Understory Height Research Articles

Can models for forest attributes based on airborne laser scanning be generalized for different silvicultural management systems?

In Finland, interest in continuous cover forestry (CCF) has increased rapidly in recent years. During those years CCF has been examined from various viewpoints but not from the perspective of forest inventories. This holds especially true for applications based on remote sensing. Conversely, airborne laser scanning (ALS) data have been widely used to predict forest characteristics such as size distribution and vertical forest structure, which are closely related to the forest information needs of CCF.In this study we used the area-based approach to predict a set of stand attributes from ALS data (5 pulses per m2) in a CCF forest management experiment in Katajamäki, eastern Finland. In addition to the CCF stands, the experiment included shelterwood stands and untreated stands. The predicted attributes included volume, biomass, basal area, number of stems, mean diameter, Lorey’s height, dominant height, standing dead wood volume, parameters of the theoretical stem diameter distribution model, understory height and number of understory stems. Our main aim was to test whether the same model could be used across different management systems. The accuracy of the attributes predicted for the CCF stands was compared with the predictions for the other management systems in the same experiment. We also compared and discussed our results in relation to the even-aged stand attribute predictions that were conducted by using separate operational forest data collected from sites surrounding Katajamäki.The results showed that forest data from the different management systems could be combined into a single model of a stand attribute, i.e., ALS metrics were found to be suitable for comparing different management systems in regard to differences in forest structure. The accuracy of the predicted attributes in the CCF plots was comparable to that of the other management alternatives in the experiment. The accuracy was also comparable to that of even-aged forests.The results of this study were promising; the stand attributes of CCF-managed forests could be predicted analogously to those of other management systems. This indicates that for the purposes of forest inventories there may not be a need to stratify forest lands by management system. It should be noted, however, that the study area was relatively small, that the forest stands were harvested in the 1980 s, and that the attributes may not have been completely exhaustive for CCF.

Factors impacting bat activity and species richness in protected parks in the oak openings region of Northwest Ohio.

Protected areas are important for wildlife, especially in heavily developed areas. Bats are one group utilizing protected areas, but it is unclear what makes an ideal place for bats to live in parks, especially since preferences vary between open and forest foraging species and at different scales. The main objective of this study was to determine the landscape and vegetation factors at multiple scales most associated with higher bat activity and species richness in protected parks. Total bat activity, species richness, and activity for open and forested foraging species were compared to small-scale data vegetation structure collected in the field and larger-scale landscape data calculated in ArcGIS and FRAGSTATS. Bat activity and species richness increased with higher percentages of dry and open land cover types such as sand barrens, savanna, cropland, and upland prairie and decreased with higher percentages of forest and wet prairies. Patch richness, understory height, and clutter at the 3-6.5 m level were negatively associated with total bat activity. The most important variables for bats differed depending on spatial scale measured and if species were open or forest adapted. When managing for bats in parks, it would be advantageous to restore open land cover types such as savanna and mid-level clutter, and excessive fragmentation. Whether species are open or forest adapted and scale-specific differences should also be considered.

Post-fire regeneration of cork oak (Quercus suber) in Kiadi forest (Akfadou- Algeria)

Cork oak (Quercus suber) as a West Mediterranean species is known for its ecological, economic and social values. Wildfires are one of the most serious problems threatening Quercus suber, endangering its occurrence in its area of distribution. Therefore, knowing the behavior of the species after fire and the factors influencing its responses are particularly important for forest management. In this study we assessed the post fire vegetative recovery in 730 trees affected by wildfires on 2014 in Kiadi cork oak forest, located in the Western side of Akfadou Mountains in Algeria. Few months after the fire, individual tree mortality was very low (7.53%), and nearly, all the trees sampled survived the fire since almost all trees resprouted from canopy and some of them showed basal resprouts. Moreover, those two modes of post fire vegetative recovery were not correlated to each other. The performed redundancy analyzes (RDA) revealed that the cork oak post-fire response was highly correlated with individual characteristics and with the environmental data. The main variables influencing the likelihood of good or poor vegetative recovery were the understory height and cover, soil characteristics, fire severity, tree status (alive/dead trees), tree diameter and tree exploitation. Our results confirmed the fire resistance of cork oak species; which is also the only Algerian tree to resprouts. Hence, this makes the species a good candidate for reforestation programs in fire prone ecosystems.

