Tree Rows Research Articles

Paolo Zermani. Scuola per l’Europa a Parma

Paolo Zermani’s School for Europe (Scuola per l’Europa) lies on the Valley of the Po as a place for recomposing the territory, aware of the fact that a world converges on it, of which it is the centre. Walking along its porticoed streets, so near the rows of mulberry trees and the irrigation canals that mark the boundary with the adjacent agricultural fields, it is possible to understand how it is the great themes of the Po Valley architecture that construct the body of this building.

APSIM model performance in simulating Piatã palisade grass growth and soil water in different positions of a silvopastoral system with eucalyptus

CONTEXTSilvopastoral systems aim to be more sustainable than conventional systems, increasing total productivity, diversifying agricultural production, and improving resource use efficiency. However, very few studies were performed to adapt crop models to simulate these systems. OBJECTIVEThis study investigates the current capacity of the APSIM Next Generation model to estimate Piatã palisadegrass growth and soil water in different positions in a silvopastoral system with eucalyptus by looking at the impact of modelling belowground and aboveground competition separately. METHODSA field experiment was conducted from December 2014 to January 2016 in a silvopastoral system with eucalyptus trees arranged in single rows, in East-West orientation, with 15 m between rows and 2 m between trees in the rows. This experiment was conducted under grazing management and rainfed conditions, during 11 growth cycles, with pasture variables, soil moisture and microclimatic conditions assessed at four distances from the eucalyptus north row (0.00 m, 3.75 m, 7.50 m and 11.25 m). APSIM testing was performed in two ways: focusing on belowground competition for soil water and nitrogen, using a multi-root-zone approach, and focusing on competition for solar radiation, using the measured data of solar radiation at each position. RESULTS AND CONCLUSIONSThe APSIM-Tropical Pasture model was effective in simulating pasture growth when only competition for solar radiation was considered (R2 from 0.75 to 0.86, Agreement index (d) from 0.88 to 0.96, and Nash-Sutcliffe efficiency (NSE) between 0.32 and 0.85). These simulations are promising taking into account the difficulties to simulate pasture growth in silvopastoral systems with grazing; however, in systems with strong belowground competition for soil water and nutrients, this approach has strong limitations. Simulations of pasture growth were not as effective when using the multi-root-zone approach (R2 between 0.57 and 0.87, d between 0.53 and 0.74, and NSE from −5.32 to −1.20), despite reasonable simulations of soil water for the positions between the tree rows (R2 between 0.70 and 0.80, d from 0.91 to 0.94, and NSE between 0.60 and 0.77). In view of these results, improvements should be performed in APSIM to better simulate silvopastoral systems, mainly for solar radiation transmission and tree roots growth and distribution. SIGNIFICANCEThis study allowed identifying the key drivers of competition within the studied environment and to inform where the main efforts should be targeted in building a more effective model for silvopastoral systems. This is important to help model development teams in organising and optimising their efforts.

Early response of soil fungal communities to the conversion of monoculture cropland to a temperate agroforestry system.

BackgroundAlley-cropping systems in the temperate zone are a type of agroforestry in which rows of fast-growing trees are alternated with rows of annual crops. With numerous environmental benefits, temperate agroforestry is considered a promising alternative to conventional agriculture and soil fungi may play a key in maintaining productivity of these systems. Agroforestry systems that are established for more than 10 years have shown to increase the fungal biomass and impact the composition of soil fungal communities. Investigations of soil fungi in younger temperate agroforestry systems are scarce and the temporal dynamic of these changes is not understood.MethodsOur study was conducted in a young poplar-based alley cropping and adjacent monoculture cropland system in an Arenosol soil in north-west Germany. We investigated the temporal dynamics of fungal populations after the establishment of agroforestry by collecting soil samples half, one, and one and a half years after conversion of cropland to agroforestry. Samples were collected within the agroforestry tree row, at 1, 7, and 24 m distance from the tree row within the crop row, and in an adjacent conventional monoculture cropland. The biomass of soil fungi, Asco-, and Basidiomycota was determined by real-time PCR. Soil fungal community composition and diversity were obtained from amplicon sequencing.ResultsDifferences in the community composition of soil fungi in the tree row and arable land were detected as early as half a year following the conversion of monoculture cropland to agroforestry. In the tree row, soil fungal communities in the plots strongly diverged with the age of the system. The presence of young trees did not affect the biomass of soil fungi.ConclusionsThe composition of soil fungal communities responded rapidly to the integration of trees into arable land through agroforestry, whereas the fungal biomass was not affected during the first one and a half years after planting the trees. Fungal communities under the trees gradually diversified. Adaptation to spatially heterogeneous belowground biomass of the trees and understory vegetation or stochastic phenomena due to limited exchange among fungal populations may account for this effect; long-term monitoring might help unravelling the cause.

