Effect of forest landscapes composition and configuration on bird community and its functional traits in a hotspot of biodiversity of Chile

Understanding the effect of landscape configuration on the bird species richness and their functional traits (dietary preferences) is important to link the conservation and restoration plans to the production of the crops. Our aims were: 1) to study the influence of forest types (native, mixed and plantations) on the bird species richness in two agroforestry landscapes (heterogeneous/homogeneous); 2) to assess the effect of size/density of forest patches in the birds’ functional traits; 3) to evaluate the effect of isolated trees on them, and 4) to discuss conservation and restoration measures for the birds’ functional traits in agroforestry landscapes. We used hierarchical occupancy models to evaluate the effect of different landscape metrics and detectability measures on bird communities. We recorded a total of 64 bird species. The estimated species richness was considerable higher in homogeneous landscape (31.7 ± 2.7) than heterogeneous (27.3 ± 2.5). Our results showed the bird assemblage had a positive trend with native forests, negative with mixed forests and neutral trend for plantations. The granivores and insectivore’s species showed significant preferences for homogeneous landscape, while omnivores had significant preferences for heterogeneous landscape. Carnivores/Piscivores and herbivores/frugivores species did not show preferences by any landscape type. The response of functional traits depended on different forests attributes. The isolated trees had a significant effect on the birds’ functional traits. In conclusion, it is necessary a deep knowledge about the relationship between the landscape configuration and the bird species richness/functional traits. These findings could help in the future with the conservation, restoration, and rewilding policies in this important hotspot of biodiversity, avoiding alterations in the ecosystem services.     

Stand-level management of plantations to improve biodiversity values

As conservation reserves expand, the likelihood that they will capture areas degraded by previous land use increases. Ecological restoration of such areas will therefore play an increasing role in biodiversity conservation. On the New South Wales North Coast, recent expansion in the conservation estate has captured over 300 softwood and hardwood plantations, many with understoreys dominated by exotic weeds. Here we present an overview of the practices we have adopted in managing flooded gum (Eucalyptus grandis) plantations infested with lantana (Lantana camara) to enhance their biodiversity value. Experiments designed to overcome barriers limiting regeneration of native forest in conjunction with measurement of soil and plant responses yielded insights into the management of former timber plantations for biodiversity. Canonical Correspondence Analysis indicated that the level of canopy retention (or logging intensity) within sites consistently explained the greatest amount of variation in plant community composition (32–38% post-treatment). Thinning and burning stimulated regeneration of native species. Retained canopy cover was proportional to the richness or abundance of native woody shrubs, understorey trees and native perennial herbs, indicating that management intensity can be varied to promote a range of conservation values. A state-and-transition model summarising purported management actions and likely outcomes for these plantations is presented. This is the first time plantations have been managed solely for biodiversity. Logging income means that plantation restoration can be cost-neutral, and the positive influence of a cover crop of trees means that plantation management may generally be manipulated to promote biodiversity conservation.     

Photosynthetic responses to overnight frost in Eucalyptus nitens and E. globulus

Significant expansion in the area of eucalypt plantations in Tasmania has led to their establishment at altitudes that are close to the upper limits of the planting distributions of Eucalyptus nitens and E. globulus, the main species planted. This has implications for plantation productivity. We investigated the processes that limit productivity in these environments through a study of freezing-induced depression of photosynthesis of E. nitens saplings in the field and plantlets of E. nitens and E. globulus clones in a controlled environment cabinet. In the field consecutive frosts of around –4.6°C had a cumulative effect, reducing maximum net photosynthesis ( A _max) by 17%, and then a further 9%, respectively, compared with saplings insulated from the frosts. Shading saplings pre-dawn had no effect on A _max measured after 1030 hours indicating that the reduction in A _max at this time was independent of photoinhibition. Recovery of A _max to pre-frost levels required at least two consecutive frost-free nights and was dependent on the severity of frost. Photosynthetic light response curves indicated that reduced A _max was associated also with decreased quantum yield and stomatal conductance. Similar intracellular carbon dioxide concentration between exposed and insulated saplings indicated that low stomatal conductance did not limit photosynthesis through carbon dioxide limitation. The timing of frost events was critical: E. nitens saplings took less time to recover from reduced A _max in the field when they were hardened. Unhardened plantlets of E. nitens and E. globulus clones had greater reduction of A _max and took longer to recover from frost events than hardened plantlets. E. globulus was more susceptible to frost-induced reduction of A _max than E. nitens. This is consistent with its planting range which is restricted to mild sites compared with that of E. nitens.     

