Patches Of Trees Research Articles

Carbon stocks and sequestration from small tree patches in grassland landscapes in Aotearoa-New Zealand

ABSTRACT Small patches of trees add structural heterogeneity to grassland landscapes, support biodiversity, and provide essential ecosystem services including carbon stocks and sequestration, erosion control, and shade provision. In Aotearoa-New Zealand (A-NZ) small patches of trees have further cultural significance within Te Ao Māori – the worldview of the indigenous Māori people. However, economic pressures have driven the management of grasslands either towards removing tree cover to enhance agricultural productivity, or large-scale conversion of grassland to production forests. Protecting existing small patches of trees, and encouraging their establishment across grassland landscapes, is challenging since the current extent and benefits of these patches is not known. This study demonstrates the critical contributions of small tree patches (those less than one hectare in area) in A-NZ grassland landscapes. Using a high-resolution tree cover dataset, we mapped 1,639,015 small tree patches in grasslands across A-NZ, with grassland small tree patches covering a total land area of between 185,589 ha and 187,928 ha. We used a probabilistic simulation approach to estimate carbon stocks and annual sequestration, revealing a potential aboveground carbon stock between 11.6 and 29.3 million tonnes (Mt) of carbon and an annual biomass sequestration of 0.3 Mt to 0.8 Mt. Despite their current exclusion from the national carbon emissions market, economic valuation suggests a liability of between $NZ 86.9 million and $NZ 8.6 billion (€47.9 million to €4.7. billion) if the small tree patches were felled, and a market value of between $NZ 2.0 million and $NZ 237.6 million (€1.1 and 130.9 million) annually for sequestration. Existing policies, including afforestation incentives, do not encourage protection or establishment of small patches of trees. Significant policy adjustments are required to recognize, protect, and incentivize the conservation and establishment of small patches of trees within grassland landscapes.

Patterns and drivers of cottonwood mortality in the middle Rio Grande, New Mexico, USA

AbstractRiparian ecosystems are some of the most valuable and vulnerable on the planet. Riparian tree mortality is increasing in the western United States, where altered streamflows are combining with warming climate. Between 2011 and 2013, one third of an extensive stand of Populus deltoides var. wislizeni (Rio Grande cottonwood) died along the middle Rio Grande on the Pueblo of Santa Ana in New Mexico. Mortality coincided with a severe drought that followed a decade of decreasing streamflow, but it was heterogeneous, with adjacent patches of dead and live trees. The goal of this research was to determine the drivers of mortality to provide insights into future risks of die‐off and potential management interventions. We compared tree age, competition, tree‐ring widths, sediment particle size and climate influences between live and dead forest patches in a nested plot design. Live and dead trees had similar age, stand density and particle sizes of shallow sediments. Tree‐ring widths had the highest correlations with July–September streamflow (1932–2013). All trees had declining ring growth since 1992, coinciding with declining late summer streamflow. An accelerated decline in growth began in 2002, corresponding to recent warmer droughts. Trees that died had lower ring growth 3 years prior to death and in the mid‐1900s. Dead trees also had coarser deep sediments 2.4–3.7 m below ground, suggesting that reduced water holding capacity was an important factor for mortality. Water management to increase streamflow during the late summer, especially during times of extended drought, could reduce mortality risk in the face of projected increasingly warm droughts.

Improving bird abundance estimates in harvested forests with retention by limiting detection radius through sound truncation

