Southeastern Oklahoma Research Articles

Octomacrum spinum (Monogenoidea: Polyopisthocotylea: Octomacridae) from highland stoneroller, Campostoma spidaceum (Cypriniformes: Leuciscidae) from Arkansas and Oklahoma, USA, with a summary of the genus from North American and European fishes.

Octomacrum spinum Dansby & Shoemaker, 1973, is reported for the first time from 23 of 146 (16%) highland stonerollers, Campostoma spadiceum collected from central and western Arkansas and southeastern Oklahoma, USA. Analysis of molecular data revealed that the SSU rRNA gene of specimens of O. spinum from Arkansas was identical to a number of Octomacrum spp. and the LSU rRNA gene was 97.46% similar to Octomacrum europaeum. We also provide a summary of the species of Octomacrum reported from North American and European fishes.

Post-Removal Mounds: Earthworks Rising in Oklahoma

Abstract: Twenty-first-century Oklahoma—where so many Southeastern, Ohio Valley, Mississippi Valley, and other mound-building and mound-stewarding peoples were forcibly removed in the nineteenth century—is witnessing a reactivation of Indigenous practices of building and stewarding large-scale, highly graphic, multiply encoded earthworks. Replicas of historical platform mounds feature prominently at the Chickasaw Cultural Center that opened in rural south-central Oklahoma in 2010 and the Choctaw Cultural Center that opened in rural southeastern Oklahoma in 2021, while a futuristic, spiraling "promontory mound" forms an integral component of the multitribal First Americans Museum that opened outside urban Oklahoma City in 2021. Constructed and curated to meet the expectations of both tribal citizens and diverse Native and non-Native tourists, how do these new earthen structures and their contextualizing environments occupy space, organize relations, and make meaning within their specific contexts of cultural celebration, Indigenous-centered education, and immersive visitor experience? And what do they tell us about the possibilities for Indigenous aesthetics and architectural design in the future?

Resin duct production of loblolly pine (Pinus taeda) in southeastern Oklahoma, USA is positively related to water availability, fertilization, and thinning

Bark beetle outbreaks frequently kill large areas of loblolly pine (Pinus taeda). Resin production is the main defense against these insects and resin duct metrics and areas are correlated with both resin flow and tree survival post bark beetle attack. Whether the number, area, or size of resin ducts is increase when trees grow faster or whether there is a tradeoff between tree growth and resin ducts is currently debated. We determined the impacts of water availability (ambient vs 30 % throughfall reduction), nutrient availability (fertilized vs non-fertilized), and thinning on vertical resin duct count (ducts per 5 mm strip of annual ring), density (ducts mm−2), area (duct area per 5 mm strip of annual ring), relative area (% duct area per ring), and average duct size (mm−2) in planted stands of loblolly pine (ages 6–13) in southeastern Oklahoma. Fertilization increased diameter growth (10 %) and metrics that scale to ring width, i.e., duct count (15 %) and duct area (22 %), but also duct relative area (8 %). Throughfall exclusion decreased diameter growth and duct count in some years, increased duct density, and reduced duct average size (8 %). The net effect was that fertilized stands with ambient water availability had the greatest resource availability among treatments in this study and had the greatest duct count, duct area, and duct relative area as well as average duct size greater than the throughfall exclusion treatments. During the post thinning period, i.e., ages 10–13, thinning increased diameter growth from 9.63 to 12.05 mm year−1, duct count from 9.69 to 12.22, duct area from 0.384 to 0.514 mm2, duct relative area from 1.67 % to 1.84 %, and average duct size from 0.0396 to 0.0428 mm2. Earlywood composed approximately 2/3 of the annual ring, but latewood had almost 5 times greater duct density such that there were more ducts and greater duct areas in the latewood. Our assessment of duct metrics provides a link between tree growth rate, resource availability, and duct metrics associated with resistance to bark beetles. Therefore, silvicultural practices used to increase tree growth likely also increase resistance to bark beetles.