Occurrence of mesocarnivores in montane sky islands: How spatial and temporal overlap informs rabies management in a regional hotspot.

Interspecific interactions among mesocarnivores can influence community dynamics and resource partitioning. Insights into these interactions can enhance understanding of local ecological processes that have impacts on pathogen transmission, such as the rabies lyssavirus. Host species ecology can provide an important baseline for disease management strategies especially in biologically diverse ecosystems and heterogeneous landscapes. We used a mesocarnivore guild native to the southwestern United States, a regional rabies hotspot, that are prone to rabies outbreaks as our study system. Gray foxes (Urocyon cinereoargenteus), striped skunks (Mephitis mephitis), bobcats (Lynx rufus), and coyotes (Canis latrans) share large portions of their geographic ranges and can compete for resources, occupy similar niches, and influence population dynamics of each other. We deployed 80 cameras across two mountain ranges in Arizona, stratified by vegetation type. We used two-stage modeling to gain insight into species occurrence and co-occurrence patterns. There was strong evidence for the effects of elevation, season, and temperature impacting detection probability of all four species, with understory height and canopy cover also influencing gray foxes and skunks. For all four mesocarnivores, a second stage multi-species co-occurrence model better explained patterns of detection than the single-species occurrence model. These four species are influencing the space use of each other and are likely competing for resources seasonally. We did not observe spatial partitioning between these competitors, likely due to an abundance of cover and food resources in the biologically diverse system we studied. From our results we can draw inferences on community dynamics to inform rabies management in a regional hotspot. Understanding environmental factors in disease hotspots can provide useful information to develop more reliable early-warning systems for viral outbreaks. We recommend that disease management focus on delivering oral vaccine baits onto the landscape when natural food resources are less abundant, specifically during the two drier seasons in Arizona (pre-monsoon spring and autumn) to maximize intake by all mesocarnivores.

Individual tree detection and crown segmentation based on metabolic theory from airborne laser scanning data

Laser scanning technology has enabled to study three-dimensional (3D) structures in forests. For example, airborne laser scanning (ALS) point cloud has been applied to detect individual trees and segment tree crowns. However, the accuracy of such approach remains a challenge because of the intersected crowns and complicated understories. We developed a metabolic theory-based algorithm for individual tree detection and crown segmentation from ALS data. The algorithm is composed of two parts, of which one is an unscaled transporting distance-based top-to-bottom detection approach, and the other is a scaled transporting distance-based segmentation approach. The unscaled transporting distance for detection is the absolute distance from tree root to crown and then to ALS point based on the tree structure models, whereas the scaled transporting distance for segmentation is the unscaled distance that is scaled by an initial tree height obtained during detection. This is based on a basic metabolic theory that vascular plants tend to minimize the material transporting distance from root to leaves. Hence, seven types of materials transporting distance models were built based on monopodial branching structure or crown-centered structure. The performance of the proposed approach was then further examined and compared with two typical canopy height model-based approaches and one typical point cloud-based approach, taking forest in Oxfordshire, UK, as a case study. The results showed that our approach can reach a recall of 1.00, a precision of 0.96, and an F-score of 0.98 and can reach to much higher accuracy for tree height (R2 = 0.8045) than the comparison approaches (R2 < 0.2) in the study plot. One of the main reasons that led to such low accuracy of comparison approaches is much overestimation of understory height with a mean error that is 2.9 times higher than that of our approach on average. Furthermore, ALS point-to-point level accuracy assessment shows 9.7% more ALS points were truly assigned in our approach than that of comparison approaches. It is noticed that the algorithm presented is not sensitive to the two key parameters: p (a percentage determining the threshold of unscaled transporting distances) ranging from 32.0% to 34.0% and λ (the proportion between the assumed crown center height and tree height) ranging from 0.70 to 0.90 based on our data set. Such high accuracy of our approach can greatly improve detections of individual tree and crown segmentation, especially in delineating understories in complex-structured forest.

