Increasing Canopy Height Research Articles

Snake diversity, occupancy, and detection on Thailand's largest university campus.

More than 240 species of snake have been described from Thailand, yet basic natural history and ecology for this group of animals remains scarce in human disturbed environments despite conservation and human medical significance of them in these habitats. We studied snake diversity at Walailak University from March to December 2023, the largest university campus in Thailand (1525 hectares) through standardized walking surveys, opportunistic notifications and observation, road surveys, and traps and evaluated diversity using the Shannon diversity index (H), Pielou's evenness of species (J), detection probabilities (p), and occupancy probabilities (ψ). We observed 195 snakes (21 species, 7 families) at Walailak University and overall snake diversity (H = 2.60) and evenness (J = 0.85) were quite high, although specific site diversity (range H = 0-1.94) and evenness (range J = 0.67-0.91) within the university were variable. The probability of detecting snakes (range p = .10-.40) increased with increasing humidity and decreased with increasing amount of rain, temperature, and wind; site occupancy probability decreased with increased canopy height and increased with increased distance to buildings, increased canopy height loss, increased distance to roads, and increased distance to water. Our findings of relatively high snake diversity, presence of snake species potentially dangerous to humans (six species), and protected snake species (Thailand WARPA and international CITES, five species) suggest significant potential for conservation and further research at Walailak University and other campuses in Thailand.

Leaf Trait Variations and Ecological Adaptation Mechanisms of Populus euphratica at Different Developmental Stages and Canopy Heights

The ability of plants to alter specific combinations of leaf traits during development and in response to abiotic stress is crucial for their success and survival. While there are numerous studies on the variation of leaf traits within the canopies of Populus species, the application of network analysis to understand the variation and combinations of these traits across different growth stages is rare. The leaves of Populus euphratica, a dominant species in arid regions, exhibit notable morphological variations at different developmental stages and canopy heights in response to water scarcity and climate change. In this study, 34 leaf traits (morphological, chemical, photosynthetic, and hydraulic) and their roles in drought adaptation were investigated in 60 Populus euphratica plants at five developmental stages and five canopy heights using leaf trait network (LTN) analysis. The aim was to analyze adaptive strategies to arid environments at different developmental stages and canopy heights through the interdependence of leaf traits. The results showed that the internal coordination capacity of leaf trait networks decreased and then increased with each developmental stage, while the functional modules of leaf trait networks were loosely connected and aggregated with the increase in tree diameter at breast height. With increasing canopy height, the coordination linkage’s ability between leaf traits showed an increasing then decreasing trend, and the traits of the leaves in the canopy at 6 m were more closely connected, less modular, and simpler in topology compared with those in the other layers. Leaves form functional modules by coordinating specific traits that promote growth and resist drought. Leaf photosynthesis, water transport, and nutrient traits were central to different developmental stages, whereas leaf morphology, nutrient metabolism, and drought-resistance-related traits were central to the canopy height. Leaf morphology and osmoregulatory traits play key roles in leaf trait network regulation, including leaf length and width, leaf shape index, soluble sugars, and soluble proteins, which are important “intermediary traits” in the Populus euphratica leaf network. Further analysis revealed that structural traits were important at different developmental stages and canopy heights. When resources are limited, the leaf preferentially maintains a stable connection between structural traits to enhance photosynthesis, and these traits and their combinations might confer drought resistance. During the rapid development stage, the connection between chemical traits becomes important, and the leaf grows by rapidly accumulating nutrients. In summary, this study provides new perspectives and insights into the drought adaptation strategies of P. euphratica at different developmental stages and canopy heights by analyzing leaf trait networks.

