Slash Pine Forest Research Articles

Evaluating the transferability of airborne laser scanning derived stem size prediction models for Pinus taeda L. stem size estimation to two different locations and acquisition specifications

ABSTRACT Airborne laser scanning (ALS) datasets are used widely for estimating forest biometrics. The transferability of predictive models among ALS acquisitions is a topic of research due to differences in timing, flight parameters, equipment specifications, environmental conditions, and processing methods. The transferability of predictive models therefore is subject to uncertainty. This paper presents an evaluation of the transferability of models for the estimation of stem volume and diameter at breast height (DBH) based on individual tree crown size and competitive neighbourhood metrics derived for managed loblolly pine (Pinus taeda) and slash pine (Pinus elliottii) forest in the Southern USA. Two predictive models types were tested: multiple linear regression (MLR) and Rand Forest (RF). We also evaluated the inclusion of additional training data to model development. Models were able to be transferred to other locations with similar structural and management conditions as the original training dataset with little decrease in accuracy, specifically unthinned stands, despite different ALS acquisitions (Plot stem volume: R2 0.7–0.8; NRMSE 10–12%; mean DBH: R2 0.4–0.7; NRMSE 10–17%; plot basal area: R2 0.7–0.8; NRMSE 12%). Increases in structural differences between the training and test data, driven by age or thinning status, introduced unacceptable levels of uncertainty (Stem volume: R2 0.4–0.7; NRMSE 12–16%; mean DBH: R2 0.4–0.5; NRMSE 18–20%; plot basal area: R2 0.5–0.6; NRMSE 22–40%). Generally, RF models most accuracy estimated DBH, and MLR for stem volume. Improvements to estimate accuracy can be achieved through the addition of relatively small datasets, representing features which were not present in the original data. ALS’s ability to provide accurate and near-complete inventories of forests hold a great deal of potential for forest management. The existence of a transferable model that can be used across different acquisitions represents a saving in terms of cost and time, we would argue that future research is therefore warranted.

Response of C:N:P Stoichiometry to Phosphorus Addition and Homeostasis of Plant Tissues in a Subtropical Slash Pine Plantation

Phosphorus (P) fertilizer is commonly used in subtropical plantations to augment nutrients including carbon (C), nitrogen (N), and P to maintain plants engaged in metabolism. Stoichiometric homeostasis reflects the adaptation of plants to various environments (including P fertilizer supply rates). It is thus of great significance to understand C:N:P stoichiometry in the plant–litter–soil system under P addition and the stoichiometric homeostasis of plant tissues for the P fertilization management of slash pine (Pinus elliottii Engelm) plantations. In subtropical China, we measured the C, N, and P contents in root, branch, needle, litter, and soil in slash pine plantations fertilized with four treatments, P1 (25 kg P ha1 yr1), P2 (50 kg P ha1 yr1), P3 (100 kg P ha1 yr1), and a control (CK), and calculated the stoichiometric homeostasis of plant tissues. The results show that P3 treatment increased the C, N, and P contents of the needle. P2 and P3 treatments increased the P content of the litter and the N:P ratio of the root while decreasing the C:N ratio of the root. P addition treatments increased C and P element accumulation in soil but had no effect on soil stoichiometry. The nutrient contents of needle and branch were higher than those of root and litter, indicating that slash pine was more inclined to allocate nutrients to the aboveground tissues. The stoichiometric homeostasis of C, N, and P among plant tissues was graded as follows: root > branch > needle. The needle’s nutritional homeostasis was C > N > P, with 1/H values of 0.08, 0.34, and 0.74, respectively. These findings demonstrate that during P addition, the C, N, and P stoichiometric homeostasis varied among plant tissues and element types. In conclusion, P application altered nutrient distribution in the plant–litter–soil system, alleviating P restriction in slash pine forests in southern China. P addition levels should be finely adjusted in the future for longer-term observation trials, and the trade-off between P addition rates and economic and ecological advantages should be properly examined.