Biomass increment and carbon sequestration in hedgerow-grown trees

The global role of tree-based climate change mitigation is widely recognized; trees sequester large amounts of atmospheric carbon, and woody biomass has an important role in the future biobased economy. In national carbon and biomass budgets, trees growing in hedgerows and tree rows are often allocated the same biomass increment data as forest-grown trees. However, the growing conditions in these linear habitats are different from forests given that the trees receive more solar radiation, potentially benefit from fertilization residuals from adjacent fields and have more physical growing space. Tree biomass increment and carbon storage in linear woody elements should therefore be quantified and correctly accounted for. We examined four different hedgerow systems with combinations of pedunculate oak, black alder and silver birch in northern Belgium. We used X-ray CT scans of pith-to-bark cores of 73 trees to model long-term (tree life span) and short-term (last five years) trends in basal area increment and increment in aboveground stem biomass. The studied hedgerows and tree rows showed high densities (168–985 trees km-1) and basal areas (22.1–44.9 m2 km-1). In all four hedgerow systems, we found a strong and persistent increase in stem biomass and thus carbon accumulation with diameter (long-term trend). The current growth performance (short-term trend) also increased with tree diameter and was not related to hedgerow tree density or basal area, which indicates that competition for light does not (yet) limit tree growth in these ecosystems. The total stem volume was 82.0–339.7 m³ km-1 (corresponding to 18.8–100.7 Mg aboveground carbon km-1) and the stem volume increment was 3.1–14.5 m³ km-1 year-1 (aboveground carbon sequestration 0.7–4.3 Mg km-1 year-1). The high tree densities and the persistent increase in growth of trees growing in hedgerow systems resulted in substantial wood production and carbon sequestration rates at the landscape scale. Our findings show that trees growing in hedgerow systems should be included when biomass and carbon budgets are drafted. The biomass production rates of hedgerow trees we provide can help refine the IPCC Guidelines for National Greenhouse Gas Inventories.

The University of Texas's “Racial Geography Tour,” designed by Dr. Edmund Gordon

The University of Texas's “Racial Geography Tour,” designed by Dr. Edmund Gordon

The structure in diameter and sanitary condition of geographical cultures of Scots pine

The study of geographical forest cultures is the scientific basis for forest-seed zoning and selection of tree species. This research identifies the structural features of the diameter of middle-aged stands of different ecotypes of Scots pine (Pinus sylvestris L.) in geographic cultures, as an assessment of its current sanitary state. We studied the stands of 18 forest-steppe and 14 steppe ecotypes. We laid test areas with measuring the diameters of trees with a measuring fork at a height of 1.3 m. Trees with a continuous count were divided into six categories of sanitary status: no signs of weakening, weakened, strongly weakened, shrinking, fresh dead wood and dead wood of past years. Based on the results of continuous recounts, the distribution rows of trees were constructed according to 2- and 4-cm thickness steps. In forest-steppe ecotypes, the distribution of trees along 2-and 4-centimeter-thick steps is single-vertex, but with right asymmetry. The distribution of trees of steppe ecotypes over 2-cm steps of thickness is asymmetric and two-peaked. The distribution of trees of steppe ecotypes by 2-cm thickness steps is asymmetric and two-vertex. The average score of the sanitary state of stands of forest-steppe ecotypes is 1.5 (healthy), in steppe – 1.7 (weakened).

