Density Of Small Trees Research Articles

Diversity, structure, and composition of melliferous and non-melliferous vegetation surrounding meliponaries of the Yucatan Peninsula, Mexico

Background: Although the loss of Melipona beecheii colonies in meliponaries suggests insufficient availability of melliferous blooming plants, there is limited knowledge about the diversity and conditions of the surrounding vegetation. Question: What is the diversity, structure, and composition of the melliferous and non-melliferous vegetation surrounding meliponaries, and how does it affect the availability of food sources for bees? Study site and dates: The vegetation surrounding nine meliponaries, three in each political state of the Yucatán Peninsula encompassing the main vegetation types, was studied in 2022 and 2023. Methods: Four 150-meter-long transects with the point-centered quadrants method were traced in each meliponary to estimate plant species composition, the availability of melliferous and blooming plants (IVI), diversity parameters (Hill-numbers), tree density, and diameter per strata. Results: 312 taxa, 250 genera, and 73 plant families were recorded. In five meliponaries, blooming melliferous plants accounted for less than 9 % of the IVI, with one meliponary having no blooming species. The highest diversity was found in a meliponary surrounded by semi-evergreen forest. The high stratum had a mean tree height of 5.5 (SD ± 2.9) meters and 3,390 (SD ± 2,702) trees/hectare across vegetation types. The tree diameter was lowest in meliponaries located in the semi-deciduous forest. Conclusions: The meliponaries are surrounded by young secondary vegetation with high density of small trees and predominance of the low stratum. We found a similar vegetation diversity among meliponaries and scarce blooming melliferous plants. Human activity seems to impact plant diversity and food availability for M. beecheii.

Elevation-Dependent Natural Regeneration of Abies georgei var. smithii Forest in Southeastern Tibet

The comprehensive impacts of biotic and abiotic factors on the natural regeneration of Abies georgei var. smithii (Abies) forests in Tibet are not thoroughly understood. To address this gap, our study focused on the regeneration densities of Abies seedlings, saplings, and small trees across 21 plots (each 20 m × 20 m) along an elevation gradient from 3730 m to 4330 m in the Sygera Mountains of Southeastern Tibet. We meticulously measured a suite of 11 variables that describe stand structures and ecological conditions. Through analyses using Spearman’s correlation analysis, hierarchical partitioning, and multiple linear regression, we identified key ecological drivers for successful Abies regeneration. Our results highlighted a peak in the abundance of seedlings, saplings, and small trees at an elevation of 3930 m. As the elevation rose from 3730 m to 4330 m, we observed an initial increase followed by a decrease in canopy cover (canopy), mother tree density (MotherT), 1000-seed weight (SeedW), litter thickness (LitterT), moss cover (MossC), moss thickness (MossT), soil moisture (SM), and soil bulk density, while mean annual temperature and soil depth to permafrost consistently decreased. The critical ecological drivers for Abies natural regeneration were identified as follows: MossT was pivotal for seedling density; canopy and MossC were influential for sapling density, and MotherT was the main factor affecting the density of small trees. This study suggests that a high density of mother trees and a thick and highly covered layer of moss are conducive to the natural regeneration of Abies in the Sygera Mountains. Understanding the current status of regeneration is vital for informing conservation and management strategies for Abies forests in Tibet.