Economic analysis of uneven-aged forest management in the southeastern United States

We determine the economic revenues and optimal forest management of uneven-aged loblolly pine, longleaf pine, and slash pine forests considering timber and carbon benefits in the southeastern United States. Our results show that uneven-aged management of southern pines generates positive total revenues, with the exception of those stands managed with high residual basal areas and long cutting cycles. The uneven-aged management of pine forests is economically more attractive with loblolly pine stands than with longleaf pine or slash pine for all cutting cycles and residual basal areas; on average, loblolly pine returns $1389.60·ha−1 more than slash pine and $1500.70·ha−1 more than longleaf pine for all cutting cycles. For uneven-aged loblolly pine forests, our results suggest that landowners should experience highest profits with the shortest viable cutting cycle (10 years) and a medium-high residual basal area (11.5 m2·ha−1). For uneven-aged longleaf pine forests, landowners would be economically better off with a longer cutting cycle (20 years) and a lower residual basal area (6.9 m2·ha−1). Notably, uneven-aged management of longleaf pine and slash pine for timber production becomes unprofitable with low-medium or high residual basal areas (9.2–11.5 m2·ha−1).

Resin exudation profile, chemical composition, and secretory canal characterization in contrasting yield phenotypes of Pinus elliottii Engelm

In conifer stems, secretory canals synthesize and store resin for defense against herbivores and pathogens. Resin terpenes are used as raw material by an array of industrial sectors. Most forest stands operationally used in resin extraction are derived from seeds, showing high genetic variation, which reflects in yield. The objective of this study was to identify adult slash pine (Pinus elliottii Engelm.) trees of high yield of resin in a short timeframe by resin mass flow rate analysis, aiming at the establishment of elite forests for tapping prior to its start. In addition, the anatomical basis of resin yield was investigated by examining the correlation between parameters such as number, shape, area and internal volume of wood canals with resin production. Monoterpene composition in resin of high and low yielding trees was also compared. The resin flow-based selection method was reliable for resin yield phenotype detection, confirming this property in trees formerly identified as being of high and low resin production by conventional tapping. The reverse test for identification of high and low yield resin features in previously untapped younger plants was in good agreement with their yields after subsequent standard tapping procedure. To evaluate and quantify the three-dimensional structure of resin canals, we used microCT scans. High yielding trees had more axial resin canals when compared with low yielding ones. Frequency of putative anastomosed canals and canal diameter were also superior in the former. Chemical analyses of resin monoterpenes revealed that the ratio of α-pinene/ β-pinene was lower in more productive trees, which also had more limonene in total terpenes compared with their low yield counterparts. Data support the use of short-term resin mass flow rate analysis as a tool to identify and select high yield trees for the establishment of elite slash pine forests for resin tapping operations. Strong correlation of the superesinous phenotype with canal density and structure was also evident.

Response of soil respiration to nitrogen addition in two subtropical forest types

Anthropogenic activities have increased nitrogen (N) deposition in terrestrial ecosystems, which directly and indirectly affects soil biogeochemical processes, including soil respiration. However, the effects of the increases in N availability on soil respiration are not fully understood. In this study, soil respiration was measured using an infrared gas analyzer system with soil chambers under four N treatments (0, 5, 15, and 30 g N m–2 year–1 as control, low N (LN), moderate N (MN), and high N (HN), respectively) in camphor tree and slash pine forests in subtropical China. Results showed that soil respiration rates decreased by 37% in the camphor tree forest and 27% in the slash pine forest on average on an annual base, respectively, in the N-fertilized treatments when compared with the control. No significant differences were found in the soil respiration rate among the LN, MN, and HN treatments in both forest types as these fertilized plots reached an adequate N content zone. In addition, soil microbial biomass carbon (C) content and fine root biomass declined in N-treated plots compared to the control. Our results indicated that elevated N deposition might alter the tree growth pattern, C partitioning, and microbial activity, which further affect soil C sequestration by reducing soil respiration in subtropical forests of China.