Response of vegetative and fruit growth to the soil volume wetted by irrigation in a super-high-density olive orchard

In most fruit tree orchards under localised irrigation, only a fraction of the rhizosphere is wetted by irrigation. As this may reduce growth and production, such that there is a demand for information on the optimum number and location of emitters. In a mature ‘Arbequina’ olive orchard with 1667 trees ha-1, we analysed the impact of applying the same amount of water with one vs. two drip irrigation pipes (laterals) per tree row. We had trees under full irrigation, for which irrigation supplies amounted to 80–100% of the crop water needs (ETc), and two deficit irrigation treatments supplying ca. 40% of ETc. We used the HYDRUS 2D/3D (v. 1.11) model to simulate the shape and volume of the fraction of the rhizosphere wetted by irrigation (irrigation bulbs), as well as drainage and soil evaporation. For both full irrigation and deficit irrigation, differences in the soil volume and the soil surface wetted by irrigation were not sufficient to affect drainage and soil evaporation. The greatest values of root length density and root surface per unit volume were found in trees under deficit irrigation with two laterals, and the lowest in fully irrigated trees with one lateral. This, however, was counterbalanced by both the greater size of the irrigation bulbs and the greater soil water contents in the bulbs of the fully irrigated trees, such that water uptake was not enhanced by the second lateral. For 2 consecutive years we found no impact of irrigating with one or two laterals per tree row on water potential and stomatal conductance, shoot and fruit growth, leaf area and production, either for full irrigation or deficit irrigation conditions. Therefore, our findings suggest no benefits of irrigating super high density olive orchards with two laterals instead of one.

The use of mulching material in the cultivation of apple and pear in a small plastic greenhouses

This article presents the results of studies that were conducted in a small-sized film greenhouse for growing аpple and pear seedlings according to different planting schemes with mulching between rows with black span bond and matting. It was found that mulching between rows creates more favorable conditions for growing plants. The temperature regime of the soil improves, especially at the depth of the root layer. The row spacing soil is less compacted, since multiple loosening and weeding are not required. The mulching materials used freely pass water and mineral elements dissolved in it. Black woven matting is recognized as the best material for mulching between rows of apple and pear trees in a small film greenhouse. The applied schemes of planting winter grafts of apple and pear trees and mulching of row spacing made it possible to completely abandon the use of intensive manual labor on weeding and loosening the soil. Using three-line planting instead of one-line planting allows to significantly increase the yield of planting material per unit area.

Irrigated trap crops impact key hemipteran pests in organic pistachio orchard

Using sown groundcovers as trap crops to protect a cash crop is a traditional pest management tool. Pistachio is a major crop in California’s Central Valley, where high summer temperatures and little to no precipitation between May and November lead to summer dry-down of annual groundcover. Hemipteran pests that consist of ‘small bugs’ and ‘large bugs’ are a major contributor to nut damage, especially in organic production. In this 2-year field study, we tested the use of irrigated trap crop mixtures, sown between tree rows, to reduce those hemipteran pests’ abundance or damage. Biweekly beat samples of the tree canopy and sweep samples of the sown groundcovers in trap crop plots and resident weedy vegetation in control plots were taken over two consecutive growing seasons. Arthropod richness and abundance were highest in the groundcover and tree canopy in the trap crop plots. Small and large bug pest populations were higher and lower, respectively, in the tree canopy in trap crop plots, indicating a mixed response of these hemipterans to the presence of the trap crops. Additionally, natural enemy populations were more abundant in the tree canopy in trap crop plots than in control plots. There was no difference in nut damage between plots with and without the trap crop. These findings suggest that populations of hemipteran pests and beneficials can be manipulated successfully with irrigated trap crops, but future studies will need to focus on doing so in a way that decreases hemipteran pistachio damage.

Growth of Vegetables in an Agroecological Garden-Orchard System: The Role of Spatiotemporal Variations of Microclimatic Conditions and Soil Properties

Garden-orchard systems (GOS) consist in intercropping various vegetables with fruit trees. They are very promising to produce fruits and vegetables in sufficient quantity and of adequate quality while limiting environmental impacts. We assessed the effects of apple trees on the spatiotemporal variations of microclimatic conditions and soil properties, and their influence on the growth of two vegetables (radish and lettuce). We performed measurements on five vegetable beds situated at different distances from apple tree rows (from 1.5 to 5 m). Vegetable beds near the apple trees received on average 8% less radiation. Air temperature near the trees was on average 1.5 °C lower during daytime while air relative humidity was up to 5% higher. Apple trees improved the soil surface properties. Soil organic matter was up to 40% higher in the vegetable beds near the rows whereas soil bulk density was 16% lower, N mineralization was up to two times faster. Mineral N and bulk density were the primary limiting factors for the growth of radish while lettuce growth was mainly affected by microclimate. Our results provide a framework to define a spatial arrangement of GOS that optimize the ecosystem services of fruit trees and, therefore, the productivity of GOS.