Estimation of canopy height based on multi-source remote sensing data using forest structure aided sample selection

ABSTRACT Forest canopy height data are crucial for estimating forest carbon storage and assessing forest ecology. By utilizing satellite imagery, canopy height data obtained from airborne or spaceborne LiDAR have been expanded from footprint and plot levels to spatially continuous elevation mapping of forests. However, current research suggests that estimating forest canopy height without forest type data presents a challenge in how to effectively integrate multi-source LiDAR data and ensure the samples adequately represent various forest types for higher estimation accuracy. Therefore, this study proposes a forest canopy height estimation method that considers forest structure and integrates multi-source LiDAR data to overcome the challenge. First, a stratified sampling method based on forest structure (SSMFS) was proposed to select training samples and enhance their representativeness. Second, we combined GEDI and ATL08 data to create a multi-source spaceborne LiDAR dataset, enhancing geographic coverage and increasing canopy height samples. Third, the spaceborne LiDAR-based canopy height estimation model incorporates previously unconsidered canopy openness features and uses SSMFS to select training samples. Finally, we improved spaceborne LiDAR canopy height accuracy by creating a residual correction model that adjusts for differences between airborne scanner (ALS) and spaceborne LiDAR estimates. This study, conducted in Zhangwu County, achieved an accuracy of R2 = 0.71, MAE = 1.20 m, and RMSE = 1.71 m. These results show a 51.06% increase in R2, a 26.38% decrease in MAE, and a 24.00% decrease in RMSE compared to recent research. In summary, this study profoundly amplifies predictive accuracy, providing a clear advantage in the delineation of regional forest canopy maps.

How does canopy height regulate autumn photosynthetic phenology in the Northern Hemisphere?

<p>Autumn photosynthetic phenology strongly regulates the length of growing season and terrestrial carbon cycle, providing feedbacks to climate change. While the climatic drivers of autumn photosynthetic phenology have received considerable attention, the regulation by forest structural features is frequently overlooked. Here, we used spaceborne LiDAR observations of canopy height, two sets of canopy height products, and satellite solar-induced chlorophyll, to characterize the role of canopy height in autumn photosynthetic phenology from 2001 to 2020. We found strong dependencies of autumn photosynthetic phenology on canopy height in 65.2% of the northern forest. Taller trees tend to end the growing season later, likely due to the enhanced acquisition of solar radiation associated with increased canopy height. Additionally, taller trees have deeper root system to maintain strong hydraulic transport capacity and higher resistance to water stress. This study highlights the importance of forest structure in regulating vegetation phenology and contributes to enhancement of phenological models and carbon cycle simulations.</p>

Finding the green in differently disturbed forests under different weather conditions: detection and occupancy of the green pit viper <em>Trimeresurus (Cryptelytrops) macrops</em> at the Sakaerat Biosphere Reserve, Thailand

The response of venomous snakes to anthropogenic landscape disturbance remains scarcely studied in tropical regions. Green pit vipers are among the most diverse venomous snakes in the Southeast Asian tropics and bite the highest number of people of any group of venomous snakes where they are found, yet conservation and snakebite management efforts have been hindered by limited prior studies of these organisms in both natural and anthropogenically disturbed landscapes. Subsequently, we sought to address key knowledge gaps regarding the persistence and response of green pit vipers to anthropogenic disturbance. Utilizing repeated field surveys coupled with remote sensing landscape feature data, we fit single-season Bayesian occupancy models to investigate the potential influences of weather variables on detection and various landscape features on the persistence of the big-eyed pit viper (Trimeresurus (Cryptelytrops) macrops). Temperature and humidity marginally positively influenced detection. The probability of T. macrops occupancy increased with increasing distance to buildings and houses, roads, water, and increased canopy height and elevation but decreased with increasing distance to the core zone of the reserve, natural forest, and if a site was a plantation. Our findings suggest that anthropogenic landscape disturbance influences the presence of T. macrops within a biosphere reserve in Thailand, contrary to the general perception that the species is resilient to land-use change. We strongly suggest further study of the green pit viper response to human disturbance, which would significantly benefit conservation and snakebite management plans for these diverse organisms.

Differences in the Functional Traits of Populus pruinosa Leaves in Different Developmental Stages.