Economic Sustainability of Payments for Water Yield in Slash Pine Plantations in Florida

Forests play an important role with respect to water resources, and can be managed to increase surface- and groundwater recharge. With the creation of a forest water yield payment system, privately-owned forests, which comprise the majority of forest area in the Southeastern US, could become an important potential source of additional water supply. The economic tradeoffs between timber revenues and water yield are not well understood. To address this, we use the example case of slash pine production in Florida, and employ a forest stand-level optimal rotation model that incorporates forest management, and assessed a range of feasible water yield prices on forest profitability. Our analysis was limited to a range of water yield prices ($0.03, $0.07, and $0.30 kL−1) that would make water yield from slash pine economically competitive with water supply alternatives (e.g., reservoir construction). Even at relatively low water prices, we found that managing slash pine forests for both timber and water yield was preferred to managing just for timber when assuming an initial tree density less than 2200 trees·ha−1. However, with higher levels of initial tree planting density and low water prices, managing slash pine for timber production alone was more profitable unless stands are heavily-thinned, suggesting that even mid-rotation stands could be included in a forest water yield payments program. Compared to low-tree planting density and lightly thinned slash pine forests, an intensive approach of planting a lot of trees and then heavily thinning them generated 8% to 33% higher profits, and 11% more ($192 ha−1) on average. We conclude that payments for water yield are economically feasible for slash pine stands in Florida, and would benefit forest landowners, particularly with higher prices for water yield.

Nitrogen addition regulates tradeoff between root capture and foliar resorption of nitrogen and phosphorus in a subtropical pine plantation

Increased nitrogen availability affects root capture and leaf resorption of nitrogen and phosphorus, and the corresponding acquisition-conservation tradeoff in slash pine forests. Plants may maintain their stoichiometric homeostasis via regulating root nutrient capture (acquisition) and leaf nutrient resorption (conservation). However, how increased nitrogen (N) availability affects root capture and leaf resorption of N and phosphorus (P), and the corresponding acquisition-conservation tradeoff remains unclear. We quantified N and P concentrations and their stoichiometric ratios of five nutrient pools (soils, absorptive fine-roots, transport fine-roots, green needles, and senesced needles) to investigate simultaneous responses of root capture (nutrient foraging potential and translocation) and needle resorption (efficiency and proficiency) to different rates and forms of N addition in a slash pine plantation in subtropical China. N addition increased N concentration in senesced needles, but reduced N capture capacity. N addition reduced P concentration in senesced needles (improved P resorption proficiency), but did not affect P capture capacity. N addition exerted no significant influence on resorption efficiency of N and P. N rate and form effects occurred only in nutrient foraging (N foraging was more responsive to high N rate and P foraging was more responsive to ammonium-based N addition), but not in nutrient translocation and resorption. The decreased root N capture capacity and increased senesced needle N concentration imply an alleviation of N limitation to plant growth and a behavior of plants to economize on cost for nutrient acquisition and conservation. P resorption rather than capture strategy was employed, indicating a more conservative use of P in response to exacerbated P limitation. These findings jointly suggest that the allocation of effort towards capture and resorption strategy depends on the strength and type of nutrient limitation. Our results have implications for understanding the acquisition-conservation tradeoff in plant nutrient economy and the mechanisms that plants maintain their stoichiometric homeostasis in the context of N loading.

Nitrogen ion form and spatio-temporal variation in root distribution mediate nitrogen effects on lifespan of ectomycorrhizal roots

Absorptive roots active in soil resource uptake are often intimately associated with mycorrhizal fungi, yet it remains unclear how nitrogen (N) loading affects lifespan of absorptive roots associating with ectomycorrhizal (ECM) fungi. Through a three-year minirhizotron experiment, we investigated the responses of ECM lifespan to different rates of N addition and examined the roles of N ion form, rooting depth, seasonal root cohort, and ECM morphotype in mediating the N effects on ECM lifespan in a slash pine (Pinus elliottii) forest in subtropical China. High rates of NH4Cl significantly decreased foliar P concentrations and increased foliar N:P ratios, and mean ECM lifespan was negatively correlated to foliar P concentration. N additions generally increased the lifespan of most ectomycorrhizas, but the specific differences were context dependent. N rates and forms exerted significant positive effects on ECM lifespan with stronger effects occurring at high N rates and under ammonium N addition. N additions extended lifespan of ectomycorrhizas in shallower soil and born in spring and autumn, but shortened lifespan of ectomycorrhizas in deeper soil and born in summer and winter. N additions reduced lifespan of dichotomous ectomycorrhizas, but increased lifespan of coralloid ectomycorrhizas. The increased ECM lifespan in response to N additions may primarily be driven by the persistent and aggravated P limitation to plants. Our findings highlight the importance of environmental contexts in controlling ECM lifespan and the need to consider potential differences among mycorrhizal morphotypes when studying N—lifespan relationships of absorptive roots in the context of N deposition.