ABSTRACT An inherent challenge with acoustically surveying birds is that the distance at which they can be detected depends on how far their song can be heard. We developed a distance-based sound detection space truncation method to correct for variable sampling radii due to surveying in forested or open conditions. The method was pivotal in evaluating bird responses to retention patches; without this methodological advancement, the impact of retention patches on songbird abundance was vastly underestimated. In the boreal forest, these patches of live trees are retained in regenerating harvested forests to provide ecological services for species adapted to natural disturbances. Although we did not verify our a priori assumption with ground observations, our findings suggest that limited-distance sampling better captures the effects of retention patches on bird use of harvested forests. When evaluated using unlimited distance surveys, retained trees had a negligible effect on bird abundance, whereas applying detection distance truncation highlighted the importance of retention on forest birds. We found that early to mid-seral forest songbirds benefited from retention patches, with notable increases in abundance after 10 years of regeneration. The size of retention patches, ranging from 0.1 to 1.2 ha, did not have a linear relationship with bird abundance. Instead, edge effects stemming from the configuration of these patches emerged as key determinants of abundance for the majority of the species studied. Retention patches that were nearest to unharvested forests were used the most, compared to further into harvest areas. Our research not only highlights the underestimated impact of small-scale live tree retention on forest songbirds but also introduces a significant methodological innovation in the field of acoustic monitoring.

Adaptive shading: How microclimates and surface types amplify tree cooling effects?

Shading is the most critical process in tree cooling. Although the influence of tree features on shade supply has been extensively studied, the efficiency of shade performance in diverse environments remains poorly understood. The latter is crucial, as urban areas are highly heterogeneous, and local microclimates and land cover heterogeneity are among the most perceptible and observable aspects. We randomly selected several typical tree patches in Beijing to explore whether and how tree-shade efficiency varies with these factors. We used temporal variations as a proxy to study the impact of microclimatic heterogeneity on tree shade efficiency by comparing sunny and cloudy conditions, as well as different times of the day. In addition, we investigated the differences in shading efficiency over various surfaces by comparing pairs of regular urban surfaces (asphalt, concrete, permeable brick, and grass). We found that tree shade significantly improved the local thermal environment, but its effectiveness varied with the environmental conditions. Tree shading resulted in a higher cooling efficiency under greater external thermal stress. In addition, the cooling efficiency was greater on surfaces with higher temperatures. We also identified a notable characteristic of tree shading for cooling: the thermal environment beneath the tree shade tends to stabilize at a relatively constant value across various external conditions. These results provide practical guidelines for optimizing tree layouts in highly heterogeneous urban environments and enhancing limited tree resources for more effective and economical improvement of urban thermal conditions.

Cattle and nurse trees shape subtropical forest–grassland ecotones

Abstract South American subtropical landscapes are dominated by open grasslands and mosaics of forest–grassland formations. Forests are often restricted to riverine margins with sharp forest–grassland ecotones. Understanding the mechanisms maintaining forest–grassland ecotones is important to anticipate the effects of changing climate and disturbance regimes on the extent of these biomes and the ecosystem services they provide. We used a combination of field surveys and long‐term field experiments to explore the mechanisms that explain tree cover expansion at the ecotone of riverine forests and grasslands in central Uruguay, within the South American Campos. We assessed the role of tree seed dispersal and seedling establishment limitations, and experimentally tested for the effects of cattle, nurse tree cover and grasses on the recruitment of forest and grassland tree species at the forest–grassland ecotone. We found that forest expansion depends on the interplay between cattle and nurse trees. Vachellia caven trees colonize the grassland successfully and facilitate the formation of forest patches by enhancing seed accumulation and seedling establishment of forest tree species. Surprisingly, grass cover had mostly positive effects on early seedling survival of forest tree seedlings. However, cattle limits tree seedling growth and survival, especially of forest tree species. This results in a nucleated vegetation pattern of tree patches that ultimately limits forest expansion. Synthesis and applications. Tree cover can potentially expand on the subtropical South American grasslands. Reductions in cattle densities and increases in rainfall levels associated with climate change could facilitate forest expansion in this region.