Populus pruinosa Schrenk has the biological characteristics of heteromorphic leaves and is a pioneer species for wind prevention and sand fixation. The functions of heteromorphic leaves at different developmental stages and canopy heights of P. pruinosa are unclear. To clarify how developmental stages and canopy height affect the functional characteristics of leaves, this study evaluated the morphological anatomical structures and the physiological indicators of leaves at 2, 4, 6, 8, 10, and 12 m. The relationships of functional traits to the developmental stages and canopy heights of leaves were also analyzed. The results showed that blade length (BL), blade width (BW), leaf area (LA), leaf dry weight (LDW), leaf thickness (LT), palisade tissue thickness (PT), net photosynthetic rate (Pn), stomatal conductance (Gs), proline (Pro), and malondialdehyde (MDA) content increased with progressing developmental stages. BL, BW, LA, leaf dry weight, LT, PT, Pn, Gs, Pro, and the contents of MDA, indoleacetic acid, and zeatin riboside had significant positive correlations with canopy heights of leaves and their developmental stages. The morphological structures and physiological characteristics of P. pruinosa leaves showed more evident xeric structural characteristics and higher photosynthetic capacity with increasing canopy height and progressive developmental stages. Resource utilization efficiency and the defense ability against environmental stresses were improved through mutual regulation of each functional trait.

Quantification of the Cumulative Shading Capacity in a Maize-Soybean Intercropping System Using an Unmanned Aerial Vehicle.

In intercropping systems, higher crops block direct radiation, resulting in inevitable shading on the lower crops. Cumulative shading capacity (CSC), defined as the amount of direct radiation shaded by higher crops during a growth period, affects the light interception and radiation use efficiency of crops. Previous studies investigated the light interception and distribution of intercropping. However, how to directly quantify the CSC and its inter-row heterogeneity is still unclear. Considering the canopy height differences (Hms, obtained using an unmanned aerial vehicle) and solar position, we developed a shading capacity model (SCM) to quantify the shading on soybean in maize-soybean intercropping systems. Our results indicated that the southernmost row of soybean had the highest shading proportion, with variations observed among treatments composed of strip configurations and plant densities (ranging from 52.44% to 57.44%). The maximum overall CSC in our treatments reached 123.77 MJ m-2. There was a quantitative relationship between CSC and the soybean canopy height increment (y = 3.61×10-2×ln(x)+6.80×10-1, P < 0.001). Assuming that the growth status of maize and soybean was consistent under different planting directions and latitudes, we evaluated the effects of factors (i.e., canopy height difference, latitude, and planting direction) on shading to provide insights for optimizing intercropping planting patterns. The simulation showed that increasing canopy height differences and latitude led to increased shading, and the planting direction with the least shading was about 90° to 120° at the experimental site. The newly proposed SCM offers a quantitative approach for better understanding shading in intercropping systems.

Effects of Compost tea on Productivity of Green bean (Phaseolus vulgaris L.) Varieties in Sudan Savanna of Nigeria

Maintenance of soil productivity is one of the significant constraints affecting crop production in tropical region. Thus, field experiments were carried out in the 2018 rainy season at the Bayero University, Kano’s Teaching and Research Farm of Faculty of Agriculture, and Federal College of Education, Katsina’s Teaching and Demonstration Farm. The study aimed to evaluate compost tea’s effect on the productivity of green bean varieties. The treatments comprised three compost tea rates (0, 50, and 100 l ha-1) and two green bean varieties (Bean Cora and Haricot Contender). The treatments were combined factorially and arranged in a Randomised Complete Block Design (RCBD) replicated three times. Collected data from the field were subjected to an analysis of variance using Genstat statistical package. The results showed that use of compost tea at 100 l ha-1 significantly increased canopy height, number of branches plant-1, number of leaves plant-1, leaf area plant-1, shoot dry matter, number of pods plant-1, pod length, pod weight plant-1, and green pods yield compared with the use of 50 l ha-1 and control. The results also indicated that varieties differed significantly (p &lt; 0.05) in most studied characters. Bean Cora recorded a considerably greater green pod yield than Haricot Contender. Based on the findings of this study, Bean Cora is a favourable variety in this location. However, it is also suggested that application compost tea at 100 l ha-1 be used as an organic source of nutrients for green bean production in the Sudan Savanna of Nigeria.