Human-driven degradation impacts on mangroves in southern Sierra Leone

Mangrove ecosystems remove carbon from the atmosphere and store it predominantly in soils constituting an important carbon sink. Additionally, they foster biodiversity and provide ecosystem services supporting local livelihoods and enhancing coastal protection. However, mangroves are declining in extent and experiencing degradation due to human activities as well as climate change impacts like sea-level rise and increasing frequency of extreme events. This study investigated how different levels of human-driven degradation affect forest structure, above- and belowground carbon stocks, tree species composition, and the population structures of dominant tree species. We investigated 19 transects of different degradation levels (pristine, moderately degraded, heavily degraded) in various locations (oceanic, riverine, interior) in the Sherbro river estuary in Sierra Leone.Results showed that total carbon stocks of pristine mangroves amounted to 707 Mg C ha−1 including soils to 1 m depth, which is higher than carbon stocks reported from many other regions in Africa.Degradation resulted in declining basal area, decreasing density of large trees (≥ 30 cm diameter) but increasing stem density of small trees (5–10 cm diameter). All carbon pools declined with increasing degradation across all locations. While above- and belowground carbon decreased by 96 %, soil carbon (up to 1 m depth) decreased by 44 %. Heavy degradation resulted in a change in the dominating species from Rhizophora racemosa to Rhizophora mangle across all locations. Overall, we found major effects of degradation on mangrove characteristics and minor effects of location. We urge conservation of pristine forests, restoration of degraded mangroves, and the establishment of management systems that are ecologically informed and based on a comprehensive understanding of human-driven degradation impacts.

Moose in our neighborhood: Does perceived hunting risk have cascading effects on tree performance in vicinity of roads and houses?

Like large carnivores, hunters both kill and scare ungulates, and thus might indirectly affect plant performance through trophic cascades. In this study, we hypothesized that intensive hunting and enduring fear of humans have caused moose and other forest ungulates to partly avoid areas near human infrastructure (perceived hunting risk), with positive cascading effects on recruitment of trees. Using data from the Norwegian forest inventory, we found decreasing browsing pressure and increasing tree recruitment in areas close to roads and houses, where ungulates are more likely to encounter humans. However, although browsing and recruitment were negatively related, reduced browsing was only responsible for a small proportion of the higher tree recruitment near human infrastructure. We suggest that the apparently weak cascading effect occurs because the recorded browsing pressure only partly reflects the long‐term browsing intensity close to humans. Accordingly, tree recruitment was also related to the density of small trees 5–10 years earlier, which was higher close to human infrastructure. Hence, if small tree density is a product of the browsing pressure in the past, the cascading effect is probably stronger than our estimates suggest. Reduced browsing near roads and houses is most in line with risk avoidance driven by fear of humans (behaviorally mediated), and not because of excessive hunting and local reduction in ungulate density (density mediated).

Reestablishing natural fire regimes to restore forest structure in California’s red fir forests: The importance of regional context

The reestablishment of natural fire regimes can have numerous benefits for forest ecosystems, including the restoration of stand structure through a reduction in tree densities and increased representation of large diameter trees. However, fire effects may depend on how departed the ecosystem is from its historical fire frequency. Red fir (Abies magnifica) forests occupy a broad geographic area across which historical fire return intervals and stand structures vary. Using historical stand inventory data from the Vegetation Type Mapping (VTM) project, we evaluated red fir forests in the Sierra Nevada in California and the Cascade-Klamath region of northwestern California and southern Oregon to determine how reintroduced fire effects vary regionally and if these differences are related to historical fire return intervals or structural conditions. We sampled a total of 29 overlapping fires and found that reestablishing fire in red fir forests consistently restored historical forest structure across a wide geographic range by reducing the density of small trees and maintaining large trees. However, the effect of fire was most evident in the Sierra Nevada where the percent difference in total tree density between unburned and burned plots was significantly greater (77% difference) than in the Cascade-Klamath (53% difference), and burned plots in the Sierra Nevada had significantly lower densities of both small (<30 cm dbh) and medium sized trees (30–60 cm dbh). These stronger fire effects may be related to greater departure from reference fire return intervals in the Sierra Nevada, as well as the region’s warmer and drier conditions increasing the availability of fuel to burn and susceptibility of trees to fire-related mortality. We found that departure from reference fire return intervals followed a similar pattern to departure from historical tree density in both study regions. Unburned plots were 61% departed from reference fire return intervals in the Cascade-Klamath and 69% departed in the Sierra Nevada. In these same plots, departure from VTM total tree density estimates were 37% in the Cascade-Klamath and 44% in the Sierra Nevada. We suggest that incorporating historical references for structural conditions together with regional or local estimates of historical fire return intervals contributes to an improved understanding of how reference conditions varied at local and regional scales, and their importance in the restoration of fire-dependent forests.

