Introduced Woody Species Research Articles

Spenders versus savers: Climate‐induced carbon allocation trade‐offs in a recently introduced woody plant

Abstract Non‐structural carbohydrate (NSC) storage may be under strong selection in woody plant species that occur across broad environmental gradients. We therefore investigated carbon (C) allocation strategies in a widespread non‐native woody plant, Tamarix. We predicted that genotypes with exposure to episodic freeze events would show elevated NSC concentrations compared to warm‐adapted genotypes with the trade‐off of reduced growth and reproduction relative to warm‐adapted populations. We established an experimental common garden using genotypes of Tamarix, sourced across a strong thermal gradient within the introduced range. We measured seasonal NSC storage in coarse roots and stems, above‐ground growth and flower production. Autumn NSC concentrations were 50% higher in genotypes from sites with episodic spring freeze events compared to genotypes from warmer sites. These cold‐adapted genotypes also had a 2.3‐fold higher starch to soluble sugar ratio than warm‐adapted genotypes. Across all genotypes and seasons, NSC storage was inversely correlated with growth and reproduction. Results suggest that Tamarix from colder locations cope with freeze events by maintaining large storage pools to support tissue regrowth, but with the trade‐off of overall reduced growth and reproduction. Our results are consistent with rapid selection in C allocation strategies in response to climate in introduced woody species. A free Plain Language Summary can be found within the Supporting Information of this article.

Prioritizing woody species for the rehabilitation of arid lands in western Iran based on soil properties and carbon sequestration

Plants are an important component in many natural ecosystems. They influence soil properties, especially in arid ecosystems. The selection of plant species based on their adaptations to site conditions is essential for rehabilitation of degraded sites and other construction sites such as check-dams. Other factors to be considered in species selection include their effects on soil properties and their abilities to meet other management objectives. The purpose of this study was to assess the effects of native (Populus euphratica Oliv. and Tamarix ramosissima Ledeb.) and introduced (Eucalyptus camaldulensis Dehnh. and Prosopis juliflora (Swartz) DC.) woody species on soil properties and carbon sequestration (CS) in an arid region of Iran. Soil sampling was collected at three soil depths (0–10, 10–20 and 20–30 cm) at the sites located under each woody species canopy and in an open area in 2017. Soil physical-chemical property was analyzed in the laboratory. The presence of a woody species changed soil characteristics and soil CS, compared with the open area. For example, the presence of a woody species caused a decrease in soil bulk density, of which the lowest value was observed under E. camaldulensis (1.38 g/cm3) compared with the open area (1.59 g/cm3). Also, all woody species significantly increased the contents of soil organic matter and total nitrogen, and introduced species had more significant effect than native species. The results showed that CS significantly increased under the canopy of all woody species in a decreasing order of P. euphratica (9.08 t/hm2)>E. camaldulensis (8.37 t/hm2)>P. juliflora (5.20 t/hm2)>T. ramosissima (2.93 t/hm2)>open area (1.33 t/hm2), thus demonstrating the positive effect of a woody species on CS. Although the plantation of non-native species had some positive effects on soil properties, we recommend increasing species diversity in plantations of native and introduced woody species to provide more diversity for the increased ecosystem services, resilience, health and long-term productivity.

The composition and state of native and introduced woody species in the zone of railway transport influence in the Kola Polar region

The paper analyzes the state and the diversity of native and introduced woody plants used in landscaping railway stations in 5 cities of the Kola Polar region. The species composition is represented by 22 species, 16 genera, and 9 families. Sorbus gorodkovii (39%) is the most common among trees, Rosa rugosa (44%) is the most common among shrubs. The authors have observed two rare introduced woody species (Larix sibirica Ledeb., Syringa josikaea Jacq. fil.) included in Red Data Books of various ranks. 6 categories of plant state have been identified. Betula pubescens has the largest share of healthy plants among indigenous trees species, Malus baccata and Larix sibirica among introduced species, Rosa pimpinellifolia, Caragana arborescens, Crataegus sanguinea among shrubs in the station territories. Sorbus gorodkovii and Padus avium are in a critical state. The agrochemical soil study showed a low availability of nitrogen compounds and a high content of phosphorus and potassium exchange forms. It has been revealed that the main weakening causes are old age of plants, violation of maintenance technology, and failure to comply with environmental conditions.