Spatial relationship between damaged understory and felled trees during the final cutting in a shelterwood forest

ABSTRACT Damage to the understory of shelterwood systems during generational succession is an issue that has been debated for a long time. In this study, we analyzed the spatial relationship between damaged understory trees and harvested trees during the final cutting in a shelterwood forest stand dominated by Chamaecyparis obtusa (cypress) in central Japan. We surveyed the positions of all cypress trees and observed the final cutting operation. By measuring the felling direction, the physical contact between the harvested trees and understory trees was reproduced using the Geographic Information System (GIS). Logistic regression was performed using the extracted frequencies of physical contact as explanatory variables and variables important for reproducing the spatial pattern of the damaged understory were selected. The model selection indicated that the damage to the understory could be explained by the contact between the understory trees and the crowns and trunks of felled trees. The understory height was relatively ineffective in explaining the spatial damage pattern. The model could reproduce the spatial distribution of damage rates more realistically than conventional models which depend on the distance from stumps or roads. It was quantitatively revealed that controlling the felling direction was an important factor in mitigating understory damage.

Breeding Habitat Associations of Eastern Whip‐Poor‐Wills in Managed Forests

ABSTRACTPopulations of the eastern whip‐poor‐will (Antrostomus vociferus; whip‐poor‐will) have declined throughout most of its range, making it a species of high conservation concern in nearly every state and province where it occurs. Researchers have reported whip‐poor‐wills are associated with forest stands with open canopies, and thus silviculture may be a promising means for promoting their populations, yet the ecological literature does not quantify fine‐scale habitat relationships capable of assisting with silviculture prescriptions. Our objective was to quantify the associations between whip‐poor‐wills, canopy openness, and other vegetation characteristics to provide managers with guidance for whip‐poor‐will management. Based on prior research, we hypothesized that whip‐poor‐wills may be associated with intermediate levels of canopy retention and that their numbers would also be affected by understory characteristics. We surveyed whip‐poor‐wills with point counts in managed forest at the Fort Drum Army installation in New York, USA, during 2015 and 2016 and collected vegetation measurements at each point count location to relate whip‐poor‐will occupancy with vegetation structure and composition. Whip‐poor‐will occupancy was strongly related to intermediate levels of basal area, with peak occupancy at 13.8 m2/ha, a value that corresponds to forest denser than most shrublands but more open than closed‐canopy forest. Whip‐poor‐will presence was negatively related to understory height, which is consistent with prior studies. These findings provide managers with quantitative targets that can be used to increase or maintain whip‐poor‐will numbers and abundance of other disturbance‐associated species similarly unable to persist in unmanaged forests stands. © 2021 The Wildlife Society.

Using GatorEye UAV-Borne LiDAR to Quantify the Spatial and Temporal Effects of a Prescribed Fire on Understory Height and Biomass in a Pine Savanna

In the pine savannas of the southeastern United States, prescribed fire is commonly used to manipulate understory structure and composition. Understory characteristics have traditionally been monitored with field sampling; however, remote sensing could provide rapid, spatially explicit monitoring of understory dynamics. We contrasted pre- vs. post-fire understory characteristics collected with fixed area plots with estimates from high-density LiDAR point clouds collected using the unmanned aerial vehicle (UAV)-borne GatorEye system. Measuring within 1 × 1 m field plots (n = 20), we found average understory height ranged from 0.17–1.26 m and biomass from 0.26–4.86 Mg C ha−1 before the fire (May 2018), and five months after the fire (November 2018), height ranged from 0.11–1.09 m and biomass from 0.04–3.03 Mg C ha−1. Understory heights estimated with LiDAR were significantly correlated with plot height measurements (R2 = 0.576, p ≤ 0.001). Understory biomass was correlated with in situ heights (R2 = 0.579, p ≤ 0.001) and LiDAR heights (R2 = 0.507, p ≤ 0.001). The biomass estimates made with either height measurement did not differ for the measurement plots (p = 0.263). However, for the larger research area, the understory biomass estimated with the LiDAR indicated a smaller difference after the burn (~12.7% biomass reduction) than observed with in situ measurements (~16% biomass reduction). The two approaches likely differed because the research area’s spatial variability was not captured by the in-situ measurements (0.2% of the research area measured) versus the wall-to-wall coverage provided by LiDAR. The additional benefit of having spatially explicit measurements with LiDAR, and its ease of use, make it a promising tool for land managers wanting greater spatial and temporal resolution in tracking understory biomass and its response to prescribed fire.

