Jennifer L. Schafer

Winthrop University · Department of Biology

Differences in the biogeochemistry of nitrogen (N) and phosphorus (P) lead to differential losses and inputs during and over time after fire such that fire may affect nutrient limitation of primary productivity. We conducted a nutrient addition experiment in scrubby flatwoods, a Florida scrub community type, to test the hypothesis that nutrient lim...

Key message: Along a fire frequency gradient, we found a savanna tree species had the greatest below ground decay compartmentalization after coppicing as compared to other resprouting species located at mesic gradient positions. Abstract: In pyrophilic ecosystems, woody plants are repeatedly injured or topkilled (i.e. aboveground tissue is killed...

The probability of stem survival after fire is strongly influenced by energy allocation to bark because bark thickness affects heat transfer during fire. Greater relative investment in inner bark versus outer bark should also enhance survival because of greater moisture content of inner bark. We measured stem diameter, bark thickness, and habitat p...

Plant nutrient stoichiometry, which regulates carbon fixation and plant growth, is often strongly affected by soil nutrient availability. Disturbances such as fire can affect the absolute and relative availability of soil nitrogen (N) and phosphorus (P), as well as biotic constraints on plant nutrient uptake and allocation. In these ways, disturban...

Resprouting is advantageous for plants in pyrogenic ecosystems because it allows for quick re-acquisition of space after fire. Resprouting species build multiple stems during their lifetime and have an established root system, which may affect growth and biomass allocation and whether resprouts conform to predicted scaling relationships. We measure...

In frequently burned ecosystems, many plants persist by repeated resprouting from basal or belowground buds. This strategy requires that plants reach a balance between biomass loss and recovery, which depends on the shape of the relationship between pre- and post-fire size. Previous analyses of this relationship, however, have focused on the size o...

Background/Question/Methods The deserts of North America have recently become fire-prone due to invasion of non-native plants (chiefly grasses) that provide fuel sources, a novel component in desert ecosystems. As many of the native desert perennials, especially shrubs and trees, lack adaptations for fire resistance, now frequently occurring fires...

Background/Question/Methods Fire risk is increasing in ecoregions historically not prone to fire, such as creosote shrublands of the desert Southwest. It is hypothesized that one of the primary drivers producing novel fire regimes in these shrublands is the increasing abundance of exotic annuals. Schismus sp. is particularly important as it can s...

Background/Question/Methods Fire is an important disturbance in many ecosystems that can alter vegetation and soil properties. Soil nutrients in desert ecosystems are scarce and heterogeneously distributed, being mainly restricted to “fertility islands” created by perennial shrubs (e.g., Larrea tridentata). The fertility islands created by Larrea...

In resprouting species, fire-induced topkill causes a reduction in height and leaf area without a comparable reduction in the size of the root system, which should lead to an increase in the efficiency of water transport after fire. However, large plants undergo a greater relative reduction in size, compared with small plants, so we hypothesized th...

In arid shrublands, soil resources are patchily distributed around shrub canopies, forming well-studied ''islands of fertility.'' While soil nutrient patterns have previously been characterized quantitatively , we develop a predictive model that explicitly considers the distance from shrubs of varying canopy sizes. In 1-ha macroplots in both the So...

Background/Question/Methods Detailed demographic data is critical in designing science-based management programs for species at risk. Paronychia chartacea Fernald (Caryophyllaceae) is a small mat-forming polygamodioecious herb endemic to Florida. Federally threatened and state endangered, the species is comprised of two geographically distinct su...

Background/Question/Methods Desert ecosystems are currently showing a dramatic increase in the arrival and spread of non-native species. Traditionally, annual plants have patchy distributions in desert scrub ecosystems, being restricted to nutrient rich areas beneath shrubs, and are not found in open areas between shrubs. We hypothesize human int...