Economic returns and the perceived obstacles to adopting active management in the forest-grassland transition ecoregion in south-central USA

Forest-grassland ecotones are a mosaic of grassland, savanna, and upland forest. As such, landowners may have opportunities to choose to manage their lands for multiple objectives. We estimated the economic returns from managing forest and rangeland in southeastern Oklahoma, USA to produce different combinations of timber, cattle forage, and white-tailed deer (Odocoileus virginianus Zimmermann) browse for a 40-year period. We further conducted a survey to understand landowner perceptions of obstacles to adopting active management that involve timber harvest and prescribed fire. The highest net return was obtained from the treatment with harvested timber that was burned every four years (uneven-aged woodland/forest) because it had the greatest gross return from a combination of timber (46%), cattle forage (42%), and deer browse (11%). The return from this treatment was greater than that for managed for timber only (closed-canopy forest) or prioritizing cattle and deer (savanna). Survey results suggested that landowners were aware of the benefits of active management but that the majority (66%) considered cost a major obstacle in the management of their forest or rangeland. In particular, women forestland owners and older landowners considered cost an obstacle. Our findings advocate integrated timber, cattle, and deer management as the best economic strategy within the forest-grassland ecotone and for targeted outreach and landowner education related to the benefits of active management.

Reproductive cycles of alligator snapping turtles (Macrochelys temminckii)

The alligator snapping turtle (Macrochelys temminckii) is a species for which captive propagation and reintroduction programs are well established; however, little is known about its reproductive behavior and physiology. In this study, we measured monthly plasma sex steroid hormone concentrations of androgen (T + DHT) estradiol-17B (E2), and progesterone (P4), and used ultrasonography to monitor annual reproductive cycles of a captive population of alligator snapping turtles that is maintained under semi-natural conditions in southeastern Oklahoma. Concurrently, we used automated radio telemetry to measure the relative activity levels of male and female alligator snapping turtles and examine these activity patterns in the context of their reproductive cycles. We also measured monthly concentrations of the glucocorticoid (GC) corticosterone (CORT). Seasonal variation was only detected for T in males, but was observed for T, E2, and P4 in females. Vitellogenesis began in August and ended in April and coincided with elevated E2. Ovulation took place 10–29 April and the nesting period lasted from 11 May – 3 June. Males exhibited greater relative activity levels than females in the fall, winter, and early spring, which coincided with the period when mature sperm would be available for mating. Females were more active than males during the peri-nesting period in the spring. Seasonal changes in CORT were detected and did not differ between males and females. CORT concentrations were elevated in the late spring and summer, coincident with the foraging season, and depressed in the fall, and winter, and at their nadir in the early spring.

Significant range extension of Streptanthus squamiformis (Brassicaceae), a Ouachita Mountain endemic

Streptanthus squamiformis Goodman (Brassicaceae) is a plant narrowly endemic to the Athens Plateau; Central Hills, Ridges, and Valleys; and Central Mountain Ranges ecoregions of the Ouachita Mountains, and previously known from five adjacent counties in western Arkansas and southeastern Oklahoma. We document a 100-km range extension of this species to Perry County in central Arkansas, its first occurrence in the Fourche Mountains Ecoregion.

Mercury Contamination of Fish and Their Prey Across a Riverine Food Web

Lakes and reservoirs are frequently monitored by researchers for elevated mercury concentrations in sportfish. Rivers and streams, especially those of smaller orders, are less frequently monitored for mercury contamination and nonsport fishes and invertebrates, although important components of the food web, are rarely examined. We addressed this gap by surveying mercury levels in a stream community in the Kiamichi River in southeastern Oklahoma, U.S., by sampling fish and macroinvertebrates at ten sites in the river. We found elevated levels of mercury across taxa within the river including individuals of smallmouth bass populations 10–25 cm in length having concentrations (2986 ± 1053 ng/g dry weight) above the U.S. Environmental Protection Agency human limit. Furthermore, we observed high concentrations in darters and logperch (1133 ± 464 ng/g dry weight), nonsport fishes found predominantly in rivers and streams. Our results indicate mercury contamination can reach elevated concentrations in rivers and stream food webs, posing risks to both humans and wildlife.

