Absence Of Forest Research Articles

Landslide susceptibility mapping using weights of evidence model on the slopes of Mount Elgon, eastern Uganda

Generally, landslide susceptibility mapping is an important step in mitigating their impacts. There is, however, particular dearth of information on the application of GIS-based bivariate methods particularly the weights of evidence model in mapping landslide susceptibility on the slopes of Mount Elgon in eastern Uganda. This study, therefore, evaluated the susceptibility of Bukalasi milli-watershed to landslides, as an early warning strategy for the major landslide hotspot in Uganda. A landslide inventory for the study area was prepared, and the weights of influence of selected landslide-conditioning factors were calculated to present their relative importance in landslide susceptibility. Eight conditioning factors were considered in this study namely; land use, lithology, rainfall, elevation, slope aspect, slope angle, plan curvature and profile curvature. Following the results of the Agterberg-Cheng conditional independence test (probability = 62.5%), the hypothesis of conditional independence among these factors was accepted. Validation using the ROC indicated satisfactory performance of the model considering the model prediction rate (Area under the Curve = 0.882) and success rate (Area under the Curve = 0.912). The final landslide susceptibility map highlights high susceptibility in the southern and western parts of the study area. It further shows that whereas Bukibumbi, Bundesi and Suume parishes are the most prone parishes, Shibanga Parish is relatively the least prone to landslides disasters. Thus, such highly susceptible areas should be prioritised during intervention programmes, especially relocation of the residents at risk. Since the absence of forests has been indicated to exacerbate susceptibility to landslides, deforestation should have severe penalties, and extensive tree-planting should instead be encouraged. Other human activities like farming on fragile slopes, which would further destabilise the slopes should particularly be discouraged.

Forest phenoclusters for Argentina based on vegetation phenology and climate.

Forest biodiversity conservation and species distribution modeling greatly benefit from broad-scale forest maps depicting tree species or forest types rather than just presence and absence of forest, or coarse classifications. Ideally, such maps would stem from satellite image classification based on abundant field data for both model training and accuracy assessments, but such field data do not exist in many parts of the globe. However, different forest types and tree species differ in their vegetation phenology, offering an opportunity to map and characterize forests based on the seasonal dynamic of vegetation indices and auxiliary data. Our goal was to map and characterize forests based on both land surface phenology and climate patterns, defined here as forest phenoclusters. We applied our methodology in Argentina (2.8 million km2 ), which has a wide variety of forests, from rainforests to cold-temperate forests. We calculated phenology measures after fitting a harmonic curve of the enhanced vegetation index (EVI) time series derived from 30-m Sentinel 2 and Landsat 8 data from 2018-2019. For climate, we calculated land surface temperature (LST) from Band 10 of the thermal infrared sensor (TIRS) of Landsat 8, and precipitation from Worldclim (BIO12). We performed stratified X-means cluster classifications followed by hierarchical clustering. The resulting clusters separated well into 54 forest phenoclusters with unique combinations of vegetation phenology and climate characteristics. The EVI 90th percentile was more important than our climate and other phenology measures in providing separability among different forest phenoclusters. Our results highlight the potential of combining remotely sensed phenology measures and climate data to improve broad-scale forest mapping for different management and conservation goals, capturing functional rather than structural or compositional characteristics between and within tree species. Our approach results in classifications that go beyond simple forest-nonforest in areas where the lack of detailed ecological field data precludes tree species-level classifications, yet conservation needs are high. Our map of forest phenoclusters is a valuable tool for the assessment of natural resources, and the management of the environment at scales relevant for conservation actions.

The intensity of slope and fluvial processes after a catastrophic windthrow event in small catchments in the Tatra Mountains