Functional losses in ground spider communities due to habitat structure degradation under tropical land-use change.

Deforestation and land-use change in tropical regions result in habitat loss and extinction of species that are unable to adapt to the conditions in agricultural landscapes. If the associated loss of functional diversity is not compensated by species colonizing the converted habitats, extinctions might be followed by a reduction or loss of ecosystem functions including biological control. To date, little is known about how land-use change in the tropics alters the functional diversity of invertebrate predators and which key environmental factors may mitigate the decline in functional diversity and predation in litter and soil communities. We applied litter sieving and heat extraction to study ground spider communities and assessed structural characteristics of vegetation and parameters of litter in rainforest and agricultural land-use systems (jungle rubber, rubber, and oil palm monocultures) in a Southeast Asian hotspot of rainforest conversion: Sumatra, Indonesia. We found that (1) spider density, species richness, functional diversity, and community predation (energy flux to spiders) were reduced by 57-98% from rainforest to oil palm monoculture; (2) jungle rubber and rubber monoculture sustained relatively high diversity and predation in ground spiders, but small cryptic spider species strongly declined; (3) high species turnover compensated losses of some functional trait combinations, but did not compensate for the overall loss of functional diversity and predation per unit area; (4) spider diversity was related to habitat structure such as amount of litter, understory density, and understory height, while spider predation was better explained by plant diversity. Management practices that increase habitat-structural complexity and plant diversity such as mulching, reduced weeding, and intercropping monocultures with other plants may contribute to maintaining functional diversity of and predation services provided by ground invertebrate communities in plantations.

Prediction of forest canopy fuel parameters in managed boreal forests using multispectral and unispectral airborne laser scanning data and aerial images

ABSTRACT This study evaluated the suitability of different airborne laser scanning (ALS) datasets for the prediction of forest canopy fuel parameters in managed boreal forests in Finland. The ALS data alternatives were leaf-off and leaf-on unispectral and leaf-on multispectral data, alone and combined with aerial images. Canopy fuel weight, canopy base height, biomass of living and dead trees, and height and biomass of the understory tree layer were predicted using regression analysis. The considered categorical forest parameters were dominant tree species, site fertility and vertical forest structure layers. The canopy fuel weight was modeled based on crown biomass with an RMSE% value of 20–30%. The canopy base heights were predicted separately for pine and spruce stands with satisfactory results the RMSE% values being 9–10% and 15–17%, respectively. Following the initial classification of the existence of an understory layer (with kappa-values of 0.47–0.53), the prediction of understory height performed well (RMSE% 20–25%) but the understory biomass was predicted with larger RMSE% values (about 60–70%). Site fertility was classified with kappa-values of 0.5–0.6. The most accurate results were obtained using multispectral ALS data, although the differences between the datasets were minor.

Estimation of Forest Structural Attributes Using ICESat/GLAS-Spaceborne Laser Altimetry Data in the Western Ghats Region of India

Three-dimensional structural information of a forest plays a significant role in global forest ecosystem management practices. Optical remote sensing successfully provides abundant spectral information regarding the horizontal distribution of forests. However, measuring the vertical structural attributes of the forest ecosystems for highly complex and heterogeneous forests such as Western Ghats (India) is typically challenging for even these technologies. The measurements of the forest stand-level structural parameters in the Western Ghats of India have not been reported to date. Therefore, the objective of the present study was the estimation of the structural attributes of Mudumalai and Sholayar reserved forests in the Western Ghats region of India using spaceborne ICESat GLAS data. The forest structural attributes estimated in the present study were as follows: canopy height, canopy density, and understory vegetation height. The results obtained indicated a strong correlation with field measurements. The ICESat/GLAS data used in the present study enabled the analysis of structural parameters, contributing significantly to the better understanding of the heterogeneous complex forest ecosystem of the Western Ghats.