FORECASTING THE DYNAMICS OF POPULATIONS OF HARMFUL INSECTS AND PATHOGENS OF WOODY PLANTS OF THE FOREST-STEPPE OF UKRAINE IN THE CONTEXT OF CLIMATE CHANGE

Climate change is one of the most pressing issues facing humanity. The emergence of dry tree patches in various parts of the globe indicates the global nature of processes related to planetary cycles and climate change. This is likely linked to various factors, including warming trends, changes in precipitation patterns, sea level rise, and alterations in ocean currents. To achieve the goal of this article, through empirical and analytical research methods, we analyzed contemporary scientific publications. We found that the projected spread of insect pests, parasites, and pathogens among tree species is increasingly concerning experts. Forest drying is a problem for both Europe and Ukraine, where the area affected by pine wilt has encompassed the Forest-Steppe region and spread to other natural zones. The paper highlights the pertinent issue of analyzing factors contributing to the weakening and deterioration of the sanitary condition of Forest-Steppe trees in Ukraine. Researchers predict significant climate changes in the near future. Due to such changes, insect pests and other pathogens may inflict even greater damage to forest plants. Climate change, particularly increased carbon dioxide emissions and warming, frequent droughts, and temperature fluctuations, affect pest populations. Common diseases of Forest-Steppe trees in Ukraine include those caused by insects, fungi, and bacteria. For instance, the most widespread affliction in forests is root rot (Fomes aппosus Fr., Heterobasidion annosum (Fr.) Bref.). Plants also suffer considerable damage from nematodes and viruses. The publication examines the impact of climate change (temperature, humidity, etc.) on the biology and ecology of insect pests and explores the potential use of modern monitoring technologies for pests and forecasting tools. Thus, projected climate changes can cause warming, altering the quantitative, qualitative, and temporal characteristics of precipitation. In this way, global climate changes affect water availability in soil, atmospheric water vapor flows, and hydrological processes. Many pests are sensitive to changes in precipitation and temperature, leading to shifts in their populations.

Black Woodpeckers Dryocopus martius use stepping stones between woodland units

ABSTRACT Capsule Black Woodpeckers Dryocopus martius used small patches of trees as stepping stones when crossing areas of open land during daily movements within their home range in the non-breeding season. Aims To document that Black Woodpeckers, although an obligate forest species, frequently cross areas of open land within their daily home range, using solitary trees or small patches of trees as stepping stones during these movements. Methods We mounted GPS-loggers on 11 Black Woodpeckers and recorded their position every 5 min for approximately 1 week. Three woodpeckers stayed within continuous forest for the duration of the study, or failed to meet assumptions, and were therefore excluded from the analysis. The remaining eight Black Woodpeckers all moved between discrete woodland units at least once during the study period. Using a habitat use-availability framework, 54 GPS-positions located in gaps of open land between separate forest patches were analysed. Results Black Woodpeckers showed a significant preference for trees at low tree availabilities in the open land. However, we could not rule out that their preference for trees was proportional to availability when tree cover was high (> 82% tree cover). The median distance traversed to a location in open land between forest patches was 731 m. Conclusion Since the preference for trees was especially pronounced at low tree availabilities, we suggest that Black Woodpeckers use solitary trees or small patches of trees as stepping stones when traversing open areas within their daily home range. We hypothesize that this behaviour lessens the costs of living in a fragmented habitat, and that conservation of trees in open land may contribute to conserving Black Woodpecker populations in areas with fragmented forests.

202 years of changes in Mediterranean fire regime in Pinus nigra forest, Corsica

Wildfires are critical socio-ecological features in the Mediterranean basin. In a context of global changes (climate, land use), we questioned whether the wildfire regime was altered in the mountains of Corsica, France. Using tree-ring analysis of fire-scarred trees, we tested for changes in frequency, seasonality, and area. We hypothesized that the fire regime changed during the middle-20th century due to human activities, as observed elsewhere in the Mediterranean. We sampled fire-scarred trees, geolocated for mapping fire areas, in a forest of black pine (Pinus nigra laricio). The oldest fire was in 1684 but the fire chronology with adequate sample depth for analysis covered 202 years [1820–1921]. Between 1820–2012, 15 fires were recorded, 8 of which scarred at least 25% of the sampled trees. The mean fire interval was 14 years, corresponding to a high fire frequency with 4 major fires per century. Most fires occurred between 1931–1970. On average, about 50% of trees were scarred by fires before 1931, but this percentage decreased thereafter. The exception was the 2000 fire that impacted 100% of living trees. Mapping showed spatially heterogenous fire areas. These results match other Mediterranean studies showing longer fire intervals since the late-20th century, and wildfires generally occurred during the period of late-earlywood or latewood formation, i.e., summer or early autumn, which is the season of contemporary fires. Although fires were recurrent for more than 200 years with no change in the fire season, the regime changed twice in frequency. These changes likely result from a combination of land use and warmer summer conditions. While pines survived most past fires of low intensity through the last large fire in the 1970’s, the severe fire of 2000, following ca 30 years of fire suppression, killed large patches of mature trees. Such chronology provides rational arguments for black pine ecosystem management, notably to consider seeking to recover the sustainable fire regime of the 19th century, for instance by using prescribed fires to manage surface fuel.