Background/Question/Methods Biological invasion, the spread of non-native organisms, is occurring rapidly worldwide, and even New World desert areas currently show a dramatic increase in the arrival and spread of non-native Old World plant species. Among the detrimental effects are alterations in fire regimes and direct negative impacts on native...

Conservation of a threatened species requires knowledge of the factors that affect its recruitment, survival, and reproduction. We conducted a long-term study on the demography of Paronychia chartacea ssp. chartacea, a short-lived, gynodioecious Florida rosemary scrub endemic. Specifically, we assessed the effects of habitat (rosemary scrub vs. roa...

Plant species distributions and transitions between vegetation types are determined by numerous factors, including disturbances such as fire. Documentation of past changes in the distribution and structure of fire-dependent ecosystems is necessary to assess the success of land management in maintaining historic vegetation types. In our study system...

Creosote bushes (Larrea tridentata) form islands of fertility that influence annual plant abundances in desert ecosystems, and the distribution of native and non-native annuals with respect to creosote may differ. We established plots on the north and south facing sides of L. tridentata in the Mojave and Sonoran Deserts within four different microh...

Background/Question/Methods In many arid shrublands, soil resources are patchily distributed as shrub canopies allow for accumulation of organic material. The concept of these “islands of fertility” in association with soil mounds under desert shrubs is well studied, as is the effect of heterogeneous resource availability on native and invasive a...

Background/Question/Methods Species that resprout after fire undergo a reduction in height and leaf area after fire without a comparable reduction in the size of the root system, and this reduction is likely to be greater for larger-statured species. An increase in the root:shoot biomass ratio post-fire should lead to an increase in the efficienc...

Background/Question/Methods Desert ecosystems are currently showing a dramatic increase in the arrival and spread of non-native species. Traditionally, annual plants have patchy distributions in desert scrub ecosystems, being restricted to nutrient rich areas beneath shrubs, and are not found in open areas between shrubs. We hypothesize that some...

Background/Question/Methods Plant productivity in boreal forest ecosystems is generally thought to be limited by nitrogen (N) availability, yet there are few experimental tests of this in natural forests. Low rates of N inputs due to the paucity of the N fixing flora and slow rates of decomposition in cold soils support the idea that N is in shor...

Background/Question/Methods The vegetation of the Sonoran and Mojave deserts is characterized by widespread shrublands dominated by Larrea tridentata (creosote bush) and Ambrosia dumosa (burrobush). These shrub species create fertility islands that influence the distribution of native and invasive annual plants. Spatial patterns in the distributi...

Background/Question/Methods Desert shrubs create an environment that supports high densities of native annual species under their canopies, particularly under the North facing side of the shrub. Non-native species invading deserts, however, can have high densities in the open areas between shrubs. Our objective was to compare patterns of seedling...

Fire may have different effects on the relative availability of nitrogen (N) and phosphorus (P) because N volatilization occurs at lower temperatures than P volatilization, and fire-mediated changes in soil nutrient availability may affect foliar nutrient concentrations. We assessed the short-term effects of fire on soil and plant nutrients and 15N...

Background/Question/Methods Nitrogen (N) and phosphorus (P) are essential plant nutrients that limit productivity in most, if not all, terrestrial ecosystems. Due to fundamental differences in the biogeochemistry of N and P, fire has the potential to alter the relative availability of N versus P both immediately following fire and over inter-fire...

Conservation of an imperiled plant species requires an understanding of its local occurrence and density in relation to habitat variation. Paronychia chartacea ssp. chartacea is a federally threatened species restricted to gaps in fire-maintained Florida rosemary scrub and to roadside sites that mimic scrub gaps. To assess the effects of time-since...

Background/Question/Methods Due to fundamental differences in the biogeochemistry of nitrogen (N) and phosphorus (P), fire has the potential to alter the relative availability of N versus P both immediately following fire and over inter-fire cycles. To investigate whether fire causes shifts in N versus P limitation of primary productivity, we esta...