Functional diversity of avian communities increases with canopy height: From individual behavior to continental-scale patterns.

Vegetation complexity is an important predictor of animal species diversity. Specifically, taller vegetation should provide more potential ecological niches and thus harbor communities with higher species richness and functional diversity (FD). Resource use behavior is an especially important functional trait because it links species to their resource base with direct relevance to niche partitioning. However, it is unclear how exactly the diversity of resource use behavior changes with vegetation complexity. To address this question, we studied avian FD in relation to vegetation complexity along a continental‐scale vegetation gradient. We quantified foraging behavior of passerine birds in terms of foraging method and substrate use at 21 sites (63 transects) spanning 3,000 km of woodlands and forests in Australia. We also quantified vegetation structure on 630 sampling points at the same sites. Additionally, we measured morphological traits for all 111 observed species in museum collections. We calculated individual‐based, abundance‐weighted FD in morphology and foraging behavior and related it to species richness and vegetation complexity (indexed by canopy height) using structural equation modeling, rarefaction analyses, and distance‐based metrics. FD of morphology and foraging methods was best predicted by species richness. However, FD of substrate use was best predicted by canopy height (ranging 10–30 m), but only when substrates were categorized with fine resolution (17 categories), not when categorized coarsely (8 categories). These results suggest that, first, FD might increase with vegetation complexity independently of species richness, but whether it does so depends on the studied functional trait. Second, patterns found might be shaped by how finely we categorize functional traits. More complex vegetation provided larger "ecological space" with more resources, allowing the coexistence of more species with disproportionately more diverse foraging substrate use. We suggest that the latter pattern was driven by nonrandom accumulation of functionally distinct species with increasing canopy height.

Performance evaluation of GEDI and ICESat-2 laser altimeter data for terrain and canopy height retrievals

With the advent of the next generation of space-based laser altimeters, ICESat-2 and GEDI, we are entering an exciting era of active remote sensing of forests that offers unprecedented opportunities for the observation of forest structure. Consistent comparisons of the accuracy of terrain and canopy height retrievals for these two missions are essential for continued improvement and further application. Because the time interval between the spaceborne products and validation data may introduce additional errors, we validate the newly released GEDI L2A product (version 2) and the ICESat-2 ATL08 product (version 4) using high-resolution, locally calibrated airborne lidar products acquired in the same year (2019) as the reference datasets. In addition, our study area contains 40 sites located in the U.S. mainland, Alaska, and Hawaii that encompass a variety of eco-climatic zones and vegetation cover types; thus, it avoids the uncertainties associated with small sample sizes and restricted spatial coverage. The results show that ICESat-2 and GEDI yield reasonable estimates of terrain height, with root mean squared errors (RMSEs) of 2.24 and 4.03 m for mid and low latitudes, respectively, and 0.98 m for high latitudes (ICESat-2 only). ICESat-2 outperforms GEDI across the board for terrain height retrieval, although they both have better accuracy than existing SRTM and GMTED DEM products. Analyses of the error factors suggest that steep slopes (>30°) present the greatest challenge for both GEDI and ICESat-2; in addition, tall (>20 m) and dense canopies (>90%) forest ecosystems also reduce the accuracy of the terrain height estimates. When ICESat-2 and GEDI data are used for canopy height retrieval, the use of only strong/power beam data acquired at night is recommended, as the overall RMSEs decrease from 7.21 and 5.02 m to 3.93 and 3.56 m, respectively, compared to using all data regardless of daytime and beam strength. GEDI outperforms ICESat-2 across the board for canopy height retrieval, as ICESat-2 has a larger potential bias for almost all forest types and cover conditions. ICESat-2 tends to overestimate the canopy height of dwarf shrublands and underestimate the canopy height of forest, and there is a gradual downward shift in the distribution of residuals with increasing canopy height. Overall, ICESat-2 with photon counting technology and GEDI with full waveform technology each represent the state of the art in spaceborne laser altimeters for terrain and canopy height retrieval. Combined, these two missions can take advantage of the unique strengths of each instrument.