A wake-up call: playback attraction data link numbers of Mount Cameroon Francolin Pternistis camerunensis to abundance and debarking of red stinkwood Prunus africana

SummaryThe little studied Mount Cameroon Francolin Pternistis camerunensis is endangered and strictly endemic to the undergrowth of Mount Cameroon’s primary forest. We surveyed the species in the Mount Cameroon National Park in July–August 2016 using call playback at 86 plots systematically placed along 17 transects in an attempt to assess the occupancy and conservation threats to the species. The study’s three main results are as follows. Firstly, Mount Cameroon Francolin occurred in the stratified vegetation types across the altitudinal range of 1,023–2,186 m. Secondly, the response rates of francolin were 15% in submontane forest (800–1,600 m altitude range); 80.8% in montane forest (1,600–1,800 m); 3.9% in montane scrub (1,800–2,400 m); and nil in the lowland forest (0–800 m). Thirdly, bird abundance significantly increased with latitude, ground vegetation height, presence of Prunus africana and tall grass cover but decreased with the density of small trees and disturbance caused by heavy Prunus exploitation, and also, based on indirect evidence, hunting. We recommend: (1) systematic use of call playback in monitoring the population status of francolins; (2) an increase in patrolling and law enforcement to control illegal hunting, land clearance and burning of the upper slopes; (3) promotion of sustainable harvesting of Prunus and agroforestry practices aimed at curbing land clearance in the park surroundings. Further research priorities and conservation strategies have been suggested based on this study’s emerging results.

Leveraging Airborne LiDAR Data and Gradient Boosting for Mapping the Density of Different Sized Trees

Information on the distribution of trees with different diameters at breast height (DBH) is needed to inform management programs aimed at achieving conservation objectives in high stem density forest stands. This article explored the feasibility of mapping the density of trees with different DBHs using airborne LiDAR data. Experiments were conducted in the largest river red gum forest in the world, located in the southeast of Australia. Field measured data on trees with different DBHs were used for the supervised learning of airborne LiDAR scans with a pulse density of 5.92 pulses/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Specifically, the hyperparameters of gradient boosting and random forest regressors were tuned to produce a viable solution for mapping the density of different sized trees at the plot level. Our results indicate that the total tree density (DBH > 0 cm; height > 1.37 m) can be mapped using airborne LiDAR data with the coefficient of determination R <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> of up to 0.67, with gradient boosting outperforming random forest. However, the accuracy of mapping the density of saplings (DBH ≤ 10 cm), small trees (10 cm <; DBH ≤ 50 cm), and large trees (DBH > 50 cm) differed with R <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> of 0.65, 0.60, and 0.42, respectively. These results show that the airborne LiDAR data can provide a viable solution for mapping the density of small trees (DBH ≤ 50 cm) over large areas and has the potential for mapping the density of large trees (DBH > 50 cm).

Movement Patterns of the Eastern Chipmunk (&amp;lt;i&amp;gt;Tamias striatus&amp;lt;/i&amp;gt;) in Four Fragmented Landscapes of Prince Edward Island, Canada