Impacts of Restoration Projects on a Sahelian Woody Vegetation after 21 Years: The Simiri Plateaus (Niger) Case Study

To face the soil and vegetation degradation in Niger, anti-erosion structures, such as scarification of the surface of the ground, half-moons, benches, trenches, stony cordons, were built in 1989 on three Simiri plateaus. Native and introduced woody species were planted and grasses were sown within the structures. This study aims at evaluating what has become the restoration of the woody vegetation cover compared to an un-restored woody cover located on a nearby similar site. Dendrometric parameters and alpha and beta diversities of the four woody stands in 36 sampled plots were analyzed and compared. The following dendrometric values were found significantly lower in the control than in the restored stands: 3.9% against 12.4-16.8% for the recovery rate, 4.3 against 6.3-10.2 cm for the largest stem diameter, 0.2 against 0.8-1.2 m²/ha for the basal area, and 1.6 against 2.0-2.5 m for the tree height. However, the number of stems per trees was found significantly greater in the un-restored stand (6.6) than in the restored ones (1.8-2.7). The values of dendrometric parameters remained low, as well as the alpha and beta diversities whatever the stand. Nevertheless, population perceptions on the restoration impacts that were collected through focus groups indicated positive impacts on downstream crop yields.

Propagule pressure, presence of roads, and microsite variability influence dispersal of introduced Quercus rubra in temperate Pinus sylvestris forest

The effective sustainable management of introduced woody species requires understanding of the mechanisms which affect successful colonization in different forest habitats. We studied the spontaneous spread of the alien species – Northern red oak (Quercus rubra) in the Scots pine (Pinus sylvestris) forest located in Poland. We analysed the impacts of seed source distance, presence of and distance from linear structures (public and forest roads) in the landscape, as well as microhabitat diversity, on the distribution of juvenile red oaks. We also studied the effects of types of acorn deposition sites (under shrubs, within clumps of Vaccinium myrtillus, in the open), and ways of seed burial (in moss wefts, in rodent corridors) by animal seed hoarders on seed germination and seedling growth. Field data were collected in six transect lines divided into 3300 plots (1 m2 each). We found that Q. rubra efficiently colonizes Scots pine monoculture. Results of spatially explicit hierarchical generalized linear models showed that distance from acorn sources and occurrence of sparse shrub layers are the most important predictors of Q. rubra ecological success, defined as establishment of juvenile specimens. The presence of roads – potential migration corridors for avian and mammalian acorn consumers/dispersers – favoured non-random red oak spread. The “nurse effect” of native understory components on red oak seed germination and seedling growth was indicated by higher numbers of juvenile specimens as well as by higher proportions of germinated seeds noted under shrubs than in open areas (without shrubs) or within clumps of V. myrtillus. All red oaks developed from seeds buried in compact moss wefts or in spacious caches and corridors created by rodents in the moss layer, which indicated a positive “burial effect”. We conclude that microhabitats make the Scots pine forests very suitable for Q. rubra invasion. Because of the wide distribution of numerous red oak stands in European temperate forests and the presence of numerous oak seed dispersers, the continuous colonization of widespread Scots pine monocultures by Q. rubra must be expected.

THE IMPORTANCE OF WOODY PLANT INTRODUCTION FOR FOREST TREES IMPROVEMENT

The history of woody plant introduction is closely linked with that of transportationand the European exploration of the planet (16th–19th centuries). Each colonialpower established major botanical gardens and experimental stations in variousparts of the world. By the 20th century, the purpose of introductions shifted fromfood plants to timber and other species yielding non-agricultural products. Finally,during the latter part of the 20th century the importance of ornamental speciesincreased dramatically, especially to the more developed and wealthier regions.Over the past two centuries many species have started to spread in their introducedranges. Until relatively recently the majority of introduced woody species havebeen highly beneficial, if not essential, to humanity’s development, but now everincreasingnumbers of species are becoming detrimental to the maintenance of theearth’s biodiversity and to the well-being of human societies. Throughout the 19thand specially in 20th century the large-scale planting of trees for timber productionhas been one of the main reasons for the introductions of a large number of species,especially conifers e.g. Pinus, Picea. Pseudotsuga and Poplars and Willowsspecies. By using methods of mass and individual selection and by establishing ofprovenances tests, as well as by half and full sib lines of selected exotics test trees,genetical potential productivity and adaptability of introduced species have beentested in numerous experimental plots in areas where introduced have been done.This paper attempts to unravel the relationships between humans and woody plantsby looking at the changes in the introduction of species, the way they are perceivedby different human groups and the impact these non native species have on foresttrees improvement and other human activities.