Variability and determinants of vascular plant species composition in patches of old managed oak forest stands dispersed within Scots pine monocultures

In the temperate zone of Europe, Scots pine forests are expected to occupy the poorest habitats which are unfavourable for deciduous trees. However, as a result of deforestation of the most fertile habitats and the preference for Pinus sylvestris in silviculture, pine forests have become the dominant feature of the landscape in Central Europe. As a result, the area of optimal habitat for deciduous forest flora has been significantly reduced. Nevertheless, remnant patches of deciduous forest persist as habitat islands within extensive pine forest complexes and may serve as important refugia for meso- and eutrophilic forest species. However, the factors that contribute to the variation in species composition of such habitat islands and their role in maintaining biodiversity remain poorly understood. This paper aims to fill this knowledge gap.The studied deciduous (oak) stands exhibited a diverse vegetation, with species composition influenced by overstorey attributes, oak age, patch location, and the area and circularity of the deciduous forest. Species traits related to environmental variables included mainly preferences for closed or open forests, requirements for soil moisture, reaction, and fertility, and requirements for light conditions. The key message from our research is that oak islands are not simply patches of trees that are different from the surrounding area. Instead, they represent distinct plant communities that have developed to adapt to the prevailing environmental conditions by recruiting species with particular traits. The presence of oak islands within Scots pine monocultures is therefore important for increasing the diversity of the forest complex.The most relevant recommendation from our research for forest management is to maintain as many patches of deciduous tree stands as possible within a single pine forest complex, as even small habitat islands can make a significant contribution to the biodiversity of the forest complex.

Bird species responses to rangeland management in relation to their traits: Rio de la Plata Grasslands as a case study.

Areas used for livestock production and dominated by native grasses represent a unique opportunity to reconcile biodiversity conservation and livestock production. However, limited knowledge of individual species' responses to rangeland management restricts our capacity to design grazing practices that favor endangered species and other priority birds. In this work, we applied Hierarchical Modelling of Species Communities (HMSC) to study individual species responses, as well as the influence of traits on such responses, to variables related to rangeland management using birds of the Rio de la Plata Grasslands as a case study. Based on presence-absence data collected in 454 paddocks across 46 ranches we inferred the response of 69 species considering imperfect detection. This degree of detail fills a major gap in rangeland management, as species-level responses can be used to achieve targeted conservation goals other than maximizing richness or abundance. We found that artificial pastures had an overall negative impact on many bird species, whereas the presence of tussocks had a positive effect, including all threatened species. Grassland specialists were in general sensitive to grass height and tended to respond positively to tussocks but negatively to tree cover. Controlling grass height via adjustments in stocking rate can be a useful tool to favor grassland specialists. To favor a wide range of bird species in ranches, a mosaic of short and tall native grasslands with patches of tussocks and trees is desirable. We also found that species-specific responses were modulated by their traits: small-sized birds responded positively to tussocks and tree cover while large species responded negatively to increasing grass height. Ground foragers preferred short grass while birds that scarcely use this stratum were not affected by grass height. Results on the influence of traits on bird responses are an important novelty in relation to previous work in rangelands and potentially increase our predicting capacity and model transferability across grassland regions.

