There are three main aspects have to be considered for a plantation design: forest function, forest type, afforestation model

1.4.1 Forest function

For a SC or a specific area of land with certain ecological site conditions Forest Functions are reflecting

• the demands of nature: to keep natural eco-systems alive or to restore “close to nature” eco-systems, as well as
• the land-use expectations/demands of human society on forests/forest types.

Forest Functions are determining the theoretical Target Forest Type/TFT (defined by tree qualities (!) only – not by tree species (!), which finally will define the Forest Types/FT) necessary, in order to influence natural (erosion, flood, climate, etc.) or human (quality of life, recreation, education, etc.) processes according to natural and/or human demands.

Forest functions are therefore guidelines for the design of the Forest Type and so also the basis for the Afforestation Model/AM (see 1.4.3)

Three functions can be classified:

• general – regional/zonal Environmental Forest Services (RES): to expect the forest
  • to become an harmoniously well balanced, most self-regulating “Close to Nature” Eco-system (including flora and fauna), sustainably and stable serving to multiple forest functions, with high vitality and resilience against natural and human impacts,
  • to contribute to the improvement of Environment (climate change, air-pollution, desertification);
• specific – local Environmental Forest Services (LES): to expect the forest
  • to contribute to Soil- & Water Conservation (wind- & water erosion, flood, water supply to local people);
• specific – local Social Forest Services (LSS): to expect the forest
  • to contribute to the visual Landscape Attraction for the city population,
  • to serve as location and subject for Recreation and Health Care,
  • to provide timber and other forest products.

For the XGEP-Project forests primarily have to serve to the regional climate and eco-system function (RES), secondly to the local soil & water conservation function (only on slopes > 15°) and thirdly/secondly (on slopes <15°) to the human interests of visual landscape attraction, recreation and forest products (Table 2).

1.4.2 Target Forest type

Target Forest Types are models theoretically reflecting and describing their function-orientated/aiming qualities concerning

• tree & shrub species composition (bio-diversity)
• structure of the forest stand (horizontal, vertical, according to age)
• species specific qualities of the individual tree/shrub (crown, trunk, root system).

The goal of a theoretical Target Forest Type is to allow target oriented silvicultural decisions and management/activities.

Technology of target forest type design:                          

For the Forest Functions under the XGEP-Project (outlined in 1.4.1) the Target Forest Types are defined as below:

Ecosystem Function: to increase “close to nature” biodiversity (flora & fauna);

• tree & shrub species composition: (nearly) all main species native to Qinghai Province shall be involved;
• structure of the forest stand: a ”close to nature” stand shall horizontally be mixed in patterns/groups (in normal density – without gaps) according to site classes, showing multi-layer vertical structure and shall be uneven-aged;
• tree/shrub qualities:
  • crown: at least ¼ of tree height; healthy (no damage to leaves and branches); vital (high “Leaf-Area-Index/LAI”); showing good growth (annual increment: height),
  • trunk: no physical and/or biological damage,
  • root system: well adapted to the site class; no damage.

Climate & Air Quality Improvement Function: to harmonize climate by increasing humidity and CO2-storage; to increase O2 ad reduce air-pollution;

• tree & shrub species composition: site adapted species with high potential of growth (wood = CO2-sink), with high transpiration and evaporation capacity; mixed conifer & broadleaved;
• structure of the forest stand: full coverage with trees & shrubs (normal density); multi-layer vertical structure; uneven-aged;
• tree/shrub qualities:
  • crown: dense (high LAI; high vitality, good growth, high absorbing filter for air-pollutants = hairy leaves), at least ¼ of tree height; half conifer (function in winter) – half broadleaved (annual deposition of leaves including pollutants on soil surface),
  • trunk: no damage,
  • root system: well adapted to the site class; no damage.

Soil & Water Conservation Function: to fix the soil against water erosion; to infiltrate rain-water into the soil, to clean water, to store and to release it in sustainable dosage;

• tree & shrub species composition: site adapted species mixed (40-50% trees, 50-60% shrubs) with low transpiration activity and evaporation capacity;
• structure of the forest stand: two-layer stand with scattered tree cover (40-50%) shading 50-60% of shrubs, gaps < 3-4m; uneven-aged;
• tree/shrub qualities:
  • crown: big diameter preferable,
  • trunk: no damages,
  • root system: deep, strong & stable tree root systems + intensive network of fine shrub roots (not to crack/break up loess soil – especially along edges of terraces or gullies);

Recreation Function: to attract people by specific qualities of stand, individual trees & shrubs via all senses (watching, listening, smelling, feeling, touching) when walking through the forest; note: for a recreation forest well maintained multiple-use infrastructure will be necessary: in steep slope area (> 15-20°) e.g. pathways, benches, toilets, refreshing zones, waste collection and management, first aid and fire-fighting stations, etc. !