Strong wind events frequently result in creating large areas of windthrow, which causes abrupt environmental changes. Bare soil surfaces within pits and root plates potentially expose soil to erosion. Absence of forest may alter the dynamics of water circulation. In this study we attempt to answer the question of whether extensive windthrows influence the magnitude of geomorphic processes in 6 small second- to third-order catchments with area ranging from 0.09 km2 to 0.8 km2. Three of the catchments were significantly affected by a windthrow which occurred in December 2013 in the Polish part of the Tatra Mountains, and the other three catchments were mostly forested and served as control catchments. We mapped the pits created by the windthrow and the linear scars created by salvage logging operations in search of any signs of erosion within them. We also mapped all post-windthrow landslides created in the windthrow-affected catchments. The impact of the windthrow on the fluvial system was investigated by measuring a set of channel characteristics and determining bedload transport intensity using painted tracers in all the windthrow-affected and control catchments. Both pits and linear scars created by harvesting tend to become overgrown by vegetation in the first several years after the windthrow. The only signs of erosion were observed in 10% of the pits located on convergent slopes. During the period from the windthrow event in 2013 until 2019, 5 very small (total area <100 m2) shallow landslides were created. The mean distance of bedload transport was similar (t-test, p=0.05) in most of the windthrow-affected and control catchments. The mapping of channels revealed many cases of root plates fallen into a channel and pits created near a channel. A significant amount of woody debris delivered into the channels influenced the activity of fluvial processes by creating alternating zones of erosion and accumulation.

Analysis of Mountain Relief for the Causes of Snow Avalanches

The descent of avalanches is quite a usual phenomenon for the Ukrainian Carpathians, as well as for the conditions of mountain terrain in general. The Gorgany range of the Carpathian mountains is a typical avalanche-prone territory. Avalanches cause significant damage to forestry and may lead to casualties. Therefore, descent of avalanches has for a long time been a subject of fundamental research in geomorphology, meteorology, topography, photogrammetry and GIS technologies. Using photogrammetric mapping, we analyzed the causes of the descent of one of the largest avalanches in the Ukrainian Carpathians for the past 15 years. The avalanche fell from Poliensky mountain in the Gorgany mountain range in 2006, causing destruction of a great amount of forest. The main causes of avalanches were divided into two groups, the first including more or less stable factors caused by impact of terrain and somewhat less by solar radiation and the second group comprising meteorological factors, such as prolonged snowstorms and snowfall, that is, different fluctuations in weather. The main attention was paid to the first group of factors. For this purpose, a digital terrain model (DTM) of the study area was developed, visualizing the terrain, demonstrating the studied slope of the mountain along which the avalanche slid. According to the digital model, we developed maps of the steepness andexposition of the slope. Also we calculated the coefficient for solar radiation incident on the slope and which depends on the height of the Sun above the horizon and the coordinates of the slope. Using these data, the illuminance map of the Poliensky mountain area was developed. Studies conducted using GIS technologies led to the conclusion that the determining factors that triggered the powerful avalanche from Poliensky mountain were the great steepness and length of the slope, as well as the absence of forest at the top of the mountain, i.e. at the beginning of the avalanche track.

Enhanced forest interior estimations utilizing lidar-assisted 3D forest cover map

Accurate estimation of forest interior is essential for large scale sustainable forest management. Conventional 2D forest cover maps only indicate the presence and absence of forests and may introduce quantity and allocation bias in the delineation of forest interior due to the inclusion of early successional/recently disturbed forests. We addressed this issue by utilizing both lidar data and National Land Cover Database (NLCD) to generate a 3D forest cover map in the forested region of western North Carolina, USA. We first classified forest cover as either early or late successional based on vertical structural information (using either a single-height threshold or a variable-height threshold by forest type). We then estimated forest interior based on these different forest cover classes and assessed disagreement in quantity and allocation of interior forests as determined using 2D forest cover maps. In addition, we determined spatial relationships between developed areas and forest interiors to evaluate the impact of landscape settings on the estimation of forest interior. Our results indicated that using a single-height threshold, the 3D forest cover map was able to distinguish early vs. late successional forests with a classification accuracy of 96.6%. A similar classification accuracy (94.6%) was achieved when applying variable-height thresholds by forest type. Based on the single-height threshold method, excluding early successional forests (6.4% of all forested area) reduced estimates of forest interior by 10.3%, 9.6% and 10.4% at spatial resolutions of 4.4 ha, 39.7 ha and 234 ha, respectively. Using variable-height threshold by forest type, the estimates of forest interior were approximately 1% less than the estimates using the single-height threshold method due to the slightly decrease of the early successional forest classification (5.7% of all forest area). Our results indicated the forest interior may be overestimated without accounting for successional stage. Moreover, geospatial distance analysis revealed the overestimation of forest interior to be most pronounced in highly-fragmented areas. Our study demonstrated the advantage of considering 3D structural information for the accurate estimation of forest interior, particularly in areas already having fragmented forests. This information can be relatively easily obtained from lidar data. This 3D method will allow for the creation of high-accuracy forest interior maps that can help to answer a variety of ecological questions and improve forest management and conservation.