The analysis of animal movement patterns can provide important information on animals’ responses to habitat features. In this study, the movement paths of eastern chipmunks (Tamias striatus) were examined in four landscapes, with different levels of habitat fragmentation, using either fluorescent powdering or spool-and-line tracking. Descriptions of the tree and ground vegetation communities were performed in the vicinity of the trail to obtain information on habitat use and habitat selection. Several key movement variables were calculated, including the total path length, net distance, fractal dimension, and radius of gyration. Despite statistically significant differences in some of the movement metrics between the four landscapes, the overall movement patterns were generically the same for all of chipmunk paths examined in this study. The data were compared to trends expected based on random or correlated random walks, as well as Lévy-walk models. The mean squared net displacement did not support the correlated random walk predictions, except at smaller spatial scales, but overall demonstrated Lévy-like super diffusive behaviour. Lévy-like patterns were also confirmed from the move-length distributions that demonstrated truncated-tail power-law behaviour. Although this would suggest invariance of the movement patterns at all spatial scales studied, fractal analysis revealed at least two transitions in movement patterns at scales of around 2 and 5 m. The transition point at 2 m was negatively correlated with the density of small trees, while the transition at ~5 m was positively correlated with the spatial distribution of large trees. As the habitat-preference data showed that small trees are among the least preferred habitat component, while large trees were among the most preferred habitat, chipmunks are likely to alter their movement behaviour to avoid small trees, and attracted towards large trees possibly to avoid predators. Overall, we determined three principal domains of movement: at smaller spatio-temporal scales, foraging activities dominate and the movement is highly correlated but also random; at intermediate spatial scales, chipmunks may be moving to avoid predators, using different environmental cues, and the movement is more directed (but still influenced by vegetation patterns at intermediate scales); at larger spatio-temporal scales, the movement is dominated by long-range/long-term memory and homing to burrows and other key habitat features, such as food caches, drives more directed movement. The fact that scale-dependent movement mechanisms could give rise to LW patterns is consistent with recent studies.

SELECTIVE LOGGING INTENSITY ALTERS THE POPULATION STAND STRUCTURE OF CULLENIA-MESUA-PALAQUIUM DOMINATED TROPICAL WET EVERGREEN FOREST OF THE WESTERN GHATS, SOUTH INDIA

The present study was conducted in a population structure of selectively logged tropical wet evergreen forest, Cullenia-Mesua-Palaquium (CMP) forest series in the tropical wet evergreen forests of the Nelliampathy Hills, Western Ghats. The study was aimed to focus on how selectively logged treatment influences the density and basal area of CMP forest series stand structure. We sampled the number of individual trees (≥ 1 cm dbh, diameter at breast height) of CMP at 30 sites (20 × 50 m quadrat size), covering an area of 30.8 hectare (ha) in total. A total of 5936 tree individuals sampled had a mean density of 246 ha-1 and basal area of 20.73 metre square (m2) ha-1 from an area of 0.1 to 2.5 ha. Tree density per hectare and basal area differed significantly among plots with different logging treatments. Tree density and basal area were significantly lower in highly logged plots as compared to moderately logged and unlogged plots. The density of smaller trees was significantly higher in moderately logged plots. We suggest that heavy logging treatments might be a serious threat to the CMP forest series and may possibly alter its population structure and that the moderately logged treatments showed positive impacts on CMP stand structure and regeneration.

English

This study characterizes the floristic and structural traits of trees in three sites of rainforest of Cameroon. The sites were exposed to dii¬€erent intensities of disturbances: Mangombe, highly and frequently disturbed; Bidou, moderately disturbed and Campo, undisturbed. Data collection were carried in a disposive comprising 65 plots of 20 m × 20 m randomly installed in each site for inventory, identification and measurement of diameter of trees greather than 10 cm at 1.30 m height. In total, 4717 plants belonging to 130 species and 43 families were recorded in all the sites. Basal area showed a declining trend with the increase in disturbance intensity while tree density, species richness and families increase with disturbances: Campo (87 m²/ha, 569 trees/ha, 75 species and 29 families); Bidou (54, 538, 88 and 32); Mangombe (49, 708, 91 and 38). The vegetation indices showed a high diversity in all the sites. The Shannon index (5.40 to 5.52) and generic diversity (1.10 to 1.16) had greater value. According to the sample, the floristic composition of Mangombe considerably differs from those of Bidou and Campo. The undisturbed site (Campo) contained young tree population showing a vigorous regeneration while in the highly disturbed site (Mangombe), tree density was scarce, with few big size trees having high cultural importance and low economic value. Low shrub density was recorded in Mangombe and Bidou due to frequent human disturbances. Canopy gaps favor direct sunlight which enhanced the abundance of Shrub in all the sites. More protection is needed for the restoration in the long term of forest cover in Mangombe, which can be done naturally due to high density of small trees composed of species generally found in the upper strata. Key words: Cameroon, dense humid forest, disturbance, species richness, structure of population.