Sledování fenologie modřínu opadavého (Larix decidua Mill.) v oblasti Drahanská vrchovina

The phenological study on the onset and duration of individual phenological phases of European larch (Larix decidua Mill.) has been performed using sample trees growing in the research station of the Faculty of Forestry and Wood Technology, MUAF Brno for altogether 15 years. This study involves also recording of meteorological data. In this region, the European larch is an introduced woody species and its share in the stand composition is approximately 8%. In European larch, the phenological stages have a markedly periodic character but they are also largely dependent on a complex of exogenous conditions, especially of climatic effects; this was corroborated also in studies on the phenology of other forest tree species growing in this region. Results of this phenological study demonstrated that the spring phenophases were influenced above all by air temperatures while the autumn ones were dependent, besides temperatures and precipitation, also on the duration of assimilation apparatus activities. The onset of breaking of needles occurred between Days 89 and the 110 of the calendar year. A full development of the assimilation area was reached between Days 125 and 150. The onset of individual phenophases was determined by threshold air temperatures, which were markedly different in individual forest trees. This requirement could be expressed at best by the sum of effective temperatures (i.e. air temperatures above 5 °C). In the analysed fifteen-year study period, the sum of effective temperatures for European larch ranged from 1 301.0 to 2 337.0 °C within the period delimited by dates of the flushing and 100-percent fall (abscission) of needles.Results of a long-term phenologic monitoring of forest woody species may be used when evaluating the condition of forest stands from the viewpoint of expected global climatic changes.

Invasive conifers reduce seed set of a native Andean cedar through heterospecific pollination competition

The invasion of natural forest communities by introduced woody species may threat processes that are critical for ecosystem integrity, including plant pollination and reproduction. In particular, invasive conifers (e.g., Pseudotsuga menziesii, Pinus spp.) escaped from forest plantations may impair seed production of anemophilous native conifers by altering the dynamics of wind-borne pollen flow among trees. In this study, we analyzed the effects of invasive conifers on the pollination and sexual reproduction of Andean cedar (Austrocedrus chilensis), a dioecious conifer native to the temperate forests of southern South America. Wind-dispersed pollen captured in pollen traps revealed that the timing of pollen release between the invasive and native conifers overlapped extensively, and the pollen cloud surrounding female cedar trees in invaded forest was heavily contaminated with pollen from the invasive conifers. Increasing abundance of invasive conifers in the proximity of female cedars decreased the local density of air-borne cedar pollen and increased contamination of the pollen cloud with pollen from the invasive conifers. This increased the chance of finding heterospecific pollen from these invaders in the micropyles of the native cedar. In turn, the presence of pollen grains from invasive conifers, particularly of P. menziesii, in the cedar’s micropyles was associated with a strong increase in the percentage of seed abortion. Our results clearly support the hypothesis that invasive conifers can interfere with the pollination and sexual reproduction of native wind-pollinated conifers. Thus, plantations of introduced and highly invasive conifers should not occur in the proximity of stands of native conifers in order to guarantee their reproduction and long-term population viability.

The framework tree species approach to conserve medicinal trees in Uganda

Framework species are indigenous tree species planted in a mixed stand to accelerate natural regeneration of forest and encourage biodiversity regeneration. In this study we used the framework species method to make multipurpose tree gardens to provide traditional healers with woody species used for medicine and other needs like food and firewood. We specifically determined the phenology, germination behaviour, survival and growth after planting 19 indigenous and 8 introduced woody species. The species were planted in a mixed stand together at a density of 3125 ha−1. Field performance was assessed by monitoring survival, height and crown width once every month for 13 months after planting. Eleven species (Artocarpus heterophyllus, Calliandra calothyrsus, Callistemon citrinus, Carica papaya, Carissa spinarum, Leucaena leucocephala, Markhamia lutea, Sarcocephalus latifolius, Senna siamea, S. spectabilis and Terminalia schimperiana) proved to be excellent framework species. Eight species qualified as ‘acceptable’ FWS (Albizia coriaria, Ceiba pentranta, Entada abyssinica, Erythrina abyssinica, Eugenia jambos, Ficus sycomorus, Maesopsis eminii and Milicia excelsa), while seven species were ranked as ‘marginally acceptable’ (Acacia macrothyrsa, Calpurnia aurea, Canarium schweinfurthii, Capparis tomentosa, Ficus natalensis, Senna sp. and Warburgia salutaris). Annona squamosa was the only species rejected since both germination and survival was low. Trees with good reforestation traits could be recommended for planting while the species that were marginally acceptable or rejected require extra research since some of them are important medicinal woody species of conservation concern.

