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Abstract: Agro-environmental schemes (AES), which pay farmers to adopt greener practices, are increasingly important components of environmental and agricultural policies both in the US and the EU. Here we study the French implementation of the EU AES program. We estimate additional and windfall effects of five AESs for a representative sample of individual farmers using difference-in-difference (DID) matching. We derive the statistical assumptions underlying DID-matching from a structural household model and we argue that the economics of the program make it likely that these assumptions hold in our data. We test the implications of the identifying assumptions, provide a lower bound using triple-difference matching, test for crossover effects and insert our estimates of both additionality and windfall effects into a cost-benefit framework. We find that the AESs promoting crop diversity have inserted one new crop into the rotation but on a small part of the cropped area. We also find that the AES subsidizing the planting of cover crops has increased cover crops by 10ha on the average recipient farm at the expense of almost 7ha of windfall effect. This AES does not appear to be cost effective. In contrast, we find that the AES subsidizing grass buffer strips could be socially efficient despite large windfall effects. We finally estimate that the AES subsidizing conversion to organic farming has low windfall effects and high additionality. [Copyright &y& Elsevier]

Effects of a catastrophic blowdown event in northern Minnesota, USA were assessed using field inventory data, aerial sketch maps and satellite image data processed through the North American Forest Dynamics programme. Estimates were produced for forest area and net volume per unit area of live trees pre- and post-disturbance, and for changes in volume per unit area and total volume resulting from disturbance. Satellite image-based estimates of blowdown area were similar to estimates derived from inventory plots and aerial sketch maps. Overall accuracy of the image-based damage classification was over 90%. Compared to field inventory estimates, image-based estimates of post-blowdown mean volume per unit area were similar, but estimates of total volume loss were substantially larger, although inaccessibility of the most severely damaged inventory plots may have depressed the inventory-based estimate. This represents the first application of state model differencing to storm damage assessment. The image-based procedure can be applied to historical archives of satellite imagery and does not require pre-disturbance field inventory data. [ABSTRACT FROM AUTHOR]

Quantification of the downed woody materials that comprise forest fuels has gained importance in Caribbean forest ecosystems due to the increasing incidence and severity of wildfires on island ecosystems. Because large-scale assessments of forest fuels have rarely been conducted for these ecosystems, forest fuels were assessed at 121 US Department of Agriculture forest service inventory plots on Puerto Rico, Vieques, and the US Virgin Islands. Results indicated that fuel loadings averaged 24.05 Mg ha-1 in 2004-2006. Forest litter decreased from wetter to drier forest life zones. These island forests showed a paucity of coarse woody fuels (CWD) (2.91 Mg ha-1) and relatively greater quantities of smaller-sized fine woody fuels (FWD) (10.18 Mg ha-1 for FWD and 10.82 Mg ha-1 for duff/litter) when compared to continental tropical forests. Between 2001 and 2006, CWD fuel loads decreased, while fine fuels and litter increased, such that total fuel loads remained constant on a subset of plots on Puerto Rico. This trend indicates that continued decomposition of CWD deposited by the last severe hurricane is balanced by increasing inputs of FWD from recovering and maturing secondary forests. Forest disturbance cycles and successional development must be taken into account by agencies charged with fire protection and risk assessment. [ABSTRACT FROM AUTHOR]

Wind damage to forests is determined by numerous factors that interact to produce complex, seemingly random damage patterns. However, the complexity may lie mostly among stands and be less within stands: in this study, I attempted to discern how predictable tree fall risk is within five southern boreal forest stands in northeastern Minnesota. I sampled five stands in the Boundary Waters Canoe Area Wilderness, following a July 1999 catastrophic windstorm. Levels of damage varied from 29.5% to 86.8% of basal area fallen and 23.3% to 63.4% of stems fallen. In all sites, the disturbance reduced mean trunk diameter of standing trees. In general, Abies balsamea (L.) Mill. was the most vulnerable species. I split the data set from each site into predictor and test portions and used the predictor data sets to derive logistic regression parameters for the relationship of tree size (trunk diameter) to probability of tree fall. Models based on these parameters allowed quite accurate predictions of the levels of damage in the test portion of each stand. For the five sites, the proportion of test trees predicted to fall differed from the proportion observed to fall by 5.7%, 3.9%, 8.3%, 1.4%, and 3.7% of the total test sample size. This suggests that while numerous factors indeed influence tree fall risk, the sizes and identities of trees may account for most of the within-stand variation in damage. [ABSTRACT FROM AUTHOR]