Little Evidence of Leaf Damage to Dwarf Palmetto (Sabal minor; Arecaceae) during an Unusual Arctic Outbreak

The dwarf palmetto (Sabal minor) is a widespread understory palm of the southeastern United States. This palm is expected to be one of the species that exhibits a range shift in response to climate change, and the population at the northwestern edge of its distribution in Oklahoma appears to be increasing in both numbers and extent. However, this palm may also be susceptible to cold damage during unusually severe winters, which could potentially limit the spread of this species. An unusually cold arctic outbreak spread across the southern Great Plains during 13–17 February 2021, with minimum temperatures of −11 °C recorded in Houston (Texas), −15 °C in San Antonio (Texas), and −26 °C in Oklahoma City (Oklahoma). In order to evaluate the effects of the arctic outbreak on Sabal minor, I examined individuals in four counties (one site in Brazoria County, TX; one site in Brazos County, TX; two sites in McCurtain County, Oklahoma; and two sites in Oklahoma County, Oklahoma) in the period of 5–16 March 2021. At nearly every site, 30 individuals were examined, and the number of palmate leaves as well as the extent of the green area on the leaf was visually estimated, with percentages rounded to the nearest 5%. There was little evidence of cold damage from southeastern Oklahoma to coastal Texas, with palmate leaves retaining a median of 85% green area. However, some damage was noted in seedlings at the northernmost population in McCurtain County, Oklahoma. In contrast, extensive leaf damage was noted in dwarf palmetto plantings in Oklahoma County, Oklahoma, with plants retaining a median of only 5% green leaf area. The results of this study suggest that arctic outbreaks are unlikely to prohibit the continued spread of this species at the northern edge of its native range but may cause damage to multiple plant growth stages that could reduce the rate at which the species survives and reproduces.

Interannual Winter Site Fidelity for Yellow and Black Rails

Yellow Rail (Coturnicops noveboracensis) is a species of conservation concern, while the Eastern Black Rail (Laterallus jamaicensis jamaicensis) has recently been listed as Threatened. Both species winter primarily in coastal areas from Texas through North Carolina. Between-year winter site fidelities of these species have not previously been reported, so we analyzed the recapture histories of Yellow Rails banded in southeastern Oklahoma (from 2008 to 2018) and coastal Texas (from 2006 to 2018), as well as Black Rails banded in Texas from 2006 to 2018. We banded 111 Yellow Rails in Oklahoma and 421 Yellow Rails in Texas during this time, as well as 94 Black Rails in Texas. Although Yellow Rails were routinely recaptured within season, only five individuals were recaptured between years. All recaptured birds were in Texas. Black Rails likewise exhibited low interannual site fidelity, with no interannual recaptures. The apparent low interannual site fidelity of Yellow Rails (1.1% in Texas, 0% in Oklahoma) and Black Rails (0%) is similar to that reported for other grassland species wintering in grasslands in this area (e.g., LeConte’s Sparrow (Ammodramus leconteii), Henslow’s Sparrow (A. henslowii), and Sedge Wren (Cistothorus stellaris)), and we speculate that low site fidelity could potentially be advantageous for species that use early successional habitats.

Drivers of ecosystem vulnerability to Corbicula invasions in southeastern North America

