Longleaf Pine (Pinus palustris Mill.) Morphology and Climate/Growth Responses Along a Physiographic Gradient in North Carolina

Geographic differences in tree morphology and climate and growth responses of longleaf pine have been documented, yet how these differences vary at a larger scale has not. In this study, we documented changes in tree morphology and climate and radial growth responses of six longleaf pine (Pinus palustris Mill.) stands in three physiographic regions in North Carolina. We sampled from more than fifteen trees per stand and compared site- and regional-level total and latewood ring width values to temperature, precipitation, and drought. All morphological characteristics expressed a strong west–east gradient. Climate and radial growth response was strongest for the Sandhills region and then Piedmont and Coastal Plain regions. The distinct morphological characteristic gradient did not covary with climate and radial growth response, suggesting that additional environmental influences affect needle length, trunk diameter, and height.     

EDAPHIC PROPERTIES AND FOLIAR ELEMENTAL CONCENTRATIONS FROM SAND PINE (PINUS CLAUSA) POPULATIONS THROUGHOUT FLORIDA

Soil physical and chemical properties, plus foliar elemental concentrations, are reported for surface (5–10 cm) and subsurface (35–40 cm) soil and foliar tissue samples from 20 sand pine (Pinus clausa) populations, 9 from the Choctawhatchee variety on the Florida panhandle and 11 from the Ocala variety on the Florida peninsula. Sand pine occurred exclusively on sandy soils, with mean sand content >97%. Soils generally were low in organic carbon and soil elemental concentrations. Both K and P were below analytic detection limits, whereas Ca and Mg were present at only modest levels. Only soil Al and Fe were relatively abundant. Foliar elemental concentrations indicated pronounced bioconcentration of nutrients by sand pine. Macronutrients (Ca, K, Mg, and P) approached or exceeded levels typical of other southern pine species. Some contrasts in edaphic and foliar tissue properties were apparent between varieties, but contrasts were more pronounced between groups of populations based on both soil color (yellow-sand group) and variety (Choctawhatchee white-sand and Ocala white-sand groups). The yellow-sand group, dominated by inland Choctawhatchee sites on sediments of mixed marine/fluvial origin, possessed less well sorted sand grains, higher clay content, lower pH, and higher levels of soil Al and Fe. The Choctawhatchee white-sand group consisted primarily of coastal dune sites, with well-sorted sands that reflect an eolian substrate. The Ocala white-sand group ranged primarily along the interior sand ridges of central Florida and was intermediate in sedimentological character. Foliar elemental concentrations did not reflect soil elemental patterns. Whereas Ocala samples were significantly higher in P and Mg, Choctawhatchee samples were higher in K, and there were no signficant varietal differences in foliar Ca. [Key words: sand pine, soil elemental concentrations, foliar elemental concentrations, Florida.]     

REMOTE SENSING FOREST BIOMASS: AN EVALUATION USING HIGH RESOLUTION REMOTE SENSOR DATA AND LOBLOLLY PINE PLOTS

Eight-year-old Loblolly pine (Pinus taeda) plots located in South Carolina were evaluated using high resolution aircraft multispectral scanner data to determine if biomass could be accurately measured. Sixteen pine plots located on both sandy and clay soils were treated with 0, 180, or 360 kg. (approximately 0, 400, or 800 lb.) of nitrogen per plot. Indices of biomass from remote sensing data were significantly correlated with in situ biomass measurements made in each plot. A ratio of infrared (.9–1.1 μm) and red (.65–.70 μm) channels yielded the best correlation. The indices were not sensitive to differences in soil type (sandy or clay).     

CLIMATIC RESPONSE IN TREE RINGS OF LOBLOLLY PINE FROM NORTH GEORGIA

The relationship between climate and tree-growth for loblolly pine in north Georgia is investigated by: 1) determining during which months climate has its strongest impact on loblolly pine growth, and 2) specifically examining the relationship between loblolly pine growth and growing season precipitation. Response function analyses indicate that precipitation during the current May-August period has a positive effect on pine growth, while the previous growing season shows no significant effect on growth. Significant negative effects of temperature were found during the previous June and August, current April, and the current June-September period. A regression model predicting the May-September growing season rainfall total as a function of tree-ring indices was highly significant (r² = 0.48). These results indicate that loblolly pine is a useful species for investigating the impact of climate and other factors on the recent decline of pine growth in the southeastern United States. [Key words: Dendroclimatology, tree rings, loblolly pine, Georgia.]     

