to primary forest in the topsoil. Apart from litter height, soil depth, pH and C/N ratio, others variables were strongly correlated to mite abundance and diversity.

Estimating the road edge effect on adjacent Eucalyptus grandis forests in KwaZulu-Natal, South Africa, using texture measures and an artificial neural network

SPOT-5 multispectral and panchromatic image data were used to compute texture measures to estimate the road edge effect on adjacent Eucalyptus grandis forests. Employing a stepwise selection algorithm enabled the selection of optimal texture measures that were input into a backpropagation artificial neural network. The R2 of best models ranged from 0.67 to 0.89 for DBH, TH, BA, Volume and LAI on an independent test data set, with a root mean square error (RMSE) range of 0.01–5.36% for the respective variables. The result is critical for understanding and spatially predicting the road edge effect on adjacent vegetation.

Invasive African big-headed ants, Pheidole megacephala, on coral cays of the southern Great Barrier Reef: distribution and impacts on other ants

Infestation of islands by exotic ants is widespread and increasing due to human activities throughout the world. Exotic ants, particularly the invasive African big-headed ant, Pheidole megacephala (Fabricius), are of great conservation concern for coral cays at the southern end of the Great Barrier Reef, Australia. Little is known, however, about the distribution and ecological impacts of invasive ants in this insular system. We surveyed the ants of 14 vegetated coral cays recording a total of 24 ant species, including at least nine exotics. Pheidole megacephala was by far the most abundant and widespread species, occurring on 11 of 14 islands, often in very large numbers. The inter-island distribution of P. megacephala was best explained by human activities, with frequently visited, and to a lesser degree disturbed islands, more likely to be infested. On large islands (≥ 10 ha) P. megacephala exhibited distinct habitat preferences, occurring in significantly lower abundances within heavily-shaded Pisonia grandis forest in the centre of islands, compared to more open, fringing woodland or shrubland. On smaller islands (<10 ha) with less extensive Pisonia stands, P. megacephala penetrated throughout the forest where its abundance was similar to that in open woodland. Despite considerable differences in biotic (floristic composition) and abiotic factors (e.g. island size) as well as the spatial configuration among islands, the severity of infestation by P. megacephala best explained variation in species richness, abundance and assemblage composition of other ants. We suggest a number of strategies to manage P. megacephala infestations on these islands.

Impact of a mutualism between an invasive ant and honeydew-producing insects on a functionally important tree on a tropical island

Mutualisms between invasive ants and honeydew-producing Hemiptera have the potential to result in unusually high population levels of both partners, with subsequent major changes to ecosystem composition and dynamics. We assessed the relationship between the invasive ant, Pheidole megacephala, and its hemipteran mutualists, Dysmicoccus sp. and Pulvinaria urbicola, on Cousine Island, Seychelles. We also assessed the impacts of the mutualism on the condition of the hemipteran host plant, Pisonia grandis, a native and functionally important tree species. There was a strong positive relationship between Ph. megacephala activity and hemipteran abundance, and the exclusion of ants from Pi. grandis resulted in a significant decline in Pu. urbicola abundance. High abundance of the mutualists was strongly associated with damage to the Pi. grandis forest. This indicates that the mutualism is contributing to the massive increase in the population levels of the mutualist species, and is intensifying their impacts on the island. The widespread trophobiosis and its associated high densities of mutualists pose serious threats to the ecosystem, highlighting the need to control the ant and associated hemipteran populations.

The effect of converting tropical native savanna to Eucalyptus grandis forest on soil microbial biomass

The aim of this work was to investigate the effect of converting native savanna to Eucalyptus grandis forest on soil microbial biomass in tropics. Soil samples were collected from three sites: undisturbed native savanna (savanna), the site of a 1-year-old E. grandis forest (1 y), and the site of a 2-year-old E. grandis forest (2 y). Soil microbial biomass C (MBC), basal respiration, substrate induced respiration (SIR), soil organic carbon (SOC), microbial, and respiratory quotients were evaluated in soil samples collected from 0–20 cm depth. One year converted forest caused a significant reduction in MBC, SIR, and microbial quotient (about 70, 65 and 75 per cent, respectively). However, after 2 years of E. grandis forest growth, there was recovery of these variables. Soil basal respiration and respiratory quotient were significantly higher in 1 y forest (about 4 and 14 times, respectively) than in savanna. The results showed a significant decrease, after 2 years, in soil respiration and respiratory quotient, suggesting a recovery of soil microorganisms as time passes. In the short term, our results showed negative changes in soil microbial biomass following the conversion of native savanna to E. grandis. Copyright © 2010 John Wiley & Sons, Ltd.

Predicting plant water content in Eucalyptus grandis forest stands in KwaZulu-Natal, South Africa using field spectra resampled to the Sumbandila Satellite Sensor

The measurement of plant water content is essential to assess stress and disturbance in forest plantations. Traditional techniques to assess plant water content are costly, time consuming and spatially restrictive. Remote sensing techniques offer the alternative of a non-destructive and instantaneous method of assessing plant water content over large spatial scales where ground measurements would be impossible on a regular basis. In the context of South Africa, due to the cost and availability of imagery, studies focusing on the estimation of plant water content using remote sensing data have been limited. With the scheduled launch of the South African satellite SumbandilaSat evident in 2009, it is imperative to test the utility of this satellite in estimating plant water content. This study resamples field spectral data measured from a field spectrometer to the band settings of the SumbandilaSat in order to test its potential in estimating plant water content in a Eucalyptus plantation. The resampled SumbandilaSat wavebands were input into a neural network due to its ability to model non-linearity in a dataset and its inherent ability to perform better than conventional linear models. The integrated approach involving neural networks and the resampled field spectral data successfully predicted plant water content with a correlation coefficient of 0.74 and a root mean square error (RMSE) of 1.41% on an independent test dataset outperforming the traditional multiple regression method of estimation. The best-trained neural network algorithm that was chosen for assessing the relationship between plant water content and the SumbandilaSat bands was based on a few points only and more research is required to test the robustness and effectiveness of this sensor in estimating plant water content across different species and seasons. This is critical for monitoring plantation health in South Africa using a cheaply available local sensor containing key vegetation wavelengths.

Declining populations of the Javan warty pig Sus verrucosus

We conducted an interview-based survey for the Javan warty pig Sus verrucosus, endemic to the islands of Java and Bawean in Indonesia. The species occurs in 10 isolated areas, although some additional, probably very small populations, may remain. Compared to a survey conducted in 1982, 17 of the 32 (53%) populations are extinct or have dropped to levels so low that local hunters have failed to encounter the species in recent years. This indicates a rapid population decline. We hypothesize that this loss is primarily caused by a decline in suitable habitat, especially stands of teak Tectona grandis forest or similar forest plantations, and by high hunting pressure. Competition from and hybridization with the Eurasian wild boar Sus scrofa may be further threats to S. verrucosus. Rapid action is needed to prevent extinction in the wild. We recommend effective protection of selected S. verrucosus populations, lobbying of the Government to give protected status to S. verrucosus, conducting ecological research and investigating crop damage issues, and establishment of conservation breeding programmes.