Testing the Performance of Fourteen Native Tropical Tree Species in Two Abandoned Pastures of the Lacandon Rainforest Region of Chiapas,Mexico

The rainforest of Mexico has been degraded and severely fragmented, and urgently require restoration. However, the practice of restoration has been limited by the lack of species‐specific data on survival and growth responses to local environmental variation. This study explores the differential performance of 14 wet tropical early‐, mid‐ or late‐successional tree species that were grown in two abandoned pastures with contrasting land‐use histories. After 18 months, seedling survival and growth of at least 7 of the 14 tree species studied were significantly higher in the site with a much longer history of land use (site 2). Saplings of the three early‐successional species showed exceptional growth rates. However, differences in performance were noted in relation to the differential soil properties between the experimental sites. Mid‐successional species generally showed slow growth rates but high seedling survival, whereas late‐successional species exhibited poor seedling survival at both the study sites. Stepwise linear regressions revealed that the species integrated response index combining survivorship and growth measurements, was influenced mostly by differences in soil pH between the two abandoned pastures. Our results suggest that local environmental variation among abandoned pastures of contrasting land‐use histories influences sapling survival and growth. Furthermore, the similarity of responses among species with the same successional status allowed us to make some preliminary site and species‐specific silvicultural recommendations. Future field experiments should extend the number of species and the range of environmental conditions to identify site “generalists” or more narrowly adapted species, that we would call “sensitive.”     

Assembly and annotation of a draft genome sequence for Glycine latifolia,a perennial wild relative of soybean

Glycine latifolia (Benth.) Newell & Hymowitz (2n = 40), one of the 27 wild perennial relatives of soybean, possesses genetic diversity and agronomically favorable traits that are lacking in soybean. Here, we report the 939‐Mb draft genome assembly of G. latifolia (PI 559298) using exclusively linked‐reads sequenced from a single Chromium library. We organized scaffolds into 20 chromosome‐scale pseudomolecules utilizing two genetic maps and the Glycine max (L.) Merr. genome sequence. High copy numbers of putative 91‐bp centromere‐specific tandem repeats were observed in consecutive blocks within predicted pericentromeric regions on several pseudomolecules. No 92‐bp putative centromeric repeats, which are abundant in G. max, were detected in G. latifolia or Glycine tomentella. Annotation of the assembled genome and subsequent filtering yielded a high confidence gene set of 54 475 protein‐coding loci. In comparative analysis with five legume species, genes related to defense responses were significantly overrepresented in Glycine‐specific orthologous gene families. A total of 304 putative nucleotide‐binding site (NBS)‐leucine‐rich‐repeat (LRR) genes were identified in this genome assembly. Different from other legume species, we observed a scarcity of TIR‐NBS‐LRR genes in G. latifolia. The G. latifolia genome was also predicted to contain genes encoding 367 LRR‐receptor‐like kinases, a family of proteins involved in basal defense responses and responses to abiotic stress. The genome sequence and annotation of G. latifolia provides a valuable source of alternative alleles and novel genes to facilitate soybean improvement. This study also highlights the efficacy and cost‐effectiveness of the application of Chromium linked‐reads in diploid plant genome de novo assembly.     

Parallel evolution in radiation ofOhomopterus ground beetles inferred from mitochondrial ND5 gene sequences

Molecular phylogenetic analyses using mitochondrial NADH dehydrogenase subunit 5 (ND5) gene sequences representing all 15 species and the majority of subspecies or races of theOhomopterus ground beetles from all over the Japanese archipelago have uncovered a remarkable evolutionary history. Clustering of the species in the molecular phylogenetic tree is linked to their geographic distribution and does not correlate with morphological characters. Taxonomically the same species or the members belonging to the same species-group fall out in more than two different places on the ND5 tree. Evidence has been presented against a possible participation of ancestral polymorphism and random lineage sorting or of hybrid individuals for the observed distribution of mitochondrial DNA haplotypes. The most plausible explanation of our results is that parallel evolution took place in different lineages. Most notably,O. dehaanii, O. yaconinus, andO. japonicus in a lineage reveal almost identical morphology with those of the same species (or subspecies) but belonging to the phylogenetically remote lineages.The nucleotide sequence data reported in this paper will appear in the DDBJ, EMBL, and GenBank nucleotide sequence databases with accession numbers D50711-DD-50733 and D87131-D87186.     