Seasonally flooded, and terra firme in northern Congo: Insights on their structure, diversity and biomass

AbstractIn the Congo basin, considerable uncertainty remains about the amount and spatial variation of carbon stocks. We studied two types of seasonally flooded forests (dominated by Guibourtia demeusei and Lophira alata) and nearby terra firme forests in northern Congo. We sampled 1.25 ha per forest type and a total of 1,400 trees ≥5 cm diameter. AGB ranged from 207–343 Mg/ha, with no significant differences between forest types. Few significant differences were observed in vegetation structure or tree diversity between forest types. Species richness and stem density of small trees were lower, and dominance was higher in Guibourtia plots, which are subject to greater flooding than Lophira plots. Guibourtia was absent from smaller diameter class in Guibourtia forests; and Uapaca spp. were more abundant in terra firme than in seasonally flooded plots. We show that both types of seasonally flooded forests store important quantities of AGB and should also be considered in forest conservation programmes. We recommend more research on seasonally flooded forests, on larger geographical extent, which assesses flood depth and duration, and measures tree height in the field, as we took a conservative approach to AGB estimates, and AGB could be even greater than we report here.

Relating Fire-Caused Change in Forest Structure to Remotely Sensed Estimates of Fire Severity

Fire severity maps are an important tool for understanding fire effects on a landscape. The relative differenced normalized burn ratio (RdNBR) is a commonly used severity index in California forests, and is typically divided into four categories: unchanged, low, moderate, and high. RdNBR is often calculated twice—from images collected the year of the fire (initial assessment) and during the summer of the year after the fire (extended assessment). Both collection times have been calibrated to field measurements, but field data with both pre-fire and post-fire observations of matched plots are typically not available. This study uses a large network of field plots (n = 175) that was surveyed the year of and one year after a large wildfire in the central Sierra Nevada, USA, to quantify forest structure, mortality, and fire effects within fire severity categories from both the initial and extended RdNBR assessments. Most plots were classified in the same severity category in both assessments, particularly when mortality was high. Comparing initial and extended assessments, plots with lower pre-fire basal area were more likely to be classified at lower severity in the extended assessment, while plots with greater tree density were more likely to be classified at higher severity. High-severity plots had significantly greater pre-fire density of small trees. The high-severity category clearly captured stand-replacing fire effects (>95% basal area mortality, >99% tree density mortality), with typically all trees exhibiting high levels of crown consumption and scorching. In other severity categories, most large-sized and intermediate-sized trees survived, and moderate-severity fire favored survival of shade-intolerant species. Results suggest that both the initial and extended RdNBR assessments give an accurate representation of forest structural change in mixed-conifer forests following fire, particularly those of high severity.

Edge Effects of Oil Pipeline Canopy Openings on Tree Community Structure and Dynamics in a Montane Atlantic Forest

The Atlantic forest has historically been severely deforested, and only fragments currently remain that are subject to a wide variety of anthropogenic impacts, including edge effects that can cause structural and functional degradation. The Tingua Biological Reserve-RJ comprises approximately 26,000 hectares of well-preserved Atlantic Forest, but it is subject to impacts caused by two canopy openings along oil pipelines. Comparisons were made between pipeline edges and forest interiors to evaluate edge effects on the structure and dynamics of those tree communities. Tree densities were higher along forest edges, apparently increasing over time. Tree basal areas, on the other hand, have decreased along edges due to higher mortality rates. Linear canopy opening edges showed higher densities of small trees, while the interior had more very large trees, indicating changes in successional processes and community structural patterns due to edge effects.