An End-to-End Learning-Based Row-Following System for an Agricultural Robot in Structured Apple Orchards

A row-following system based on end-to-end learning for an agricultural robot in an apple orchard was developed in this study. Instead of dividing the navigation into multiple traditional subtasks, the designed end-to-end learning method maps images from the camera directly to driving commands, which reduces the complexity of the navigation system. A sample collection method for network training was also proposed, by which the robot could automatically drive and collect data without an operator or remote control. No hand labeling of training samples is required. To improve the network generalization, methods such as batch normalization, dropout, data augmentation, and 10-fold cross-validation were adopted. In addition, internal representations of the network were analyzed, and row-following tests were carried out. Test results showed that the visual navigation system based on end-to-end learning could guide the robot by adjusting its posture according to different scenarios and successfully passing through the tree rows.

The Effects of Residential Street Tree Spacing and Crown Interactions on Crown Dimensions and Canopy Cover

Urban trees provide people with a range of ecosystem services. Trees planted along streets have been a large focus of urban forest research and practice, and municipalities invest significant resources in their survival. However, the optimal spacing of street trees is not addressed in the scientific literature, and existing municipal street tree spacing standards are highly variable and poorly enforced. In this study, we examine variability in crown shape and size for street trees to test for possible interaction effects at closer spacings. We measured variability in crown diameters both parallel and perpendicular to street tree rows to test whether changes in crown dimensions can be explained by interaction effects with neighbouring trees, and whether crown interactions lead to a reduction in total crown projection area (i.e., canopy cover). We measured the crown dimensions and diameter at breast height of 1,338 street trees in Halifax, Canada. We used two-way analysis of variance to test whether crown shape and crown projection area were affected by crown interactions and spacing. We found that the effect of narrower spacing and interactions (i.e., crowns touching/overlapping) among trees translated to crowns extending away from the direction of interaction. We also found that these changing crown dimensions were associated with increases in canopy cover. Urban forest ecosystems are a vital resource for the increasingly urban population. There is a need for empirical research on spacing standards and practices that investigate their influence on the supply of ecosystem services, such as stormwater retention, air pollution removal, and cooling.

Spatial distribution of soil organic carbon in apple orchard soils of Kashmir Himalaya, India

Apple orchards constitute an important agro-ecosystem across Kashmir Himalayan Region (KHR), but estimates of their soil organic carbon (SOC) are unavailable. We investigated 174 apple orchards for estimating SOC spatial distribution across KHR at regional scale and evaluate accuracy of five interpolation methods. The selected orchards were representative of varied size, age, and management practices prevalent across KHR. Soil samples were collected from both tree rows and alleys between tree rows by digging pits at three depth intervals of 0–10; 10–20 and 20–30 cm. A total of 1044 soil samples were collected. The interpolation methods used included, ordinary kriging (OK), inverse distance weighing, empirical bayesian kriging, radial basis functions and local polynomial interpolation. Cross validation was used to assess the comparative performance of each method by measuring interpolation bias and accuracy. The soils were structurally less stony, with weak granular to moderate crumb at surface and sub-angular to angular blocky structure at sub-surface. The soils exhibited lowest co-efficient of variation for soil acidity and highest for soil electrical conductivity. With mean value of 12.33 ± 3.98 g kg−1 on concentration basis and 48.45 Mg C ha−1 on stock basis, the SOC declined with increasing soil depth, so much that near surface (0–10 cm) SOC content could explain well over 64% and 35% of second (20–30 cm) and third layer (20–30 cm) variation respectively. Exponential model best described SOC content across all depths. Semi-variograms of SOC at topsoil exhibited larger nugget effect while nugget sill ratios of 43% suggested moderate SOC spatial dependence. Cross validation exhibited better accuracy for OK in terms of indicating good match between observed and predicted SOC. This study exemplifies that apple orchards across KHR are significant carbon pool, improves our understanding of spatial distribution of SOC and help in evaluating soil health by providing site specific maps.