Ecological Determinants of Species Richness and Abundance of Endemic and Threatened Owls in the Andaman Islands, India

Factors that influence the distribution and abundance of the endemic and threatened owls of the Andaman Islands have not been assessed, in contrast to those affecting diurnal birds. Such studies would assist in prioritising habitats that have high conservation importance for owls. We evaluated the status and species composition of owls along c. 343km of the Andaman Trunk Road, employing one-time point counts between December 2013 and April 2015. We conducted spontaneous listening, broadcasting of conspecific calls and spotlight searches as survey protocols. The pointcentred quarter method was used to evaluate the habitat at each count site. We recorded five owl species whose mean abundance was 2.09 owls/point. Species richness and abundance were greater in unlogged sites and deciduous forests. Habitat differences between owl species were noted according to land use, cover type and intensity of logging activity. However, these factors had no significant effect on the abundance of Oriental Scops-owl and Hume's Boobook, but were significant for Andaman Boobook and Andaman Scops-owl. Mean understory height, tree height and grass cover positively influenced the owl species richness and abundance. The Andaman Boobook and Andaman Scops-owl appeared stenotopic in habitat use and in contrast to the eurytopic Oriental Scops-owl and Hume's Boobook. A review of the conservation status of Andaman Scops-owl and Andaman Boobook is suggested bearing in mind their low abundance, restricted distribution and less preference for altered habitats.–Babu, S., Sureshmarimuthu, S. & Kumara, H.N. (2019). Ecological determinants of species richness and abundance of endemic and threatened owls in the Andaman Islands, India.Ardeola, 66: 89-100.

Occupancy and Conservation Prospects of Endemic Banded Wattle-Eye Platysteira laticincta in the Kilum–Ijim Community Forest, Northwestern Cameroon

The banded wattle-eye bird species, BWE ( Platysteira laticincta) is rare, endangered, and endemic to the Bamenda Highlands, Western Cameroon. Kilum–Ijim Community Forest is its last stronghold. Little is known about BWE’s distribution and habitat requirements—the present baseline study aimed at reducing this knowledge gap. Bird occurrence—using call playback technique—and vegetation variables were recorded in 50-m radius sampling plots placed in the altitude range 2,100 to 2,800 m. The BWE occurred at 43 (35%) of 123 plots mostly within Kilum sector of the Community Forest, at altitude range 2,168 to 2,707 m. The log-odds of BWE occurrence significantly (a) increased with canopy height, herb relative abundance, bare soil relative abundance, and shrub relative abundance and (b) decreased with altitude and understory height. These results suggest that the BWE may prefer forest areas at lower altitude with more bare ground and denser undergrowth cover. The implications for BWE conservation are discussed.

Richness of Chrysomelidae (Coleoptera) depends on the area and habitat structure in semideciduous forest remnants

ABSTRACT The total area of a habitat patch can increase the local species richness both directly (through balance between immigration and extinction) and indirectly (by increasing the habitat heterogeneity and/or as an effect of sample effort). More heterogeneous environments present a wider variety of resources and conditions, allowing species to coexist through niche differentiation. This study shows that the diversity of Chrysomelidae depends on the area and habitat structure of semideciduous forest remnants. We sampled 16 remnants with Malaise traps in August 2012 to March 2013. In order to characterize the habitat, the area, structural heterogeneity of the understory, coverage and canopy height were measured. These variables were used in a path analysis to determine their direct and indirect effects on leaf beetle diversity. A total of 450 specimens from 99 species and five subfamilies were captured. The total area and the understory heterogeneity presented a positive effect on species richness, while canopy cover exerted a negative one. The canopy height only had a negative and indirect effect on leaf beetle richness. In such fragments with more area and more open spaces, plant abundance and richness tend to be higher and favor the coexistence of many Chrysomelidae species.