Ecohydrology of epiphytes: Modelling water balance, CAM photosynthesis, and their climate impacts

AbstractEpiphytes are aerial plants, often characterized by CAM (crassulacean acid metabolism) photosynthesis, which make up a significant portion of the biomass in some rainforests. Their unique characteristics have not yet been included in ecohydrological models, and their potential impact on local hydrometeorology is largely unexplored. This work introduces a water balance model for epiphytes, which adapts the soil‐plant‐atmosphere continuum model to represent a plant system without soil and couples it to the Photo3 photosynthesis model, which includes CAM photosynthesis. The model, which is parameterized with field data of Guzmania monostachia, accurately captures the observed hydraulic and photosynthetic behaviour of the epiphytic species. The application of vertical profiles of environmental inputs within the rainforest canopy shows increasing transpiration rates and decreasing water use efficiency with increasing canopy height, which corresponds to observed distributions of epiphytes in rainforests. Given that vascular epiphytes constitute a maximum of 35–50% of the foliar biomass in rainforests and contribute up to 13% of forest net primary production, they may contribute up to 10–50% of total rainforest evapotranspiration, a significant portion of the water cycle on the local ecosystem scale. The results of this work provide a missing piece to current ecohydrological models and can be integrated into Earth system models to help improve the physical representation of transpiration and free‐surface evaporation from canopy in current and future climates.

Evaluating the effects of plastic film mulching patterns on cultivation of winter wheat in a dryland cropping system on the Loess Plateau, China

Plastic film mulching (PFM) can increase or stabilize crop yields worldwide when applied to agricultural planting systems, especially in arid and semi-arid areas. Although the adverse effects that are caused by residual plastic film, such as plastic pollution, are becoming a global concern, the application of PFM will not be replaced by other materials in the short-term in agriculture. It is important to understand the various PFM patterns (different mulching periods and coverage rates) that impact on soil physicochemical properties and characteristics of crop growth. Therefore, based on a field experiment that we established in 2002, we conducted consecutive field observations from 2013 to 2016 to determine the optimum PFM mulching period and coverage rate. Three mulching periods were included: (I) summer fallow period (FM), (II) growth period (GM), and (III) whole growth year (WM). Two coverage rates were included: (i) 50%, half mulching (HM), and (ii) 100%, total mulching (TM). That is, there were six different PFM treatments. No mulching (NM) over the growth years was considered the CK treatment. PFM increased canopy height and leaf area index of winter wheat (Triticum aestivum L.) in the growing season by 29.5% and 19.4%, respectively. Average winter wheat grain yields of various PFM patterns were 5318.5 kg ha−1 and 4557.7 kg ha−1 in 2013–2014 and 2015–2016, respectively; these yields were 13.8% and 23.7% higher than NM in 2013–2014 and 2015–2016, respectively. However, the difference in the growth characteristics and grain yield of winter wheat under various PFM patterns resulted from the change in the mulching period and coverage rate. Winter wheat grain yield and biomass increased with GM and WM compared with FM and NM in normal rainfall years. PFM coverage rates improved yield significantly (P < 0.05) and influenced soil nutrient concentrations. HM maintained or increased soil organic matter (SOM) and total nitrogen concentrations, but TM decreased SOM concentration by 8.3%. Water use efficiency (WUE) and rainfall use efficiency (RUE) were improved by various PFM patterns. Furthermore, WM had the most significant impact on SOM concentrations, GM was second, and FM was minor. Considering the costs and benefits of PFM patterns, the half coverage rate of PFM during the whole year (FWH) had the best index (BI) value, and the total coverage rate of PFM during the growth period (FGT) and the half coverage rate of PFM during the growth period (FGH) had higher BI values than other PFM patterns; the values for BI for FWH, FGT, and FGH were 10.3, 8.9, and 8.5, respectively. In conclusion, ignoring the amount of PFM pollution in the environment (or use biodegradable film instead of polyethylene film), FWH was the best PFM pattern with the highest WUE and RUE in dryland rainfed agriculture. But, to decrease the amount of PFM application and pollution, FGH was more beneficial for soil health with a low coverage rate and short mulching period. FGH was the optimal pattern for PFM when applied to winter wheat on the Loess Plateau, China based on our field experiment.