Bioenergy production effects on SOM with depth of loblolly pine forests on Paleaquults in southeastern USA

Managed loblolly pine (P. taeda L.) forests comprise a major land-use across the “wood basket” of the southeastern US. Lower coastal plain loblolly pine forests can enhance carbon (C) storage in fast-growing vegetation and soils, representing a significant opportunity to manage these forests for improved soil health through an understanding of soil C and nitrogen (N) storage. Furthermore, these forests have unrealized potential to produce biomass for emerging bioenergy markets. Despite this, very little is known about how intensified management (herbaceous bioenergy production) of these forests influences short-term soil organic C (SOC) and soil organic N (SON) pools in surface and subsurface soil horizons. The field site was located in the Lower Coastal Plain of North Carolina, USA in which trees were planted in bedded (e.g., raised) rows (bed) and intercropped with or without switchgrass (P. virgatum L.) between the bedded rows of trees (interbed). Soils were collected from four depths (0–5, 5–15, 15–30, and 30–45 cm) and two locations (bed and interbed regions) and fractionated into light and heavy mineral-associated SOC and SON pools using a sequential density fractionation technique. Bulk soil SOC and SON concentration as well as C:N ratio decreased with depth for both treatments, while 15N became enriched. Free and occluded lighter fractions (< 1.65 g cm−3) had higher SOC and SON concentration (~45% C and ~ 1.15% N) compared to medium (1.65–2.00 g cm−3) and heavy (> 2.00 g cm−3) fractions. At the 0–5 cm depth in interbeds, SOC and SON were concentrated in the free light fraction (~45%), but transitioned to being concentrated in the heaviest mineral-associated fraction at the 15–30 (~55%) and 30–45 (~70%) cm depth. The 15N analysis of density fractions indicated progressive enrichment with increasing density, suggesting increasing incorporation of microbially-derived products into stable mineral-associated soil organic matter (SOM) pools. In the pine-switchgrass treatment, SOC and SON concentrations were higher in the light and medium fractions in beds and interbeds compared to the pine only treatment, particularly at the 30–45 cm depth. The C:N ratio in the pine-switchgrass treatment was higher compared to the pine only treatment indicating inputs of new plant-derived organic matter. Furthermore, the δ13C stable isotope signature was enriched in both the occluded light fraction (1.65 g cm−3) and the mineral-associated fraction (1.65–1.85 g cm−3). Our results suggest that switchgrass intercropping is contributing to the early buildup of SOM in particulate and mineral-associated SOM pools possibly through additions of new root-derived organic matter and the positive effect on soil microbial activity through priming of microbes.

An Algorithm for Linearizing the Collatz Convergence

The Collatz dynamic is known to generate a complex quiver of sequences over natural numbers for which the inflation propensity remains so unpredictable it could be used to generate reliable proof-of-work algorithms for the cryptocurrency industry; it has so far resisted every attempt at linearizing its behavior. Here, we establish an ad hoc equivalent of modular arithmetics for Collatz sequences based on five arithmetic rules that we prove apply to the entire Collatz dynamical system and for which the iterations exactly define the full basin of attractions leading to any odd number. We further simulate these rules to gain insight into their quiver geometry and computational properties and observe that they linearize the proof of convergence of the full rows of the binary tree over odd numbers in their natural order, a result which, along with the full description of the basin of any odd number, has never been achieved before. We then provide two theoretical programs to explain why the five rules linearize Collatz convergence, one specifically dependent upon the Axiom of Choice and one on Peano arithmetic.

