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.     

Variation in insect damage and growth in Eucalyptus globulus

Abstract

• 1 Objectives of this study were to examine (i) between‐provenance variation in susceptibility to insects in Eucalyptus globulus and (ii) relationships between insect damage and tree growth. We planted seedlings of 18 provenances of E. globulus from south‐east Australia in a field trial and measured tree growth and insect damage.
• 2 Christmas beetles Anoplognathus spp. were the dominant herbivores during this experiment, and 99% of trees were affected by them. Defoliation of individual trees by Anoplognathus spp. ranged from 0% to 85%.
• 3 The main results of this study were that: (i) provenances of E. globulus from Tasmania and the Bass Strait islands, which had previously shown resistance to autumn gum moth Mnesampela privata and leaf blister sawfly Phylacteophaga froggatti tended to be resistant to Anoplognathus spp.; (ii) mean tree volume was reduced by herbivory; and (iii) the volume‐based performance ranking of provenances changed depending on the probability of insect outbreaks.
• 4 Fast‐growing provenances should be planted in optimal growing areas for E. globulus with low probability of insect outbreaks. However, in suboptimal growing areas, planting slightly slower growing but more resistant provenances is likely to result in greater output than planting fast‐growing provenances when the probability of insect outbreaks is high.

     

Silvopastoralism in the Alps: Native plant species selection under different grazing pressure

To evaluate the suitability of wood pastures as a managing tool in subalpine regions it is essential to know more about the influence of grazing on the ground vegetation. This study assessed native plant species selection by cattle at different stocking rates, feeding habits and site preferences of cattle. Based on the results, conclusions concerning the value of silvopastoral systems in the Alps were drawn. A field study on six different wood pasture areas, grazed by cattle at different stocking rates, was accompanied by an experiment on three adjoining areas of 0.51 ha each, stocked with either three, six, or nine heifers. Plant species were recorded in plots of 20 cm × 20 cm before and after grazing, and the intensity of grazing on each species was assessed. At low stocking rates, grasses and tall species were most intensely grazed, while at higher stocking rates the intake of forbs and small species increased. Since no relationship was found between nutritional value and species preference, other factors such as accessibility of a plant seem to be important for the feeding preferences of cattle. The preference for grasses at low and medium stocking rates suggests that an increased growth of forbs might lead to an increase in plant species diversity.     

Soil water depletion by Eucalyptus spp. integrated into dryland agricultural systems

Spatial patterns of soil water depletion by Eucalyptus spp. were surveyed to assess the potential of tree belts and short rotation phase farming with trees for groundwater recharge reduction and salinity control. Soils were sampled to depths of up to 10 m in transects perpendicular to 4- to 7-year-old mallee eucalypt belts (Eucalyptus horistes, E. kochii ssp. plenissima, E. loxophleba ssp. lissophloia, E. polybractea) and in a 4 year-old block of E. astringens. Results indicate that the eucalypt species can exploit soil water to depths of at least 8–10 m within 7 years of planting. The root systems of these eucalypts were able to penetrate clayey subsoils with bulk densities of up to 2.0 g cm⁻³. Leaf area indexes of tree belts were 2–10 times greater than those predicted for natural vegetation, probably as a result of exploiting a greater amount of soil water stored under the agricultural system. The lateral influence of mallee belts, as indicated by soil water contents that were depleted to wilting point, ranged from 15–42 m. The resulting dry soil zone provided an effective barrier to groundwater recharge by incident rainfall thereby lessening the risk of salinisation in the agricultural landscape. The width of this barrier to recharge was predicted to range from 7 m to 54 m based on leaf area.     

Managing genetic variation in tropical trees: linking knowledge with action in agroforestry ecosystems for improved conservation and enhanced livelihoods

Tree species in agroforestry ecosystems contribute to the livelihoods of rural communities and play an important role in the conservation of biodiversity. Unless agroforestry landscapes are productive, however, farmers will not maintain or enhance the range and quality of tree species in them, and both income opportunities and biodiversity will be lost. Productivity depends on both tree species diversity and genetic (intra-specific) variation, but research on the latter has until recently not received the recognition it deserves. Worse, when knowledge on tree genetic variation in agroforestry systems has become available, it has not generally been linked in any systematic way with management, indicating a disjunction between research and field-level practice. In this essay, we attempt to bridge this gap by considering three questions: why is genetic diversity important in tree species? What is our current state of knowledge about intra-specific variation in trees in agroforestry systems? And, finally, what practical interventions are possible to support the conservation of this diversity in agricultural landscapes, while enhancing farmers’ livelihoods? A wide genetic base in agroforestry trees is essential to prevent inbreeding depression and allow adaptation to changing environmental conditions and to altering markets for tree products. Recent evidence shows, however, that many species are subject to poor germplasm collection practice, occur at low densities in farmland, and are found in highly aggregated distributions, all of which observations raise concerns about productivity and sustainability. A range of germplasm-access based interventions is necessary to improve current management, including the enhancement of community seed- and seedling-exchange networks, and the development of locally based tree domestication activities. Equally necessary, but more difficult to address, is the development of markets that support genetic diversity in tropical tree species; we discuss approaches by which this may be undertaken.     