Urban woodland understory characteristics in relation to aesthetic and recreational preference

Urban woodlands provide aesthetic experiences and recreational opportunities for people. The characteristics of vegetation are closely linked to these benefits. However, previous research has primarily focused on the effects of trees on aesthetic preference, while less research has involved the understory. This paper explored the relationship between understory characteristics and aesthetic or recreational preference. Twenty one images were rated for preference by participants (n=184) on a five-point scale. Except for the original picture, these images were created using the photomontage method that manipulated understory height, the flowers and the path of the original picture. Results indicated that: (1) concerning aesthetic preference, all vegetated images were preferred more than the paved image, but for recreational preference, the paved image was preferred over the vegetated images; (2) the height of understory vegetation had a significant influence on aesthetic and recreational preference; (3) flowers and path increased aesthetic and recreational preference significantly. These results suggest that, in management of woodland, (1) maintaining the understory vegetation in middle height (0.5–1.0m) or in full-mixed heights (low+middle+tall) (2) increasing shade-tolerance flowers and constructing a winding path in woodland would be preferred by the public.

An Assessment of the Repeatability of Automatic Forest Inventory Metrics Derived From UAV-Borne Laser Scanning Data

We assessed the reproducibility of forest inventory metrics derived from an unmanned aerial vehicle (UAV) laser scanning (UAVLS) system. A total of 82 merged point clouds were captured over six 500-m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> plots within a Eucalyptus globulus plantation forest in Tasmania, Australia. Terrain and understory height, together with plot- and tree-level metrics, were extracted from the UAVLS point clouds using automated methods and compared across the multiple point clouds. The results show that measurements of terrain and understory height and plot-level metrics can be reproduced with adequate repeatability for change detection purposes. At the tree level, the high-density data collected by the UAV provided estimates of tree location (mean deviation (MD) of less than 0.48 m) and tree height (MD of 0.35 m) with high precision. This precision is comparable to that of ground-based field measurement techniques. The estimates of crown area and crown volume were found to be dependent on the segmentation routine and, as such, were measured with lower repeatability. The precision of the metrics found within this paper demonstrates the applicability of UAVs as a platform for performing sample-based forest inventories.

Validation of Mobile Laser Scanning for Understory Tree Characterization in Urban Forest

This study was dedicated to validating mobile laser scanning (MLS) for understory tree characterization, which now is still an open issue of interest in the fields of forest inventory and remote sensing. The program of validation was divided into three steps aiming at its three premise questions, respectively: 1) Can MLS record echoes with precise coordinates in the scenario of forest overstory shading satellite wireless positioning signals? 2) Can MLS samplings subject to spatial distribution inconsistency show the basic structures of understory trees? and 3) Can MLS data, further, present the local details of understory tree structures? The examinations were carried out based on the related typical feature variables, i.e, 1) overstory tree stem positioning accuracy as a substitute and 2) understory tree height and crown width and the newly proposed measure of object detail characterization, i.e, 3) primary nearest point distance (PNPD). The results proved to be positive. Overall, although the discussions suggested that MLS has its shortages, e.g, its cover still restricted by tree obscuration, this endeavor has primarily validated MLS for understory tree characterization in urban forest.

Restoring habitat for the northern Idaho ground squirrel (Urocitellus brunneus brunneus): Effects of prescribed burning on dwindling habitat