Mortality rates of desert vegetation during high-intensity drought at Uluru-Kata Tjuta National Park,Central Australia

Precipitation variability and heatwaves are expected to intensify over much of inland Australia under most projected climate change scenarios. This will undoubtedly have impacts on the biota of Australian dryland systems. However, accurate modelling of these impacts is presently impeded by a lack of empirical research on drought/heatwave effects on native arid flora and fauna. During the 2018–2021 Australian drought, many parts of the continent's inland experienced their hottest, driest period on record. Here, we present the results of a field survey in 2021 involving indigenous rangers, scientists and national parks staff who assessed plant dieback during this drought at Ulur u-Kata Tjut a National Park (UKTNP), central Australia. Spatially randomized quadrat sampling of eight common and culturally important plants indicated the following plant death rates across UKTNP (in order of drought susceptibility): desert myrtle (Aluta maisonneuvei subsp. maisonneuvei) (91%), yellow flame grevillea (Grevillea eriostachya) (79%), Maitland's wattle (Acacia maitlandii) (67%), waxy wattle (A. melleodora) (65%), soft spinifex grass (Triodia pungens) (53%), mulga (A. aneura) (42%), desert oak (Allocasuarina decaisneana) (22%) and quandong (Santalum acuminatum) (0%). The sampling also detected that seedling recruitment was absent or minimal for all plants except soft spinifex, while a generalized linear mixed model (GLMM) indicated two-way interactions among species, plant size and stand density as important predictors of drought survival of adult plants. A substantial loss of biodiversity has occurred at UKTNP during the recent drought, with likely drivers of widespread plant mortality being extreme multi-year rainfall deficit (2019 recorded the lowest-ever annual rainfall at UKTNP [27 mm]) and record high summer temperatures (December 2019 recorded the highest-ever temperature [47.1°C]). Our findings indicate that widespread plant death and extensive vegetation restructuring will occur across arid Australia if the severity and frequency of droughts increase under climate change.     

How disturbance,competition, and dispersal interact to prevent tree range boundaries from keeping pace with climate change

Climate change is expected to cause geographic shifts in tree species' ranges, but such shifts may not keep pace with climate changes because seed dispersal distances are often limited and competition‐induced changes in community composition can be relatively slow. Disturbances may speed changes in community composition, but the interactions among climate change, disturbance and competitive interactions to produce range shifts are poorly understood. We used a physiologically based mechanistic landscape model to study these interactions in the northeastern United States. We designed a series of disturbance scenarios to represent varied disturbance regimes in terms of both disturbance extent and intensity. We simulated forest succession by incorporating climate change under a high‐emissions future, disturbances, seed dispersal, and competition using the landscape model parameterized with forest inventory data. Tree species range boundary shifts in the next century were quantified as the change in the location of the 5th (the trailing edge) and 95th (the leading edge) percentiles of the spatial distribution of simulated species. Simulated tree species range boundary shifts in New England over the next century were far below (usually <20 km) that required to track the velocity of temperature change (usually more than 110 km over 100 years) under a high‐emissions scenario. Simulated species` ranges shifted northward at both the leading edge (northern boundary) and trailing edge (southern boundary). Disturbances may expedite species' recruitment into new sites, but they had little effect on the velocity of simulated range boundary shifts. Range shifts at the trailing edge tended to be associated with photosynthetic capacity, competitive ability for light and seed dispersal ability, whereas shifts at the leading edge were associated only with photosynthetic capacity and competition for light. This study underscores the importance of understanding the role of interspecific competition and disturbance when studying tree range shifts.     

Strategies for genetic conservation of trees in the Peruvian Amazon

Forestry practices and high rates of land clearance for agriculture are causing genetic erosion of valuable tree species in the Peruvian Amazon, thereby endangering the economic sustainability of rural communities and limiting Peru's opportunities for the development of new timber and non-timber forest products. The potential utility and limitations of six low-input interventions to help forestall further genetic erosion in the region are discussed, with a focus on local community involvement. Improved agroforestry systems may help reduce deforestation by increasing farm productivity, although methods to increase the currently low adoption rate of these technologies need to be developed. Use of strategic tree domestication techniques can also improve farm productivity and prevent inadvertent genetic drift and inbreeding associated with traditional domestication practices, although to have a major impact, current programs need to be extended across the region. Woodlot forestry could supplant selective extraction of timber and offers an attractive opportunity for poverty alleviation if appropriate credit and land tenure policies can be developed. However, it may also result in increased deforestation if activities on public land cannot be controlled. The implementation of improved seed collection systems and simple seed transfer guidelines would help to reduce the collection of seed of poor quality and low genetic diversity, and avoid maladapted plantings, although such programs are difficult to monitor and seed costs may increase. Strategic identification and design of in situ conservation areas would help to ensure the viability of conserved populations, but requires the forfeiture of significant revenue from timber concessions.     