The influence of stand variables and human use on biomass and carbon stocks of a transitional African forest: Implications for forest carbon projects

The viability and effectiveness of forestry-based carbon projects depends on the accurate estimation of carbon stocks as well as understanding the variables that influence carbon stocks, including human activity. However, for much of Africa, accurate, ground-based measurements are few, forests have centuries of human use, and the variables that influence forest biomass and carbon stocks are not well understood. The objectives of this study were to use field-based sampling to estimate aboveground biomass (and associated carbon stocks), and explore AGB variation in relation to forest stand characteristics and human biomass removal in an African tropical forest that lies in a transitional ecological zone between lowland equatorial and moist montane forest. We quantified tree densities, estimated plot aboveground biomass (AGB) using pan-tropical allometric equations, and estimated human biomass removal in four regions of Kakamega Forest in western Kenya that varied in historical and current human use. Our carbon stock estimate (173.3MgCha−1) was above large biome averages for moist tropical forests. Diameter of the largest tree, stem densities of large trees, and wood density were the most important variables influencing biomass, accounting for over 75% of the variation. While historical disturbance influenced biomass removal, we did not find that this disturbance or biomass removal significantly influenced AGB. The reason was that most biomass removal involves trees in small size classes, which are insignificant contributors to biomass. Our findings provide a field based estimate of carbon stocks for a transitional tropical forest. We also conclude that processes (both natural and anthropogenic) which influence the presence and health of species which can attain large size will have the greatest impact on biomass, while processes that influence stem densities of small trees will have no measurable effect. The application of these findings for forestry-based carbon projects would translate to the need for special attention being paid to activities which prevent or minimize loss of large dense trees (e.g. charcoal production, selective logging) if the carbon stock of a forest is to be maintained. On the other hand, activities which limit subsistence use in terms cutting small stems (e.g. energy efficient stoves), might not have measureable immediate effects on carbon stocks and the financial outcomes associated with the generation and sale of the carbon credits.

Empirically validating a dense woody regrowth ‘problem’ and thinning ‘solution’ for understory vegetation

In landscapes with a short history of intensive land use, woody plant regrowth on cleared land is often favorably received as a shift back to a more natural state. However, it is common for these regrowth stands to be much denser than undisturbed forest. High stem density can adversely affect stand structure, understory composition, and habitat for dependent fauna. Thinning to reduce stem density is one common silvicultural method used to manage dense stands for ecological or restoration objectives. The effect of thinning on the stand structure is well understood but those on the understory vegetation are not. We address this knowledge gap in anticipation of an increasing call for public investment in ‘ecological’ thinning across public and private land. Our case study is from the eucalypt woodlands and forests of central Victoria, Australia, an ecosystem in which dense woody regrowth is common. From a broad survey of 98 sites, spanning a range of stem densities, we explored the effect of density on understory vegetation. High densities of small trees (<20cm DBH) caused the greatest suppression of native and exotic cover and species richness. We compared our observations with benchmarks and found that sites with stem densities exceeding their benchmark had median values approximately one-seventh of the benchmark native understory cover, which was also less than a quarter of the cover of those sites with benchmark or lower stem density. We conducted an additional targeted survey of 11 thinned sites paired with non-thinned sites to evaluate the effects of thinning. We built models combining broad and targeted survey data relating understory response to stem density, thinning, land tenure and environmental covariates. These models predicted that thinning is likely to elicit positive responses from the understory plant community in the short term. This is the desired response from native species, but we caution that thinning can equally favor exotic plant species.

Mixed-conifer forests of central Oregon: effects of logging and fire exclusion vary with environment.