Soil CO2 Flux in Different Types of Forests Under a Subtropical Microclimatic Environment

The flux of carbon dioxide (CO2) from soil surface presents an important component of carbon (C) cycle in terrestrial ecosystems and is controlled by a number of biotic and abiotic factors. In order to better understand characteristics of soil CO2 flux (FCO2) in subtropical forests, soil FCO2 rates were quantified in five adjacent forest types (camphor tree forest, Masson pine forest, mixed camphor tree and Masson pine forest, Chinese sweet gum forest, and slash pine forest) at the Tianjiling National Park in Changsha, Hunan Province, in subtropical China, from January to December 2010. The influences of soil temperature (Tsoil), volumetric soil water content (θsoil), soil pH, soil organic carbon (SOC) and soil C/nitrogen (N) ratio on soil FCO2 rates were also investigated. The annual mean soil FCO2 rate varied with the forest types. The soil FCO2 rate was the highest in the camphor tree forest (3.53 ± 0.51 μmol m−2 s−1), followed by, in order, the mixed, Masson pine, Chinese sweet gum, and slash pine forests (1.53 ± 0.25 μmol m−2 s1). Soil FCO2 rates from the five forest types followed a similar seasonal pattern with the maximum values occurring in summer (July and August) and the minimum values during winter (December and January). Soil FCO2 rates were correlated to Tsoil and θsoil, but the relationships were only significant for Tsoil. No correlations were found between soil FCO2 rates and other selected soil properties, such as soil pH, SOC, and C/N ratio, in the examined forest types. Our results indicated that soil FCO2 rates were much higher in the evergreen broadleaved forest than coniferous forest under the same microclimatic environment in the study region.

Dissolved Organic Carbon Dynamics and Controls of Planted Slash Pine Forest Soil in Subtropical Region in Southern China

Soil dissolved organic carbon (DOC) is an active fraction of the soil organic carbon (SOC) pool and links terrestrial and aquatic systems. The degradation of DOC can affect carbon cycling, nutrient dynamics and energy supply to microorganism, and consequently change biogeochemical processes. This study investigated the vertical and seasonal variability of soil DOC concentrations and its controls in a 23-year-old planted slash pine (Pinus elliottii) forest at Qianyanzhou Forest Experimental Station (QFES) in Southern China. Soil solutions were collected at bimonthly intervals at depths of 10, 20 and 30 cm by a mechanical-vacuum extractor from November 2007 to March 2009, and at monthly intervals at depths of 10, 30 and 50cm from April 2009 to October 2010. The DOC concentrations were determined with a total organic carbon (TOC) analyzer. Mean (±standard deviation) DOC concentrations at depths of 10cm, 20cm, 30cm and 50cm were 12.4±4.4, 10.6±6.3, 8.7±2.6, and 8.0±5.9 mg L-1, respectively. Both seasonal and spring means of DOC concentration showed a decreasing trend with increasing depth, while there was no clear trend for the summer, autumn, or winter seasons. DOC concentrations during spring, summer, autumn and winter ranged from 4.8 to 21.5, 4.9 to 26.2, 5.4 to 17.1, 4.9 to 14.6 mg L-1, respectively, their mean DOC concentrations were 10.2, 10.5, 10.8 and 8.3 mg L-1, respectively. No consistent pattern of seasonal variability of DOC concentrations at different depths was observed. No obvious relationship between organic carbon content of forest litter and DOC concentration was found. There was a positive linear relationship between SOC and DOC concentration (R2=0.19, p<0.01), which showed that SOC was one of the main controls of DOC. A positive exponential relationship existed between soil temperature at 5 cm and DOC concentrations at 10 cm depth in slash pine, masson pine (Pinus massoniana) and Chinese fir (Cunninghamia lanceolate) planted forests (R2=0.12, p<0.01). DOC concentrations showed a negative linear relationship with soil moisture at all depths in slash pine forest (R2=0.15, p<0.001), and DOC concentrations at depth of 10 cm demonstrated a negative exponential relationship with soil moisture at 5 cm depth in three planted forests (R2=0.13, p<0.001). Precipitation in sampling months and mean seasonal DOC concentration were not correlated. However, a more detailed analysis of precipitation events at different times before sampling and seasonal DOC concentration showed that the timing of precipitation events prior to sampling had different effects on seasonal DOC concentrations at different depths. Our study highlights the importance of DOC dynamics for the carbon cycle in planted slash pine forest and it provides evidence for evaluating the effects of ecological restoration in subtropical red soil region.