Land use and fire exclusion have contributed to an increase in ponderosa pine (Pinus ponderosa) forest extent and density in west-central Idaho. Open areas within ponderosa pine forests are decreasing, thus reducing habitat for the endemic northern Idaho ground squirrel (NIDGS; Urocitellus brunneus brunneus). In 2000, the NIDGS was listed on the Endangered Species Act as threatened in part due to habitat loss. Therefore, recovery plans encourage the use of burning to expand meadows and open corridors. We gathered data on habitat attributes altered by prescribed fall burning at three sites selected for habitat restoration. Each site was divided into two units: a CONTROL unit occupied by the NIDGS and a BURN unit not occupied by the NIDGS. We sought to assess whether the prescribed fall burning fulfilled management goals and generated habitat features similar to CONTROL conditions that are suitable for the NIDGS. Data were collected before the fall prescribed burn and one and two years post-burn. Before the prescribed burn, BURN units had higher tree densities and canopy cover than CONTROL units; however, the prescribed fall burn did not reduce tree density or canopy cover one year later. Understory height in the BURN unit decreased slightly post-burn, approaching CONTROL conditions. Majority of understory characteristics were similar between CONTROL and BURN units before, one, and two years after the burn, but understory community structure remained strongly dissimilar. This study preliminarily examines NIDGS habitat and is the first paper to evaluate the effects of prescribed burning as restoration practices to create NIDGS habitat. Key habitat attributes associated with NIDGS presence include tree canopy cover, understory height and community structure, and litter depth. Management goals were not attained within the stated timeline, one year post-burn, or even two years after prescribed burn was implemented. Based on our results, managers should consider extending the timeframe for restoration goal achievement and perhaps modifying goals to include changes in tree canopy cover, understory height and community structure, and litter depth. Future efforts should monitor beyond two years post-fire, focus on long-term effects of prescribed burning, and examine how repeat burns may help attain habitat restoration goals.

A Starting Point: An Ecosystem of Reference for Habitat Restoration of the Northern Idaho Ground Squirrel, Urocitellus brunneus brunneus

The Northern Idaho Ground Squirrel (NIDGS, Urocitellus brunneus brunneus) is threatened by habitat loss due to fire exclusion in west-central Idaho. Increases in Ponderosa Pine (Pinus ponderosa) density and extent have closed historically open meadows. Management practices for NIDGS recovery include thinning and burning to reduce tree encroachment. Baseline habitat data help create restoration goals and refine present management plans, but no pristine reference sites exist for the NIDGS, due to 100 y of land use and a lack of historical records. Therefore, we provided the first quantitative habitat descriptions of NIDGS habitat at 7 currently occupied sites that may be useful as an ecosystem of reference. We chose habitat attributes that are likely important to NIDGS, as well as attributes that are potentially altered by restoration treatments, which included overstory canopy cover, tree density, ground cover, litter depth, and soil texture. Habitat attributes were described with Bayesian 95% credibility intervals. Sites occupied by NIDGS had tree canopy cover of 10 to 15%, tree densities of 64 to 118 trees/ha, and understory height was 20 to 25 cm. Understory vegetation of occupied habitat consisted of 20 to 30 species, while across-site richness was 153 species. We also identified 15 understory species with the highest constancy and cover across the 7 sites. Litter depth was 0.7 to 0.9 cm, and the soil texture was clay loam. Our study provides valuable baseline information about NIDGS habitat. Managers may use our results to develop appropriate restoration targets when implementing habitat restoration. Information on occupied habitat may increase the efficacy of currently implemented restoration techniques and provide knowledge to be used in an adaptive management framework.

3-D mapping of a multi-layered Mediterranean forest using ALS data

This study presents a robust approach for characterization of multi-layered forests using airborne laser scanning (ALS) data. Fuel mapping or biomass estimation requires knowing the diversity and boundaries of the forest patches, as well as their spatial pattern. This includes the thickness of the main vegetation layers, but also the spatial arrangement and size of the individual plants that compose each stratum. In order to decompose the ALS point cloud into genuine 3-D segments corresponding to individual vegetation features, such as shrubs or tree crowns, we apply a statistical approach based on the mean shift algorithm. The segments are progressively assigned to a forest layer: ground vegetation, understory or overstory. Our method relies on a single biophysically meaningful parameter, the kernel bandwidth, which is related to the local forest structure. It is validated on 44 plots of a Portuguese forest, composed mainly of eucalyptus (Eucalyptus globulus Labill.) and maritime pine (Pinus pinaster Ait.) trees. The number of detected trees varies with the dominance position: from 98.6% for the dominant trees to 12.8% for the suppressed trees. Linear regression models explain up to 70% of the variability associated with ground vegetation and understory height.