What is the productive potential of digit grass in response to nitrogen fertilization?

The digit grass is a highly cultivated species in Northeast Brazil, especially in Sergipe and Alagoas. However, research related to the management of fertilization of this specie is incipient. This experiment was carried out to examine the productive potential of digit grass and its morphological changes in response to nitrogen fertilization. The experimental period was from August 2014 to July 2015. Treatments consisted of five levels of nitrogen fertilization (0, 50, 100, 300 and 600 kg ha-1) arranged in a randomized-block design with four replicates. Urea was used as a source of nitrogen. Height, light interception (LI), leaf area index (LAI), total tiller density (TTD), basal tiller density (BTD) and total (TDM), leaf (LDM) and stem dry matter (SDM) accumulations were influenced (P&lt;0.05) by the nitrogen doses, fitting a positive quadratic equation. Nitrogen fertilization did not influence (P&gt;0.05) dead material accumulation rate or aerial tiller density. Overall, the increasing nitrogen doses culminated in increased canopy height, LI and LAI as a result of the increase in TTD and BTD, which in turn elevated TDM, LDM and SDM. The herbage yield potential of digit grass can be increased with the application of 478 kg N ha-1, enabling its use as an alternative in intensive animal production systems.

Influence of Burner Position on Temperature Distribution in Soybean Flaming

The main objective of this study was to identify optimal burner orientation for a newly designed flame cultivator by quantifying the flame temperature distributions of cross, back, and parallel position of burners at different heights of the soybean canopy (distance from the soil surface). Flame temperatures were measured within-row for three burner orientations at seven propane doses (20–100 kg/ha) and eight different canopy heights (0–18 cm above soil surface). Soybean plants in V3 growth stage were flamed with the same doses and burner orientations, and 28 days after treatment (DAT) crop injury (0%–100%), plant height (cm), dry matter (g) and grain yield (t/ha) were assessed. All three burner orientations had high flame temperatures at lower canopy heights (&lt;6 cm high) that gradually decreased with increasing canopy height (6–18 cm). Measured temperatures ranged from 33 to 234 ℃ for cross flaming, 29 to 269 ℃ for back flaming and 23 to 155 ℃ for parallel flaming, with high variability in temperature patterns. Back flaming generated flame temperatures above 100℃ at a lower propane dose (27 kg/ha) compared to cross and parallel flaming (40 and 50 kg/ha). For all tested parameters, parallel and cross flaming had better impact on soybeans than back flaming, but for weed control in crop rows, cross flaming is recommended.

Tillering dynamics of ‘Mulato II’ brachiariagrass under continuous stocking

AbstractLong‐term stand persistence is a desirable characteristic of sustainable grassland ecosystems, and tillering dynamics is an important determinant of persistence. Grazing intensity and nutrient supply affect tiller density, weight, and survival. Understanding the relationships among these factors can help optimize performance of grazed pastures. The objective of this research was to determine the effects of canopy height (10, 25, and 40 cm; maintained under mimicked continuous stocking) and N fertilization (50 and 250 kg ha−1 yr−1) on the tiller dynamics and canopy stability index (SI) of ‘Mulato II’ hybrid brachiariagrass (Brachiariaspp. syn.Urochloaspp.) during two growing seasons. Tiller population density (TPD) increased by 9% with greater N fertilization and decreased linearly from 1,130 to 900 tillers m−2as canopy height increased from 10 to 40 cm. Tiller weight (TW) increased from 0.39 to 1.46 g as canopy height increased from 10 to 40 cm, but TW decreased by 9% with a greater N rate. Tiller appearance rate increased by 30% and tiller survival rate (TSR) decreased by 13.5% as N rate increased. The TSR was greater for 25‐ and 40‐cm than for 10‐cm canopies (81, 82, and 74 tillers per 100 tillers per 30 d, respectively). The SI increased from 0.91 to 1.0 with increasing canopy height from 10 to 40 cm. Mulato II canopies followed the tiller size–density compensation mechanism, displaying phenotypic plasticity in response to canopy height, but these results suggest a 25‐cm canopy height is near optimal for continuously stocked Mulato II brachiariagrass pastures.