Invasive species introduction is one of the major ongoing ecological global crises. Identifying factors responsible for the success of invasive species is key for the implementation of effective management actions. The invasive filter-feeding bivalve, Corbicula, is of particular interest because it has become ubiquitous in many river basins across North America and elsewhere. Here we sampled bivalve assemblages, environmental indicators, and land cover parameters in the Ouachita highlands in southeastern Oklahoma and southwestern Arkansas, and in the Gulf Coastal Plain of Alabama to test three working models (using structural equation modeling, SEM) based on a priori scientific knowledge regarding Corbicula invasions. Our models tested three competing hypotheses: (1) Native mussel declines are related to land use changes at the watershed level and subsequent Corbicula colonization is a result of an empty niche; (2) Corbicula abundance is one of the factors responsible for native mussel declines and has an interactive effect with land use change at the watershed level; (3) Native mussel declines and Corbicula success are both related to land use changes at the watershed level. We found no evidence for the first two hypotheses. However, we found that environmental indicators and land cover parameters at the watershed scale were robust predictors of Corbicula abundance. In particular, agricultural land cover was positively related with Corbicula density. These results suggest that further improvement of conventional agricultural practices including the optimization of fertilizer delivery systems may represent an opportunity to manage this species by limiting nutrient inputs to stream ecosystems. Preservation of extensive floodplain habitats may help buffer these inputs by providing key ecosystem services including sediment and nutrient retention.

Mississippian southern Laurentia tuffs came from a northern Gondwana arc

Abstract A Paleozoic arc that formed by southward subduction of the Rheic oceanic plate beneath northern Gondwana has long been inferred, but its history and geochemical signatures remain poorly understood. New U-Pb ages, juvenile εHf signatures, and trace-element composition data of young zircons from tuffs at two southern Laurentia sites indicate their derivation from a continental arc that was active from ca. 328 to ca. 317 Ma and permit correlation of sedimentary sequences 800 km apart in southern Laurentia. These include the Stanley tuffs in the Ouachita Mountains of southeastern Oklahoma and southwestern Arkansas and the newly discovered Barnett tuff in the subsurface of the Midland Basin in west Texas (USA). The Barnett tuff has a zircon chemical abrasion–isotope dilution–thermal ionization mass spectrometry U-Pb date of 327.8 ± 0.8 Ma, similar to the oldest Stanley tuff in the Ouachita Mountains. Zircon Hf isotope depleted mantle model ages further suggest that the source was a continental arc on basement with both Grenville and Pan-African affinities, pointing to northern Gondwana or peri-Gondwana terranes. The new data link the tuffs to granitoids (326 Ma) of the Maya block in southern Mexico, which was part of northern Gondwana. Correlation of the Stanley-Barnett tuffs across southern Laurentia suggests the likely presence of Mississippian tuffs over a broad region in southern Laurentia, and their usefulness for constraining absolute ages of basin fills and characterizing the Gondwanan arc.

Radial growth responses of post oak (Quercus stellata) to climate variability and management in southeastern Oklahoma, USA

We investigated radial growth of post oak (Quercus stellata Wangenh.) growing in a range of stand structures (forest to savanna) created in 1984 by different harvesting, thinning, and prescribed fire intervals. We related ring width index (RWI) to monthly and seasonal climate variables and time since fire to assess impacts of climate variability and interactions with management on radial growth. The RWI of all treatments was positively correlated to minimum daily temperature the previous September and precipitation late spring and early summer the current year, and negatively correlated to maximum daily temperatures and drought index late spring – early summer. June weather was most strongly correlated in four of five treatments. While stand structure affected absolute diameter growth, the RWI of savanna and forest stands responded similarly to climate variability, and low intensity prescribed fire did not influence RWI. On average, a 100 mm reduction in June precipitation decreased RWI by 7%, a 1 °C increase in previous-year September daily minimum temperature increased RWI by 3.5%, and a 1 °C increase in June maximum daily temperature decreased RWI by 3.7%. Therefore, negative effects of drought and warmer spring and summer temperatures may be reduced by a longer growing season under warmer climate scenarios. However, management did not appear to influence RWI.