The Role of Fire-Return Interval and Season of Burn in Snag Dynamics in a South Florida Slash Pine Forest

AbstractStanding dead trees, or snags, are an important habitat element for many animal species. In many ecosystems, fire is a primary driver of snag population dynamics because it can both create and consume snags. The objective of this study was to examine how variation in two key components of the fire regime—fire-return interval and season of burn—affected population dynamics of snags. Using a factorial design, we exposed 1 ha plots, located within larger burn units in a south Florida slash pine (Pinus elliottii var. densa Little and Dorman) forest, to prescribed fire applied at two intervals (approximately 3-year intervals vs. approximately 6-year intervals) and during two seasons (wet season vs. dry season) over a 12- to 13-year period. We found no consistent effect of fire season or frequency on the density of lightly to moderately decayed or heavily decayed snags, suggesting that variation in these elements of the fire regime at the scale we considered is relatively unimportant in the dynamics of snag populations. However, our confidence in these findings is limited by small sample sizes, potentially confounding effects of unmeasured variation in fire behavior and effects (e.g., intensity, severity, synergy with drought cycles) and wide variation in responses within a treatment level. The generalizing of our findings is also limited by the narrow range of treatment levels considered. Future experiments incorporating a wider range of fire regimes and directly quantifying fire intensity would prove useful in identifying more clearly the role of fire in shaping the dynamics of snag populations.

Forest management effects on in situ and ex situ slash pine forest carbon balance

In this study we analyzed the effect of silviculture on carbon (C) budgets in Pinus elliottii (slash pine) plantations on the southeastern U.S. Coastal Plain. We developed a hybrid model that integrates a widely used growth and yield model for slash pine with allometric and biometric equations determined for long-term C exchange studies to simulate in situ C pools. The model used current values of forest product conversion efficiencies and forest product decay rates to calculate ex situ C pool. The model was validated from a variety of sources, accurately simulating C estimates based on multiple measurement techniques and sites. Site productivity was the major factor driving C sequestration in slash pine stands. On high productivity sites, silvicultural schemes that promote sawtimber-type products are more suitable for increasing C storage (even not taking in account the consequent economical revenues associated with sawtimber production). When rotation length was increased from 22 to 35 years on unthinned and thinned stands, respectively, we estimated net increments of 26 and 20 MgC ha −1 in average C stock of the first five rotations. Even though in situ C pool in slash pine accounts for most of this net increment, C in sawtimber products increased from 8 and 14 to 23 and 24 MgC ha −1, on unthinned and thinned stands, respectively. Thinning effects on net C stock depended on intensity and timing of intervention, mainly due to changes in diameter classes that promote higher proportion of long-lived products. Emissions associated with silvicultural activities, including transportation of logs to the mill, are small compared to the magnitude of net C sequestration, accounting for between 2.2 and 2.3% of gross C stock. This slash pine plantation C sequestration model, based on empirical and biological relationships, is appropriate for use in regional C stock assessments or for C credit verification.