Canopy height explains species richness in the largest clade of Neotropical lianas

AbstractAimTall and structurally complex forests can provide ample habitat and niche space for climbing plants, supporting high liana species richness. We test to what extent canopy height (as a proxy of 3‐D habitat structure), climate and soil interact to determine species richness in the largest clade of Neotropical lianas. We expect that the effect of canopy height on species richness is higher for lianas from closed tropical rain forests compared to riparian and savanna habitats.LocationNeotropics.Time periodPresent.Major taxa studiedTribe Bignonieae (Bignoniaceae).MethodsWe used structural equation models to evaluate direct and indirect effects of canopy height, climate (temperature, precipitation and precipitation seasonality), and soil (cation exchange capacity and soil types) on overall Bignonieae species richness (339 liana species), as well as on species richness of lianas from forest, riparian and savanna habitats, respectively. We further performed multiple regression models with Moran's eigenvector maps to account for spatial autocorrelation.ResultsCanopy height was a key driver of liana species richness, in addition to climate and soil. Species richness of forest lianas showed a strong positive relationship with canopy height whereas the relationship was less pronounced for riparian species. Richness of savanna species decreased with increasing canopy height. Climate also explained a substantial proportion of variation in liana species richness whereas soil variables showed little explanatory power.Main conclusionsThe relationship between canopy height and liana species richness differs among habitats. While forest and riparian lianas benefit from tall and complex habitats that provide physical support to reach the canopy to escape low light availability in the understorey, high light availability in open habitats and an increased risk of embolism of conductive vessels for lianas with long stems living in areas with high seasonality might explain the inverse relationship between species richness and canopy height in savannas.

Effect of Thiamethoxam on Injurious Herbicides in Rice

Increases in the number of herbicide-resistant weeds in rice has led to the need for new herbicides and modes of action to control these troublesome weeds. Previous research has indicated that insecticide seed treatments can safen rice from herbicide drift. In 2014 and 2015, two field experiments were conducted at the Rice Research and Extension Center (RREC) near Stuttgart, Arkansas, and at the University of Arkansas Pine Bluff (UAPB) farm near Lonoke, Arkansas, to determine if insecticide seed treatments could prevent unacceptable levels of herbicide injury from preemergence (PRE)- and postemergence (POST)-applied herbicides that are typically injurious to rice. Both studies were planted with the imidazolinone-resistant, inbred variety CL151. ‘Treated’ plots contained the insecticide seed treatment thiamethoxam while ‘nontreated’ plots contained no insecticide seed treatment. Seven herbicides were evaluated in the PRE experiment: clomazone, pethoxamid, fluridone, S-metolachlor, thiobencarb, clethodim, and quizalofop to determine crop injury, stand counts, groundcover, and rough rice yield with and without an insecticide seed treatment compared to plots with no herbicide treatments. Overall, an insecticide seed treatment provided increased rice stands and less herbicide injury than the ‘nontreated’ seed while increasing yield by 500 kg ha-1. Of the herbicides tested, clomazone-, thiobencarb-, clethodim-, and quizalofop-treated plots had equivalent yields to the no-herbicide plots. The POST experiment evaluated propanil, saflufenacil, carfentrazone, and acifluorfen in various tank-mixtures and application timings. Similar to the PRE experiment, plants from treated seed had less herbicide injury 1 and 5 weeks after treatment (WAT) along with an increased canopy height and groundcover percentage. Plants having treated seed also had increased yields when used with some herbicide programs. Overall, the use of an insecticide seed treatment can give the added benefit of less injury from injurious herbicides as well as increased groundcover.