RADIAL GROWTH OF HUASHAN PINE AND ITS RESPONSE TO CLIMATE

Intr0ducti0nltiswell-knownthattl1eannualringSoftreeprovideuniqueinformationfOrdeductionofpastclimaticchange.ProPertiesoftreeringrsuchaswooddensityandringwidthvaryinresPOnsetoclimaticc0nditionsthatlimittreegrowth[7,l4].ByunderstandingtherelationsllipsbetweentreegroWthandclimatevariables,PaStclimaticvariationscanbederivedfromtree-ringdata.InChina,mostdendroclimaticstudieshavebeenconductedonclimaicallyextremesites[l2,l8,l9].TreesgrOwingonsuchsiteshavestrongandstraightfO~relationshipswithclim…     

Holocene regional and local vegetation history and lake-level changes in the Torneträsk area, northern Sweden

A combination of pollen and macrofossil analyses from six lakes at altitudes between 370 and 999 m above sea level (a.s.l.) in the Torneträsk area reflect the Holocene vegetation history. The main field study area has been the Abisko valley at altitudes around 400 m a.s.l. The largest lake, Vuolep Njakajaure has annually laminated (varved) sediments. The chronology and sedimentation rates in the pollen-influx calculations are based on varve yrs in this lake and on radiocarbon dated terrestrial plant macrofossils in the other lakes. A strong increase of mountain birch (Betula pubescens ssp. tortuosa) during the early Holocene with a tree-line c. 300 m above the present, indicates that the summer temperature was c. 1.5 °C higher than today, assuming that the land uplift has been 100 m since then. Scattered stands of pine (Pinus sylvestris) may have been growing in the area immediately after the deglaciation but a forest consisting of pine and mountain birch expanded first at low elevations and reached the eastern parts of the Torneträsk area at c. 8300 cal BP and the western parts at c. 7600 cal BP. The highest pine-birch forest limit was not reached until 6300 cal BP (110 m above present pine limit). Warm and dry conditions during the pine forest maximum led to lowering of the water level documented in Lake Badsjön in the Abisko valley about 1-1.5 m lower than today. Pine and mountain birch were growing at the maximum altitude until c. 4500 cal BP. Assuming that land uplift has been in the range of 20-40 m since the mid-Holocene, this implies that the temperature was then c. 1.5-2 °C higher than today. Rising lake-levels and lowering limits of pine and mountain birch since c. 4500 cal BP indicate a more humid and cool climate during the late Holocene.     

A 545-Year Drought Reconstruction for Central Oregon

Using a 545-year ponderosa pine (Pinus ponderosa) tree-ring chronology, we examine the drought history of central Oregon to: (1) determine the relationship among drought, ENSO (El Niño/Southern Oscillation), and the PDO (Pacific Decadal Oscillation), and (2) compare the climatic sensitivity of ponderosa pine and western juniper (Juniperus occidentalis) to determine their suitability as interchangeable climate proxies. Our climatic reconstruction explained 35% of the variance in historical Palmer's Drought Severity Index (PDSI) values and revealed severe drought periods during the 1480s, 1630s, 1700s, and 1930s. The most sustained drought period in our reconstruction occurred during the 1930s, with the most severe single drought year occurring in 1489. We found a significant (p ≤ .01) but weak relationship between our ponderosa pine chronology and ENSO and the PDO, explaining 9% and 12% of the variation respectively. Both ponderosa pine and western juniper record periods of severe regional drought, but western juniper is more sensitive to regional and seasonal climatic variations, whereas ponderosa pine is more responsive to temperature change. These differences suggest that their substitutability as climate proxies in dendroecological studies is limited.     