Impacts of reforestation approaches on runoff control in the hilly red soil region of Southern China

Vegetation structure and soil properties are not only correlated with forest management practices, but also affect soil and water loss significantly. To estimate the long-term influences of regenerating forest cover on soil and water loss from degraded land, the runoff and soil loss in the context of different forest restoration approaches, including a control plot (CL) and plantations of slash pine (Pinus elliottii), Chinese fir (Cunninghamia lanceolata), tea-oil camellia (Camellia oleifera), and natural secondary forest, were monitored in runoff plots over a 4-year period (2000–2003) in a hilly red soil region in Southern China. Relevant ecological factors and management intensity, were also measured. The results indicated that the four forest restoration approaches decreased surface runoff by 63.0–88.1% and soil erosion by 75.5–97.1% compared to the control. Moreover, runoff and soil erosion in tea-camellia plantation (TCP) and natural secondary forest (NSF) plots were significantly lower than with other treatments. Canopy cover, litter fall, plant roots, plant life forms, soil properties, and vegetation structure are important ecological factors that determine the magnitude of soil loss. Vegetation structure and plant life forms are the main factors reducing surface runoff and the movement of sediments. Effective control of soil and water loss in NSF and TCP are closely related to multiply stratified communities and the presence of specific plant life forms (the herbaceous keystone species Dicranopteris linearis), respectively. In addition, the above mentioned factors were sensitive to forest management patterns, including improper mechanical cultivation. Management practices should attempt to minimize disturbances to these factors to control runoff and soil erosion in each forest management unit. In particular, mechanical cultivation should loosen the soil around the base of a tree only, instead of over the entire ground surface, in the early stages of forest restoration.

Aboveground biomass of three conifers in the Qianyanzhou plantation, Jiangxi Province, China

Regressive models of the aboveground biomass for three conifers in subtropical China—slash pine (Pinus elliottii), Masson pine (P. massoniana) and Chinese fir (Cunninghamia lanceolata)—were established. Regression analysis of leaf biomass and total biomass of each branch against branch diameter (d), branch length (L), d3 and d2L was conducted with functions of linear, power and exponent. A power law equation with a single parameter (d) was proved to be better than the rest for Masson pine and Chinese fir, and a linear equation with parameter (d3) is better for slash pine. The canopy biomass was derived by adopting the regression equations to all branches of each individual tree. These kinds of equations were also used to fit the relationship between total tree biomass, branch biomass, foliage biomass and tree diameter at breast height (D), tree height (H), D3 and D2H, respectively. D2H was found to be the best parameter for estimating total biomass. However, for foliage biomass and branch biomass, both parameters and equation forms showed some differences among species. Correlations were highly significant (P<0.001) for foliage biomass, branch biomass and total biomass, among which the equation of the total biomass was the highest. With these equations, the aboveground biomass of Masson pine forest, slash pine forest and Chinese fir forest were estimated, in addition to the allocation of aboveground biomass. The above-ground biomass of Masson pine forest, slash pine forest and Chinese fir forest was 83.6, 72.1 and 59 t/hm2 respectively, and the stem biomass was more than the foliage biomass and the branch biomass. The underground biomass of these three forests which estimated with others’ research were 10.44, 9.42 and 11.48 t/hm2, and the amount of carbon-fixed were 47.94, 45.14 and 37.52 t/hm2, respectively.

Economics of Cogongrass Control in Slash Pine Forests

Cogongrass (Imperata cylindrica), an invasive weed, is a threat to slash pine forests. Using a dynamic optimization model, we estimated the impact of cogongrass on the profitability of slash pine forestry under four scenarios: no threat of cogongrass infestation; infestation is uncertain, and no control measures are taken; infestation is uncertain, but control measures are undertaken by one landowner but not the neighbors; and infestation is uncertain, and control measures are undertaken by everyone. Results indicate that annual net returns per acre under each scenario, respectively, are $25.30, $16.97, $13.89, and $17.38. Results suggest fostering a cooperative behavior among landowners is desirable.