Green trees preservation: A sustainable source of valuable mushrooms for Ethiopian local communities.

In Ethiopia, Pinus radiata and Pinus patula are extensively cultivated. Both plantations frequently serve as habitats for edible fungi, providing economic and ecological importance. Our study aims were: (i) to investigate how plantation age and tree species influence the variety of edible fungi and sporocarps production; (ii) to determine edaphic factors contributing to variations in sporocarps composition; and (iii) to establish a relationship between the most influencing edaphic factors and the production of valuable edible mushrooms for both plantation types. Sporocarps were collected weekly from permanent plots (100 m2) established in 5-, 14-, and 28-year-old stands of both species in 2020. From each plot, composite soil samples were also collected to determine explanatory edaphic variables for sporocarps production and composition. A total of 24 edible species, comprising 21 saprophytic and three ectomycorrhizal ones were identified. Agaricus campestroides, Morchella sp., Suillus luteus, Lepista sordida, and Tylopilus niger were found in both plantations. Sporocarp yields showed significant variation, with the highest mean production in 28-year-old stands of both Pinus stands. Differences in sporocarps variety were also observed between the two plantations, influenced by factors such as pH, nitrogen, phosphorus, potassium, and cation exchange capacity. Bovista dermoxantha, Coprinellus domesticus, and A. campestroides made contributions to the variety. The linear regression models indicated that the abundance of specific fungi was significantly predicted by organic matter. This insight into the nutrient requirements of various fungal species can inform for a better plantation management to produce both wood and non-wood forest products. Additionally, higher sporocarps production in older stands suggests that retaining patches of mature trees after the final cut can enhance fungal habitat, promoting diversity and yield. Thus, implementing this approach could provide supplementary income opportunities from mushroom sales and enhance the economic outputs of plantations, while mature trees could serve as a source of fungal inoculum for new plantations.

Chronobiology of free-ranging domestic cats: Circadian, lunar and seasonal activity rhythms in a wildlife corridor

Among domestic animals, the domestic cat (Felis catus) probably has the highest proportion of free-ranging individuals in the population and as such is an important component (i.e. predator) in ecosystems. Due to their potential impact on wildlife, the management of domestic cats is a hot topic today. However, there are few studies on the chronobiology and activity of domestic cats in relation to natural cycles. Therefore, the aim of our research was to investigate their circadian, lunar and seasonal rhythms. We monitored the activity of free-ranging cats in a selected corridor within an approximately 800 m2 patch of shrubs and trees in an agricultural landscape that is regularly used by wildlife in the surrounding area. Monitoring was carried out for two consecutive years using a trail camera. Data collection was based on video analysis of all recorded video clips (n = 2081 from 732 camera trap nights). A total of at least 15 individuals were identified in the area. Cats were most frequently observed in spring and summer (a total of 70% of all observations). Cats with prey were mostly observed in summer (∼56%) and never in winter. Circadian activity of domestic cats was nocturnal/crepuscular (p < 0.0001) with two peaks of activity, one in the late evening (∼21.00 h) and another in the early morning (∼5.00 h). The appearance of the cats with the prey corresponded to the general circadian activity. Slight shifts in activity due to day length (sunset/sunrise) were observed when comparing circadian rhythms in relation to seasons, especially in winter when there was a pronounced peak in activity in the early evening. For cat activity in relation to the lunar cycle, we found a tendency for higher nocturnal activity around new moon (p = 0.065), with this pattern being significant in spring (p < 0.05). However, the appearance of cats with prey was not related to the lunar cycle. Understanding the circadian, lunar and seasonal activity rhythms of domestic cats is an important prerequisite for developing an optimal cat management strategy that takes into account both welfare aspects (especially natural behaviour) and minimising the impact of domestic cats on wildlife.