Radial Growth and Increased Water-Use Efficiency for Ponderosa Pine Trees in Three Regions in the Western United States

We examined changes in and relationships between radial growth and intrinsic water-use efficiency (iWUE) of ponderosa pine (Pinus ponderosa) trees, climate, and atmospheric CO₂ in the western United States since the mid-nineteenth century. We developed tree-ring chronologies for eight sites in three climate regions and used carbon isotope data to calculate pentadal values of iWUE. We examined relationships among radial growth, climate, iWUE, and CO₂ via correlation and regression analyses. Significant upward trends in iWUE occurred at all sites, and despite an absence of climate changes that would favor growth, upward radial growth trends occurred at five sites. Our findings suggest that increased iWUE associated with rising CO₂ can positively impact tree growth rates in the western United States and are thus an evolving component of forest ecosystem processes.     

COMPARING INVASIVE NETWORKS: CULTURAL AND POLITICAL BIOGRAPHIES OF INVASIVE SPECIES*

ABSTRACT. Under what cultural and political conditions do certain species become successful invaders? What impact does species invasion have on human culture and politics? The work assembled in this special issue of the Geographical Review suggests complex interspecies interactions that complicate any answer to these questions. It demonstrates the need to advance a more integrative human/environment approach to species invasion than has hitherto been seen. Reviewing the concepts demonstrated in these articles and applying them to case histories of Mimosaceae (a family that includes genera such as Acacia, Prosopis, and Mimosa) invasion, two general principles become clear. The status and identification of any species as an invader, weed, or exotic are conditioned by cultural and political circumstances. Furthermore, because the human “preparation of landscape” is a prerequisite for most cases of invasion, and because species invasions impact local culture and politics in ways that often feed back into the environmental system, specific power‐laden networks of human and non‐human actors tend to create the momentum for invasion. It is therefore possible to argue a more general cultural and political account of contemporary species expansion: It is not species but sociobiological networks that are invasive.     

Geographical variation on cone and seed production of natural Pinus halepensis Mill. forests in Tunisia

Aleppo pine (Pinus halepensis Mill.) is found in discontinuous bands along the Mediterranean Basin, usually at low elevations and in dry climates. This study was conducted to relate bioclimatic zones and geographic distribution with representative individual tree of populations for cone number and weight from the driest to the wettest Aleppo pine forest zones. Epidometric values were recorded in all sample stands in the monitoring plots set in 79 native populations from the Algerian border to the eastern coast of Tunisia, representing a wide range from each region in northern Africa. Simple and multiple regressions were performed on the data. Results showed that the canopy seed bank increased according to elevation, latitudinal and longitudinal gradients. The simple regression analysis showed a latitudinal effect positively relating increasing latitude to greater cone crop. Similarly, longitudinal and elevation variations were related to significant differences in cone dimensions. Higher average seed mass was related to populations located westwards or at higher elevation. The multiple regression analysis indicated that the longitudinal variations were the most determinant geo-positional factors in Aleppo pine cone dimensions and average seed mass in natural Aleppo pine forests in Tunisia.     

樟子松沙地适应性的初步研究

根据樟子松形态、生态和生理特征，初步分析讨论了其沙地适应性。     

The effects of seasonal changes to in-stream vegetation cover on patterns of flow and accumulation of sediment

In-stream macrophytes are typically abundant in nutrient-rich chalk streams during the spring and summer months and modify the in-stream environment by altering river flows and trapping sediments. We present results from an inter-disciplinary study of two river reaches in the River Frome catchment, Dorset (UK). The investigation focused on how Ranunculus (water crowfoot), the dominant submerged macrophyte in the study reaches, modified patterns of flow and sediment deposition. Measurements were taken on a monthly basis throughout 2003 to determine seasonal patterns in macrophyte cover, associated changes in the distributions of flow velocities and the character and amount of accumulated fine sediment within stands of Ranunculus.Maximum in-stream cover of macrophytes exceeded 70% at both sites. Flow velocities were less than 0.1 m s^− 1 within the stands of Ranunculus and accelerated to 0.8 m s^− 1 outside the stands. During the early stages of the growth of Ranunculus, fine sediment mostly accumulated within the upstream section of the plant but the area of fine sediment accumulation extended into the downstream trailing section of the plant later in the growing season. The fine sediment accumulations were dominated by sand (63–1000 μm) with silts and clays (0.37–63 μm) comprising < 10% by volume. The content of organic matter in the accumulated sediments varied within stands, between reaches and through the growing season with values ranging between 9 and 105 mg g^− 1 dry weight. At the reach scale the two sites exhibited different growth forms of Ranunculus which created distinctive patterns of flow and fine sediment deposition.     