Ranking of invasive woody plant species for management on Réunion Island

SummaryThe native flora of Réunion Island in the Indian Ocean is threatened by invasive woody plants introduced for agriculture, forestry or as ornamentals. We reviewed archives to identify woody plants introduced since colonisation and ranked the biological impact of the main non‐indigenous species on native vegetation. The relationship between cumulative number of non‐indigenous plants and population follows an s‐shaped curve, but the rate of introduction was mainly determined by historical periods with five main introduction phases identified. A total of 318 introduced woody species were recorded with 132 identified as naturalized in natural ecosystems. Of these, 26 of the more serious invasive species (i.e. having a large biological impact on the new environment) were selected and ranked by biological impact to native ecosystems. Hiptage benghalensis, Ligustrum robustum var. walkeri, Acacia mearnsii, Ulex europaeus and Psidium cattleianum were identified as having the highest invasiveness capacity and the greatest impacts on succession and utilization of resources in natural areas. A strategy is required to manage high‐priority invasive species and reduce the rate of non‐indigenous plant introductions to the island.

Recent changes in riparian vegetation: possible consequences on dead wood processing along rivers

AbstractLittle is known about changes in the composition of dead wood jams along rivers and the possible consequences of any such changes on the river ecosystem. Although tree zonation along the upstream‐to‐downstream continuum is weak and highly variable from a system to another, a clear transition appears in the piedmont zone, which is reflected by transitions in dead wood sources as well as for dead wood transport, storage and decomposition processes. In this paper, we focus on large lowland rivers of southwestern France, where riparian vegetation is increasingly fragmented, reduced in area and/or is entirely replaced by planted forests (poplar plantations). The amount and the potential role of dead wood is practically unknown in these rivers. One reason is that French legislation obliges landowners and public service managers to remove all material from the stream in order to maintain unobstructed river flows. The other reason is that unlike pristine streams in northern regions, these rivers have been regulated for several decades (Adour River) or even for several centuries (Garonne River). The vegetation component of the managed riparian landscape has changed in particular as a result of i) a decrease in stream dynamics, ii) the replacement of natural forests by planted ones, and iii) the invasion of natural communities by introduced woody species.The possible consequences of biological invasions on the role of dead wood jams are discussed in light of: i) a local study of wood jams along a moderately modified system; ii) changes observed in the composition of trees along the Adour River over the past 10 years; iii) a regional case study involving two chosen species. Whereas white willow populations are declining along streams in southwestern France, the box‐elder, introduced from the United States, has spread extensively in the last two decades. Statistical models would suggest that competitive pressures are limited between these two species, boxelder is expected to replace white willow in the near future as a consequence of an increase in river regulation and global warming. This can be expected to have important consequences on dead wood dynamics, and on the management of woody debris, especially since trends indicate a replacement of softwood species by hardwood species. Copyright © 2003 John Wiley & Sons, Ltd.

Prescribed Fire and the Response of Woody Species in Willamette Valley Wetland Prairies

A single fall‐season prescribed burn and two consecutive fall‐season prescribed burns were conducted in 1988 and 1989 to quantify the effects of fire intensity and frequency on woody species in two Willamette Valley wet prairies. Fuel biomass, fuel properties, fire behavior, biomass consumption, and changes in woody species density and height were documented before and after the burns. Before burning, Rosa nutkana (Nootka rose) was the most abundant woody species at both sites. In 1988, burns were significantly more intense, produced more heat per unit area at Fisher Butte than at Rose Prairie, and were fairly complete, with 37% and 35% woody biomass consumption, respectively. In 1989, burns were spotty; only 11% of woody biomass was consumed at Fisher Butte. The one‐burn treatment did not affect R. nutkana density in 1 × 15 m transects at either site; the two‐burn treatment significantly increased its density in three of the five communities sampled. Burning significantly reduced height growth by eliminating taller individuals while stimulating sprouts from belowground tissues. Redistribution of R. nutkana and trees into shorter height classes indicates the possibility of reducing the visual dominance of woody species if periodic burns were conducted in native Willamette Valley prairie. The low‐intensity burns in this study were sufficient to remove the woody shoots under 3 m tall but did not reduce their capacity to regenerate and did not reduce the density of woody species. After decades of fire suppression, two burns were not sufficient to reestablish the desired balance between native herbaceous and woody species or to reduce the presence of introduced woody species. A long‐term commitment to the reintroduction of fire as a management tool will be required to maintain native wetland prairies in the Willamette Valley.