Where are the large trees? A census of Sierra Nevada large trees to determine their frequency and spatial distribution across three large landscapes

Large trees (≥76.2 cm/≥30″ DBH) and especially very large trees (≥101.6 cm/≥40″ DBH) are key structures of Sierra Nevada forests for their ecological function, habitat, and carbon storage. Many of these trees have been lost to historic harvest and more recently to drought and wildfires. Understanding the current frequency and distribution of these large trees is essential to understanding their ecological contribution and management needs. We used airborne lidar to census large trees across three Sierra Nevada landscapes (cumulatively 396 K ha) in lower (dominated by ponderosa pine and mixed conifer) and upper (dominated by red fir) montane forest zones. We used data from a network of Forest Inventory and Analysis (FIA) plots to interpret our lidar-based results for large tree frequency, species, and ages. The lidar data identified > 8 M large and > 2.7 M very large trees, and their mean densities were similar to those from FIA data. Large portions of our study areas had either no or low densities (<20) of large trees per hectare. We found that large and very large tree concentrations were spatially aggregated with most in denser patches containing 20 to 50 + large trees per hectare. Depending on the study area, these often sizable (>1000 ha) patches of dense large trees can cover 20% to 40% of the landscape. (Patches of denser very large trees cover less of the landscape, typically 5% to 10%). However, these large patches are rarely simple blocks. Instead, they typically form complex amorphous matrices interspersed with patches of forests containing shorter trees or non-forest cover. Crucially, almost all large trees were in stands with high canopy cover, suggesting horizontal fuel continuity and low resilience to future wildfires. For lower montane large trees, canopy cover versus large tree density showed almost a unimodal response with canopy cover of 60% to 80% for locations with > 20 large trees per ha. For upper montane large trees, canopy cover versus large tree density showed a more linear relationship for all three study areas. High levels of canopy cover, especially for lower montane forests, suggest settings in which infilling following decades of fire suppression have created overly dense stands with lower resilience to drought and wildfire. Other studies have documented substantial recent losses of these large trees to both factors. The high canopy cover within which almost all large trees exist emphasizes the need for treatment almost everywhere that large trees are present for lower montane forests. This likely will require treatments both within the stands that contain large trees and across the landscapes in which they are found.

Pollen production, release and dispersion in Himalayan alder (Alnus nepalensis D. Don.): a major aeroallergens taxa

Abstract Alnus nepalensis is a medium-sized, deciduous tree that occurs in the Indian sub-continent, South America, Hawaii, and China. It is a prolific pioneer species in freshly exposed soil in landslide areas of the western Himalayas and has the potential of fixing nitrogen. A study was conducted to assess the reproductive phenology, pollen production, pollen release, and pollen-mediated gene flow of Alnus nepalensis by considering a patch of trees as a pollen source in the temperate forest of Garhwal Himalaya to develop sustainable management strategies relating to the plantation geometry in seed orchards. Staminate flowers of A. nepalensis are composed of “cymules”. The presence of bifid stigma and protandry condition were the unique features of the species. Flowering in the male phase was initiated in the last week of September and continued till November. Peak shedding of pollen generally proceeds peak receptivity by 1–2 weeks. The time between onset and peak flowering was 2 weeks 4 days and the total average duration of the flowering period was about 24.8 days. Temperature and relative humidity played a major role in pollen release and the maximum pollen release occurred at 29.2 °C at 13.00 hrs of the day. Pollen production per catkin varied significantly among trees. The average pollen grains per tree were 2.20 × 1010. The pollen-ovule ratio suggests that the breeding system of A. nepalensis falls under the class xenogamy. Pollen mediated gene flow revealed that the significant pollen which can cause pollination of A. nepalensis can travel up to 40 m uphill and 80 m in downhill directions. Thus, an isolation strip of 80 m is sufficient to manage the seed orchard of A. nepalensis in the western Himalayan region.

Cemeteries

The first house we bought in West Virginia was sandwiched between two cemeteries. The larger one stood behind our house and was hidden by a patch of trees, so we could see it only in the winter when the trees lost their leaves and the headstones emerged, rectangular specks visible between the bare branches. The smaller cemetery perched on top of a low hill across from our house, on the other side of the narrow, dead-end street.