Frondicola australicus gen. nov., sp. nov., isolated from decaying leaf litter from a pine forest

An aerobic bacterium, designated strain E1HC-02(T), was isolated from the decaying leaf litter of a slash pine forest located in southeast Queensland, Australia. Cells of strain E1HC-02(T) were short irregular rods (0.5-1.0 x 0.2-0.4 microm) which stained Gram-positive and possessed a cell-wall ultrastructure which appeared to be made of protein subunits. The novel strain grew optimally in 1 % trypticase soy broth (TSB) at 25 degrees C and at a pH of 9.1. Strain E1HC-02(T) metabolized a range of carbohydrates, organic acids and amino acids. The G+C content of the DNA was 71+/-1 mol% as determined by the thermal denaturation method. 16S rRNA gene sequence analysis of strain E1HC-02(T) showed that it was a member of the family Microbacteriaceae, phylum Actinobacteria. The cell wall contained a type B2beta peptidoglycan, the dominant cellular fatty acid was 18 : 1omega7c and the major hydroxy fatty acid was 2-OH 14 : 0. The major menaquinones were MK-8 (76 %) and MK-7 (24 %) and the glycolipids present were disphosphatidylglycerol, phosphatidylglycerol and three unidentified phospholipids. The chemotaxonomic properties of strain E1HC-02(T) were distinctly different to all of the 17 genera of the family Microbacteriaceae and hence strain E1HC-02(T) is designated as representing a novel species of a new genus, Frondicola australicus gen. nov., sp. nov. The type strain of the type species is E1HC-02(T) (=JCM 13598(T)=DSM 17894(T)).

Bacillus decisifrondis sp. nov., isolated from soil underlying decaying leaf foliage

An aerobic bacterium, designated strain E5HC-32(T), was isolated from soil underlying the decaying leaf litter of a slash pine forest located in south east Queensland, Australia. The strictly aerobic, motile rod-shaped cells (0.8-1.6 x 2.6-4.8 microm) produced subterminal spherical spores which distended the cells. Strain E5HC-32(T) grew optimally in 1 % trypticase soy broth (TSB) at 30 degrees C (temperature range for growth, 25-40 degrees C) and a pH of 8.4 (pH growth range, pH 7.1-9.1). Electron microscopic examination of negatively stained cells revealed the presence of peritrichous flagella and thin sections showed the presence of a typical Gram-positive type cell-wall ultrastructure. The strain was catalase-positive and oxidase-negative and metabolized pyruvic acid methyl ester, D-galactonic acid lactone, alpha-ketobutyric acid, alpha-ketovaleric acid, L-proline, L-alanine, urocanic acid, inosine, uridine, thymidine, glycerol, alpha-cyclodextrin, alpha-D-lactose, D-psicose, D-raffinose, L-rhamnose, D-sorbitol, turanose, cis-aconitic acid, alpha-hydroxybutyric acid, L-alaninamide and 2-aminoethanol. The G+C content of DNA was 41+/-1 mol% as determined by the thermal denaturation method. 16S rRNA gene sequence analysis revealed that strain E5HC-32(T) was placed equidistantly as a member of the class Bacilli, phylum Firmicutes, with Bacillus sphaericus DSM 28(T) and Bacillus odysseyi ATCC PTA-4993(T) (similarity of 93 %). In addition to its significant phylogenetic separation from its nearest relatives, strain E5HC-32(T) possessed phenotypic traits that also suggested that it represented a novel species, for which the name Bacillus decisifrondis sp. nov. is proposed. The type strain is E5HC-32(T) (=JCM 13601(T)=DSM 17725(T)).