Deposition of exotic bird-dispersed seeds into three habitats of a fragmented landscape in the northeastern United States

Dispersal by frugivorous birds facilitates invasion by many exotic plants. We measured the seed rain of ornithochorous native and exotic plants at three habitats of a fragmented landscape of the northeastern United States for 1 year. We studied maple-beech forests, old fields, and abandoned conifer plantations. Across all sites we collected 2,196 ornithochorous seeds, including seeds from six exotic species and 10 native species. The majority (90%) of collected seeds were from exotic species. Seed dispersal was broadly similar among habitats, though seed rain of exotic species was higher in old fields than forested habitats. Seed rain was not strongly influenced by artificial perches for most species. However, seeds of exotic species were more commonly found in traps under an artificial perch in old fields. Seed rains for the exotic Elaeagnus umbellata, Rhamnus cathartica, and Rosa multiflora were positively associated with local density of mature plants. Seed rain of R. cathartica was positively associated with abundance of seedlings but not saplings, suggesting that post-dispersal mortality was important. Seed dispersal of the exotic Lonicera spp. was high in all habitats, accounting for 66% of all seeds collected. With the exception of Lonicera spp., seed rain of common exotic invaders was affected by the abundance of seed sources, and these species might be effectively controlled by elimination of local fruiting plants. Fruits of Lonicera morrowii, which has extensively invaded our area, are apparently a common component in the diet of frugivores.     

香港三种人工林下植物多样性的调查

报道了作者于1995年6月至19％年1月期间对香港3种人工林－红胶木林、相思树林、荷树及其混交林林下植物区系调查的初步结果。在10个面积为200-400m2的人工林样方中,共记载了184种非栽培的植物种类,它们分属于70个科139属,其中42％的种类是树木,约占香港树木区系的20％。最常见的植物种类通常具有可以被鸟类传播的小型浆果或核果,它们也是天然次生林中的常见种。这些人工林样方的树木多样性（Shannon指数）在0-2．66之间,随着人工林的年龄增长呈增加的趋势。人工林在加速森林植被的恢复和促进退化地区生物多样性的发展中具有重要的作用,特别是植物种源严重贫乏地区森林植被恢复的重要手段。在营造速生人工林时,适当引入鸟播的野生树种,可加速人工林的自然演替速度和提高人工林的生态效益。     

Leaf-Litter Arthropods in Restored Forests in the Colombian Andes: A Comparison Between Secondary Forest and Tree Plantations

Tree monocultures of native and exotic species are frequently used as tools to catalyze forest recovery throughout the tropics. Although plantations may rapidly develop a canopy cover, they need to be evaluated as habitat for other organisms. We compared samples of leaf‐litter arthropods from two elevations in restored forest in the Colombian Andes. At the upper elevation (2,430 m), we compared native Andean alder (Alnus acuminata) plantation and secondary forest, and at the lower elevation (1,900 m) exotic Chinese ash (Fraxinus chinensis) plantation and secondary forest. Samples were obtained in two periods, March–April and September 1995. Species richness and abundance of arthropods were highest in secondary forest at the lower elevation. There were no differences in richness between both plantations and high‐elevation forest. Arthropod richness and abundance increased in the second sampling period in both secondary forest types and the ash plantation but not in the alder plantation, reflecting population recovery after the dry season. Alder leaf litter apparently buffered seasonal variations in arthropod richness and abundance. Composition of morphospecies was different among forest types. Although arthropod richness was lower in ash plantations compared to secondary forest, plantations still provided habitat for these organisms. On the other hand, the alder plantation was not different from secondary forest at the same elevation. At our site, plantations are embedded in a forested landscape. Whether our results apply to different landscape configurations and at different spatial scales needs to be established. The use of plantations as a restoration tool depends on the objectives of the project and on local conditions of forest cover and soils.     