Detection and Monitoring of Woody Vegetation Landscape Features Using Periodic Aerial Photography

Woody vegetation landscape features, such as hedges, tree patches, and riparian vegetation, are important elements of landscape and biotic diversity. For the reason that biodiversity loss is one of the major ecological problems in the EU, it is necessary to establish efficient workflows for the registration and monitoring of woody vegetation landscape features. In the paper, we propose and evaluate a methodology for automated detection of changes in woody vegetation landscape features from a digital orthophoto (DOP). We demonstrate its ability to capture most of the actual changes in the field and thereby provide valuable support for more efficient maintenance of landscape feature layers, which is important for the shaping of future environmental policies. While the most reliable source for vegetation cover mapping is a combination of LiDAR and high-resolution imagery, it can be prohibitively expensive for continuous updates. The DOP from cyclic aerial photography presents an alternative source of up-to-date information for tracking woody vegetation landscape features in-between LiDAR recordings. The proposed methodology uses a segmentation neural network, which is trained with the latest DOP against the last known ground truth as the target. The output is a layer of detected changes, which are validated by the user before being used to update the woody vegetation landscape feature layer. The methodology was tested using the data of a typical traditional Central European cultural landscape, Goričko, in north-eastern Slovenia. The achieved F1 of per-pixel segmentation was 83.5% and 77.1% for two- and five-year differences between the LiDAR-based reference and the DOP, respectively. The validation of the proposed changes at a minimum area threshold of 100 m2 and a minimum area percentage threshold of 20% showed that the model achieved recall close to 90%.

Supervised Classification of Tree Cover Classes in the Complex Mosaic Landscape of Eastern Rwanda

Eastern Rwanda consists of a mosaic of different land cover types, with agroforestry, forest patches, and shrubland all containing tree cover. Mapping and monitoring the landscape is costly and time-intensive, creating a need for automated methods using openly available satellite imagery. Google Earth Engine and the random forests algorithm offer the potential to use such imagery to map tree cover types in the study area. Sentinel-2 satellite imagery, along with vegetation indices, texture metrics, principal components, and non-spectral layers were combined over the dry and rainy seasons. Different combinations of input bands were used to classify land cover types in the study area. Recursive feature elimination was used to select the most important input features for accurate classification, with three final models selected for classification. The highest classification accuracies were obtained for the forest class (85–92%) followed by shrubland (77–81%) and agroforestry (68–77%). Agroforestry cover was predicted for 36% of the study area, forest cover was predicted for 14% of the study area, and shrubland cover was predicted for 18% of the study area. Non-spectral layers and texture metrics were among the most important features for accurate classification. Mixed pixels and fragmented tree patches presented challenges for the accurate delineation of some tree cover types, resulting in some discrepancies with other studies. Nonetheless, the methods used in this study were capable of delivering accurate results across the study area using freely available satellite imagery and methods that are not costly and are easy to apply in future studies.

Geomorphodynamics, evolution, and ecology of vertical roots.

The roots of some coastal and wetland trees grow peculiar vertical protrusions, the function of which remains unclear. Here, using computational simulations based on first-principles fluid and sedimentation dynamics, we argue that the protrusions work together to create an elevated patch of sediment downstream of the tree, thereby creating its own fertile flood-protected breeding grounds for the seedlings. In our simulations, we vary the vertical root diameter, root spacing and total root area and show that there is an optimal vertical root spacing that depends on root thickness. Next, we quantify and discuss the cooperative effects between adjacent vertical root patches. Lastly, by varying vertical root spacing of a patch of trees, we estimate a maximal vegetation density for which vertical-root production has a beneficial geomorphological response. Our hypothesis suggests that vertical roots, such as the 'knee roots' of baldcypress trees, have an important role in shaping riparian geomorphology and community structure.