The sensitivity of tree growth to air mass variability and the Pacific Decadal Oscillation in coastal Alabama

This study investigates the relationship between tree growth and air mass type variability, using the spatial synoptic classification (SSC) in a bottomland slash pine forest in coastal Alabama (USA). The use of an air mass approach in dendroclimatology is somewhat unconventional and has not been fully explored. However, we believe that it may be useful because the air mass approach represents a holistic and comprehensive measure of surface conditions. Cores from 36 slash pines (Pinus elliotti) were extracted and ring widths were measured to the nearest 0.01 mm. The cores were then cross-dated and a standardized ring index series was established. Relationships were explored between the index series and several climate variables and teleconnections. The index series showed significant relationships with SSC air mass types and SSC air mass ratios, but insignificant results with teleconnections. Specifically the Dry Tropical air mass type was negatively correlated with tree growth while Moist Moderate was positively correlated. Concomitantly, Dry Tropical : Moist Moderate, Dry Tropical : Moist Tropical, and Dry Moderate : Moist Moderate air mass ratios also showed negative correlations. Positive Pacific Decadal Oscillation (PDO) sea surface temperatures were also associated with significant moisture and air mass variability in the region, although the PDO did not have a significant relationship with tree growth. The significance between SSC air mass variability and tree growth in the humid subtropical climate of coastal Alabama has favorable implications for dendroclimatological research in drier environments where trees are more sensitive to climatic variables.

Upscaling fluxes from tower to landscape: Overlaying flux footprints on high-resolution (IKONOS) images of vegetation cover

In this paper, we describe the process of assessing tower footprint climatology, spatial variability of site vegetation density based on satellite image analysis, and sensor location bias in scaling up to 1 km × 1 km patch. Three flat sites with different vegetation cover and surface heterogeneity were selected from AmeriFlux tower sites: the oak/grass site and the annual grassland site in a savannah ecosystem in northern California and a slash pine forest site in Florida, USA. The site vegetation density was expressed in terms of normalized difference vegetation index (NDVI) and crown closure (CC) by analyzing the high-resolution IKONOS satellite image. At each site, the spatial structure of vegetation density was characterized using semivariogram and window size analyses. Footprint maps were produced by a simple model based on the analytical solution of the Eulerian advection–diffusion equation. The resulting horizontal arrays of footprint functions were then superimposed with those of NDVI and CC. Annual sensor location biases for the oak/grass and the pine forest sites were <4% for both NDVI and CC, requiring no flux corrections in scaling from tower to landscape of 1 km 2. Although the annual grassland site displayed much larger location biases (28% for NDVI, 94% for CC), their temporal changes associated with averaging time showed a real potential to develop algorithms aimed at upscaling tower fluxes to the landscape in an effort to provide validation data for MODIS products.

Effects of regenerating forest cover on soil microbial communities: A case study in hilly red soil region, Southern China

The stability and function of a soil ecosystem depends on the cycling of nutrients by the soil microbial community. To evaluate the effects of regenerating forest cover on the function of microbial community, the differences of four forest restoration approaches, including plantations of slash pine, Chinese fir, tea-oil camellia and natural secondary forest, in soil microbial community size, activity and metabolic diversity were measured by microbial biomass and metabolic diversity (BIOLOG) assays in a hilly red soil region, Southern China. Native soils were sampled and assessed with 0–20 and 20–40 cm layers. Results showed that significant differences ( p < 0.05) were found in soil microbial biomass among four forest restoration approaches. It was highest in the soil of natural secondary forest, medial in the plantations of tea-oil camellia and Chinese fir and the least in slash pine plantation. Principal component analysis (PCA) further revealed consistent differences of the metabolic diversity patterns in 0–20 cm soil, but not for Chinese fir plantation, tea-oil camellia plantation and natural secondary forest in 20–40 cm soil. Average well colour development (AWCD) and indices of richness and diversity showed significant difference in the four forest restoration approaches. The variable tendency of the indicators was the same as microbial biomass. These suggested that the ability to utilize sole-carbon-source and functional diversity (metabolic diversity) for soil microbial community were stronger in natural secondary forest than that in plantations. Altogether, microbial biomass and metabolic diversity patterns in 0–20 cm soil of natural secondary forest were dominant, comparing with that of three plantations, viz. slash pine plantation, Chinese fir plantation and tea-oil camellia plantation. While in 20–40 cm soil there were no recognizable differences for above indicators among four vegetation types. Factors affecting the structure and function of soil microbial community appeared to be linked closely with artificial tending, soil and water loss, root biomass and litter production. The information gathered from the studies can be used to baseline data for forest restoration projects.