Assessing the interaction between mountain forests and snow avalanches at Nevados de Chillán, Chile and its implications for ecosystem-based disaster risk reduction

Abstract. Gravitational natural hazards such as snow avalanches, rockfalls, shallow landslides and volcanic activity represent a risk to mountain communities around the world. In particular, where documentary records about these processes are rare, decisions on risk management and land-use planning have to be based on a variety of other sources including vegetation, tree-ring data and natural hazard process models. We used a combination of these methods in order to evaluate dynamics of natural hazards with a focus on snow avalanches at Valle Las Trancas, in the Biobío region in Chile. Along this valley, natural hazards threaten not only the local human population, but also the numerous tourists attracted by outdoor recreational activities. Given the regional scarcity of documentary records, tree-ring methods were applied in order to reconstruct the local history of snow avalanches and debris flow events, which are the most important weather-related processes at respective tracks. A recent version of the model Rapid Mass MovementS (RAMMS), which includes influences of forest structure, was used to calculate different avalanche parameters such as runout distances and maximum pressures, taking into consideration the presence or absence of forest along the tracks as well as different modeled return periods. Our results show that local Nothofagus broadleaf forests contribute to a reduction of avalanche runout distances as well as impact pressure on present infrastructure, thus constituting a valuable ecosystem disaster risk reduction measure that can substitute or complement other traditional measures such as snow sheds.

A Risk Model for the Lyme Disease Vector Ixodes scapularis (Acari: Ixodidae) in the Prairie Provinces of Canada.

Lyme disease is emerging in Canada due to geographic range expansion of the tick vector Ixodes scapularis Say. Recent areas of emergence include parts of the southeastern Canadian Prairie region. We developed a map of potential risk areas for future I. scapularis establishment in the Canadian Prairie Provinces. Six I. scapularis risk algorithms were developed using different formulations of three indices for environmental suitability: temperature using annual cumulative degree-days > 0 °C (DD > 0 °C; obtained from Moderate Resolution Imaging Spectroradiometer satellite data as an index of conditions that allow I. scapularis to complete its life cycle), habitat as a combined geolayer of forest cover and agricultural land use, and rainfall. The relative performance of these risk algorithms was assessed using receiver-operating characteristic (ROC) area under the curve (AUC) analysis with data on presence-absence of I. scapularis obtained from recent field surveillance in the Prairie Provinces accumulated from a number of sources. The ROC AUC values for the risk algorithms were significantly different (P < 0.01). The algorithm with six categories of DD > 0 °C, habitat as a simple dichotomous variable of presence or absence of forest, and normalized rainfall had the highest AUC of 0.74, representing "fair to good" performance of the risk algorithm. This algorithm had good (>80%) sensitivity in predicting positive I. scapularis surveillance sites, but low (50%) specificity as expected in this region where not all environmentally suitable habitats are expected to be occupied. Further prospective studies are needed to validate and perhaps improve the risk algorithm.

Population structuring of the ubiquitous stingless bee Tetragonisca angustula in southern Brazil as revealed by microsatellite and mitochondrial markers.

Tetragonisca angustula is one of the most widespread stingless bees in the Neotropics. This species swarms frequently and is extremely successful in urban environments. In addition, it is one of the most popular stingless bee species for beekeeping in Latin America, so nest transportation and trading is common. Nest transportation can change the genetic structure of the host population, reducing inbreeding and increasing homogenization. Here, we evaluate the genetic structure of 17 geographic populations of T. angustula in southern Brazil to quantify the level of genetic differentiation between populations. Analyses were conducted on partially sequenced mitochondrial genes and 11 microsatellite loci of 1002 workers from 457 sites distributed on the mainland and on 3 islands. Our results show that T. angustula populations are highly differentiated as demonstrated by mitochondrial DNA (mtDNA) and microsatellite markers. Of 73 haplotypes, 67 were population-specific. MtDNA diversity was low in 9 populations but microsatellite diversity was moderate to high in all populations. Microsatellite data suggest 10 genetic clusters and low level of gene flow throughout the studied area. However, physical barriers, such as rivers and mountain ranges, or the presence or absence of forest appear to be unrelated to population clusters. Factors such as low dispersal, different ecological conditions, and isolation by distance are most likely shaping the population structure of this species. Thus far, nest transportation has not influenced the general population structure in the studied area. However, due to the genetic structure we found, we recommend that nest transportation should only occur within and between populations that are genetically similar.