BIOMETRIC CHARACTERISTICS OF 'CATHERINE SEL 1' PEACH CULTIVAR IN SEMIARID ENVIRONMENT

In arid and semi-arid regions, irrigation application is mandatory for modern fruit growing, but the optimal irrigation application requires large amounts of water. In the context of global warming, water saving is a major objective. Therefore, deficit irrigation (DI) is an attractive alternative. The plant studied was thirteen years old ‘Catherine Sel.1’ peach trees. The trees were grafted on franc rootstock and planted in a 4 m x 3 m layout. Soil management was represented by clean cultivation both between tree rows and in the row. Fruit size and weight are important qualities and yield traits in peach (Prunus persica (L) Batsch), but the factors that influence fruit size and weight remain to be explored. The fruit biometrical characteristics was influenced by the irrigation regime, with the irrigated treatment with 100% AHI (T1) showing significantly (P &lt;5%) higher differences versus T2 and T3. As with fruit biometrical characteristics, the fruit weight determined on the fruits of the studied treatments had the same trend. In this study, we investigated the impact of stress hydric on fruit size and weight at 'Catherine sel 1' peach cultivar in 2019-2020 period.

Carbon life cycle assessment of shelterbelts in Saskatchewan, Canada

Shelterbelts are rows of trees planted around farmyards and field for protection against soil erosion, promotion of biodiversity and wildlife habitat. Additionally, to carbon sequestration through growth in tree biomass and carbon sinks in agricultural soil. In recent years, removal of shelterbelts has become more common, as crop land is preferred under higher crop prices, resulting in increased GHG emissions and decreases in carbon sinks. It is likely that landowners are making decisions without the knowledge of carbon sequestered by these trees. In this study, the level of carbon sequestration for the six common shelterbelt tree species found in Saskatchewan (hybrid poplar, green ash, Manitoba maple, Scots pine, white spruce, and caragana) was estimated using a carbon - life cycle analysis method. Net amount of carbon sequestered was estimated for five sequestration/emission stages – 1) seedling production, 2) transportation of seedlings to farm, 3) planting, 4) maintenance, and 5) growth of shelterbelts on farm. Since some landowners are removing shelterbelts, a removal stage was also included. During removal of shelterbelts, CO2 emissions were produced through: (i) physical process of removing the trees and subsequent burning of the wood; and (ii) loss of soil carbon after the removal over a long period of time. The functional unit for the analysis was one linear kilometer of shelterbelt, the normal structure of shelterbelts on agricultural land. All emissions/sequestration levels were measured as carbon dioxide (CO2) by multiplying the molecular weight of carbon dioxide to that of carbon (44/12). Other than the growth stage of shelterbelts, all other stages contributed net greenhouse gas emissions, which offset by carbon sequestration during tree growth. Hybrid poplar is a rapidly growing tree and sequesters the most carbon of the six species in all soil zones. A one km long hybrid poplar shelterbelt sequestered upwards of 1923 t CO2 by age 60 years in the Brown soil zone, compared to 2086 t CO2 over the same period in the Black soil zone. In comparison, in the Brown soil zone, Manitoba maple and white spruce sequestered 756 and 732 t CO2, respectively over the same period. If a landowner decides to remove a 60-year-old shelterbelt, 1205 t CO2 is lost within a short period after removal, whereas 718 t of remaining CO2 is retained as dead organic matter, which is slowly released over a period. Although field shelterbelts may emit greenhouse gases in the earlier stages of development, overall, they are net sinks of carbon and can therefore play a significant role in Canada's plan to reduce GHG emissions from agriculture.

Tree Canopy Management Affects Dynamics of Herbaceous Vegetation and Soil Moisture in Silvopasture Systems Using Arboreal Legumes

Understanding ecological interactions between the arboreal and the herbaceous components is key to get the full benefits from silvopastoral systems. The objective of this 2-yr research was to evaluate productivity and nutritive value of signalgrass (Urochloa decumbens (Stapf.) R. Webster) subjected to shading from the tree legumes Gliricidia (Gliricidia sepium (Jacq.) Steud) or Mimosa (Mimosa caesalpiniifolia Benth.) under different tree canopy management. Trees were planted in double rows and were either unharvested or harvested only one row, leaving the other row unharvested. Response variables for the herbaceous vegetation included canopy height, herbage mass (green leaf blade, green stem, senescent leaves, and senescent stem), herbage accumulation rate, canopy bulk density, and soil moisture. Total herbage mass, green herbage mass, and green leaf mass were affected by treatment × month and harvest management × month interactions. Herbage accumulation rate in Gliricidia was greater (55 kg DM ha−1d−1) than Mimosa (32 kg DM ha−1d−1). Soil moisture was lesser at the Mimosa sites (16.2%) compared with the Gliricidia ones (17.2%), and it was greater between tree rows (21.9%) compared with full sun (11.5%), varying across the season. Harvesting management had a short-term transient effect on herbage responses. Tree canopy management can affect forage quantity and quality; however, these effects are transient and vary with tree spacing. Signalgrass grew faster and had better nutritive value when growing with Gliricidia.