MIGRAT: A COMPUTER-ASSISTED INSTRUCTIONAL PROGRAM FOR THE SIMULATION OF MIGRATION

Primary individuals and the households that they head now compose a significant proportion of US households. This paper examines the regional and intraurban distribution of primary households. Macro-scale data from the 1960 and 1970 Censuses are used to examine the evolving regional patterns of primary individuals and households. Using intraurban data for the 1970's, the paper also examines the impact of recent rapid growth in the number of primary individuals on the spatial distribution of primary households within urban areas. Inferences are drawn with respect to the macro- and micro-scale distributions of primary individuals and households and the impact of continued growth of this subpopulation on urban form and population distribution.     

Natural reforestation of abandoned farmland: the role of soils

Natural regeneration of abandoned farmland in several areas within the catchments of the Sydney Water Board has been very slow. Several hypotheses have been put forward to explain the fact that natural reforestation has not occurred, even after up to 50 years of abandonment. This study examines regeneration in relation to substrate, soil types and soil chemistry. The abandoned farmlands occur on four main soil types: (i) eutrophic krasnozem, now occupied mainly by bracken fern (Pteridium esculentum) associated with young seedlings of Eucalyptus and Acacia; (ii) mesotro‐phic yellow earth, now occupied by blady grass (Imperata cylindrica), with few tree seedlings and scattered, dead Acacia trees; and (iii) mesotrophic alluvial soil, and (iv) oligotrophic lithosol, which both support stands of Acacia. The soil properties of the krasnozem and the yellow earth appear to be suitable for tree establishment and growth, and do not differ from similar soils in nearby areas currently under cultivation or supporting undisturbed forest. Poor forest establishment in these soils might be the result of frequent fires and biotic factors such as competition from the bracken and blady grass sward. The lack of eucalypt reforestation of the poorer soils might be explained by their poorer fertility, perhaps tolerated better by the Acacia species.     

气候变化对我国红松林的影响

在对红松适生范围、生态习性等广泛深入调查分析基础上,依据环境因子对树木生长影响的作用规律,首先推出一个能反映红松年生长量与水热因子间关系的W-T模式,进而分析了各种可能的气候变化对红松生长量与分布的影响。结果表明,气温升高,无论降水增减,都将使红松适生范围与生长量大幅度减少。但在可预见的气候变化范围内,红松不会退出我国的东部山地。     

Radial growth rates of two co-occurring coniferous trees in the Northern Rockies during the past century

We examined radial growth rates of locally co-occurring Douglas-fir (PSME – Pseudotsuga menziesii var. glauca) and ponderosa pine (PIPO – Pinus ponderosa var. ponderosa) trees growing within the Northern Rockies to determine if there are differential growth and climatic responses between these species and whether these responses are consistent among topographically and climatologically diverse sites. We developed standardized tree-ring chronologies from seven sites, with each site a matched pair of PSME and PIPO. For each chronology we examined the climate response of radial growth by comparing the standardized ring widths to a suite of climatic variables. We examined temporal changes by comparing 1905–1950 and post-1950 growth rates and climatic conditions. Both conifers experience increased radial growth post-1950. A combination of spring/summer moisture conditions related positively to radial growth and the primary climatic drivers were consistent both between species and within the region. The primary climatic drivers of radial growth remain unchanged during the last century or have trended toward drier conditions unfavorable for growth. We conclude that increases in standardized radial growth rates are unlikely climatically-driven. Other potential vectors of radial growth change, such as atmospheric CO₂ enrichment, have affected these co-occurring species on a largely equal basis and positively.     

