Dear Sarvade,

Really nice question you put across the community of forest scientific fora. What you perceived of density of 8 trees is the reality in dry areas, I have surveyed 5 watershed in Karnataka and Andhra Pradesh, no farmers really practicing agroorestry but naturally grown few neem, pongam trees on the bunds but in irrigated belts, in dryland horticulture belts and in high rainfall areas density will change. Reality can be checked using google earth image.

dear sarvade,

i also need such answer....minimum and maximum tree density in any agroforestry system without reducing the agriculture crop production.

Suitable tree crop combination in agroforestry particularly tribal dominated state of jharkhand near ranchi district based on land capability/productivity.

Dear Sarvade,

      It mainly depends upon species and nature of the system as you might be aware of it. General recommendation is to have a 4m spacing between tree component, so that mechanization will be also possible

Sir,

If you talk about traditional agroforestry system of Rajasthan i.e. Khejari, Acacia nilotica is varing from 8-50 tree per ha. Again it depends on climatic, edaphic, irrigation sources, cropping pattern factors. If you want information i can provide you about Rajasthan state,

Dear, Sangram

Thanks for the reply.

But, I have a query. In agriculture practices generally local peoples kept very few number of trees (8trees/ha) on bunds, is it agroforestry system? 

Dear Sarvade,

Really nice question you put across the community of forest scientific fora. What you perceived of density of 8 trees is the reality in dry areas, I have surveyed 5 watershed in Karnataka and Andhra Pradesh, no farmers really practicing agroorestry but naturally grown few neem, pongam trees on the bunds but in irrigated belts, in dryland horticulture belts and in high rainfall areas density will change. Reality can be checked using google earth image.

Dear Sarvade,

In the area when I am working on (semiarid forests of central Argentina) it is also common that farmers left 8 to 10 trees/ha for agricultural practices, but this density of trees could not be considered as an agroforestry system. In Argentina, forests are defined as system with, at least 20% of tree crown cover, you will never get it with 8-10 trees. It is my opinion according to my experience in my country maybe it can be useful for you.

Best wishes,

Stella.

Dear Stella

Really good answer, but can it applicable for agroforestry. You told about forest.

I think, according to dear Ramesha's reply, we can go for remote sensing applications to decide tree density in traditional agroforestry.   

I think the tree density should vary following the basal area; in Cameroon, the spacing between two individuals of cashew is often 5 m. This spacing is 2.5 m between individuals of neem. But I think, the density of trees could have an influence on the yield.

 thanks dear for your information

Sir,

If you have single tree on your farm you can say that the influence area by particular tree is agroforestry. In traditional agrofrestry systems, homegarderns consist of more than 500 trees per ha. In my perspective, the influential zone of trees on crop is agroofrestry area. Its up to our consideration.

Dear Servade,

Have you considered forest cover instead of the number of trees as best suited to characterize agroforestry? Because the same number of trees can provide different coverage. Depends on tree species. In Spain we consider that a coverage below 50% may be a "dehesa" (the way we call open forest or agroforestry). But our dehesas usually have much lower canopy cover. But there is no single answer to which coverage is best. It depends on what is expected of the trees and what of the agricultural and pasture usesl. Both from the economic and environmental point of view.

Best wishes

Inés

Sorry, I forgot it. The minimun tree cover coul be 5%. The white book of the Spanish "dehesa" (unpublished, pg 28) indicates coverage values between 5 and 60% (usually 20-40%) And densities of 5 to 80 feet per hectare (usually 15-45).

I hit the link, but it's in spanish

http://www.eweb.unex.es/eweb/accionporladehesa/documentos/libro_verde_dehesa.PDF

My best wishes again

Inés

Thanks dear Dongle, Stella, Sangram and Ramesha for valuable solutions. 

Dear Sarvade, A very interesting and relevant question. A direct answer may not be possible. The minimum number of trees will depend on a number of factors including the goal of the farming household, type of tree (fruit tree or other multi purpose tree species), tree structure, the canopy architecture, the type of understory crop, the geographical location (dry or semi-arid), type of envisaged tree management practice, etc, etc.  Trees with large crowns cast a lot of shade while those with narrow crowns do not cast too much shade. If the crops are shade tolerant then more trees would not hurt. The number of tree per hectare would be a balance between the the expected economic, environmental/ecological and socio-economic benefit the farming household expects from the practice.

Thanks Doncel and Dawoe for valuable comments

As the definition of agroforestry is inherently flexible I would suggest there is no minimum number of trees (>1), rather, that the number of individuals should be matched with the production goals desired by the land manager. Here the manager must establish what he or she requires from the tree component (timber/NWFP etc.) and what he/she requires from the intercrop. In turn the requirements of the annual/perennial intercrop must be reflected in silvicultural planning decisions such as light/water/nutrient availability. Therefore, a high resource demanding intercrop will command fewer trees.

Likewise, the one must also consider the management of the intercrop - trees may become obstacles in the field. the manager must effectively plan the spatial layout of the field to suit. this many result in having fewer trees.

Regarding the maximum number of trees: see below for an example from a temperate agroforestry system, here the land manager plants sufficient trees to fulfill the foreseen production goal of high value timber, spacing is based on crown diameter at the time of stem target diameter. the same approach could be applied to assess the effect of any number of trees on the intercrop, especially when minimal numbers of individuals are desired: (Alley coppice—a new system with ancient roots. Available from: https://www.researchgate.net/publication/262807713_Alley_coppice-a_new_system_with_ancient_roots [accessed Dec 6, 2016].