Management and climate variability effects on understory productivity of forest and savanna ecosystems in Oklahoma, USA

AbstractThe productivity of herbaceous and understory woody vegetation is critical for wildlife habitat, livestock forage, and biodiversity, and is influenced by both annual weather patterns and tree dominance. With the goals to inform management and understand climate change implications, we determined the effects of tree harvest, prescribed fire, and 31 yr of climate variability on understory aboveground net primary productivity (ANPP) for ecosystems ranging from mature forest to grassland in a long‐term study in southeastern Oklahoma, USA. In 1984, starting with a mature forest dominated by Pinus echinata and Quercus stellata, replicated experimental units were created by various combinations of pine harvest, hardwood thinning, and subsequent fire return intervals (1–4 yr and none). Understory ANPP (forbs, grasses, and woody plants) was measured by clip plots at the end of each growing season. Stepwise regression models were developed between understory ANPP and tree basal area, litter accumulation, fire return interval, and monthly, seasonal, and annual weather variables. Understory ANPP was dominated by grasses and ranged from 27 g·m−2·yr−1 for the mature forest to 374 g·m−2·yr−1 for an annually burned grassland/savanna. In general, herbaceous ANPP was inversely related to tree dominance (basal area), litter accumulation, and early and late growing season temperatures, and positively related to June precipitation. Understory woody ANPP was influenced by tree basal area, positively influenced by precipitation, and negatively influenced by summer soil moisture deficits. Our results indicate that prescribed fire, through its negative influence on tree basal area and litter accumulation, is critical to maintaining highly productive understories and that a three‐year return interval is a threshold to stall redevelopment of forest. For herbaceous ANPP, timing of precipitation, especially mid‐growing season, appears more important than total precipitation, and higher temperatures within the range our site experienced did not have a large negative effect. In contrast, understory woody ANPP was negatively influenced by drought indicating climate change may have variable effects on different functional groups.

Long-term growth effects of simulated-drought, mid-rotation fertilization, and thinning on a loblolly pine plantation in southeastern Oklahoma, USA

Loblolly pine (Pinus taeda L.) is the most productive commercial softwood species in the southeastern USA. More frequent drought due to climate change will likely alter loblolly pine productivity, especially in areas where the climate is already highly variable such as the Upper Gulf region of the south-central USA. In a long-term study, we examined the effects of drought treatment (30% throughfall exclusion), fertilization, and thinning on a loblolly pine plantation growing in southeastern Oklahoma, USA to determine how nutrient availability and stand density interact with drier conditions to affect productivity. Our treatments were applied at mid-rotation: throughfall reduction ages 5 to 13, fertilizer ages 5 and 10, and thinning age 10. Treatment effects on diameter and height increment depended on year, with drought treatment tending to decrease diameter and height growth in drier years and fertilization having a stronger positive effects on diameter growth in the years closely following fertilization events. The net effect on standing volume was that fertilization (+7%) and simulated-drought (−8%) countered each other by age 13. Positive fertilization effects were supported by increased foliar nitrogen (N) and phosphorus (P) concentrations, along with increased leaf area index (LAI, +14% measured age 12). Three and four years after thinning, diameter increment increased by 38%, and positive fertilization effects on gross current annual increment were greater in thinned compared to non-thinned stands. Basal area increment in drought-treated stands relative to non-drought-treated stands decreased more during drier years and exhibited recovery during wetter years. The fairly small growth decline in response to 30% throughfall reduction, positive fertilizer effects, and possible post-drought recovery indicate continued plantation viability in the future even at the drier, western fringe of loblolly pine’s commercial range.

A needle in the haystack? Applying species co-occurrence frameworks with fish assemblage data to identify species associations and sharpen ecological hypotheses.