华南丘陵地区农林复合生态系统晚稻田甲烷和氧化亚氮排放

采用静态箱-气相色谱法对晚稻田甲烷(CH4)和氧化亚氮(N2O)排放进行田间原位测定。结果表明,有植株参与的稻田CH4排放通量季节变化与地下5cm温度呈显著正相关关系。稻田CH4和N2O季节平均排放通量在有植株参与时分别为1.16±0.38mgm-2h-1和42.33±20.00μgm-2h-1,而无植株参与的分别为0.15±0.11mgm-2h-1和51.69±15.87μgm-2h-1。水稻种植对CH4的排放影响较大,对N2O的排放影响较小,有植株参与的稻田CH4平均排放量显著高于无植株参与的稻田,N2O的平均排放量无显著差异。     

Determining bioclimatic space of Himalayan alder for agroforestry systems in Nepal

Himalayan alder species are proven to be very useful in traditional as well as contemporary agroforestry practice. These nitrogen-fixing trees are also useful in the land restoration. Therefore, understanding the distribution of Himalayan alder and the potential zone for plantation is meaningful in the agroforestry sector. Suitable climatic zones of Alnus spp. were modelled in MaxEnt software using a subset of least correlated bioclimatic variables for current conditions (1950-2000), topographic variables (DEM derived) and Landuse Landcover (LULC) data. We generated several models and selected the best model against random models using ANOVA and t-test. The environmental variables that best explained the current distribution of the species were identified and used to project into the future. For future projections, ensemble scenarios of climate change projection derived from the results of 19 Earth System Models (ESM) were used. Our model revealed that the most favorable conditions for Alnus nepalensis are in central Nepal in the moist north-west facing slope, whereas for Alnus nitida they are in western Nepal. The major climatic factor that contributes to Alnus species distribution in Nepal appears to be precipitation during the warmest quarter for A. nepalensis and precipitation during the driest quarter for A. nitida. Future projections revealed changes in the probability distribution of these species, as well as where they need conservation and where they can be planted. Also, our model predicts that the distribution of Alnus spp. in hilly regions will remain unchanged, and therefore may represent sites that can be used to revitalize traditional agroforestry systems and extract source material for land restoration.     

紫胶林-农田复合生态系统地表甲虫多样性——以云南绿春为例

为揭示紫胶林-农田复合生态系统地表甲虫多样性, 于2006-2007年在云南省绿春县牛孔乡采用陷阱法调查了天然紫胶林、人工紫胶林和旱地的地表甲虫群落。共采集标本1 678头, 分别隶属于24科120种, 其中步甲科(Carabidae)和金龟科(Scarabaeidae)种类最丰富, 均占全部种类的12.50%。拟步甲科(Tenebrionidae)个体数量最丰富, 占个体总数的64.48%; 金龟科次之, 占个体总数的17.58%。大多数科的物种数和个体数在不同土地利用生境中的分布没有显著差异, 而步甲科、隐翅甲科(Staphylinidae)、叩甲科(Elateridae)、拟步甲科、瓢虫科(Coccinellidae)和小蠧科(Scolytidae)在不同土地利用生境中的分布有显著差异。天然紫胶林地表甲虫个体数量最少, 物种较丰富, 优势度最低, 多样性最高; 人工紫胶林个体数和物种数均丰富, 优势度和多样性居中; 旱地个体数量最多, 物种最贫乏, 优势度最高, 多样性最低。种级水平的聚类分析体现出人工紫胶林与旱地之间在种类组成上距离较近; 而科级水平的聚类反映出人工紫胶林和天然紫胶林更接近。结果提示, 紫胶林-农田复合生态系统具有区域内土地利用方式多样化的特点; 天然紫胶林在维持地表甲虫多样性水平上具有重要作用, 而人工紫胶林虽具有积极作用, 但仍需进一步恢复。     

传统农业生态系统中桤木改良土壤效应研究综述

桤木(Alnus nepalensis)是一种重要的非豆科固氮植物,广泛分布于喜马拉雅山脉东部地区。在东南亚地区的传统农业生态系统中,多用桤木作为休耕树种,或将其与农作物间作。桤木根瘤固氮量随季节和年龄而变化,在桤木-小豆蔻(Elettaria cardamomum)系统中15年达到高峰(155 kg·hm^-2);桤木通过共生固氮对系统产生的氮增加量在纯桤木林中7年达到高峰(117 kg·hm^-2)。桤木与农作物间作可显著提高农作物的产量,桤木-小豆蔻立地上小豆蔻的经济产量是在森林-小豆蔻立地上的2.2倍。桤木休闲地的休闲效果明显好于自然休闲地,其地上部分生物量在休闲6年后是自然休闲地的4倍,N蓄积量是自然休闲地的3倍,P、K蓄积量是自然休闲地的2倍。桤木根系特征似乎最适合混农林系统,其细根生物量(FRB)集中于土壤剖面上层10 cm范围内,在此范围内,FRB在“树+农作物”间作条件下比在“只有树”条件下高5%;在两种立地条件下,60%以上的细根都分布于树干周围0.5 m内,大部分木质根(直径>0.5 mm)都分布于土壤上层0~10 cm处,长度都不超过1 m。桤木可加速系统的养分循环。桤木凋落物降解速率比非固氮植物快,并且与其它植物凋落物混合后的降解速率与自身凋落物降解速率一样快。在传统刀耕火种系统中,用桤木替代自然林休闲在3~6年内即可恢复土壤肥力,改善土壤理化性质,显著缩短休闲周期。该文综述了近30年来桤木在传统农业生态系统中改良土壤效应的研究成果,以提高人们对桤木的生态作用的重视程度,使人们更好地将桤木利用到农业生态系统中,达到发展山区农业和保护生态环境双赢的目的。