Non-lethal Fires Research Articles

A New Method for Evaluating the Visual Quality of Loblolly Pine (Pinus Taeda L.) Forest

<p>Most of the forested lands in the south-eastern United States were largely the result of the frequent, low intensity, non-lethal fires that swept through the pre-settlement forests. In the absence of fire, forested stands develop a thick undergrowth of broad-leaved species and herbaceous vegetation. In this study, we compared the influence of prescribed fire on the understory vegetative cover of loblolly pine stands in relation to visual quality assessment. To examine the visual quality of prescribed fire management, a box-counting method was used to analyze photographs of prescribed fire management. The photographs were taken from: a) one-year fire return interval, b) two-year fire return interval, c) three-year fire return interval, and d) no-burn. The objectives of this study were: 1) develop a comparison of aesthetic value of the different fire return intervals of fire management with areas not experiencing prescribed fire; and 2) provide an estimate of enhancing visual quality of forest stands with prescribed fire management. The results showed that one-year interval prescribed fire application stands had more abundant grass cover (Andropogon sp.) than two- and three-year interval treatments. There was a significant decrease in grass cover between one-year and two-year prescribed burning. A positive relationship was also found between frequency of fire treatment and abundance of grass. No burn areas were covered by woody vegetation which may have a negative impact on scenic beauty and visual quality.</p>

Comparing historical and current wildfire regimes in the Northern Rocky Mountains using a landscape succession model

Wildland fire is a key ecosystem process that shapes the landscape of Western United States. Changes in fire regimes can therefore have profound impact on ecosystem functions and services, including carbon cycling, habitat conditions, and biodiversity. This study examined fire regime changes in the Northern Rocky Mountain region using a landscape succession model (LANDSUMv4). The objective is to report a new method to develop fire regime condition class (FRCC) maps by comparing historical reference conditions of fire regimes – simulated using historical fire record and the LANDSUMv4 model – with current fire regimes developed using 27years remote sensing fire product and LANDSUMv4. Results of this study indicate that most forest ecosystems in the study region experienced less frequent but more severe fires during the contemporary time period compared to the historical conditions. Fire regimes have changed the most for montane forests which historically were dominated by frequent and nonlethal fires. Forest ecosystems characterized by infrequent stand replacement fires also experienced moderate departure from historical fire conditions. FRCC assessment method proposed in this study can be applied to other areas of U.S. The findings of this study will help reveal contemporary fire dynamics in this region and serve for future fire and fuel studies and other forest management applications.

Influence of fire intensity on structure and composition of jack pine stands in the boreal forest of Quebec: Live trees, understory vegetation and dead wood dynamics

North American jack pine ( Pinus banksiana Lamb.) stands are generally characterized by an even-aged structure resulting from high intensity fires (HIF). However, non-lethal fires of moderate intensity (MIF), which leave behind surviving trees, have also been reported. The objectives of this study were two-fold: (1) assess the concurrent dynamics of live trees, understory vegetation and different types of coarse woody debris (CWD) during succession after HIF; and (2) document how MIF affects stand structure component dynamics compared to HIF. Stands affected by both HIF and MIF were selected. Tree characteristics and age structure, understory biomass, and CWD volume were assessed. Our results suggest that the structural succession of jack pine stands following HIF comprises three stages: young stands (<48 years), premature and mature stands (58–100 years) and old stands (>118 years). Canopy openness and jack pine density significantly decreased with time since HIF, while black spruce density and CWD volume significantly increased. The highest structural diversity was measured in the premature and mature stands. Compared to HIF, MIF increased mean jack pine basal area, decreased average stand density, delayed the replacement of jack pine by black spruce replacement in the canopy, decreased CWD volume, and significantly increased bryophytes mass. MIF increased the diversity of live trees and generally decreased CWD structural diversity. The study confirms the diversity of natural disturbance magnitude and successional processes thereby initiated. Thereafter, it appeared to be relevant for adjustment of disturbance emulating forest-management systems.

Effects of Fire Regime on the Serotiny Level of Jack Pine

1 Serotiny, the capacity to retain seed in the plant canopy, has evolved in many species under the selective pressure of fires. The effect of disturbance type (lethal or nonlethal fire), time-since-fire and different fire regimes on the serotiny of jack pine (Pinus banksiana), was evaluated in populations from two adjacent landscapes in the southern part of the Canadian boreal forest. The island landscape (Lake Duparquet) has a complex fire regime of small fires of variable intensity, whereas the adjacent mainland has a fire regime characterized by large intense fires. 2 Twenty-four jack pine populations (11 island and 13 mainland) on xeric sites were sampled for the degree of serotiny of trees. Fire history and age structure were reconstructed for each population using the fire scar method. For each tree, recruitment was categorized as after a lethal fire, after a nonlethal fire or in the absence of fire. 3 Likelihood chi-square tests were used to investigate the variation in serotiny at individual, population and landscape levels. 4 At the individual level, the results support our prediction that the occurrence of lethal fires favours trees with high serotiny while low serotiny trees are favoured by other types of disturbances. 5 At the population level, the frequency of low serotiny trees increases with time since stand initiation, as a result of higher establishment opportunities after disturbances other than lethal fires. The proportion of low serotiny trees also increases with the occurrence of nonlethal fires. 6 Significant differences were found between the two landscapes. On the mainland, serotinous trees were more abundant, whereas on the islands where nonlethal fires were recorded, low serotiny trees were more frequent. These results support the hypothesis that fire imposes differential selective pressures on serotiny in jack pine.

Fire ecology of red pine (Pinusresinosa) in northern Vermont, U.S.A.

Red pines (Pinusresinosa Ait.) in northern New England exist within small islands of fire-prone habitat surrounded by relatively nonflammable, deciduous forest. We studied the fire history and age structure of six red pine stands at an upland site in northwestern Vermont. Red pine is dominant in the canopy but rare in seedling and sapling size classes. Red pine is usually dependent on fires for regeneration. Fire scars record at least 17 different fires in the study area between the early 1800s and 1922. No fires are recorded between 1922 and 1987. The survival of numerous saplings in burned stands indicates that most of the fires were light surface fires. At least eight fires preceded periods of red pine recruitment recorded by the ages of living trees. These fires were probably locally intense, tree-killing fires. A similar regime of frequent, nonlethal fires and infrequent, lethal fires occurs in other parts of red pine's range.