Different species can associate or interact in many ways, and methods exist for inferring associations and underlying mechanisms from incidence data (e.g., co-occurrence frameworks). These methods have received criticism despite their recent resurgence in the literature. However, co-occurrence frameworks for identifying nonrandomly associated species pairs (e.g., aggregated or segregated pairs) have value as heuristic tools for sharpening hypotheses concerning fish ecology. This paper provides a case study examining species co-occurrence across 33 stream fish assemblages in southeastern Oklahoma, USA, which were sampled twice (1974 and 2014). This study sought to determine (a) which species were nonrandomly associated, (b) what processes might have driven these associations and (c) how consistent patterns were across time. Associations among most pairs of species (24 species, 276 unique pairs) were not significantly different from random (>80%). Among all significant, nonrandomly associated species pairs (54 unique pairs), 78% (42 pairs) were aggregated and 22% (12 pairs) segregated. Most of these (28 pairs, 52%) were hypothesized to be driven by nonbiotic mechanisms: habitat filtering (20 pairs, 37%), dispersal limitation (two pairs, 0.4%) or both (six pairs, 11%). The remaining 26 nonrandomly associated pairs (48%) had no detectable signal of spatial or environmental factors involved with the association, therefore the potential for biotic interaction was not refuted. Only five species pairs were consistently associated across both sampling periods: stonerollers Campostoma spp. and orangebelly darter Etheostoma radiosum; red shiner Cyprinella lutrensis and bullhead minnow Pimephales vigilax; bluegill sunfish Lepomis macrochirus and redear sunfish Lepomis microlophus; redfin shiner Lythrurus umbratilis and bluntnose minnow Pimephales notatus; and bigeye shiner Notropis boops and golden shiner Notemigonus crysoleucas. Frameworks for identifying nonrandomly associated species pairs can provide insight into broader mechanisms of species assembly and point to potentially interesting species interactions (out of many possible pairs). However, this approach is best applied as a tool for sharpening hypotheses to be investigated further. Rather than a weakness, the heuristic nature is the strength of such methods, and can help guide biologists toward better questions by employing relatively cheap diversity survey data, which are often already in hand, to reduce complex interaction networks down to their nonstochastic parts which warrant further investigation.

Mapping and modeling the components of human tolerance for black bears in eastern Oklahoma

In North America, challenges associated with human-black bear (Ursus americanus) interactions have increased in recent decades. We used the structural equation modeling framework to understand how psychological factors such as perceived benefits, risks, social trust, salient value similarities, and locus of control interacted and described human tolerance of black bears in Oklahoma. Our results suggested that trust in the state wildlife agency's ability to manage black bears significantly affected both risk and benefits perception. The spatial hotspot analysis showed that residents of metropolitan areas had more positive attitudes toward black bears compared to rural residents, and more trust in the state wildlife management agency's ability to manage black bear populations. Trust in the state wildlife agency was low in rural areas, and specifically southeastern Oklahoma. Conversely, risk perception was higher in rural areas near one of the state's two extant black bear populations than in metropolitan areas removed from black bear ranges. We suggest that managers focus efforts on building strong relational foundations for trust between wildlife management personnel and rural residents in addition to demonstrating competence in black bear management techniques.

Effects of climate variability and management on shortleaf pine radial growth across a forest-savanna continuum in a 34-year experiment

We investigated the radial growth response of shortleaf pine (Pinus echinata) to climatic variation and management using tree cores collected in southeastern Oklahoma at the drier, western limit of its range. Beginning in 1984, experimental units were created by various combinations of pine harvest, hardwood thinning, and fire return intervals (1, 2, 3, 4 years and none) that produced ecosystems ranging from mature, closed canopy forest to open savanna. Monthly and seasonal weather for previous- and current-year as well as growing seasons since fire were used to determine the relationship between radial growth and climate variability (1987–2018) for different management regimes. Across all treatments, growing season precipitation (~5% decrease per 100 mm decrease in precipitation), average summer temperature maximum (~7% decrease with 1 °C increase), and previous year’s average October minimum temperature (~6% increase per 1 °C increase) were the variables most frequently correlated with variation in ring width. Annual wood and latewood growth increments were correlated (R2 = 0.60) and generally responded similarly to climate variability, with latewood more sensitive to late growing season conditions. Management with frequent fire that resulted in savanna ecosystems reduced growth sensitivity to annual variation in precipitation relative to trees in a closed-canopy forest condition. Suppressed trees were also less responsive to climate variability than intermediate or co-dominant trees. Both annual wood and latewood growth were reduced by 21–33% the first year after prescribed fire for treatments with a 2- and 3-year fire return interval. Multiple regression combing temperature and precipitation variables as well as time since fire accounted for 55% of the variability in annual ring growth.Our findings indicate that a drier climate with hotter summers will likely reduce the growth of shortleaf pine growing at the western margin of its range while warmer temperatures in October, by extending the growing season, may help ameliorate the effects of warmer summers. Management to reduce stand density, either through thinning or by prescribed fire, may dampen some of the variation of growth in response to climate variability.