Resistance to the pink potato aphid, Macrosiphum euphorbiae, in two accessions of Lycopersicon hirsutum f. glabratum

An integrated programme of pheromone-mediated mating disruption using Isomate-C®, post-harvest removal of fruit, and trapping overwintering larvae with cardboard tree bands, was used to control codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), in four commercial organic apple orchards in Cawston, British Columbia during 1989–1992. One application of 1000 dispensers ^{– 1} on May 1 delivered estimated seasonal totals of 16.6, 16.5 and 19.9 g of E,E-8,10-dodecadien-1-ol [=codlemone] ^{– 1}in 1990, 1991 and 1992, respectively, at median rates of 8.4, 8.3, and 13.3 mg · < ha^–1 · ha^–1 during dusk flight periods of first brood and 5.3, 4.7 and 4.6 mg · ^{– 1}· ha^–1 in second brood, respectively. Over this 3-year period damage from codling moth at harvest ranged from 0.08 to 2.4%, and averaged 60.7% in these four organic orchards, while damage in five conventional orchards receiving sprays of azinphosmethyl ranged from 0.02 to 1.85%, and averaged 0.5%. Damage in an experimental orchard that was banded only, ranged from 43.5 to 56.7%, and averaged 48.9%. Between 1990 and 1992 cumulative male catches in Pherocon 1-CP wing traps baited with 10 mg of codlemone declined by 52% and densities of overwintering codling moth larvae declined an average of 49.5% in all organic orchards. Overwintering populations in the banded experimental orchard showed an increase of 57.7% during this study period. We conclude that an integrated programme of pheromone-mediated mating disruption, post-harvest fruit removal and tree banding, controls codling moth effectively enough to make organic apple production viable in British Columbia.     

Relationships between ontogenetic changes in prey selection,head shape,sexual maturity,and colour in an Australasian python (Morelia viridis)

We describe a 15‐year study of the loss of reproductive fitness and population decline in Adenostoma sparsifolium, a rosaceous shrub endemic in the fire‐prone chaparral vegetation of southern California (USA) and adjacent northern Baja California, Mexico. Our studies of background extinction concentrated on small relict populations occurring in the eastern Santa Monica Mountains where reproduction is genetically compromised by uniquely high rates of embryonic/endosperm abortion (97–99%) resulting largely from self‐pollination in highly heterozygous populations. Environmental factors further reduce reproductive fitness. The relatively few viable seeds produced are not well adapted to survive wildfires that are a regular (approximately 21 years) occurrence in chaparral. Seedling recruitment after burning is rare and any established seedlings ultimately die from the annual 4–9‐month summer droughts typical of Mediterranean climates. Adult mortality is manifest from wildfire (approximately 6%) and occasional multiple‐year droughts (approximately 15%). Given the virtual absence of new post‐fire reproduction and a low but persistent rate of adult mortality, slow population demise resulting in background extinction is inevitable. We posit that A. sparsifolium is ecologically ‘out of place’ in the present chaparral environment and appears best adapted to a moister climate with summer rains and few wildfires that prevailed before the increasing aridity and warming from mid‐Holocene to the present. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 269–292.     

Negative plant-soil feedbacks may limit persistence of an invasive tree due to rapid accumulation of soil pathogens

Soil organisms influence plant species coexistence and invasion potential. Plant-soil feedbacks occur when plants change soil community composition such that interactions with that soil community in turn may positively or negatively affect the performance of conspecifics. Theories predict and studies show that invasions may be promoted by stronger negative soil feedbacks for native compared with exotic species. We present a counter-example of a successful invader with strong negative soil feedbacks apparently caused by host-specific, pathogenic soil fungi. Using a feedback experiment in pots, we investigated whether the relative strength of plant-soil feedbacks experienced by a non-native woody invader, Sapium sebiferum, differed from several native tree species by examining their performance in soils collected near conspecifics ('home soils') or heterospecifics ('away soils') in the introduced range. Sapium seedlings, but no native seedlings, had lower survival and biomass in its home soils compared with soils of other species (negative feedback'). To investigate biotic agents potentially responsible for the observed negative feedbacks, we conducted two additional experiments designed to eliminate different soil taxa ('rescue experiments'). We found that soil sterilization (pot experiment ) or soil fungicide applications (pot and field experiments) restored Sapium performance in home soil thereby eliminating the negative feedbacks we observed in the original experiment. Such negative feedbacks apparently mediated by soil fungi could have important effects on persistence of this invader by limiting Sapium seedling success in Sapium dominated forests (home soils) though their weak effects in heterospecific (away) soils suggest a weak role in limiting initial establishment.