Soil moisture response to experimentally altered snowmelt timing is mediated by soil, vegetation, and regional climate patterns

AbstractSoil moisture in seasonally snow‐covered environments fluctuates seasonally between wet and dry states. Climate warming is advancing the onset of spring snowmelt and may lengthen the summer‐dry state and ultimately cause drier soil conditions. The magnitude of either response may vary across elevation and vegetation types. We situated our study at the lower boundary of persistent snow cover and the upper boundary of subalpine forest with paired treatment blocks in aspen forest and open meadow. In treatments plots, we advanced snowmelt timing by an average of 14 days by adding dust to the snow surface during spring melt. We specifically wanted to know whether early snowmelt would increase the duration of the summer‐dry period and cause soils to be drier in the early‐snowmelt treatments compared with control plots. We found no difference in the onset of the summer‐dry state and no significant differences in soil moisture between treatments. To better understand the reasons soil moisture did not respond to early snowmelt as expected, we examined the mediating influences of soil organic matter, texture, temperature, and the presence or absence of forest. In our study, late‐spring precipitation may have moderated the effects of early snowmelt on soil moisture. We conclude that landscape characteristics, including soil, vegetation, and regional weather patterns, may supersede the effects of snowmelt timing in determining growing season soil moisture, and efforts to anticipate the impacts of climate change on seasonally snow‐covered ecosystems should take into account these mediating factors. Copyright © 2015 John Wiley &amp; Sons, Ltd.

Use of a porous material description of forests in infrasonic propagation algorithms

Infrasound can propagate very long distances and remain at measurable levels. As a result infrasound sensing is used for remote monitoring in many applications. At local ranges, on the order of 10 km, the influence of the presence or absence of forests on the propagation of infrasonic signals is considered. Because the wavelengths of interest are much larger than the scale of individual components, the forest is modeled as a porous material. This approximation is developed starting with the relaxation model of porous materials. This representation is then incorporated into a Crank-Nicholson method parabolic equation solver to determine the relative impacts of the physical parameters of a forest (trunk size and basal area), the presence of gaps/trees in otherwise continuous forest/open terrain, and the effects of meteorology coupled with the porous layer. Finally, the simulations are compared to experimental data from a 10.9 kg blast propagated 14.5 km. Comparison to the experimental data shows that appropriate inclusion of a forest layer along the propagation path provides a closer fit to the data than solely changing the ground type across the frequency range from 1 to 30 Hz.

Tipos de escorrentía y ritmo de evacuación de sedimentos en la Sierra de la Demanda : Sistema Ibérico

To relate the changes in flow with solid load and to analyze the relative importance of the different flows which take place on slopes, we have measured flow, suspended load and water conductivity in two basins of the Sierra de la Demanda, one with a significant forestry cover and the other with an almost complete absence of forest. Solid load and flow are closely related all year long, but in many events the basin covered by forest has a greater loss of sediments, though, in any case, the figures are very low. Most of the runoff of this basin takes place through pipes which proved to be the most efficient in sediment transport, at least during snowmelt

After the lava flow: The importance of external soil sources for plant colonization of recent lava flows in the central Oregon Cascades, USA

Effusive volcanic eruptions repave landscapes rapidly with lava flows, resetting broad areas of the underlying landscape and ecosystem. The unique physical properties of lava pose interesting challenges for ecologic recovery, as lava is dense, sterile, and generally inhospitable towards life. In this study we examine two sites of recent volcanism in the central Oregon Cascades, notable for the juxtaposition of barren exposed lava and mature forests on lava flows of the same or roughly the same age. We use a combination of LiDAR analyses, field observations, and soil characterization to examine soil and vegetation at these two sites, and find that the presence of an external sediment or soil source, particularly flood-borne deposits or syn- or post-eruptive tephra, greatly facilitates plant establishment, growth, and survival. The nature of the external sources of sediment or soil dictates the geographic extent of forests on these young lava flows: flood-borne deposits cover localized regions near river channels, while tephra can cover large regions. In general, our results suggest that external sources of soil provide a substrate for plants to grow in along with key nutrients and sufficient moisture retention. We conclude that external sources of soil source are key for the initial recovery following an effusive volcanic disturbance, in particular in temperate climates. Thus, unrelated geomorphic processes, such as past glaciations that provide local sources of mobile sediments, or concurrent volcanic processes, such as tephra production, dictate the presence or absence of forests on young lava flows.