Linking urban park cool island effects to the landscape patterns inside and outside the park: A simultaneous equation modeling approach

Urban parks have significant cooling effects that alleviate the urban heat island (UHI). The park cool island intensity (PCII), the temperature difference between outside and inside a park, is a widely used indicator of a park’s cooling ability. Understanding the driving factors of the PCII is crucial for better urban park planning and management. Taking the subtropical city of Changsha, China, as a case study, factors such as the landscape patterns inside and outside a park and the geometric morphology of a park were investigated, based on 153 urban parks. A novel simultaneous equation modeling (SEM) approach was used to account for the mutual interactions between the temperatures of a park and its buffer. The results show that: (1) Park geometric morphology and landscape patterns inside and outside the park all significantly impact the PCII. Specifically, doubling the park size can increase the PCII by 0.8 K. Increasing by ten percent the tree cover and water cover in the park can enhance the PCII by 0.12 K and 0.41 K, respectively. Increasing the mean tree patch size by 1 ha can increase the PCII by 0.43 K. Decreasing by one unit the mean tree patch shape index can increase the PCII by 0.31 K. (2) An elasticity analysis, which measures the PCII percent change resulting from one percent change in a driving factor, indicates the relative importance ranking of these driving factors: percent cover of impervious surface outside the park (0.77), park size (0.72), percent cover of tree within the park (0.51), percent cover of water within the park (0.12), and mean patch size of tree cover within the park (0.086). To enhance the PCII, we recommend building parks in the hot areas of the city, increasing their size, increasing the percentages of tree cover and water cover in the park, and optimizing the spatial configuration of the tree cover in the park (i.e., aggregating trees in a smaller number of large patches and reducing the irregularity of tree patches).

Short-term effects of retention forestry on the diversity of root-associated ectomycorrhizal fungi in Sakhalin fir plantations, Hokkaido, Japan

We have examined the effects of dispersed and aggregated retention on the diversity of root-associated ectomycorrhizal fungi (EcMf) in Sakhalin fir (Abies sachalinensis) plantations, 4 years after logging. Roots of Sakhalin fir seedlings and the adjacent broadleaved or Sakhalin fir trees were sampled in broadleaved dispersed retention sites (10, 50, or 100 trees/ha), conifer aggregated retention sites (a single 60 × 60 m square patch of Sakhalin fir trees per site), clear-cut sites, unharvested Sakhalin fir plantations, and natural broadleaved forest stands. The EcMf on the roots were grouped into operational taxonomic units based on the similarity of the internal transcribed spacer sequences within the nuclear ribosomal DNA. Clear-cutting significantly reduced the species richness and diversity of the EcMf and altered the species composition when compared with the unharvested Sakhalin fir plantations and natural broadleaved forests. In contrast, both the aggregated and dispersed retention sites maintained higher levels of EcMf diversity, as well as different EcMf communities when compared with the clear-cut sites. Aggregated retention was effective at conserving EcMf diversity at the unharvested Sakhalin fir plantations, but the effects were limited within retained patches. Broadleaved dispersed retention did not retain the EcMf communities that were present prior to logging even at high retention levels, but they could retain unique EcMf communities, which differed between the Sakhalin fir plantations, natural broadleaved forests, and clear-cut sites. The species richness and diversity values for some of the dispersed retention sites were comparable to the values for the unharvested Sakhalin fir plantations and tended to be greater than the values for the aggregated retention sites. The results indicate that dispersed retention could be an effective strategy by which to preserve a larger number of EcMf species and unique EcMf communities in logged conifer plantations, although the positive effects were likely limited spatially within the rooting zones of the retained broadleaved trees. Finally, naturally regenerating Sakhalin fir seedlings were found to share a large amount of their EcMf with adjacent broadleaved retention trees, indicating that multi-host EcMf of retained trees largely contribute to ectomycorrhizal colonization of the surrounding regenerated seedlings in the logged areas. Our findings demonstrated that both dispersed and aggregated retention methods could be used to mitigate the impacts of logging on EcMf diversity in Sakhalin fir plantations, in Japan, and that there were large differences in the effects among the different retention methods.