Twentieth-century land management has altered the structure and composition of mixed-conifer forests and decreased their resilience to fire, drought, and insects in many parts of the Interior West. These forests occur across a wide range of environmental settings and historical disturbance regimes, so their response to land management is likely to vary across landscapes and among ecoregions. However, this variation has not been well characterized and hampers the development of appropriate management and restoration plans. We identified mixed-conifer types in central Oregon based on historical structure and composition, and successional trajectories following recent changes in land use, and evaluated how these types were distributed across environmental gradients. We used field data from 171 sites sampled across a range of environmental settings in two subregions: the eastern Cascades and the Ochoco Mountains. We identified four forest types in the eastern Cascades and four analogous types with lower densities in the Ochoco Mountains. All types historically contained ponderosa pine, but differed in the historical and modern proportions of shade-tolerant vs. shade-intolerant tree species. The Persistent Ponderosa Pine and Recent Douglas-fir types occupied relatively hot–dry environments compared to Recent Grand Fir and Persistent Shade Tolerant sites, which occupied warm–moist and cold–wet environments, respectively. Twentieth-century selective harvesting halved the density of large trees, with some variation among forest types. In contrast, the density of small trees doubled or tripled early in the 20th century, probably due to land-use change and a relatively cool, wet climate. Contrary to the common perception that dry ponderosa pine forests are the most highly departed from historical conditions, we found a greater departure in the modern composition of small trees in warm–moist environments than in either hot–dry or cold–wet environments. Furthermore, shade-tolerant trees began infilling earlier in cold–wet than in hot–dry environments and also in topographically shaded sites in the Ochoco Mountains. Our new classification could be used to prioritize management that seeks to restore structure and composition or create resilience in mixed-conifer forests of the region.

Changing forest structure across the landscape of the Sierra Nevada, CA, USA, since the 1930s

Understanding the dynamics of forest structure aids inference regarding future forests and their distributions around the world. Over the last few decades, several papers have addressed changing forest structure in the Sierra Nevada, CA, USA, but these studies were limited in scope. We carried out a broad comparison of forest density and composition in the 1930s versus the 2000s for the west slope of the central and northern Sierra Nevada, using the two most extensive data sets available. Forests in this region have endured a long, complex history of human disturbance, and are now experiencing climatic shifts. We subdivided the landscape into elevation and latitude zones and compared historical and modern tree densities within each zone. We compared densities in historical plots to burned and unburned modern plots, as well as densities of individual tree species in historical vs. modern plots for their entire elevational distribution. Density of small trees (10.2–30.4 cm dbh) was significantly higher in the modern data set for all elevations and all latitudes, ranging from 20 to 148% higher. However, density of large trees (≥61.0 cm) was lower in the modern data set for most elevations and latitudes, ranging from 41% to 60% lower in most zones. Density difference of mid‐sized trees (30.5–60.9 cm) was mixed, but was generally higher in modern plots. The pattern of more small trees but fewer large trees held for most individual species as well, but with notable exceptions. Our comparison of burned and unburned plots strongly implicates fire suppression as a driver of increased density of small trees in low‐ to mid‐elevation forests. However, modern high‐elevation (&gt;2500 m) forests, where fire suppression impacts should be minimal, were also significantly denser than historical plots. Changing climatic conditions may be driving increased densities of small trees in high elevations, as well as decreased densities of large trees across the region.

Floristic Composition and Physiognomy of Pagbilao Mangrove, Quezon Province, Philippines

The species composition, physiognomy and importance value of PagbilaoMangrove, a typical satoumi site in southern Luzon, Philippines was determinedfrom May 2009 to August 2010. Vegetation analysis was done within a 20x20mquadrat established in each of the landward, middleward and seaward zones.A total of 37 species were identified in all zones comprising 744 individualsbelonging to 28 genera and 18 families. Using Shannon Index of diversity, thelandward zone has the highest diversity followed by the seaward zone. The leastdiverse was the middleward zone. There was a similar trend in the proportion ofvarious tree heights and diameter in seaward, middleward and landward zones.The density of small trees was higher than those of the big ones. The IV ofthe species varied within the zones. In the order of decreasing IV A. marina&gt; A. floridum &gt; Sonneratia alba in seaward zone. In the middleward zone, A.officinalis &gt; C. decandra &gt; S. hydrophyllacea. At the landward zone, X. granatum&gt; A. officinalis &gt; R. mucronata &gt; A. marina var. rumphiana. The current floristiccomposition of Pagbilao mangrove indicates that this ecosystem is still diversebased on the number and kinds of species present. With the satoumi frameworkin place, there is much hope in the conservation and management of thismangrove ecosystem.Keywords: Ecology, mangrove, floristic composition, physiognomy, species composition,physiognomy, importance value, descriptive design, Philippines