Scots pine plantations growth adaptation to climate warming in locations at the southernmost distribution limit of the species

Under the current climate change conjuncture, understanding the forest plantations capacity of acclimation to warming and increased drought stress is crucial for forest managers. To get some understanding of their adaptability, plantations of similar provenance but located in climatically contrasting sites can be compared. Here we study the growth dynamics and their relationship with climate and drought in two Scots pine (Pinus sylvestris L.) plantations located in the center (Sierra de Guadarrama, wetter site) and south (Sierra Nevada, drier site) of Spain, the latter situated at the southernmost distribution limit of the species. Our objectives are to quantify the trends in radial growth of these plantations, to quantify the influence of climate on growth, and to project the plantations growth as a function of forecasted climate. Results reveal that the plantations from the drier site show lower, and less responsive to climate, growth and greater resilience than those from the wetter site. Furthermore, if the current climate-growth relationships continue in the future, these plantations would maintain the current limited growth rate during the 21st century. On the contrary, plantations from the wetter site show higher growth rate and more resistance to drought, and they are projected to increase growth under the warmer conditions forecasted for the 21st century. Our study shows that plantations in drier sites may have a great capacity to acclimate to local climate conditions and would not be negatively impacted by the projected climate warming.     

Indigenous woody species diversity in Eucalyptus globulus Labill. ssp. globulus plantations in the Ethiopian highlands

The naturally regenerated native woody species diversity was studied ineucalypt plantations at Menagesha, where there was remnant natural forest, and atChancho, where natural forests were absent. A total of 22 and 20 woody speciesbelonging to 18 and 17 families were found, and of these species, treesaccounted for 68 and 55% at Menagesha and Chancho, respectively. About 83% ofthe woody species found in the adjacent natural forest, including importanttimber species were represented in the eucalypt understory at Menagesha.However, the relative abundance of species in eucalypt plantations and theadjacent natural forest varied considerably. Woody species richness andabundance of sample plots at Menagesha were on average 2.4 times and 5.7times higher, respectively, than the sample plots at Chancho. This resultdemonstrates the crucial role of the remnant small patches of natural forest,as a source of diaspores for the restoration of the woody species diversity indegraded areas of the Ethiopian highlands. There was no significant differencein woody species diversity between the eucalypt stand margin and centre. Theunderstory woody species density in eucalypt plantations was up to 8325stems/ha, indicating that the numerous eucalypt stands have a highpotential for restoring the woody species diversity in the Ethiopian highlands.In order to fully re-establish the diverse and economically valuable naturalforest, complementary measures such as enrichment planting of missing primaryforest species may be required.     

Non-native plantation forests as alternative habitat for native forest beetles in a heavily modified landscape

The once extensive native forests of New Zealand’s central North Island are heavily fragmented, and the scattered remnants are now surrounded by a matrix of exotic pastoral grasslands and Pinus radiata plantation forests. The importance of these exotic habitats for native biodiversity is poorly understood. This study examines the utilisation of exotic plantation forests by native beetles in a heavily modified landscape. The diversity of selected beetle taxa was compared at multiple distances across edge gradients between each of the six possible combinations of adjacent pastoral, plantation, clearfell and native forest land-use types. Estimated species richness (Michaelis–Menten) was greater in production habitats than native forest; however this was largely due to the absence of exotic species in native forest. Beetle relative abundance was highest in clearfell-harvested areas, mainly due to colonisation by open-habitat, disturbance-adapted species. More importantly, though, of all the non-native habitats sampled, beetle species composition in mature P. radiata was most similar to native forest. Understanding the influence of key environmental factors and stand level management is important for enhancing biodiversity values within the landscape. Native habitat proximity was the most significant environmental correlate of beetle community composition, highlighting the importance of retaining native remnants within plantation landscapes. The proportion of exotic beetles was consistently low in mature plantation stands, however it increased in pasture sites at increasing distances from native forest. These results suggest that exotic plantation forests may provide important alternative habitat for native forest beetles in landscapes with a low proportion of native forest cover.