..... "Hein and Spiecker (2009) suggest a simple species-based thinning rule utilising a constant value based on the arithmetic mean of trees with a diameter at breast height of 30 and 60 cm, assuming crown cover of 70 % for ash and sycamore, and 50 % for wild cherry. The mean distance between crop trees or standards is dependent on the mean radial increment. It should be set at between 20 and 28 times the target diameter at breast height (ash, sycamore and wild cherry). For example, for a target diameter of 50 cm at breast height for wild cherry, this rule dictates a final distance of 12.5 m between trees. Dupraz and Liagre (2008) agree that trees should not be planted too closely on the tree line and recommend distances between 4 and 10 m depending on the expected tree canopy size of mature trees. Using an optimal spacing as described above, high annual diameter increments of 1 cm per year can be achieved (Spiecker 2006). Adequate spacing of trees ensures that tree canopies do not close or shade each other out until the point of harvest; this minimises dead branches and the potential for fungal infection (Oosterbaan et al.2009). To ensure a high success rate of the timber trees, we advocate the planting of trees in groups of two or three at a 2-m spacing within the rows so that poor trees can be removed and only the best trees can be chosen as future crop trees. Nevertheless, the initial tree density is comparable with other agroforestry systems and should be as low as possible consistent with a final harvest of 50 to 80 mature trees per hectare (Balandier and Dupraz 1998)"......

Article Alley coppice—a new system with ancient roots

I think JP Sheppard's contribution is spot on. SS all the best

I like to elaborate on the contributions from Evans and Jonathan. In fact, the question of Dr. Sarvade cannot be answered without formulation of the agroforestry goal. Supposing that the goal concerns in the first place an increasing crop production, I am convinced that tree numbers do not matter. As explained in “Woody plants in agro-ecosystems of semi-arid regions (with an emphasis on the Sahelian countries)” (Breman, H. & J.J. Kessler, 1996. Advanced Series in Agricultural Sciences 23. Springer-Verlag, Berlin. 340 p.), what counts is the total cover of the tree crowns and the annual biomass that is produced for soil improvement. The optimum found is a cover of 20 – 25%, ensuring that the trees are homogeneously distributed and that the crowns are high in the sky, ensuring a thin and homogeneous shadow. Beside, superficial roots have to be cut annually, about 2 m from the stem. The key factor through which the tree improves crop production appears to be indirect, by improving the fields’ soil organic matter status. This leads to a significant improvement of the water and nutrient capacity of the soil; the crop benefits also.

In theory and in practice, I showed that using trees in this way for increasing the efficiency of fertilizer while decreasing possible risks, is much more interesting for farmers than using trees to avoid fertilizer use (as much as possible). The choice of tree species is very different in these two cases.

What crop: coffee, cocoa, etc.?

Answering Julio Lopez Payes: My analyses concern mainly cereals until know.

Dear Julio I am asking about any kind of woody and perennial plants in agroforestry 

Farmers' priorities determine tree density in agroforestry:

While these trees provide a number of essential products (e.g., fuelwood, timber and stakes) in agroforestry systems, it is clear that without proper pruning and high extra N inputs from leaf litter, a yield reduction can always be expected due to shade. The farmers’ priorities will ultimately determine

the balance of crop and tree products on farm. Below is one of my papers where I explain this:

Ndoli, A., Baudron, F., Schut, A. G., Mukuralinda, A., & Giller, K. E. (2017). Disentangling the positive and negative effects of trees on maize performance in smallholdings of Northern Rwanda. Field Crops Research, 213, 1-11.

The number will not be very important. In case your trees have to promote crop growth, it's the density that counts; shade will influence negatively the positive effect of trees. Well chosen tree species and specially managed trees should not reach a cover more than 25 percent of the field.

Thanks Dr. Breman for your valuable remark

I agree with H. Breman that a minimum 20-25% coverage by tree species can be called agroforestry. It is not practical to have 8-10 trees per ha to be called agroforestry. further in traditional agroforestry which practices largely in hills or semi arid zones has that 40-50 trees per hectare density which comes 20- 25% coverage. This density will not harm the crop production and so used in traditional agroforestry.

Thanks Dr. Manmohan J.R. Dobriyal sir

Sorry Mr Dobriyal, where you speak about a minimum of 20-25 percent, I spoke about a maximum. But I presented first the goal of the agroforestry system for which I mentioned the density: trees serve the increase of crop production. It is far from easy. Even with a coverage (well) below 20 percent, trees can easily cause lower crop yields. In such cases, the tree products value should (over) compensate the lower crop yield loss.

Breman, I agree with you. Here is an extract from my PhD thesis entitled "Farming with Trees: A Balancing Act in the Shade":

Rao et al. (1997) argue that in spite of substantial crop yield decreases under scattered trees, the overall effect of the trees on crop yields could still be small, since only a small proportion of the area is subjected to tree-crop interactions. For instance, in Ethiopia farmers usually grow

between 1 to 20 trees of a selected species per hectare and minimize the impact on the companion crops by occasional lopping and pollarding the trees (Poschen 1986; Iiyama et al. 2017). In such a system of 20 scattered trees ha-1 with each tree reducing the crop yield by 50% over a 100 m2 area, the crop yields in the field would be only 10% lower than it had been without the trees. We should also realize that on-farm trees have a value for farmers that compensates for the reduction in crop yields.

Thesis Farming with trees: a balancing act in the shade

Thanks Ndoli Alain for sharing your views

Thanks Dr Ndoli. I have already a hard copy of your thesis.

@ H. Breman yes it maximum 20-25% coverage for agroforestry which after that may reduce crop yield. I told with respect to minimum number of trees be present in agri field as 2- 4 trees on filed will make it agroforestry as there is no significant interaction of tree crop.

It depends on the cultural practices of the farmers

It will depend on the landholding of the farmer. For 1 acre, it should be 20-30 trees.

Is there any published record for 20-30 trees/acre? @Raza H Rizvi