Parasites (Monogenoidea, Cestoda, Nematoda) of the Banded Pygmy Sunfish, Elassoma zonatum Jordan (Perciformes: Elassomatidae), from Arkansas and Oklahoma, U.S.A.

Between January 2013 and September 2016, 14 juvenile and adult Banded Pygmy Sunfish, Elassoma zonatum Jordan, were collected in southwestern Arkansas (n = 13) and southeastern Oklahoma (n = 1) and examined for parasites. Five (36%) were infected, including 3 (21%) harboring the monogenean, Gyrodactylus heterodactylus Rogers and Wellborn, 2 (14%) with Proteocephalus sp. plerocercoids, and 5 (36%) with larval nematodes, Spiroxys sp. We document a new host as well as a new geographic distributional record for parasites of E. zonatum.

A stand level application of efficiency analysis to understand efficacy of fertilization and thinning with drought in a loblolly pine plantation

Loblolly pine (Pinus taeda L.) is the most important and productive commercial timber species in the southern USA. Common plantation management practices such as fertilization and thinning could become inefficient and economically disadvantageous given anticipated climate change effects, such as increased drought severity, especially in the drier Upper Gulf region of the south-central USA. To calculate technical and economic efficiency, we used data envelopment analysis (DEA) to assess the ability of fertilized, thinned, and drought-induced loblolly pine plots in southeastern Oklahoma (n = 32) to turn volume growth and stand density (inputs) into timber products- pulpwood, chip-n-saw, sawtimber- and stored carbon (outputs) across 21, 26, and 31-year rotations. The highest efficiencies were for the fertilized-thinned treatments. We found that thinned stands remain technically, economically, and overall efficient as rotation age increased. Non-thinned stands had lower efficiencies than thinned stands and exhibited a 28% decrease in overall efficiency between ages 21 and 31. Drought decreased overall efficiency by at least 11% when rotation age was 26 years or longer. Fertilization with drought decreased overall efficiency on average by 24%. The results reiterate the importance of thinning to efficiently mediate drought conditions and should remain a staple of plantation silviculture. Results also indicate that fertilization is not likely to help ameliorate drought impacts, from an efficiency standpoint. Study results will benefit practitioners in gauging active forest management decisions and their likely outcomes from a resource efficiency perspective.

The Process of Scientific Investigation

Book Review| December 01 2020 The Process of Scientific Investigation What Science Is and How It Really Works, By James C. Zimring. Cambridge, England: Cambridge University Press, 2019. 406 pp. Paperback, $25.99. Stanley A. Rice Stanley A. Rice Department of Biological Sciences, Southeastern Oklahoma State University, Durant, OK 74701, E-mail: srice@se.edu Search for other works by this author on: This Site Google The American Journal of Psychology (2020) 133 (4): 517–518. https://doi.org/10.5406/amerjpsyc.133.4.0517 Cite Icon Cite Share Icon Share Facebook Twitter LinkedIn MailTo Permissions Search Site Citation Stanley A. Rice; The Process of Scientific Investigation. The American Journal of Psychology 1 January 2020; 133 (4): 517–518. doi: https://doi.org/10.5406/amerjpsyc.133.4.0517 Download citation file: Zotero Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All Scholarly Publishing CollectiveUniversity of Illinois PressThe American Journal of Psychology Search Advanced Search The text of this article is only available as a PDF. Copyright 2020 by the Board of Trustees of the University of Illinois2020 Article PDF first page preview Close Modal You do not currently have access to this content.