• tree & shrub species composition: multiple species conifer and broadleaved single trees, blocks/groups mixed with individual shrubs & shrub blocks;
• structure of the forest stand: dense shady multi-layer blocks changing to small sunny gaps with shrubs and single trees in not strict and regular but flexible order; offering a huge variety of sensual impressions (noises, smells, feelings; including visual observation of small animals, bees, birds); uneven-aged;
• tree/shrub qualities:
  • crown: multiple shaped (to create imagination); the more unique the more attractive; multi-colourful and good smelling flowers in spring & summer; colourful leafs in autumn;
  • trunk: the more crocket and unique the more attractive; tending may support these shapes;
  • root system: suitable to the site classes.

Timber production Function: to produce high quality timber, meet peoples demand;

• tree & shrub species composition: single species, in monoculture;
• structure of the forest stand: one-layer stand; even-aged;
• tree/shrub qualities:
  • growth: fast growth for general timber species, or slow growth for precious wood species
  • yield: high timber yield;
  • quality: good in timber quality
  • trunk: no damages;
  • root system: suitable to the site classes;

1.4.3 Afforestation Model/AF

Afforestation Models are “best practise” guidelines, which show for each Site Class or Forest Function/Category

• the selected suitable Tree & Shrub Species composition (see 1.3.2) as well as
• the Silvicultural Technologies for detailed activities to be carried out.

Both components of the AF (as above) are serving to reach the goals of Forest Functions on different Site Classes. Afforestation Models are recommending species for planting based on their ecological requirements (Site Classes) for high vitality/good growth as well as high stability and resilience, and so for good survival percentage as well as for Forest Function oriented services the trees have to serve to.

Tree Species Selection is one of the two main components of the Afforestation Model Designs/AFD, which offer different options to reach the goals of the Forest Functions on different Site Classes. The final decision on tree & shrub species has to reflect a joint collaboration process balancing between limitations caused by

• the ecological preconditions of the site (natural Site Classes), and
• options of private and/or public benefit (Forest Functions).

Based on the potential natural vegetation or based on practical experience over previous decades about their good site suitability tree species are selected for the Forest Types according to their experienced qualities (benefits, resistances; see Annex 1). The species have to meet the demands of the local site conditions and have to focus on the forest functions and reflecting the forest target types (Annex 1).

Under the XGEP-Project 15 site suitable main/dominant tree species (>60%) are found to be eligible for afforestation:

• 6 conifers
  • Picea crassifolia
  • Picea wilsonii
  • Pinus tabulaeformis
  • Pinus silvestris mongolica
  • Sabina przewalskii
  • Platycladus orientalis
• 9 broaleaved
  • Populus cathayana
  • Populus simonii
  • Populus simonii fastigiata
  • Populus hopeiensis
  • Populus alba var. pyramidalis
  • Ulmus pumila
  • Ulmus laevis
  • Salix matsudana
  • Salix babylonica

The species composition of the Afforestation Models will be completed by several Economic/Fruit trees (Prunus spp, Malus spp, Armeniaca spp, Elaeagnus spp, a.o.) as well as more than 15 mostly ornamental Shrub species (minor shrub species < 40%).

Table in Annex 1 are referring carefully and detailed on the ecological site demands and the environmental as well as the functional benefits of each species prepared for selection.

Example XGEP-Project: Afforestation Models (see Annex 2)

In the Afforestation Models the species are grouped into two categories, which are reflecting more (main species) or less (minor species) the qualities of the tree species necessary to meet the requirements of the Forest Function. So more than 60% of species with best qualities shall be planted:

• Main / Dominant Species (> 60%; high effect / impact on the forest function)
• Minor / Accompanying Species (< 40%; low-medium effect / impact on the forest function).

See online APFNet Course 6: Forest Resource Management and Protection (http://blogs.ubc.ca/apfnet06/) Module I, Topic 1 Principles of silviculture, 1.1.3 Forest structure.