Effects of Habitat Degradation on Sleeping Site Choice and Use in Sahamalaza Sportive Lemurs (Lepilemur sahamalazensis)

Sleeping sites may be beneficial for animals in terms of thermoregulation, proximity to foraging sites, and protection from predators and infectious diseases. The abundance of adequate sleeping sites is thus essential for the survival of primates. We investigated microhabitats around sleeping sites, and the influence of habitat degradation on sleeping site choice and usage, in the nocturnal Sahamalaza sportive lemur, Lepilemur sahamalazensis. We used quarter point sampling (N = 315) to describe five forest fragments and 57 sleeping sites and continuous focal animal sampling (N = 45) to determine the diurnal activity budget, to determine whether individuals inhabiting different fragments or sleeping site types showed different levels of vigilance. Our results suggest that tall trees with large crowns, a high density of small trees, and dense canopy are particularly important for sleeping site choice. Microhabitat structure around sleeping sites did not differ between forest fragments or sleeping site types. Diameter at breast height, crown diameter, canopy cover, and bole height were similar for all sleeping trees, as were the number of lianas in trees with tree-tangle sleeping sites, and the volume of tree holes. Tree holes used as sleeping sites were most often found in dead trees of Bridelia pervilleana (50–62.5 %), whereas tree tangle sites were most often located in Sorindeia madagascariensis (20–62.5 %). Lemurs were active 5–14 % of the daytime, although they never left their sleeping sites or fed. Individuals occupying tree holes had higher levels of activity than those in tree tangles, and those in more degraded fragments were more active. Our results suggest that Sahamalaza sportive lemurs choose their sleeping sites according to specific habitat characteristics, and that factors associated with old and intact forest are likely to be crucial for their survival.

Estimating habitat value using forest inventory data: The fisher (Martes pennanti) in northwestern California

Managing forests for multiple objectives requires balancing timber and vegetation management objectives with needs of sensitive species. Especially challenging is how to retain the habitat elements for species that are typically associated with late-seral forests. We develop a regionally specific, multivariate model describing habitat selection that can be used – when linked to an institutional forest inventory program – to assess, monitor and forecast habitat conditions for a key wildlife species. We use the fisher (Martes pennanti) in northwestern California as our example and develop a predictive model for resting habitat that is created using data from the specific region where it will be used. We explore how this resting habitat model differs from a similar model developed for the Sierra Nevada and consider the implications for forest management. We developed the model using MaxEnt by comparing vegetation data at 99 randomly selected fisher resting structures on public and tribal lands in northwestern California with 883 Forest Inventory and Analysis (FIA) plots within the same ecoregion. A total of 58 alternative vegetation models were specified and the top 10 were nearly identical in their performance (Gain>1.08; Area Under the Curve [AUC]>0.89). We chose a five-variable model (canopy closure, tree age, total basal area, volume of “large” wood and basal area of hardwoods) because it included the fewest variables and included only those that could be affected by management. This model was similar to the Sierra Nevada model, but did not include topographic features (e.g., slope) nor did it include a variable representing the density of small trees. The absence of variables related to topography may make it easier for managers to affect positive change in resting habitat suitability since all variables can be influenced by management actions. Moreover, the model indicates that small trees appear to be less important (compared to southern Sierra Nevada) and therefore the probability of producing high-value resting habitat without higher fire risk is greater. We also created a spreadsheet that simplifies the process of generating habitat predictions from new data. Since metrics of stand structure and wildlife habitat are sensitive to sample design, collecting new data with FIA protocols will provide the most accurate estimates of predicted habitat with this model. Together, the Sierra Nevada and northwest California models provide managers in California a quantitative means to assess and monitor resting habitat suitability using current and future data that are part of an institutionally supported program to inventory forest vegetation.