Landscape genetic structure of coastal tailed frogs (Ascaphus truei) in protected vs. managed forests

Habitat loss and fragmentation are the leading causes of species' declines and extinctions. A key component of studying population response to habitat alteration is to understand how fragmentation affects population connectivity in disturbed landscapes. We used landscape genetic analyses to determine how habitat fragmentation due to timber harvest affects genetic population connectivity of the coastal tailed frog (Ascaphus truei), a forest-dwelling, stream-breeding amphibian. We compared rates of gene flow across old-growth (Olympic National Park) and logged landscapes (Olympic National Forest) and used spatial autoregression to estimate the effect of landscape variables on genetic structure. We detected higher overall genetic connectivity across the managed forest, although this was likely a historical signature of continuous forest before timber harvest began. Gene flow also occurred terrestrially, as connectivity was high across unconnected river basins. Autoregressive models demonstrated that closed forest and low solar radiation were correlated with increased gene flow. In addition, there was evidence for a temporal lag in the correlation of decreased gene flow with harvest, suggesting that the full genetic impact may not appear for several generations. Furthermore, we detected genetic evidence of population bottlenecks across the Olympic National Forest, including at sites that were within old-growth forest but surrounded by harvested patches. Collectively, this research suggests that absence of forest (whether due to natural or anthropogenic changes) is a key restrictor of genetic connectivity and that intact forested patches in the surrounding environment are necessary for continued gene flow and population connectivity.

Modeling of the long-term effect of tree species (Norway spruce and European beech) on soil acidification in the Ore Mountains

The MAGIC model was applied to estimate soil and soil water (−90 cm) chemistry between 1854 and 2094 at two experimental stands (Načetín, Ore Mountains), one covered by a Norway spruce monoculture and the other by a natural European beech forest. The primary aims were to evaluate the influence of tree species on long-term acidification and to predict future development under different forest management scenarios. Depletion of base cations from the soils, caused by high acidic deposition, resulted in low base saturations of 8.2% at the spruce stand and of 6.4% at the beech stand in 2003. The concentration of aluminum in soil water was 135 μmol l −1 and pH 4.32 at the spruce stand, and 70 μmol l −1 and pH 4.4 at the beech stand, respectively, in 2005. During the peak of acidification in the mid 1980s, modeled aluminum concentrations contributed 70% to neutralizing acidity at the spruce stand, and 55% at the beech stand. In addition, SO 4 concentration was significantly higher at the spruce stand (525 μequiv. l −1) compared to the beech stand (330 μequiv. l −1) as a result of higher dry deposition onto the spruce canopy. The enhanced leaching of base cations was comparable at both stands (191 μequiv. l −1 at the spruce stand and 215 μequiv. l −1 at the beech stand). The higher deposition of base cations onto the spruce canopy was able to partially mitigate the effect of high leaching. The model results suggest that future recovery of soil water will be significantly better at the beech stand (higher pH, ANC, Bc/Al ratio and lower SO 4 2− and Al concentrations). Interestingly, modeled soil base saturation for 2094 will be lower at the beech stand. Alternative scenarios such as clear-cutting and new re-forestation resulted in more favorable soil chemistry for the beech plantations compared to the spruce. The best regeneration of the soil environment is predicted for the scenario with an absence of forest. This suggests, that future soil recovery from acidification will be delayed by the removal of base cations through harvesting.

Early-Holocene spruce, Picea abies (L.) Karst., in west central Sweden as revealed by pollen analysis

Lateglacial and early Holocene macrofossils of Norway spruce (Picea abies) found in the Swedish Scandes have challenged the prevailing theory, based on pollen analyses, that spruce arrived rather late ( c. 3500 yr cal. BP) to Sweden. The aim of this study was to investigate whether the early-Holocene spruce establishment could be effectively assessed by pollen analysis. Four pollen analyses were carried out on peat mires in a river valley in the southern Swedish Scandes, where spruce has been present since the lateglacial. One site was analysed for the occurrence of macrofossil wood remains. The pollen diagrams display the local vegetation history for the last c., 10 000 years, and reveal the first occurrence of spruce pollen c. 9000 yr cal. BP. Spruce apparently became established in the northern part of the valley around 9000 BP, and thereafter spread south wards. The results are discussed in terms of the background pollen signal for spruce, i.e., local versus regional pollen, the presence or absence of forest on the sites during the Holocene, and the selection of study sites in relation to the aim of the investigation. Pollen analysis, as applied in this study, is shown to be a relevant method for the study of tree immigration in the early Holocene, at both a local and a landscape level.