Eucalyptus tree influence on spatial and temporal dynamics of fine-root growth in an integrated crop-livestock-forestry system in southeastern Brazil

Integrated farming systems are promising strategies towards land-use efficiency and sustainable agriculture. The integrated crop-livestock-forestry (ICLF) system stablish complex interactions were synergies or competition depend on the arrangements throughout time and space. Fine root (≤2 mm) growth dynamics of crops, pasture and trees remains unclear when these species are integrated. We aimed to assess root growth dynamics after Eucalyptus urograndis introduction into an integrated crop-livestock (ICL) system. Previous ICL area was used as a reference. We assessed ICLF 1.9, 4.3 and 7.5 m distances from tree rows, starting the study when trees had three years of age. Eucalyptus rows were spaced 15 m apart and integrated to annual crops and pasture. We evaluated the root growth under two different successional periods: (i) corn cultivation interspaced with palisade grass (Urochloa brizantha); and (ii) a pasture, when palisade grass was grazed. We tracked fine root length using the minirhizotron technique, capturing 3200 images scanning up to 70 cm soil depth. Data of photosynthetically active radiation (PAR) transmission, soil bulk density, rainfall and air temperature were used as complementary information to support the discussion. Our results showed that Eucalyptus trees impaired root growth of annual crops cultivated in the interrow position, regardless of distance from the row. From 31 to 80 days after corn germination, root length production in ICLF was reduced by 120–179 cm m−2.d−1 along the tree interrow space. For the pasture period, total produced root length density reduced 6% at 1.9 m but increased 25% at 4.3 and 7.5 m, when compared to ICL. Shade of Eucalyptus trees at ICLF 1.9 m position, with PAR transmission mainly below 60%, sharply impaired root growth. Eucalyptus roots represented 12% from total root length produced in ICLF system, and 38% of these roots had positive ectomycorrhizal status. In conclusion, under Eucalyptus trees higher than 20 m, pasture of palisade grass is more adaptable than corn when considering the root growth dynamics of our studied ICLF arrangement. Based on our findings, corn intercropped with palisade grass should not be introduced in future management of the ICLF system, unless part of the trees is chopped to reduce light competition. However, implemented pasture of palisade grass showed belowground synergies with Eucalyptus, increasing root growth in intermediary interrow positions and emerging new fungal symbiosis, which could be playing important functions in soil, as soil carbon storage and nutrient cycling.

Assessing Spatial Variability of Barley Whole Crop Biomass Yield and Leaf Area Index in Silvoarable Agroforestry Systems Using UAV-Borne Remote Sensing

Agroforestry systems (AFS) can provide positive ecosystem services while at the same time stabilizing yields under increasingly common drought conditions. The effect of distance to trees in alley cropping AFS on yield-related crop parameters has predominantly been studied using point data from transects. Unmanned aerial vehicles (UAVs) offer a novel possibility to map plant traits with high spatial resolution and coverage. In the present study, UAV-borne red, green, blue (RGB) and multispectral imagery was utilized for the prediction of whole crop dry biomass yield (DM) and leaf area index (LAI) of barley at three different conventionally managed silvoarable alley cropping agroforestry sites located in Germany. DM and LAI were modelled using random forest regression models with good accuracies (DM: R² 0.62, nRMSEp 14.9%, LAI: R² 0.92, nRMSEp 7.1%). Important variables for prediction included normalized reflectance, vegetation indices, texture and plant height. Maps were produced from model predictions for spatial analysis, showing significant effects of distance to trees on DM and LAI. Spatial patterns differed greatly between the sampled sites and suggested management and soil effects overriding tree effects across large portions of 96 m wide crop alleys, thus questioning alleged impacts of AFS tree rows on yield distribution in intensively managed barley populations. Models based on UAV-borne imagery proved to be a valuable novel tool for prediction of DM and LAI at high accuracies, revealing spatial variability in AFS with high spatial resolution and coverage.