Pine plantation bands limit seedling recruitment of a perennial grass under semiarid conditions

Pine plantations coexist with Stipa tenacissima grasslands in many semiarid western Mediterranean areas. We compared three microsites created by a 30-year-old Pinus halepensis plantation: below pine plantation line (BP), below canopy of pines (BC) and interline bare band (BA). They were evaluated in terms of soil properties, pine litter and suitability as recruitment niches for S. tenacissima. Next, in a manipulative experiment in growth chambers we tested the hypothesis that pine litter interferes with the seedling emergence of S. tenacissima. Three treatments in pots were compared: (a) soil from BA; (b) intact soil + litter from BP; and (c) soil + litter from BP, which was mixed in the laboratory (BPMX). In the field the main microsite differences were pine cover and litter cover and thickness. Seedling emergence was significantly greater in BA than in BP. Emergence and litter depth fits a linear regression model. In the growth chamber litter did not interfere with the emergence of S. tenacissima. However, seedlings grown without litter were 28% longer and their mass was 27% greater than in the litter treatments. The detected pine litter interference may be relevant for plant dynamics and might be considered in forestry management programs.     

Modeling the Invasion of Holly (Ilex aquifolium): Spatial Relationships and Spread Trajectories

In this study, we investigated the environmental factors associated with the establishment of invasive English holly (Ilex aquifolium) and the spatiotemporal trajectories of its potential spread. We collected georeferenced presence and absence and demographic data of holly between 2011 and 2014 in Saint Edward State Park, Washington. We analyzed them through a spatially explicit framework that combines multiple logistic regression, cellular automata, and bivariate quadratic modeling. Results showed that the presence of holly is influenced by the proximity to evergreen coniferous vegetation and forest edge, distance to streams, forest structure, and slope direction. Our study confirmed that local environmental conditions, species characteristics, and vegetative and dispersal mechanisms play a significant role in determining the rate and success of holly establishment across the different phases of invasion. Invasive species management plans should consider both species characteristics and their habitat and the interactions among them when planning long-term strategies for control and eradication.     

Reconstructing a cultural fire regime in the Pennsylvania Anthracite Region

Abstract

Fire history reconstructions provide fire managers with valuable information regarding historical fire regime dynamics. Yet, in the Central Hardwood Forest Region (CHF), there is an absence of dendroecological studies where frequent wildfires have persisted into the twenty-first century. This study presents the first documented tree-ring reconstruction of fire history in the Pennsylvania anthracite coal-producing region. An approximately 150-year fire chronology was developed from fire-scarred pitch pine (Pinus rigida) and sassafras (Sassafras albidum) collected on Spring Mountain in Schuylkill County. Principal component analysis and k-means cluster analysis were used to identify four fire regime clusters based on interacting fire and non-fire parameters. Results indicate that fires occurred under a variety of moisture conditions and that a mid-twentieth century increase in fire activity on Spring Mountain was associated with the collapse of the regional anthracite industry and possibly amplified by the 1960s drought. Fires continue to burn on Spring Mountain in the twenty-first century, contrary to the dominant pattern of fire exclusion across the CHF. Future research needs are highlighted regarding historical fire regime dynamics and cultural ties to landscape burning in the Pennsylvania Anthracite Region.     

Palynological study of Holocene sediments from Lake Doirani in northern Greece

A palynological investigation was conducted on two cores with Holocene sediments collected from the northeastern littoral part of the border Lake Doirani in northern Greece. The radiocarbon dates indicated that the analyzed sediments accumulated during the last 5000 yrs. The pollen-stratigraphic record revealed the environmental changes in the catchment area, starting from a natural undisturbed landscape to one modified by increasing anthropogenic influences. The tree vegetation dominated by Quercus woods in the lowlands and byPinus, Abies, and Fagus at higher altitudes, lasted for the period 2900 - 830 cal. B.C. Subsequently it was replaced by xerothermic herb and tree vegetation as a result of intensive human activity - and farming and stock-breeding. The accumulation of sediments with more sand and gravel in historical time was the result of increased erosion.