Late Pleistocene vegetation and climate history of Lake Selina, western Tasmania

Abstract Analysis of pollen, NRM intensity of sediments, and dating of a 397 cm core from Lake Selina in western Tasmania provides a detailed record of vegetation and climate changes for the Last Interglacial–Last Glacial cycle. The vegetation record shows that cool temperate rainforest was present during Isotope Substage 5e and during the Holocene. Wet montane forest and subalpine shrublands dominated the early Last Glacial interstades; subalpine–alpine heathlands and herbfield the stadials. Stages 4–2 mainly had grassland, herbland and heath vegetation. There is close correlation between phases of maximum magnetic intensity in the sediments with pollen zones indicating presence of herbaceous vegetation. This suggests erosion of the catchment was greater in the absence of forest or woodland. Climate may have been slightly cooler than present during Substage 5e but the evidence is not definitive. Climate was colder at all times during the Last Glacial Stage until after ca. 14 kyr BP. Maximum temperature depression from present during Stage 2 was >3.5°C at Lake Selina, but probably as much as 6.5°C in the West Coast Range. Holocene climate was cool and wet. Comparison of the Lake Selina record, with others in western Tasmania and Victoria, indicate that variations in vegetation during the Last Interglacial–Last Glacial cycle were primarily responses to temperature changes in western Tasmania, and to precipitation changes, particularly summer drought, in western Victoria.

Application of the ETH Snow Model to Three Basins of Different Character in Central Europe

The performance of a version of the HBV-ETH model is evaluated, taking into account various aspect classes in each elevation belt in three different types of catchments: an alpine basin, and two basins in Bohemia at much lower elevation, with a snowpack which is smaller and of shorter duration. In all three cases a reasonably good agreement between modelled and observed runoff and between modelled and observed snowpack was achieved. In the smaller of the Bohemian basins (1.87 km2, 775-885 m a.s.l., influenced by deforestation), the effect of the presence and age or absence of forest on the development of the snow-water equivalent was found to be as important as the effect of aspect and altitude.

Evaluation of a water equivalent of snow cover map in a small catchment area using a geostatistical approach

AbstractWe describe an objective method for evaluating the spatial distribution of water equivalents of the snow cover within a small catchment. Regression analysis is used to quantify the relationship between elevation, presence or absence of forest, and potential direct solar radiation as independent variables and water equivalent as measured at a number of sites. First, this regression relationship is used to interpolate water equivalent data all over the basin area. Then we interpolate the residuals of the regression using a geostatistical approach. Superimposing the results obtained by interpolating the regression relationship and the interpolated residuals eventually yields the water equivalent distribution over the test area. The advantages of the interpolation method used lie in the optimal (effective, unbiased) estimation of the interpolated values as well as in the possibility to quantify the associated estimation variances.

Observations on Natrix septemvittata (Say) in Southwestern Ohio

The queen snake, Natrix septemvittata, is distributed over a broad range in eastern United States, extending from western New York south to northern Florida, and from western New Jersey west to Wisconsin. In some areas the population is discontinuous, and uncommon where encountered, a situation frequently encountered east of the Appalachian mountains. In other regions the numbers of individuals are large, and the queen snake shows such local abundance in suitable habitat that it becomes the dominant Natrix in the area. Southwestern Ohio is particularly favorable as a field laboratory for certain types of observation on Natrix septemvittata because of the remarkable local abundance of the species, and the position of the region not far north of the geographic center of the known range. For purposes of this report the part of southwestern Ohio known as Miami Valley consists of all counties drained in whole or in part by the Great or Little Miami Rivers and their important tributaries, the Mad and Stillwater Rivers. My observations, made in Miami Valley, were made in an intensively cultivated, formerly forested region, a part of the glaciated till plains of Ohio. Drastic changes in the character of the streams due to *he erosion of soil, change in water run-off, and change in water temperature resulting from the absence of forest do not appear to have had an unfavorable effect on the Natrix septemvittata population. I have observed this species on many field trips from 1940 through 1947, and have examined over 1,000 specimens. Due to the troglodytic behavior of Natrix septemvittata during much of its active season few field observations of behavior are recorded here.