Three major disturbances affect subalpine forests in the Rocky Mountains: blowdown, insect outbreaks, and fire. These disturbances may influence one another temporally and spatially, creating a mosaic of disturbance patches. In 1997, a severe windstorm blew down trees on over 10,000 ha of subalpine forest in northern Colorado. Did previous disturbances influence the spatial pattern of blowdown in a representative part of the blowdown in the Middle Fork Elk River watershed? Dendrochronological evidence and a geographic information system were used to reconstruct the disturbance history, and the relationship between disturbance history (i.e., patch age) and the 1997 blowdown was examined. The fire regime varies temporally and spatially, with an area-weighted mean fire interval/fire rotation of 108 to 195 years. Stand-replacing fires appear to have had the most impact on the fire regime, but evidence of nonstand-replacing fires was also found. South-facing, lower-elevation slopes were the settings most likely to burn. Lowseverity spruce-beetle disturbance was found in the mid-1700s and mid- to late 1800s, possibly related to regional outbreaks. Sheep-grazing and fire suppression may have influenced tree-regeneration and fire-frequency patterns. Each disturbance event occurred with varying severity across the landscape, influenced, in part, by the patterns of severity of previous disturbances. Patch age contributed to the pattern of the 1997 blowdown, but the relationship is complicated. The vegetation mosaic influenced spatial patterns of blowdown, resulting in new complexity and maintaining landscape heterogeneity. Key Words: blowdown; disturbance interactions; fire ecology; subalpine forest. [ABSTRACT FROM AUTHOR]

Large wood recruitment and redistribution mechanisms were investigated in a 3.9 km² basin with an old-growth Pseudotsuga menziesii (Mirb.) Franco and Tsuga heterophylla (Raf.) Sarg. forest, located in the southern Coast Range of Oregon. Stream size and topographic setting strongly influenced processes that delivered wood to the channel network. In small colluvial channels draining steep hillslopes, processes associated with slope instability dominated large wood recruitment. In the larger alluvial channel, windthrow was the dominant recruitment process from the local riparian area. Consequently, colluvial channels received wood from further upslope than the alluvial channel. Input and redistribution processes influenced piece location relative to the direction of flow and thus, affected the functional role of wood. Wood recruited directly from local hillslopes and riparian areas was typically positioned adjacent to the channel or spanned its full width, and trapped sediment and wood in transport. In contrast, wood that had been fluvially redistributed was commonly located in mid-channel positions and was associated with scouring of the streambed and banks. Debris flows were a unique mechanism for creating large accumulations of wood in small streams that lacked the capacity for abundant fluvial transport of wood, and for transporting wood that was longer than the bank-full width of the channel. [ABSTRACT FROM AUTHOR]

We investigated the influence of differing patch types on the germination, growth, and survival of two species of tree seedlings in a catastrophic, old-growth forest windthrow. We documented environmental conditions, and experimentally introduced seeds, transplanted seedlings, and manipulated litter and herbivore access to determine the effects of patch types during initial forest regrowth. Among patch types defined by substrate condition and exposure, we found significant differential influence of patch type on germination of seeds of a common colonizer, Betula alleghaniensis . Patch types that provided exposed mineral soil allowed greater germination than other patch types, regardless of light availability. Germination of Acer rubrum varied among patch types in a fashion similar to that of B . alleghaniensis , although differences among patch types were not significant. Litter can also be the basis of patch classification. Both type and amount of litter significantly influenced emergence of seedlings, with broad-leaf litter (in amounts typical of intact forest) producing greater inhibition of emergence than amounts of conifer needles typical of intact forest. Survival and performance of fenced and unfenced Acer rubrum seedlings transplanted into different patch types reflected influences of both herbivory and competition with existing vegetation. Survival was lowest where the Acer seedlings were most apparent to mammalian herbivores. Growth of Acer seedlings was greater when they were protected from herbivory and free of competition from surrounding vegetation. These findings demonstrate that patch types offer different suitability as regeneration microsites during early tree life history stages. Because these patch types are common and easy to recognize, the differences in species’ responses may be sufficiently general to apply in other disturbances of this type. If general species responses to patch types can be combined with knowledge of propagule abundance and patch abundance, it could provide a basis for improved understanding of post-disturbance regeneration, via patch influences. [ABSTRACT FROM AUTHOR]

Examines the relationship among forest landscape dynamics, environmental factors and disturbance history in the Bull Run Basin, Oregon. Analysis of environmental factors and windthrow patterns; Disturbance type and forest composition and structure; Climate and landform controls; Use of biotic controls; Climate-disturbance and forest management interactions.

Examines forest response to catastrophic wind in the United States. Relationship of tree damage patterns with mortality and regeneration, vegetation recovery and ecosystem processes; Importance of pre-disturbance forest structure in determining severity of impact; Role of tree resilience and understory vegetation in ecosystem processes.

Assesses the soil respiration in pits and mounds after an experimental forest blowdown at the Harvard Forest Long-Term Ecological Research site in Massachusetts. Soil disturbance in temperate forests by uprooting of trees; Comparison between area-weighted soil respiration estimate and control measurements; Measurements from undisturbed plots.