Landscape metrics as functional traits in plants: perspectives from a glacier foreland.

Spatial patterns of vegetation arise from an interplay of functional traits, environmental characteristics and chance. The retreat of glaciers offers exposed substrates which are colonised by plants forming distinct patchy patterns. The aim of this study was to unravel whether patch-level landscape metrics of plants can be treated as functional traits. We sampled 46 plots, each 1 m × 1 m, distributed along a restricted range of terrain age and topsoil texture on the foreland of the Nardis glacier, located in the South-Eastern Alps, Italy. Nine quantitative functional traits were selected for 16 of the plant species present, and seven landscape metrics were measured to describe the spatial arrangement of the plant species’ patches on the study plots, at a resolution of 1 cm × 1 cm. We studied the relationships among plant communities, landscape metrics, terrain age and topsoil texture. RLQ-analysis was used to examine trait-spatial configuration relationships. To assess the effect of terrain age and topsoil texture variation on trait performance, we applied a partial-RLQ analysis approach. Finally, we used the fourth-corner statistic to quantify and test relationships between traits, landscape metrics and RLQ axes. Floristically-defined relevé clusters differed significantly with regard to several landscape metrics. Diversity in patch types and size increased and patch size decreased with increasing canopy height, leaf size and weight. Moreover, more compact patch shapes were correlated with an increased capacity for the conservation of nutrients in leaves. Neither plant species composition nor any of the landscape metrics were found to differ amongst the three classes of terrain age or topsoil texture. We conclude that patch-level landscape metrics of plants can be treated as species-specific functional traits. We recommend that existing databases of functional traits should incorporate these type of data.

Foliar water use efficiency of Platycladus orientalis of different canopy heights in Beijing western mountains area, China

In this study, we focused on Platycladus orientalis, a widely distributed tree species in Beijing western mountains area, and precisely determined its foliar water use efficiency (including instantaneous water use efficiency derived from gas exchange and short-term water use efficiency obtained on carbon isotope model) by carefully considering the discrepancies of meteorological factors and atmosphere CO2 concentration and δ13C among different canopy heights, hoping to provide theoretical basis for carbon sequestration and water loss in regional forest ecosystem, and offer technical support for regional forest management and maintenance. The results showed that the foliar instan-taneous water use efficiency tended to increase with the increasing canopy height, following the order of the upper canopy > the middle canopy > the lower canopy. A variety of meteorological factors synergistically influenced stomatal movement, and stomatal conductance would in turn have an effect on foliar instantaneous water use efficiency. Foliar short-term water use efficiency also increased with increasing canopy height, following the order of the upper canopy > the middle canopy > the lower canopy. The differences of foliar short-term water use efficiency among different heights could be explained by discrepancies of environmental drivers and atmosphere CO2 concentration and δ13C. Platycladus orientalis leaves in upper canopy adapted to ambient condition by improving water use efficiency.

Importance of soft canopy structure for labrid fish communities in estuarine mesohabitats

Hard structural complexity is widely recognised as important for assessing fish habitat quality, but our understanding of the importance of soft habitat microstructure for temperate marine fishes is less developed. We used best-subsets modelling of underwater surveys in sponge, soft coral, and macroalgae mesohabitats within a temperate estuary to assess what measures of soft habitat structure best predicted differences in wrasse (family: Labridae) fish community composition. We found that significant differences in the labrid fish community among and within mesohabitat types were best explained by a combination of percent canopy cover and soft canopy height, with increased canopy height being correlated with increased fish abundance and species richness. Sponge and macroalgae mesohabitats emerged as particularly important, but vulnerable habitats for a diversity of fishes unique to these mesohabitat types. Ultimately, mesohabitats with high percent canopy cover and height appear to be particularly valuable for supporting estuarine fish communities. Due to this importance, and the potential for decadal-scale recovery times within sponge canopies, we suggest patches with high-quality canopy structure warrant special protection from local threats, such as anchor and fishing damage.